Stalling issues - Code 31 (Camshaft Position Sensor)

[MuRCieLaGo]

1991 ZR-1

Hello guys,

I will explain my problem on this thread now.

I just bought the car yesterday and I drove the 800 kms back home.

Intermittent Service Engine Soon light.

When I come to stops or red lights, engine has a hard time going at idle.

50% of time: engine dies. I can start it back (I need to crank a bit longer but it starts).
Other 50% of time: idle goes to 500 rpm, go back a bit higher than 1,000 rpm, bounces for some seconds and then sets to normal idle (800?).

When it is cold, I don't have the problem at all (tested only this morning, can't tell if it is always like that).

Plus, I don't know if it has something to do with that problem, but when I go at WOT at around 75 mph (6th speed), the engine has a hard time going higher in RPM. WOT at 3,000 RPM at pretty much any speed is hard (it bucks, feels like misfires). WOT at 4,000 RPM and higher is nice and smooth.

Seller said:
-Plugs have been changed last year.
-Injectors have been changed last year.

No receipts at all. I know he's a honest guy though, no question there.

Anybody can help me? These LT5s are intimidating, I've a lot of stuff to learn there.

Thanks!

[secondchance]

1991 ZR-1

Hello guys,

I will explain my problem on this thread now.

I just bought the car yesterday and I drove the 800 kms back home.

Intermittent Service Engine Soon light.

When I come to stops or red lights, engine has a hard time going at idle.

50% of time: engine dies. I can start it back (I need to crank a bit longer but it starts).
Other 50% of time: idle goes to 500 rpm, go back a bit higher than 1,000 rpm, bounces for some seconds and then sets to normal idle (800?).

When it is cold, I don't have the problem at all (tested only this morning, can't tell if it is always like that).

Plus, I don't know if it has something to do with that problem, but when I go at WOT at around 75 mph (6th speed), the engine has a hard time going higher in RPM. WOT at 3,000 RPM at pretty much any speed is hard (it bucks, feels like misfires). WOT at 4,000 RPM and higher is nice and smooth.

Seller said:
-Plugs have been changed last year.
-Injectors have been changed last year.

No receipts at all. I know he's a honest guy though, no question there.

Anybody can help me? These LT5s are intimidating, I've a lot of stuff to learn there.

Thanks!

Post title says "code 31". Is this the code you are seeing with scanner or using pin grounding method? Faulty or disconnected cam position sensor will exhibit symptoms you are describing.
First check the cam position sensor connector - from cam position sensor on driver side head (on the side) wrapped in 1/4" black flex conduit to a weatherpak plug above the brake booster. If connected, you may need a new sensor.

[MuRCieLaGo]

The code has been scanned with an unknown GM scanner (seems to be worth a lot of money). It showed no signal coming from the cam sensor. Cam sensor has an easy access and is connected. I'm pretty sure there's a way to measure the resistance of it to determine if it is bad or not?

If that's the problem, I'll be glad to pay $200+ for the sensor!

[We Gone]

Time to make your first tool buy and a must for any ZR-1 owner.. A FSM...

I would follow the code, check the plugs maybe ohm the wires. If all is good new Sensor.

[MuRCieLaGo]

I'll test everything related to fire tomorrow. I hope coil packs have an easy access, I don't feel comfortable to pull the plenum yet.

Thank you I appreciate your help!

[secondchance]

I'll test everything related to fire tomorrow. I hope coil packs have an easy access, I don't feel comfortable to pull the plenum yet.

Thank you I appreciate your help!

If scanner is throwing code 31, even though connected, I'm pretty sure it's cam sensor failure.
Unfortunately, coil packs are under the plenum. Pulling the plenum, once you do it a couple of times, is no big deal. Especially with coolant passage plugged I can get in and out in less than an hour. It's a ZR-1 ownership initiation.

[Z51JEFF]

CHECK ENGINE LIGHT, bucking and the present throuble code 31 is what my 91 did when the cam sensor died.

