Help! Unable to rev past 5000

[chriskinzel]

I have a problem that has me stumped (not hard to do). I am unable to get the car above 5k. When it get close to that rpm it starts missing really badly. If I try to push past it I will get the camshaft sensor error, and the tach bounces from 4500 down to around 2000. This winter I removed the secondaries and installed Marc's chip. It runs great up to about 5000. I installed new fuel injectors last summer and it ran fine with those. I have installed a fuel preassure gauge. I have 42 psi on startup, and 50-51 psi at 5000 rpm. I have put on new Accel coils, new Delco spark plug wires, new spark plugs. Marc send me a spark controller and the problem is still there. I also have installed a new cam shaft sensor, but I only get the code when I don't let off when it starts missing. I have no codes being set.

I need more help from you smart people.

Thanks in advance
Chris :(

[tf95ZR1]

Removed.
Head up my ....

[KILLSHOTS]

You removed your secondaries and now you can't pass 5K? Hmmmm, I'm trying to get feedback on removing secondaries in another thread right now. Maybe this is something to consider. My car runs great right now; I'll be pizzed if I do the old remove-the-secondaries "upgrade" and it messes everything up! Best of luck finding the issue, hopefully something simple.

[Paul Workman]

You removed your secondaries and now you can't pass 5K? Hmmmm, I'm trying to get feedback on removing secondaries in another thread right now. Maybe this is something to consider. My car runs great right now; I'll be pizzed if I do the old remove-the-secondaries "upgrade" and it messes everything up! Best of luck finding the issue, hopefully something simple.

No, I think this is an isolated case, and I've not seen any evidence (yet) that would lead to a conclusion. (Mine and dozens and dozens of others run fine w/o SPTs from the first moment. (I'm using Marc's calibration as well.))

[chriskinzel]

I don't think that removing the secondaries has caused this problem. I just mentioned it because it eliminated a lot of extra stuff that could cause problems.

Still searching.
Chris

[Paul Workman]

I don't think that removing the secondaries has caused this problem. I just mentioned it because it eliminated a lot of extra stuff that could cause problems.

Still searching.
Chris

Ah! Excellent point. Removing the SPTs does eliminate an entire "sub-routine" of related troubleshooting banter!

Long story short, one of the best single investments after buying a Field Service Manual (FSM) I ever made was my scanner. That thing has put a finger right on sooo many issues on several (not all of 'em being Corvettes) cars. Having access to a scanner - especially if you can record real time windows - is a fantastic tool.

You might see if an auto parts store will scan it, and maybe do a ride-along to further diagnose the problem.

When I first got my 90, as the temperatures warmed up from early spring to summer, I discovered the plastic accordion snorkel tube between the filter housing and the throttle body horn was collapsing at WOT, causing it to nose dive and sputter at about 5000 rpm. I fixed it by making an aluminum sheet metal insert that supports the hose. No more problems.

Marc Haibeck can provide some little metal hoops that fit inside the folds of the snorkel. These, I suppose, you might be able to make yourself, if you find the right kind of wire.

P.

P.

[Tony Davila]

Last time that same situation happened to me I found out I had a weak primary fuel pump. Fuel Pressure looked good static but could not keep up with requirement. Replaced pump and it would now rev passed 7K.

[PhillipsLT5]

You removed your secondaries and now you can't pass 5K? Hmmmm, I'm trying to get feedback on removing secondaries in another thread right now. Maybe this is something to consider. My car runs great right now; I'll be pizzed if I do the old remove-the-secondaries "upgrade" and it messes everything up! Best of luck finding the issue, hopefully something simple.
my secondaries are removed & pulls to 7200, his problem is elsewhere

[GOLDCYLON]

my secondaries are removed & pulls to 7200, his problem is elsewhere


Concur.. Mine pulls like a freight train. :cheers:

[GOLDCYLON]

I have a problem that has me stumped (not hard to do). I am unable to get the car above 5k. When it get close to that rpm it starts missing really badly. If I try to push past it I will get the camshaft sensor error, and the tach bounces from 4500 down to around 2000. This winter I removed the secondaries and installed Marc's chip. It runs great up to about 5000. I installed new fuel injectors last summer and it ran fine with those. I have installed a fuel preassure gauge. I have 42 psi on startup, and 50-51 psi at 5000 rpm. I have put on new Accel coils, new Delco spark plug wires, new spark plugs. Marc send me a spark controller and the problem is still there. I also have installed a new cam shaft sensor, but I only get the code when I don't let off when it starts missing. I have no codes being set.

