1982 crossfire-bad idle_ dies

[jeanie2002]

I have a 82 coupe with its original crossfire which has had a surging idle for the past few years. Lately it will idle so low it dies. Sitting still it bounces back and forth from almost dying to a fast idle for a short time then dies. It has a even rythym to the flucuation in rpms. Low/high low/high low/high. It is even starting to die while driving slow on road. Any Ideas??? Thanks

 

[BigJimZ16]

I have a 82 coupe with its original crossfire which has had a surging idle for the past few years. Lately it will idle so low it dies. Sitting still it bounces back and forth from almost dying to a fast idle for a short time then dies. It is even starting to dies while driving slow on road. Any Ideas??? Thanks

Sounds like the throttle-body butterfly pivot shafts are worn out causing both a vacuum leak and a variable throttle position at idle. Probably time for a rebushing of the shafts.

 

[jeanie2002]

Sounds like the throttle-body butterfly pivot shafts are worn out causing both a vacuum leak and a variable throttle position at idle. Probably time for a rebushing of the shafts.

Thanks Jim,
Is that something I can do/get myself. Does anyone suppy new bushings or do they have to be machined?

 

[geekinavette]

Are you getting a Check Engine light?

 

[BigJimZ16]

Thanks Jim,
Is that something I can do/get myself. Does anyone suppy new bushings or do they have to be machined?

I'm pretty sure that most of the major Corvette Parts Houses can source the kit.

 

[Buccaneer]

It sounds like a vacuum leak for sure, but do you get a CEL like mentioned by Geekinavette? If not, check the top plate bolts, TB bolts etc...

 

[geekinavette]

Sounds more likely to be an IAC problem to me, or lean air/fuel mixture for whatever reason. ECM might not report an IAC problem, so check those for carbon buildup that would restrict air through the ports (but would likely only effect idle). If that checks out ok...then I'd do a fuel pressure test, and make sure both injectors are spraying evenly and a nice steady cone-shaped pattern. (keeping any and all body parts AWAY from those TB's while its running!)

A vacuum leak tends to cause a high idle, not a low one...but stranger things have happened.

Of course if the CEL is on...that is THE place to start.

 

[jeanie2002]

Sounds more likely to be an IAC problem to me, or lean air/fuel mixture for whatever reason. ECM might not report an IAC problem, so check those for carbon buildup that would restrict air through the ports (but would likely only effect idle). If that checks out ok...then I'd do a fuel pressure test, and make sure both injectors are spraying evenly and a nice steady cone-shaped pattern. (keeping any and all body parts AWAY from those TB's while its running!)

A vacuum leak tends to cause a high idle, not a low one...but stranger things have happened.

Of course if the CEL is on...that is THE place to start.

I do not have a CEL. My wife told me about this so I just went for a drive in it and I don't think the 2 problems are related. It always did the idle surge but not ever to the point of dying, it will idle and does die sometimes sitting at idle, but when trying to drive it acts like I am not getting fuel. I give it gas and it falls on its face, however if I pump the pedal I can get little bursts of acceleration but only achieve 20 mph. It will die while driving unless I pump pedal, but always starts right back up. I just replaced the rubber fuel line from pump in tank to steel line, the old one had dissolved, I drained tank and replaced pump screen and fuel filter and it ran awesome. Now I am wondering if pump may be weak {I know I should have replaced while it was out} but it pumped great. Any thoughts???? One thing I should add, the headlights did work great but now quit lifting, so I may have loss of vac. there but do not hear any hissing. Thanks

 

[geekinavette]

When you say "don't have CEL"...do you mean it doesn't work at all?

 

[jeanie2002]

No, I just mean I don't have one lit while operating. It does work when turn ign. switch.

 

[geekinavette]

Ok.

In that case, refer back to the recommendations in post #7.

 

[wishuwerehere82]

I think your fuel pump's shot.
Remember all that rust you scrubbed off the outside of the dip tube?
Imagine how much junk has gone though the pump.
JMHO.