[Paul Workman]

Jerry's Gaskets (http://www.jerrysgaskets.com/electrical-sensors-modules-ecm/?sort=featured&page=2) has cam position sensors for $150. You'll want to get acquainted with Jerry - seems like most of us do, sooner or later - for all things LT5-related. (Click on the link and it should take you right to the page w/ the sensor on it!)

I agree w/ Secondchance: Pulling the plenum is "a right of passage" for a ZR-1 owner. All the crap you see on the outside of other motors is hidden under the plenum on the LT5. And*, after installing plugs in the INJECTOR HOUSING coolant ports leading to the throttlebody, and having a long nose "T" star tool or a 4" (~10 cm) Snap-On star extension and a drill makes pulling the plenum off about a 5-10 minute job - about like pulling a carb. (Oh...and get a set (or two) of the plenum gaskets from Jerry too, while your at it!):)

There's nothing scary about the LT5. It is different and requires certain techniques and sealants, etc; different; not intimidating, and actually FUN to work with, if having the right tools and the FSM!

Welcome to the club! You've come to the right site for "all things ZR-1!

Paul

[Dynomite]

after installing plugs in the INJECTOR HOUSING coolant ports leading to the throttlebody, and having a long nose "T" star tool or a 4" (~10 cm) Snap-On star extension and a drill makes pulling the plenum off about a 5-10 minute job - about like pulling a carb. (Oh...and get a set (or two) of the plenum gaskets from Jerry too, while your at it!):)

Paul

Concur with Paul :cheers:

Removing Plenum (including the 10 minute Plenum Removal) (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-4.html#post1581663365)

Injector Housing TB Coolant Blocking (http://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-10.html#post1588695506)

Jerrys Plenum Gasket (http://www.jerrysgaskets.com/gasket-set-intake-plenum-1-32-90-95-11d2/)

I don't feel comfortable to pull the plenum yet.


Just Do It :p
Get the right tools handy and we will be here as you go.....just post up any questions as someone will answer within a few minutes usually.
If a Torx bolt does not want to move....take it easy and post up as you do not want to strip the heads of any Torx. Same goes with metric bolt. Usually not an issue however except on Injector Housing Coolant Manifold Bolts if you decide to Block TB Coolant.

And.......when you get Plenum Off....there are some simple things to do list including Valley Drain Cleaning, Starter Solenoid Reconditioning, Tightening Crank Case Cover Bolts, Checking Vacuum System for Leaks...........all of which only take a few minutes each.

You can even take a Pressure Washer to the Valley after the coils and starter have been removed.

[MuRCieLaGo]

If scanner is throwing code 31, even though connected, I'm pretty sure it's cam sensor failure.
Unfortunately, coil packs are under the plenum. Pulling the plenum, once you do it a couple of times, is no big deal. Especially with coolant passage plugged I can get in and out in less than an hour. It's a ZR-1 ownership initiation.

CHECK ENGINE LIGHT, bucking and the present throuble code 31 is what my 91 did when the cam sensor died.

I removed the cam sensor and went to test it in a well-known electrical shop where I live. Cam sensor works fine.


Jerry's Gaskets (http://www.jerrysgaskets.com/electrical-sensors-modules-ecm/?sort=featured&page=2) has cam position sensors for $150. You'll want to get acquainted with Jerry - seems like most of us do, sooner or later - for all things LT5-related. (Click on the link and it should take you right to the page w/ the sensor on it!)

I agree w/ Secondchance: Pulling the plenum is "a right of passage" for a ZR-1 owner. All the crap you see on the outside of other motors is hidden under the plenum on the LT5. And*, after installing plugs in the INJECTOR HOUSING coolant ports leading to the throttlebody, and having a long nose "T" star tool or a 4" (~10 cm) Snap-On star extension and a drill makes pulling the plenum off about a 5-10 minute job - about like pulling a carb. (Oh...and get a set (or two) of the plenum gaskets from Jerry too, while your at it!):)

There's nothing scary about the LT5. It is different and requires certain techniques and sealants, etc; different; not intimidating, and actually FUN to work with, if having the right tools and the FSM!