I need more help from you smart people.

Thanks in advance
Chris :(

Spark controller? Are you stating a DIS or a Quad Driver?

[Paul Workman]

Last time that same situation happened to me I found out I had a weak primary fuel pump. Fuel Pressure looked good static but could not keep up with requirement. Replaced pump and it would now rev passed 7K.

Ah! Good point. A partially plugged fuel filter and a bad secondary pump was revealed by taping a fuel pressure gauge to the windshield. At WOT pressure would drop to around 43#...NOT good. Filter and a pump fixed it.

http://i185.photobucket.com/albums/x220/6PPC_bucket/Vettes/FPtestLarge.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/Vettes/FPtestLarge.jpg.html)

[USAZR1]

Spark controller? Are you stating a DIS or a Quad Driver?


Pardon my ignorance,Darryl,but what is a Quad Driver? Never heard that term,before.

[chriskinzel]

I have a fuel preassure gauge mounted on the 'a' pillar. Good fuel preassure. I have the sheet metal insert in the accordion air intake. Marc sent me a known good DIS module. I also have a Tech-1, and there are no codes. I talked with Marc today and he wants me to change the 'Crank Positioning' sensor. I will do that tonight or tomorrow. Wish me luck. Thanks for all of the ideas!

Thanks
Chris

[GOLDCYLON]

Pardon my ignorance,Darryl,but what is a Quad Driver? Never heard that term,before.

They mount next to the frame and the battery and control the Secondaries in concert with the DIS. The Quad drivers come in pairs and command 4 injectors each of the secondaries hence the name "Quad" I forget which year no longer has them but it might be 93 and up with the 405HP release.

[GOLDCYLON]

I have a fuel preassure gauge mounted on the 'a' pillar. Good fuel preassure. I have the sheet metal insert in the accordion air intake. Marc sent me a known good DIS module. I also have a Tech-1, and there are no codes. I talked with Marc today and he wants me to change the 'Crank Positioning' sensor. I will do that tonight or tomorrow. Wish me luck. Thanks for all of the ideas!

Thanks
Chris

Quad drivers or fuel filter would be my next guesses. Crank sensor is an easy replacement.

[USAZR1]

They mount next to the frame and the battery and control the Secondaries in concert with the DIS. The Quad drivers come in pairs and command 4 injectors each of the secondaries hence the name "Quad" I forget which year no longer has them but it might be 93 and up with the 405HP release.


Any have a photo of a Quad Driver? I know what a DIS looks like.

[GOLDCYLON]

Quad Driver AKA Secondary Injector Relays. Come in pairs. Rare as hensteeth. Long NLA Henco en Canada

http://i1120.photobucket.com/albums/l498/goldcylon/QUAD1_zpsa5919393.jpg (http://s1120.photobucket.com/user/goldcylon/media/QUAD1_zpsa5919393.jpg.html)

http://i1120.photobucket.com/albums/l498/goldcylon/quad2_zps10369239.jpg (http://s1120.photobucket.com/user/goldcylon/media/quad2_zps10369239.jpg.html)

http://i1120.photobucket.com/albums/l498/goldcylon/Quad3_zpsfa932287.jpg (http://s1120.photobucket.com/user/goldcylon/media/Quad3_zpsfa932287.jpg.html)

http://i17.photobucket.com/albums/b79/MRBLU/ZR1plugandmoduleleftwheelwell.jpg

http://i17.photobucket.com/albums/b79/MRBLU/ZR1SecondaryRelaygraphic.jpg

[chriskinzel]

When I read the FSM it says that the quad driver runs the secondary injectors. If I am running Marc's chip wouldn't the injectors be running all the time? Not just after 5000rpm? If this was the problem, wouldn't the rpm's just rise slower, and not just cut out? Don't know much about these just asking. Ya all keep thinking out there.:dancing

Chris

[GOLDCYLON]

When I read the FSM it says that the quad driver runs the secondary injectors. If I am running Marc's chip wouldn't the injectors be running all the time? Not just after 5000rpm? If this was the problem, wouldn't the rpm's just rise slower, and not just cut out? Don't know much about these just asking. Ya all keep thinking out there.:dancing

Chris

They still command the secondary injectors. Don't know I haven't experienced what you have either before. Check the Crank sensor and the fuel filter first which are easy to do. This is just one of the possibilities since to me it appears your secondary's are not engaging. Since these fire secondary injectors its a good guess.

