Need Help....

[Lowflight]

Should The Vacum Line coming from the Secondary MAP Sensor Have Vacum--if so, Than when? when you unplug it form the secondary MAP and blow, it is like a straw all the way through, no resistance and no vacum...with the car running or not.


Also, can you get a secondary MAP sensor and how much?

[Lowflight]

No help yet...

Oh well, this is the dumbest **** ever.

All I did was unplugg the vacuum line and connector from the secondary vacuum sensor under the ECM, remove the ECM and its holding tray with vacuum sensor attached out of the wya so I could change my master cylinder. I waas very careful and put everything back. Drove the car, and now with the key on, the thing hesitates and at full throttle it detonates all over the place before falling on its face...turn the key off and it is fine. SO, obviously something wrong with the secondary system. Pump burps once as it should. Everything is plugged in. Car has driven like a champ...I pull in the shop to do the work, and BAM, bend over. There is no way in hell that this is happening by chance....something I did caused this...However, the only thing NON BRAKE RELATED that I touched was that vacuum attachment and connector under the ECM.

Where can I get a vacuum secodary sensor? Autozone? It looks almost just like the MAP sensor...are they the same unit? HAs this happened to anyone before? I have checked everything I touched. I did not touch ANYTHING nor pull on any of the lines outside of the small area areound the Master Cylinder.....FCK FCK FCK FCK FCK this car:mad::mad::mad::mad:

[1990 quasar blue]

Hang on Harold. Let me go check the book.

[Lowflight]

Hang on Harold. Let me go check the book.

I have a FSM, it really doesn't help me much...but what is that sensor UNDER the ecm that has a connector and a nipple for a vacuum line...is is another MAP sensor or a Vacuum Sensor? What is the proper name, I am looking for one, but don't know what the F it is called?

I think this is it....
http://www.whiteracingproducts.com/index.php?main_page=product_info&products_id=242

[Lowflight]

I know I am screwed when a search on this sensor does not come up:thumbsdo:

[1990 quasar blue]

Harold, the only way that I can find to test it is with a scan tool. If you have access to one, I can post how the book says to test it. Is this it?

http://www.whiteracingproducts.com/index.php?main_page=product_info&products_id=242

[Lowflight]

Which book are you looking in to find what it does and what symptoms it creates when fouled? I can't find it in my FSM books anywhere?Harold, the only way that I can find to test it is with a scan tool. If you have access to one, I can post how the book says to test it. Is this it?

http://www.whiteracingproducts.com/index.php?main_page=product_info&products_id=242

[1990 quasar blue]

Sorry, we're looking in the same places and tripping over each other. Vacuum Sensor (Secondary System) is what the FSM calls it. Kurt calls it something else but, it sure as hell looks the same. Shoot him an email or a phone call just to verify. If you can get in there with a volt meter you might be able to check it that way. Engine at idle with valet key off should be about .54-.62volts. Valet on 1.3-3.1 volts.

Page 6E3-C1-8 also 6E3 -C1-11 and 6E3-C1-19
Any chance you tried disconnecting the negative battery terminal for 10 min. to reset?

[Lowflight]

Thanks

Another question:

Is there supposed to be ANY vacuum to that line that comes from the plenum all the way over to the VAcuum sensor under the ECM? Not only does it not have ANY vacuum, but you can blow and suck on it and it is acting like it isn't connected to ANYTHING...

[1990 quasar blue]

Thanks
you can blow and suck on it and it is acting like it isn't connected to ANYTHING...
I suppose this is no time for jokes.:mrgreen:

I don't know but, a failure should set a code 56. Also re-read my last post. I changed and added a couple of things to it.

[Lowflight]

I found out that the line does NOT hold a vacuum so that is normal. I dissconnected the Positive for about 5 minutes...is that wrong?

[Lowflight]

This is kinda sorta what I have going on...

http://forums.*************.com/showthread.php?t=1744281&highlight=vacuum+sensor

[1990 quasar blue]

I've always heard disconnect the negative so that's what I've done. Any chance it stored a quick code 56 without you seeing it happen? It may have quickly flashed SES during the stumble then went out. Just a guess. I already searched the other place for code 56 and didn't find anything helpfull.

[Lowflight]

I will pull codes tomorrow. I am almost convinced after searches that I ned to replace that VAcuum MAP looking sensor under the ECM....I must have screwed it up. But, the syptoms are inline with a code 61 or 56. The car is detonating and falling on its face the higher the RPM you go with the Key ON. The fact that I unplugged this sensor today AND it is having symptoms related to its failure are begining to convince me.