Welcome to the club! You've come to the right site for "all things ZR-1!

Paul

Alright, I'll remove the plenum then. I thought it was a harder job. Unfortunately I don't have the FSM. Is there a digital copy of a 1991 somewhere? Thanks for the welcome words, I really appreciate this forum.


Concur with Paul :cheers:

Removing Plenum (including the 10 minute Plenum Removal) (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-4.html#post1581663365)

Injector Housing TB Coolant Blocking (http://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-10.html#post1588695506)

Jerrys Plenum Gasket (http://www.jerrysgaskets.com/gasket-set-intake-plenum-1-32-90-95-11d2/)



Just Do It :p
Get the right tools handy and we will be here as you go.....just post up any questions as someone will answer within a few minutes usually.
If a Torx bolt does not want to move....take it easy and post up as you do not want to strip the heads of any Torx. Same goes with metric bolt. Usually not an issue however except on Injector Housing Coolant Manifold Bolts if you decide to Block TB Coolant.

And.......when you get Plenum Off....there are some simple things to do list including Valley Drain Cleaning, Starter Solenoid Reconditioning, Tightening Crank Case Cover Bolts, Checking Vacuum System for Leaks...........all of which only take a few minutes each.

You can even take a Pressure Washer to the Valley after the coils and starter have been removed.


I'll remove the plenum this afternoon. However, I need to search for how to test the injectors (that's the next thing I need to test I guess). Haven't found some good, easy explanations yet.

Thanks Dynomite for the complete answer!

[MuRCieLaGo]

Oh and quick updates...

-SES light doesn't come on if I put my key on for 5 seconds before starting the engine.

-Runs perfect when cold.

-WOT at Full Power is perfect at all time (I don't think the LT5 is supposed to be faster).

[-=Jeff=-]

Did you check to see if the SES bulb is there and not removed?

if you have no active SES light, when are you seeing the stalling?

[MuRCieLaGo]

Hi Jeff,

The SES lights up sometimes, the bulb is there and works fine. I think it lights up easier if I start the engine without leaving the key on for a few seconds. On or off, it has no effect on my stalling issue.

[-=Jeff=-]

How did you check codes? simple way is a paper clip across ALDL A&B turn the key to on.. SES will flash each code 3 times.. Code 12 is normal.

There is another way to get it on the LCD display and it will show current and history codes.

Okay Stalling

When does it stall? slowing down? cruising along? A/C On or off?

I have an intermittent stall and i know it is IAC based and I need to adjust the Minimum Air to get it to run a bit better, I will do that this winter.. right now that is my main gripe, every once in a while the car just stalls

[MuRCieLaGo]

Codes have been checked with "the big expensive scanner", when I was there with the seller.

Should I retrieve the codes again?

A/C is always off. It stalls at the red lights. It has a hard time finding its idle but when it finds it, it is OK.

Seller told me IAC has been cleaned not long ago. To me it sounded like it needs an adjustement, but everybody agree I should look into the injectors, even if they have been changed in the last year (not even 1,000 miles).

[MuRCieLaGo]

Since yesterday, here is what I've been told to test. I'm trying to pinpoint what I should look into first. I don't like to look at that list.

-Cam sensor - Tested, working fine
-Injectors
-Spark plugs
-Spark plugs wires
-Coil packs
-Fuel pumps
-IAC
-VSS
-Map sensor
-PCV valve
-TPS
-ECM
-Fuel pressure regulator

These guys on this thread have the same problem I got, and it seems they never managed to fix it...

http://www.corvetteforum.com/forums/c4-zr-1-discussion/1519486-problem-with-occasional-stalling.html

[We Gone]

All the items you listed are fairly easy to check.