[chriskinzel]

I will be changing crank sensor and fuel filter tomorrow. I don't know what to do about the quad drivers. Keep your fingers crossed!

Chris

[WVZR-1]

They mount next to the frame and the battery and control the Secondaries in concert with the DIS. The Quad drivers come in pairs and command 4 injectors each of the secondaries hence the name "Quad" I forget which year no longer has them but it might be 93 and up with the 405HP release.

I've never heard the term "quad driver" except from Daryl and I never knew what the he!! he was talking about. All years have the "pair" of injector drive modules, on the later cars they're mounted on the rear of the RH wheel-house on a multi relay bracket.

Clint - your '94 should be on the RH wheel-house

Quad driver failure has specific error codes when GM ECM utilizes them and they're built into GM ECM circuitry. Do these modules serve a similar function? Don't know. Now I do know what Daryl has been referring to though.

Where the terminology came from? I have no idea.

There's been many conversations regarding quad-drivers through the years and Tyler mentions ECM, it's been mentioned they were on the PROM - all sorts of silliness.

[GOLDCYLON]

I've never heard the term "quad driver" except from Daryl and I never knew what the he!! he was talking about. All years have the "pair" of injector drive modules, on the later cars they're mounted on the rear of the RH wheel-house on a multi relay bracket.

Clint - your '94 should be on the RH wheel-house

Quad driver failure has specific error codes when GM ECM utilizes them and they're built into GM ECM circuitry. Do these modules serve a similar function? Don't know. Now I do know what Daryl has been referring to though.

Where the terminology came from? I have no idea.

There's been many conversations regarding quad-drivers through the years and Tyler mentions ECM, it's been mentioned they were on the PROM - all sorts of silliness.

I learned this term from a few members quad was used as each module controls 4 injectors. However I posted both terms to not confuse anyone. Your right however after a little research all ZR-1s have these modules but as stated they moved. GC

[GOLDCYLON]

I will be changing crank sensor and fuel filter tomorrow. I don't know what to do about the quad drivers. Keep your fingers crossed!

Chris

Chris I forgot to mention a few of the Crank Position Sensors out there had a bad batch for a while. The magnet was installed backwards. When you pull the OEM unit match up the replacement unit tip to tip. If they attract the replacement unit is bad. They should repel each other if the magnet is installed correctly.

[chriskinzel]

Chris I forgot to mention a few of the Crank Position Sensors out there had a bad batch for a while. The magnet was installed backwards. When you pull the OEM unit match up the replacement unit tip to tip. If they attract the replacement unit is bad. They should repel each other if the magnet is installed correctly.

I will be sure to verify magnet orientation before anything is replaced.
Chris

[chriskinzel]

Update
Decided to drive the car to dinner tonight. The miss is now starting anywhere from 2500 to 3500 rpm. I revved it in out of gear until it started to miss. It was at 3000 rpm. Fuel preassure was 48psi. Dark smoke coming from the exhaust. Tach had about a 1000 rpm swing. This is with no load on the engine. I will still be replacing the crank sensor and fuel filter tomorrow.

Chris:censored:

[GOLDCYLON]

Update
Decided to drive the car to dinner tonight. The miss is now starting anywhere from 2500 to 3500 rpm. I revved it in out of gear until it started to miss. It was at 3000 rpm. Fuel preassure was 48psi. Dark smoke coming from the exhaust. Tach had about a 1000 rpm swing. This is with no load on the engine. I will still be replacing the crank sensor and fuel filter tomorrow.