[1990 quasar blue]

I will pull codes tomorrow. I am almost convinced after searches that I ned to replace that VAcuum MAP looking sensor under the ECM....I must have screwed it up. But, the syptoms are inline with a code 61 or 56.
56 would confirm that vacuum sensor.

The car is detonating and falling on its face the higher the RPM you go with the Key ON. The fact that I unplugged this sensor today AND it is having symptoms related to its failure are begining to convince me.
It makes sense. Any chance that elbow was lose or dry rotted or might have gotten pinched? I can't imagine why simply moving it would cause all this. Wish I could have helped you more.

[Lowflight]

Thanks for the help...all the hoses look nice and glossy...no cracks or anything.

56 would confirm that vacuum sensor.


It makes sense. Any chance that elbow was lose or dry rotted or might have gotten pinched? I can't imagine why simply moving it would cause all this. Wish I could have helped you more.

[Lowflight]

Checked the codes this morning and there were none...just code 12 over and over.

[tccrab]

This might prove useful:
http://www.corvetteactioncenter.com/forums/showthread.php?t=14272

It sounds to me like you've got a plenum pull in your immediate future.

Tom

[Lowflight]

nevermind

[lbszr]

nevermind

Seems a lot of the numbers have changed but looks like maybe 16231141 is the number for sensor also called manifold differintial sensor by some parts stores if you still need it. Or is it fixed now?

[Lowflight]

Seems a lot of the numbers have changed but looks like maybe 16231141 is the number for sensor also called manifold differintial sensor by some parts stores if you still need it. Or is it fixed now?

I have the correct sensor coming in the morning. I said nevermind, because I bought the wrong sensor and it caused a Code 61...I realized it was the wrong sensor and took it back.

We will know if I am a genius or in deep crap in the morning when I swap out for the right sensor.

[Lowflight]

Now that the forum is back...here is the update.

I changed the sensor and it did not help. I took the Haibeck chip OUT and put the stock chip back in. That helped some in that it removed the detonation at high RPM, but the car still stumbles at around 3500rpm and above that it feels like the key is off, even when it is on. In the NORMAL position, the car runs as it should. I give up, I took the car to my mechanic shop down the road. The mechanic was trained on the ZR-1, but admits it was nearly 20 years ago....BUT said he will get to the bottom of the problem. I have to rely on him since I have no help from anyone else....as soon as it is fixed, this car is up for sale. I have had it with these damn cars

Later

[XfireZ51]

Now that the forum is back...here is the update.

I changed the sensor and it did not help. I took the Haibeck chip OUT and put the stock chip back in. That helped some in that it removed the detonation at high RPM, but the car still stumbles at around 3500rpm and above that it feels like the key is off, even when it is on. In the NORMAL position, the car runs as it should. I give up, I took the car to my mechanic shop down the road. The mechanic was trained on the ZR-1, but admits it was nearly 20 years ago....BUT said he will get to the bottom of the problem. I have to rely on him since I have no help from anyone else....as soon as it is fixed, this car is up for sale. I have had it with these damn cars

Later

I wonder if you'll change your mind once its fixed?

[Nick]

I have no help from anyone else
From where I sit, you've had a lot of help over the years with all of your ZR-1 issues...including the present issue.

....as soon as it is fixed, this car is up for sale. I have had it with these damn cars
Didn't see that one coming. :mrgreen:

Honestly, sorry you are having trouble, Harold, but that's the way it goes with these cars. The price of admission, if you will.

[Jeffvette]

Harold, a couple of paths to try.

ECM, bent pin
Quad driver
Prom getting fubar'd when you unplugged the ecm

[GOLDCYLON]

From where I sit, you've had a lot of help over the years with all of your ZR-1 issues...including the present issue.


Didn't see that one coming. :mrgreen:

Honestly, sorry you are having trouble, Harold, but that's the way it goes with these cars. The price of admission, if you will.


Harold geesh I know your frustrated but http://home.earthlink.net/~goldcylon/sitebuildercontent/sitebuilderpictures/galletos.gif

Jeff Flint posted some possible areas to look at.

[Lowflight]

I wonder if you'll change your mind once its fixed?

Unless it is something real easy and cheap, I am done. I love the car, but the headache of never haveing everything working at one time is getting stupid. I bought the car to drive, not spend 1/2 the time in the shop or up on jackstands. I do not enjoy working on cars nor paying someone to work on them unless it is a modification or cleaning project. I have neither the time, nor money, nor desire to work on this thing or learn all the technical ins and outs of it. As many know, I was selling it for a C6Z06 eventually anyway, I will just accelrate that project and do without for 6 months.