I would start with IAC check and reset, TPS easy check with a meter, Map, fuel pressure issues easy just need a FP gauge.

Most if not all this stuff can be found in Dynomite's sticky

This may be a bit out there but what chip is in the car?

http://www.zr1specialist.com/HAT%20Web/products/LT5%20Performance%20Engine%20Calibrations.htm

Also slow down and get the FSM.

[MuRCieLaGo]

All the items you listed are fairly easy to check.

I would start with IAC check and reset, TPS easy check with a meter, Map, fuel pressure issues easy just need a FP gauge.

Most if not all this stuff can be found in Dynomite's sticky

This may be a bit out there but what chip is in the car?

http://www.zr1specialist.com/HAT%20Web/products/LT5%20Performance%20Engine%20Calibrations.htm

Also slow down and get the FSM.

I'm sorry if I feel a bit lost, I've pretty much only worked on rotary engines in the past.

There's no chip in the car, but that will probably be the first mod (after I fix ALL the problems, of course).

Do you think this manual is OK? Not sure if it has info on ZR-1s.

http://www.ebay.ca/itm/311455908176?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I'm actually searching hard on how to test the IAC. One thing at a time.

Thanks We_Gone for your help here and via PM!

[-=Jeff=-]

Yes that Manual is correct and what I use

[MuRCieLaGo]

Yes that Manual is correct and what I use

Thanks! Will buy it then.

Do you think Dynomite's ALDL Code reader is a must to read codes quickly? It seems to be pretty awesome.

[We Gone]

That FSM should have what you need, Their is one more supplement for the LT5

Here are the book #s

ST-364-91 Service Manual covers L98 & LT5.
ST-364-91 EDM Electrical Diag, supplement.
ST-364-91SB Service updates.
ST364-1990/93-LT5-Supp.

When you get them read-read-read

I brought up the chip as GM had a few revisions to address idle issues they should be in the link on Mark's site

http://www.zr1specialist.com/HAT%20Web/presentations/Calibrations.pdf

Thanks! Will buy it then.

Do you think Dynomite's ALDL Code reader is a must to read codes quickly? It seems to be pretty awesome.

A very good tool to have, makes reading codes so much better than the paper clip!!!

[MuRCieLaGo]

All the 4 books are about to be bought now. Will probably be on their way home tomorrow.

Dynomite's Code reader will also be bought if he is OK to ship in Canada.

I hope it will help me in the future.

I know you must think I'm in a rush. Reality is: I won't be able to drive the car in less than two weeks because of winter time. I don't want to have the car sit in the garage for the next two weeks... I can easily fix it as a winter project (but I got all my time now to fix it, I work on a ship and I'm off at the moment).

Do you think the chip *could* fix my problem?

[MuRCieLaGo]

And I hope the manual will help me diagnosing the IAC because I can't find anything on that subject on the forum...

[We Gone]

Do you think the chip *could* fix my problem?

No, When I first got my 91 back in 02 it had an outdated chip I changed it than later went to one of Mark's tunes, also one of the first things I did when I got my 93, So just worth checking.

I'm not in any way suggesting your rushing, Just know when I get frustrated I stop and reread about what I'm checking many times just to be sure I don't miss something.

[secondchance]

Murcielago,

I suggest one quick check. Check the MAP sensor to back of the plenum hose. If it has blown off or if you see a soft rubber hose replace it with proper MAP sensor hose - hard plastic with rubber fittings at the end only. Regular vacuum hose will soften with time and collapse under high vacuum preventing the MAP sensor from getting accurate info. It's an easy check with a flashlight.

Also check the code using paper clip method to be sure.

[MuRCieLaGo]

No, When I first got my 91 back in 02 it had an outdated chip I changed it than later went to one of Mark's tunes, also one of the first things I did when I got my 93, So just worth checking.

I'm not in any way suggesting your rushing, Just know when I get frustrated I stop and reread about what I'm checking many times just to be sure I don't miss something.