Chris:censored:

Well here's my thoughts on that. I did not suspect the crank sensor because it was not having a problem until the 5k rpm range. If the crank sensor was bad it would have problems at all rpm ranges. Sounds like you could be on to something. GC

[Demps]

PROM installed correctly? Have a good ECM to compare?
Ted

[GOLDCYLON]

PROM installed correctly? Have a good ECM to compare?
Ted

Yep Ted that's a possibility as well :eek::eek::eek:

[chriskinzel]

PROM installed correctly? Have a good ECM to compare?
Ted

I think the PROM is installed right. I don't have any other ECM to compare with. I will have more results in the morning. Too hot now to mess with.

Chris

[Pete]

Update
Decided to drive the car to dinner tonight. The miss is now starting anywhere from 2500 to 3500 rpm. I revved it in out of gear until it started to miss. It was at 3000 rpm. Fuel preassure was 48psi. Dark smoke coming from the exhaust. Tach had about a 1000 rpm swing. This is with no load on the engine. I will still be replacing the crank sensor and fuel filter tomorrow.

Chris:censored:

Sounds like secondaries not coming on or shutting down.
Check codes.
Check secondary vacuum solenoid under plenum make sure it's pluged in.
Also make sure MAP sensor under ECM is pluged in.

When secondaries don't work it shuts her down at 3k rpm(like rev limiter)

Maybe recheck chip program sometimes the best can miss something.

Do not throw parts at it.

Pete

[WVZR-1]

Is this a car with headers? If this is a car with headers and it was thought to maybe be a secondary injector issue couldn't you just use a pyrometer and check cylinder temps? Just asking. Sort the cylinders to those controlled by each injector module.

Pete - a swap of PROM would substantiate the possible issue there?

Chris - you do have another?

[chriskinzel]

:mad:
Replaced the crank sensor, and the fuel filter. I also reseated the PROM. Went for a drive and it still stalls out at 5000. I pulled over in a parking lot and while in neutral slowly reved it. Sometimes it would stop at 5000, other times I could get it to 7200. If it went past 5000 it would keep going to the end. If it stopped at 5000 the tach would only bounce about 100 rpm, just about what the engine is running. I am now totally confused. I don't have headers, secondaries removed, with Marc's chip the ECM is open the the atmosphere, no vaccume pump anymore. I am stumped!! Fuel Preasure is still good.

Chris::cry:

[Pete]

Does it shut down at 3k or5k
3 would be secondaries 5k sounds
like ignition module.
I meant make sure the electrical plugs are
plugged in.
Changing to stock chip will not help since he has removed secondaries.
When did this start what was the last change to car.

Pete

[chriskinzel]

Does it shut down at 3k or5k
3 would be secondaries 5k sounds
like ignition module.
I meant make sure the electrical plugs are
plugged in.
Changing to stock chip will not help since he has removed secondaries.
When did this start what was the last change to car.

Pete

It ran good up to 5k this time. I didn't drive it far, so it didn't get really hot. It has been this way all summer. It seems to have happened after I removed secondaries. All plugs are in tight, even rechecked plug tightness and wires. Really frustrating. Anyone have a known good ignition module they would lend, or rent me? The permagrin is fading.:cry:

Chris

[QB93Z]

To me, it sounds like the problems I have seen in cars that still have the secondaries installed and the secondary vacuum system is not tight. The ECM shuts down the secondaries and turns off the secondary injectors and you see a code (which I don't remember the number but it references something like secondary vacuum low)

So in your case, with the secondaries removed, the ECM still has to get an input from the Secondary Vacuum Pressure Switch. Is the pressure switch connected it's normal wiring connector. If not, the ECM may not be turning on the secondary injectors.

Good luck with your trouble shooting!

Jim

[chriskinzel]

To me, it sounds like the problems I have seen in cars that still have the secondaries installed and the secondary vacuum system is not tight. The ECM shuts down the secondaries and turns off the secondary injectors and you see a code (which I don't remember the number but it references something like secondary vacuum low)

So in your case, with the secondaries removed, the ECM still has to get an input from the Secondary Vacuum Pressure Switch. Is the pressure switch connected it's normal wiring connector. If not, the ECM may not be turning on the secondary injectors.

Good luck with your trouble shooting!

Jim

Where is the Secondary Vacuum Pressure Switch located? What does it look like?

Chris

[QB93Z]

The pressure switch looks like the MAP sensor (without the sheet metal cover).

On a 1990 it is under the ECM, and a vacuum line from the operator side of the Secondary Actuator Solenoid Valve, comes from under the plenum and runs to the Vacuum Switch.