 

[Buccaneer]

GeekyBill could be right about the IACs. However, if you have a large enough vacuum leak the motor will surge like you described and the IACs will try to correct at idle...hence the surging effect. OR you could have very dirty pintles on the IACs and they can't shut properly and could be cycling. You could also have a fuel pressure issue and the only way to find that out is by checking in-between the TBs and see what it is set to, 13-14psi is plenty as long as the pump can output the volume under load.

A quick "gross" check of the fuel pressure to kind of see where you're at thing can be done by looking at the back of the rear TB, there's a small window (cutout) area that you can see into on the tower, thats the fuel pressure regulator can, "tab" and spring through there. Look inside with a flashlight and see where the "tab" is sitting in the slot. If it's at the bottom or really close to the bottom, your FP is low. You want the "tab" to be about half to 3/4 of the way up the slot. Again, this is only a "gross" check to get a feel of where your at.

I'm willing to bet that if its at the bottom that your FP is only around 9-10psi and is running the motor pretty lean. Check it with a gauge to find out for sure though. Also check the fuel filter/replace and maybe the pump filter/sock in the tank.

Since you said the headlights were working (coming up) and now they don't and they are run strictly by vacuum, I'd start there first, then the top plate or whichever you want first and then proceed from there. I would also think that if the vacuum was too low that you would be setting a MAP Sensor 33 or 34 code maybe.

There's a pretty good vacuum troubleshooting diagram in the Tech Section over at the CFI forum, check it out. CrossFire Injection Forum

So, since you aren't getting a CEL during operation, that would indicate that the issue is mechanical in nature whereby the ECM is not controlling or monitoring that problem and thinks everything is fine which would also eliminate a sensor input for now. It could also be the ECM, but that would be my last thing I checked. So to sum it up, we're back to either fuel or vacuum or both and of course a possible IAC issue.

The best thing you can buy is a GM Service Manual off of Fleebay or something for a car that is 28 years old and you want to maintain it, just a suggestion and well worth the money spent. Good luck and hope you find the root cause.

 

[shark454]

Clean ALL the pins and connectors (ECM PC board as well ) connected to the ECM.

Back out the pins with a removal key ( you can make one ) and clean all the pins.

Your problem will probably go away. Mine did!

The PC board edge connector design is a cheap horrible solution. Dirt, tarnish and corosion cause signals to intermittantly get to the ECM. Clean the contacts and communication is restored. I even retinned the PC board connectors with solder.

 

[jeanie2002]

I think your fuel pump's shot.
Remember all that rust you scrubbed off the outside of the dip tube?
Imagine how much junk has gone though the pump.
JMHO.

I think you are probably right. need to check out further, I really should have installed a new pump when I had that out-was just in a hurry to get it on road again, and it did awesome for awhile but may have finished off what was left of the pump. I need to add, it is crazy to let any car set, this thing has about 10 new problems that it did not have before storing her. Most have been simple, but things go bad from non use, drive them and enjoy them at least start once a week!!!

 

[wishuwerehere82]

I think you are probably right. need to check out further, I really should have installed a new pump when I had that out-was just in a hurry to get it on road again, and it did awesome for awhile but may have finished off what was left of the pump. I need to add, it is crazy to let any car set, this thing has about 10 new problems that it did not have before storing her. Most have been simple, but things go bad from non use, drive them and enjoy them at least start once a week!!!

Let me tell you how mine went out on me.
My uncle and I took a nice drive down to the Finger Lakes in NY State from my house, probably a couple of hours driving just fine. Stopped for lunch, and it would just barely run afterwards. 20 MPH top speed and stumbling and bucking all the way until it died going up a hill with gear lube coming out the differential shaft seal and smoking off the mufflers from all the jerking back and forth.
Sound familiar?
Towed it all the way back home for $260.00 and it started right back up again as if nothing ever happed as soon as it came off the flatbed.
The tow truck driver told me half of his towing jobs were fuel pump related.
I changed it the next day, and it has been good ever since.
That's how I learned about 82 fuel pumps.