Speaking about chips, I just found that sticker on the ECM.

https://scontent-yyz1-1.xx.fbcdn.net/hphotos-xfp1/t31.0-8/905920_10156453356760221_8125023942611907464_o.jpg

P/S 30353. 12/22/2014 is pretty recent... I'm not yet frustrated, I just read a lot at the moment.

Murcielago,

I suggest one quick check. Check the MAP sensor to back of the plenum hose. If it has blown off or if you see a soft rubber hose replace it with proper MAP sensor hose - hard plastic with rubber fittings at the end only. Regular vacuum hose will soften with time and collapse under high vacuum preventing the MAP sensor from getting accurate info. It's an easy check with a flashlight.

Also check the code using paper clip method to be sure.

Alright secondchance I'll look at that as soon as possible, should be easy. I like easy checks. Thanks!

[MuRCieLaGo]

I also noticed an oil leak there. What is that hose?

http://i841.photobucket.com/albums/zz332/TiGarsRotatif/20151027_152019.jpg

[Dynomite]

I'll remove the plenum this afternoon. However, I need to search for how to test the injectors (that's the next thing I need to test I guess). Haven't found some good, easy explanations yet.

Thanks Dynomite for the complete answer!

INJECTORS
Changing Fuel Injectors TIPS (http://www.zr1.net/forum/showthread.php?t=18722")
Bad injector/burnt valves TIPS (http://www.zr1.net/forum/showthread.php?p=93385")
Secondary Injector Drivers TIPS (http://www.zr1.net/forum/showthread.php?p=120759)
Checking Injector Resistance with Plenum in Place TIPS (http://www.zr1specialist.com/HAT%20Web/articles/Measuring%20Fuel%20Injector%20Resistance%20with%20 the%20Plenum%20in%20Place.pdf")
RC Injectors (http://forums.corvetteforum.com/c4-zr-1-discussion/3104808-daily-driver.html#post1581589253)
Fuel injector testing electrical (http://www.zr1.net/forum/showthread.php?p=17299")
Fuel injector testing pressurized (http://www.zr1.net/forum/showthread.php?p=83991")
Bad injectors (http://www.zr1.net/forum/showthread.php?p=102500")

[MuRCieLaGo]

INJECTORS
Changing Fuel Injectors TIPS (http://www.zr1.net/forum/showthread.php?t=18722")
Bad injector/burnt valves TIPS (http://www.zr1.net/forum/showthread.php?p=93385")
Secondary Injector Drivers TIPS (http://www.zr1.net/forum/showthread.php?p=120759)
Checking Injector Resistance with Plenum in Place TIPS (http://www.zr1specialist.com/HAT%20Web/articles/Measuring%20Fuel%20Injector%20Resistance%20with%20 the%20Plenum%20in%20Place.pdf")
RC Injectors (http://forums.corvetteforum.com/c4-zr-1-discussion/3104808-daily-driver.html#post1581589253)
Fuel injector testing electrical (http://www.zr1.net/forum/showthread.php?p=17299")
Fuel injector testing pressurized (http://www.zr1.net/forum/showthread.php?p=83991")
Bad injectors (http://www.zr1.net/forum/showthread.php?p=102500")

Yes thanks, your sticky threads are a bible!

Just need to understand the diagram now.

http://i158.photobucket.com/albums/t120/sdba11/CheckingZR1FuelInjectorResistances.gif

FSM is on its way.

[MuRCieLaGo]

Update:

Just started the car cooled down now. It's cold here (38F) heater was off. As soon as I pushed the arrow to increase heating (from 73 to 74), the car died. Started back, went up to 2,000 RPM and died again. Pushed the OFF button and no dying issue. Now I really don't know what it means.

[MuRCieLaGo]

OFF button doesn't fix the problem, but AUTO makes it worst.

Personal guess: could it be the battery?