On 1993 and up, the Vacuum Switch is fastened to the under side of the Plenum, forward of the Ignition Module.

For 1991, I don't remember the location. Sorry.

I believe that the ECM requires the Vacuum Switch to be plugged in but a "Secondaries Removed" chip changes the set point to atmospheric.

Jim

[chriskinzel]

I think that I removed it when I pulled the secondaries. The ECM is now atmospheric. Thanks anyway....keep thinking.:)

Chris

[QB93Z]

I think that I removed it when I pulled the secondaries. The ECM is now atmospheric. Thanks anyway....keep thinking.:)

Chris

The Pressure Switch needs to be installed for the ECM to energize the 2nd injectors.

Jim

[chriskinzel]

The Pressure Switch needs to be installed for the ECM to energize the 2nd injectors.

Jim
According to the FSM, if there is too much, or too little vacuum there should be an error code. No codes. I may, or may not have this switch. I will keep looking for it. I do have a wire connection ( 2 wires with a white connector) that is not hooked up under my plenum. It is towards the front. Not sure where this goes, but I rember unplugging it when removing the secondaries. Problem?

Chris

[XfireZ51]

What EXACTLY did you ask Marc to do w your chip?

[QB93Z]

According to the FSM, if there is too much, or too little vacuum there should be an error code. No codes. I may, or may not have this switch. I will keep looking for it. I do have a wire connection ( 2 wires with a white connector) that is not hooked up under my plenum. It is towards the front. Not sure where this goes, but I rember unplugging it when removing the secondaries. Problem?

Chris

The two-wire plug is for the Secondary Solenoid that actuated the secondary throttle plates. I don't know if it needs to be connected. Hopefully, some who has removed the secondaries will join in.

Jim

[Pete]

The two-wire plug is for the Secondary Solenoid that actuated the secondary throttle plates. I don't know if it needs to be connected. Hopefully, some who has removed the secondaries will join in.

Jim

Yes that's the one needs to be connected even if the vacuum lines are off plug needs to be plugged in.
That's the one I mention in an earlier post.
White plug 2 wires under plenum.

Pete

[QB93Z]

Yes that's the one needs to be connected even if the vacuum lines are off plug needs to be plugged in.
That's the one I mention in an earlier post.
White plug 2 wires under plenum.

Pete

Good info Pete, I had the plugs confused.

Jim

[XfireZ51]

Yes that's the one needs to be connected even if the vacuum lines are off plug needs to be plugged in.
That's the one I mention in an earlier post.
White plug 2 wires under plenum.

Pete

R U sure? The ECM just needs to see a +.7 v signal from the Differential Map Sensor. That's what allows secondaries to open. I don't have that solenoid under the plenum. By changing the calibration, the sensor always puts out the necessary signal.

[Pete]

R U sure? The ECM just needs to see a +.7 v signal from the Differential Map Sensor. That's what allows secondaries to open. I don't have that solenoid under the plenum. By changing the calibration, the sensor always puts out the necessary signal.


Dom,at this time I don't know how the chip was programed.
So I would suggest plug in the solenoid under the plenum and the MAP sensor under the ECM.(don't need vacuum)
I mentioned both sensors on an earlier post.

I figure this is easy and free instead of throwing parts at it.

Also if the error code was programed out of the chip it will not show a code.

Pete

[chriskinzel]

What EXACTLY did you ask Marc to do w your chip?

I had him do whatever needs to be done to remove the secondaries. He also did the usual stuff with his chips. 1 to 4 skip removed, radiator fans on sooner, full power default. Maybe I can send the PROM back and have him verify the settings. When I talked with him on Friday he seemed kind of stumped too. You guys are the best:dancing. Would have a boat anchor without you all!!

Chris

[Pete]

I had him do whatever needs to be done to remove the secondaries. He also did the usual stuff with his chips. 1 to 4 skip removed, radiator fans on sooner, full power default. Maybe I can send the PROM back and have him verify the settings. When I talked with him on Friday he seemed kind of stumped too. You guys are the best:dancing. Would have a boat anchor without you all!!

Chris

Heck it's the weekend no shipping till Monday just check these little things.