The loss of vacuum to your headlights could be related to the problem, or a separate one altogether.
You can check the vacuum with a gauge if the engine will run at all, or you can get a hand pump and check each line separately to the headlight vacuum accumulator and to the actuators all the way back to the source at the intake manifold.

 

[jeanie2002]

Let me tell you how mine went out on me.
My uncle and I took a nice drive down to the Finger Lakes in NY State from my house, probably a couple of hours driving just fine. Stopped for lunch, and it would just barely run afterwards. 20 MPH top speed and stumbling and bucking all the way until it died going up a hill with gear lube coming out the differential shaft seal and smoking off the mufflers from all the jerking back and forth.
Sound familiar?
Towed it all the way back home for $260.00 and it started right back up again as if nothing ever happed as soon as it came off the flatbed.
The tow truck driver told me half of his towing jobs were fuel pump related.
I changed it the next day, and it has been good ever since.
That's how I learned about 82 fuel pumps.

The loss of vacuum to your headlights could be related to the problem, or a separate one altogether.
You can check the vacuum with a gauge if the engine will run at all, or you can get a hand pump and check each line separately to the headlight vacuum accumulator and to the actuators all the way back to the source at the intake manifold.

Pete, You told me about using a FP for a 85 for more volume, but looking at them the 85 has a plug instead of the eyelet terminals for a 82, what did you do there? I won't have time to mess with this until weekend, one thing I am concerned about I had so much trouble getting power to the pump last month, I am wondering if I could be intermittantly losing power to pump??? Not as likely as pump being bad I quess but remember how much trouble I was having just getting power to the pump. Every connection all the way back had some corrosion even ECM. I need to do a Fuel press test-see what I get. But I bet its time for a pump, Thankshnoes

 

[wishuwerehere82]

Pete, You told me about using a FP for a 85 for more volume, but looking at them the 85 has a plug instead of the eyelet terminals for a 82, what did you do there? I won't have time to mess with this until weekend, one thing I am concerned about I had so much trouble getting power to the pump last month, I am wondering if I could be intermittantly losing power to pump??? Not as likely as pump being bad I quess but remember how much trouble I was having just getting power to the pump. Every connection all the way back had some corrosion even ECM. I need to do a Fuel press test-see what I get. But I bet its time for a pump, Thankshnoes

I didn't use an 85 pump, just a replacement 82 pump. Didn't find out about that till afterward.:W
I bet Buccaneer has one, maybe he can tell you how to do it.
I guess the only way to be sure about the power connections is to go back and check them for continuity of zero ohms at each connection, but getting a pressure gauge on it is more telling what the result is. You can go back and retrace things if you prove you have a problem first.

 

[Buccaneer]

I'm not entirely sure what your asking in reference to the 85 pump. I'm assuming you are asking if its a direct fit...it is. The 85-87 corvette AC Delco pump comes with a two wire short harness that you can easily adapt to your exsisting one. Cut the two wires, black goes to ground which one should be soldered to the frame of the sending unit already and the other is power. Use heat shrink to go over your connections and your done. Install rubber short line supplied at pump, rubber sleeve around pump and new sock/strainer filter and install pump. I have installed a dozen or so pumps in 82s and 84s and its a piece of cake really. BTW, I use an 85 pump now, but will be switching to a LT1 pump soon. For my application, the 85 pump isn't good enough when running a parallel plummed system at higher pressures at 24+psi.

When your done, put a gauge in-between the TBs and see what the pressure is and set it to 13-14psi and you'll good to go. If you have any other questions, feel free to send me a PM if needed.

 

[jimbil208]

I just read all the posts. I have an '82 sounds like the same problem.
I have a service manual and a laptop hooked up using winaldl.
And I am not have much luck.
Please let me know is you find the trouble BigJim
Thanks