[MuRCieLaGo]

Car also pulls definitely stronger when heater is at OFF position.

[MuRCieLaGo]

And another update: as soon as the RESERVE light came on, car ran like COMPLETE ****, scary. SES light came on more and more when the tank was becoming more and more empty.

Put 4 gallons of gas: no more SES and engine doesn't run like **** anymore.

Oh my god...

[MuRCieLaGo]

Fully tested the battery now.

Battery is fine.

[RICHARD TILL]

I had the very same symptoms and was getting a code 31 with the paper clip. Went thru the diagnosis with the service manual. Still could`nt locate the problem. Got a used sensor from a member who bought a new one and didn`t need it. Problem solved.

[Paul Workman]

And another update: as soon as the RESERVE light came on, car ran like COMPLETE ****, scary. SES light came on more and more when the tank was becoming more and more empty.

Put 4 gallons of gas: no more SES and engine doesn't run like **** anymore.

Oh my god...

Not sure... Not sure if you're saying it might have been a low fuel issue all along??

Just a bit-o-info for ya:


The fuel pumps are liquid cooled, and if allowed to 'suck air' it tends to shorten their life...significantly.

It doesn't cost any more to take fuel from a full tank than it does from a near empty tank, and that way too the pumps remain submerged (and cool).

AND with cold weather nearly upon us, there's less condensation (i.e., water) to mix with the fuel - and react with the alcohol (in particular).


Sounds like the previous owner left several 'gremlins' for the next guy to 'discover'. When I got my 90 it had several; mostly under the plenum. But, once cleared of all the neglected maintenance items, she's been 'running wicked' ever since!:dancing

[rkreigh]

alot of time the car sits and the fuel pumps become an issue check the fuel rail pressure tape the gauge on the hood so you can see if the FP holds as you go WOT

FSM is a must have. and scanners are nice too to monitor the fuel trims so you can see what's going on. I have EASE but it's overkill and there are much cheaper solutions.

with a bit of persistence the problem will be revealed!

the botherhood of the beast is a tight knit group and we will help you!

if anyone needs the early FSM, I have a spare set, $75 + $15 shipping and they will be at your door! just PM me.

[MuRCieLaGo]

I had the very same symptoms and was getting a code 31 with the paper clip. Went thru the diagnosis with the service manual. Still could`nt locate the problem. Got a used sensor from a member who bought a new one and didn`t need it. Problem solved.

Local electric shop tested the sensor (and I was there), and it worked perfectly.

-Connected the sensor to a 7 volts battery
-Looked at the voltage through multimeter. Showed 0 when the magnet was near metal and 7 when it was in the air.
-Initial scan showed no signal coming from the cam sensor, which makes no sense now.

Will consider a used one if I find one though and I won't put that possibility in garbage now. Thanks Richard!


Not sure... Not sure if you're saying it might have been a low fuel issue all along??

Just a bit-o-info for ya:


The fuel pumps are liquid cooled, and if allowed to 'suck air' it tends to shorten their life...significantly.

It doesn't cost any more to take fuel from a full tank than it does from a near empty tank, and that way too the pumps remain submerged (and cool).

AND with cold weather nearly upon us, there's less condensation (i.e., water) to mix with the fuel - and react with the alcohol (in particular).


Sounds like the previous owner left several 'gremlins' for the next guy to 'discover'. When I got my 90 it had several; mostly under the plenum. But, once cleared of all the neglected maintenance items, she's been 'running wicked' ever since!:dancing

Ok I'll try to keep a full tank in the future, but at the moment I think it can be useful to locate my problem? (as it is worst when half of fuel is remaining in the tank)

No it is no a low fuel issue all along, I'm having the problem with a full tank of fuel. But like I said, it seems to be worst when the fuel is getting lower and lower.