[Lowflight]

Harold, a couple of paths to try.

ECM, bent pin
Quad driver
Prom getting fubar'd when you unplugged the ecm

Did not unplug the ECM, just lifted it and the cradle it sits in to the winshield wiper tray.

Quad Driver?

[Jeffvette]

Quad Driver?

Controls the secondary injectors.

[flyin ryan]

Harold geesh I know your frustrated but http://home.earthlink.net/~goldcylon/sitebuildercontent/sitebuilderpictures/galletos.gif

i think he's a little past frustrated. this game can force you to take up a new religion some days.

[GOLDCYLON]

i think he's a little past frustrated. this game can force you to take up a new religion some days.

Yep sounds like hes ready to move on. I know he didnt have these troubles with the 91. Damn...

[Lowflight]

Location on a 92? I know they aren't in the ECM..but

Controls the secondary injectors.

[-=Jeff=-]

Location on a 92? I know they aren't in the ECM..but

for the Quad Driver? internal to the ECM

[Lowflight]

for the Quad Driver? internal to the ECM

In a search...I thought I saw that 90-92 had them external rather than part of the ecm.

"in 90-92 they were a separate module on the wiring harness. On the later cars, it was incorporated into the ecm"


But which harness? The main wrapped bundle plugged into the ECM?

[-=Jeff=-]

interesting, I always knew them to be in the ECM, Jeffvette will know for sure

[Jeffvette]

for the Quad Driver? internal to the ECM

The early cars had them seperate. One is mounted directly beneath the brake master cylinder and the other is just behind the battery mounted to the firewall.

[-=Jeff=-]

The early cars had them seperate. One is mounted directly beneath the brake master cylinder and the other is just behind the battery mounted to the firewall.

learn something new everyday..

Now, is it still Avail?

[Lowflight]

l
Now, is it still Avail?
:sign10::sign10::sign10::sign10::sign10::sign10:

yeah right

[GOLDCYLON]

:sign10::sign10::sign10::sign10::sign10::sign10:

yeah right

No and its a hard find but Progs had a set before he deployed. Johnny are you tuning in here.

[-=Jeff=-]

anybody got a picture of this fine piece?

[Lowflight]

$370 from Kurt's

http://www.whiteracingproducts.com/index.php?main_page=product_info&products_id=234



So, is there a way to check and see if this is the problem before I play catcher:rolleyes:

[Jeffvette]

Harold, I'll go through my electrical book tonight. They rarely fail. And I mean rarely.

[Lowflight]

ok Jeff, thanks

[flyin ryan]

new avatar Jeff to cheer Harold up? your always thinking of everyone's feeling's. nice:worship: . it can't fix the problem but at least take his mind off it for a while.

[Lowflight]

I apologize for stepping on some toes, but I am not backing down from my comments. No need to re-hash what I said, I am just asking for as much help as possible to fix this problem so that I can sell this thing and you guys will never hear from me again. I did not hear from the shop today, I drove by 3-4 times and it was outside, so they probably did not get to it. When they get to a car, they stay on it until it is fixed, instead of coming back and forth. Tony says it has to be vacuum, ignition, or fuel. At this point, I hope it is something like fuel pumps or injectors instead of something impossible to find or the ECM. I cannot see how it is the ECM though, I did not unplug it or even twist it upside-down (like you would to swap chips) when I carefully moved it. I cannot see how it is the ECM. I failed to remove the negative batt terminal when I initially unplugged the MDP sensor if that matters.

Is there any other parts under the plenum that I will be tough to find and or expensive? that could be the problem?

[XfireZ51]

LF,

OK. What are the particulars on the car and how much do you want for it?

[Lowflight]

LF,

OK. What are the particulars on the car and how much do you want for it?

Serious, because I will knock $1k off my bottom line to cover the repair of whatever is wrong with it.

IM me

[Lowflight]

PM sent back

[petefias]

I was going to link to my thread on DTC56, but noticed you already saw it.

The bottom line, on my car I had a DTC56 and the SES light on along with the 3.5K RPM limit. Replacing the MDP sensor fixed it in my case. Before I ordered a new one (MSRP $92) I traced the circuit and measured the voltage (have the service manual) and knew it was the problem. The only other problem could have been a short in the wireing. My DTC56 only showed up when the car was hot. The sensor (on MY95) is under the plenum and exposed to engine heat.

The MDP sensor sees no vacuum under idle and it is open to the atmosphere. When the secondaries are activated the sensor should see vacuum and its voltage increase from around 0.58V to over 2V.