Pete

[XfireZ51]

So it worked fine w Marc's cal changes but then it didn't. correct? You get a code if you don't let off because the ECM doesn't set a code unless the malfunction occurs for longer than 2sec. You're sure you are not getting a Code 64 or 44?
Cam sensor error is a Code 17


I have a problem that has me stumped (not hard to do). I am unable to get the car above 5k. When it get close to that rpm it starts missing really badly. If I try to push past it I will get the camshaft sensor error, and the tach bounces from 4500 down to around 2000. This winter I removed the secondaries and installed Marc's chip. It runs great up to about 5000. I installed new fuel injectors last summer and it ran fine with those. I have installed a fuel preassure gauge. I have 42 psi on startup, and 50-51 psi at 5000 rpm. I have put on new Accel coils, new Delco spark plug wires, new spark plugs. Marc send me a spark controller and the problem is still there. I also have installed a new cam shaft sensor, but I only get the code when I don't let off when it starts missing. I have no codes being set.

I need more help from you smart people.

Thanks in advance
Chris :(

[chriskinzel]

So it worked fine w Marc's cal changes but then it didn't. correct? You get a code if you don't let off because the ECM doesn't set a code unless the malfunction occurs for longer than 2sec. You're sure you are not getting a Code 64 or 44?
Cam sensor error is a Code 17

I put Marc's chip in when I pulled the secondaries this winter. When I started driving it this spring it had the miss. I thought that I had bad plugs, or wires, or coils, Maybe plugged fuel filter of bad pumps. I have replaced or confirmed all of those items are working.
The only code I get is a 17 when I stay on it when it starts missing. I have replaced the cam sensor already to rule that problem out.

Chris

[WVZR-1]

The only code I get is a 17 when I stay on it when it starts missing. I have replaced the cam sensor already to rule that problem out.

Chris

I don't understand the code 17 - where did you get the diagnostics for a code 17 for an LT5 in the drivability?

[chriskinzel]

Oops. The code I get is the cam positioning sensor. I can't remember the number.

Chris

[vilant]

Oops. The code I get is the cam positioning sensor. I can't remember the number.

Chris

That would be ECM code 31. I know, cause mine just started popping up. I can rev to redline but I don't feel the secondaries kicking in. I'll be checking the connection soon, but I'll probably need a new sensor.

[RICHARD TILL]

I`m all ears on this subject of code 31. I`m getting it too. I recently tied my secondaries open and got a chip from Mark H.. Was getting the code before i changed the chip. I`ve tried to troubleshoot it with a stored code and the service engine light off and got good readings. It`s nearly constantly on now so i`ll give it another try. Anyone know where the best/cheapest price is?

[chriskinzel]

I bought mine at NAPA for about $20. The one I took out was good, I was doing the 'throw parts at it because I'm stuck' thing. If you want, I will send you my old but still good one and you can see if it fixes your problem.

Chris

[vilant]

I bought mine at NAPA for about $20. The one I took out was good, I was doing the 'throw parts at it because I'm stuck' thing. If you want, I will send you my old but still good one and you can see if it fixes your problem.

Chris

Were you talking to me or Rich? That's very generous of you, Rich should have first dibs, but I'd have to pay you something if you were talking to me. A NOS one is worth @ $250.

[chriskinzel]

Were you talking to me or Rich? That's very generous of you, Rich should have first dibs, but I'd have to pay you something if you were talking to me. A NOS one is worth @ $250.

Whoever needs it to verify that there sensor is bad. Just let me know. I already bought a new one, and it didn't fix my problem so I don't need it anymore. I would be happy to help a brother out.:cheers:

Chris

[vilant]

I cleared the code and have been driving it, no problems so far. I think it's a grounding issue (for me at least) as from time to time I do notice the DIC and Full Power light get slightly dim for a bit, then bright again. We'll see, maybe the sensor is starting to go instead. I'll clean up the ground connections and if it pops up again, I'll replace the sensor.
Did you figure out what was going on with your car?:cheers:

[chriskinzel]

No. I still have the problem. I will drive it, just not past 5000 RPM until I have saved up enough lunch money to have Marc do his 510 magic. He told me that when I get it back from him it will be perfect. I have no doubt about that. So, for now I drive it like a responsible adult.:censored:

Chris