Maybe I should have told you before that last winter, the car was left outside and it snowed on it. Water came in the fuel tank via the fuel cap and the fuel tank froze.


alot of time the car sits and the fuel pumps become an issue check the fuel rail pressure tape the gauge on the hood so you can see if the FP holds as you go WOT

FSM is a must have. and scanners are nice too to monitor the fuel trims so you can see what's going on. I have EASE but it's overkill and there are much cheaper solutions.

with a bit of persistence the problem will be revealed!

the botherhood of the beast is a tight knit group and we will help you!

if anyone needs the early FSM, I have a spare set, $75 + $15 shipping and they will be at your door! just PM me.

Would have been a deal with me rkreigh, too bad I paid yesterday an eBay member and it's on its way now. And I simply ordered Dynomite's codes reader.

I don't really know where to tape a fuel pressure gauge, but that's the next thing I'd like to do: check fuel pumps pressure. Especially because I've red that there's only one pump where the car is cold (everything runs perfectly A1 when cold).

Can't find much on the forums, unfortunately. I feel like a student who forgot his books at home, can't wait to receive the FSM.

What are the specs for fuel pressure?

Thanks a lot, I can see this is an awesome group! I'm a member of RX7Club since 2007 and I can already tell that the Registry is way friendlier.

[We Gone]

You will find everything on the fuel system here.

http://www.zr1.net/forum/showthread.php?p=148378

[MuRCieLaGo]

You will find everything on the fuel system here.

http://www.zr1.net/forum/showthread.php?p=148378

Thanks, I'll continue my investigation...

Update:

-Fuel pumps hoses are OK.
-Just red the codes again using the paper clip - only Code 31 shows up, again.

[Mr Blue]

When I bought my car it was leaking from the cam sensor.
It worked fine but he mounting flange was broken. I have the old one in a drawer somewhere. I'll look for it when I get home from work. It might at least be a diagnostic tool.

David

[MuRCieLaGo]

When I bought my car it was leaking from the cam sensor.
It worked fine but he mounting flange was broken. I have the old one in a drawer somewhere. I'll look for it when I get home from work. It might at least be a diagnostic tool.

David

Thank you very much, I'm looking for a camshaft position sensor at the moment, few people said they had the exact same problem and that was it...

[MuRCieLaGo]

Don't bother finally David,

I just ordered a brand new Cam sensor. Thanks a lot anyway I appreciate it.

[MuRCieLaGo]

I just found that this three-way hose is pretty loose on all ends. Tried to spray brake cleaner on it and it doesn't affect the idle at all...

I would really like to adjust the IAC though. My 2 best guesses are either the IAC or the cam sensor (ordered).

http://i841.photobucket.com/albums/zz332/TiGarsRotatif/10675734_10156459058475221_9092322430697523225_n.j pg

[We Gone]

Be sure to check the map sensor hose also its under the silver cover at the rear, has a hose on the bottom as mentioned before it is pron to oil soak and one of the most common issues. It will most likely come off if the motor happens to pop back while stating.

[MuRCieLaGo]

Be sure to check the map sensor hose also its under the silver cover at the rear, has a hose on the bottom as mentioned before it is pron to oil soak and one of the most common issues. It will most likely come off if the motor happens to pop back while stating.

I tried to find it last time - no luck. Under the silver cover, I'll try again to find it. What about that tiny oil leak from the PCV valve?

http://i841.photobucket.com/albums/zz332/TiGarsRotatif/20151027_152019.jpg

[We Gone]

The oil under the plenum is most likely from the vent box under the plenum or cam covers. If its the PCV fitting Jerrys sells them new.

Map
http://imagizer.imageshack.us/v2/800x600q90/907/ZOYCxZ.png

http://imagizer.imageshack.us/v2/800x600q90/911/Ed6iLc.jpg

[MuRCieLaGo]

-46F outside (warmer than usual), heavy rain.

-Cleaned PCV hose from the outside, to make sure oil is coming from there, time will tell.
-Cleaned map sensor hose with brake cleaner. A bit of black "something" (probably oil) was in there.
-The hose was a bit too long so it was bent. I shortened it by about 2".