Marc Haibeck helped me troubleshoot and he was spot on.

Since replacing the sensor I had 3 track days on the car and it performed flawlessly.

With yours, I would start with the basics, check for codes, insure connectors and grounds are making good contacts.

Even if your car is being looked at by a certified mechanic, he will be lost without a service manual. Make sure he has access to one.

Good luck and keep the faith.

Peter '95 #442

[Kevin]

so that I can sell this thing and you guys will never hear from me again.
yeah i don't buy that at all. I do hope your get you car fixed and you find one you'll hold onto for more the 16 months. Life is to short to drive something you don't like.

[Lowflight]

yeah i don't buy that at all. I do hope your get you car fixed and you find one you'll hold onto for more the 16 months. Life is to short to drive something you don't like.


Uh...ok:rolleyes:

[Pete]

Harold,i ran into the same issue where one of the plastic hard lines was pushed in too far into one of those 90* rubber pieces and blocking vacuum,was doing the same thing, same code would not go past 3500rpm.
Drove me nuts i pulled the hard plastic hose out a bit and all was fine.
Make sure you can blow thru all the hoses.
Just a thought and easy to try.
Basicly something is block vacuum to the secondaries.

Pete

[Lowflight]

Harold,i ran into the same issue where one of the plastic hard lines was pushed in too far into one of those 90* rubber pieces and blocking vacuum,was doing the same thing, same code would not go past 3500rpm.
Drove me nuts i pulled the hard plastic hose out a bit and all was fine.
Make sure you can blow thru all the hoses.
Just a thought and easy to try.
Basicly something is block vacuum to the secondaries.

Pete

I blew air through the line to the MDP sensor and it is clear. No word yet from the mechanic.

[XfireZ51]

Did you try sucking thru it to see if a vacuum formed?

[Lowflight]

Did you try sucking thru it to see if a vacuum formed?

yep, it is clear both ways as it is supposed to be

[Nick]

I did not hear from the shop today, I drove by 3-4 times and it was outside, so they probably did not get to it.
Obsess much? :mrgreen:
Please keep us posted.

[-=Jeff=-]

Lowflight,

are there any ZR-1 brothers near you that can help?

[Lowflight]

Obsess much? :mrgreen:
Please keep us posted.

No, I literally have to drive past it to get out of my subdivision. I could walk there (and have)

[Lowflight]

Lowflight,

are there any ZR-1 brothers near you that can help?
Not anymore:-({|=

[XfireZ51]

All your secondary throttle stuff still on? Have you tried running hose from vacuum pump directly to the MDP and blocking the other lines?
What about checking the #2 Fuel Pump for pressure?

[Lowflight]

Just a quick note, I got a call today when I landed in Las Vegas

It was a vacum leak, the car runs perfect again.

That and MC install was $400

[Jeffvette]

Good deal Harold! Still coming to BG?

[Kevin]

glad to hear she's fixed. are you still selling her or are you going to keep her?

[XfireZ51]

Just a quick note, I got a call today when I landed in Las Vegas

It was a vacum leak, the car runs perfect again.

That and MC install was $400


OK! OK! I'll give you six hundred for it.

:worship: :sign10:

[Paul Workman]

I've always heard disconnect the negative so that's what I've done.

Nuttin' important to add to the discussion, except to say that the battery is (in effect/as they say) the "prime mover" in the circuit. I've been "doin' 'lectronics;) enjuneerin' since 1970, and I have yet to conclude (or hear an informed opinion) as to what difference it makes which terminal is removed from the battery: the circuit is broken. Now, I wouldn't go clashing the terminals together (or do anything with other wiring), even accidently - especially for 30-60 seconds or so until the various capacitors have time to discharge. But, as to which terminal comes off - positive or negative - I doesn't make a lot of difference (except the positive is easy to get to on our Vettes.)

FWIW,

P.

[XfireZ51]

Paul,

I always pull off the negative. It seems the easiest for me to reach.

[Nick]

Just a quick note, I got a call today when I landed in Las Vegas

It was a vacum leak, the car runs perfect again.

That and MC install was $400
Good news, Harold. Where was the leak? Was this something coincidental, or was it related to the work you did?

[Lowflight]

Good news, Harold. Where was the leak? Was this something coincidental, or was it related to the work you did?

I don't know yet, I am in vegas....I will call them Friday.


BTW, I did pull the negative battery and never the positive. My batt is RED in color and I mispoke I have always pulled the negative.

[Lowflight]

OK! OK! I'll give you six hundred for it.

:worship: :sign10:

LEt;s put it this way, the price went up $1000