-5 miles ride in the city: problem has been fixed

To be continued.

[MuRCieLaGo]

SES light just came on again but no stalling issue; still Code 31.

[vilant]

I had the same exact problem. I did everything to correct. Turns out my ECM was bad and was chasing a phantom because of it. I strongly suggest you drop a known, good functioning ECM in and see if you get the same codes before you start throwing parts at it, like I did.

[MuRCieLaGo]

Thanks vilant, I will receive my cam sensor next week, if my stalling issue is still fixed by then and if after the new cam sensor is installed I still got the Code 31, I'll have to think ECM.

But I guess good luck finding a ECM somewhere...

[MuRCieLaGo]

Alright stalling issue is definitely fixed now, another 10 miles without the problem.

BUT.

The SES light comes on way more often.

[MuRCieLaGo]

I've red that on another forum...

I observed several times by my and customers cars code 31 were set when the alternator was going to die. Check it too.

Sam

Strange enough, alternator failed last week (changed by a new one). Do you think I can simply clear the code...? If so, how do I do that?

[32valvesftw]

When my cam sensor went out it acted just like your car. I think once you change the sensor you will be OK. In general ECM failures are rare.

[MuRCieLaGo]

When my cam sensor went out it acted just like your car. I think once you change the sensor you will be OK. In general ECM failures are rare.

I like to read that! New cam sensor is on its way, hope it will fix my SES light!

[Dynomite]

Do you think I can simply clear the code...? If so, how do I do that?

To Erase Fault Codes....Depress/Hold the appropriate Diagnostic Button (Green in this case) and turn the Ignition Key ON....(not all the way to START). Wait for the Diagnostic light to start flashing for the Button Depressed. Release the Button for 3 seconds and then Depress/Hold the Button for about 3 seconds and Release. Turn the Ignition Key OFF.

ALDL Fault Code Reader/Eraser on CF (http://www.corvetteforum.com/forums/c4-zr-1-discussion/3718607-aldl-fault-code-flasher-eraser.html).

[MuRCieLaGo]

To Erase Fault Codes....Depress/Hold the appropriate Diagnostic Button (Green in this case) and turn the Ignition Key ON....(not all the way to START). Wait for the Diagnostic light to start flashing for the Button Depressed. Release the Button for 3 seconds and then Depress/Hold the Button for about 3 seconds and Release. Turn the Ignition Key OFF.

ALDL Fault Code Reader/Eraser on CF (http://www.corvetteforum.com/forums/c4-zr-1-discussion/3718607-aldl-fault-code-flasher-eraser.html).

When I will receive your ALDL code reader/eraser it will be that easy, but for now only the paper clip is my friend!

[MuRCieLaGo]

I erased the code 31 by unplugging the battery 10 seconds - never came back after a 200 miles ride today.

Stalling issue happened twice, map sensor hose was still too long and bent a bit - cut it again. Hope it fixed the issue for good.

[A26B]

..................................Stalling issue happened twice, map sensor hose was still too long and bent a bit - cut it again. Hope it fixed the issue for good.

Sounds like you have a piece of rubber hose instead of the hard plastic pipe for the MAP Sensor. If there is the slightest low point in the rubber hose, it can collect oil and block the vacuum signal to the MAP Sensor and cause problems as you describe.

Here is what it's supposed to look like.
http://cdn3.bigcommerce.com/s-nkg90o/products/313/images/1578/10106118_N__85738.1441374787.1280.1280.jpg?c=2

[MuRCieLaGo]

The answer to my stalling issue is that hose for sure Jerry so I will look into that.

Thanks a lot!

[MuRCieLaGo]

Just received a PM, someone wondering what fixed the issue.

The problem was the bent map sensor hose.

[-=Jeff=-]

Thanks for posting the resolution, I am not seeing a Code 31 but I am seeing the random stalls..