1982 Crossfire issues
Thread Starter
7th Gear
Joined: Dec 2024
Posts: 7
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1982 Crossfire issues
Didn’t really find anything in the threads but here’s my issue. At one time my idle wouldn’t come down below 1200 rpm’s. I replaced both idle controls and fixed it. Now, when warming up the rpm’s drop to about 550 and then the engine states to “lope”. Rpm’s will go from 500 to 1500 repeatedly. Up down, up down. Seems fine on the road but the initial warm up sucks, not knowing if it’s going to die or what. Any ideas? I have removed the battery cables numerous times to make it relearn what it’s supposed to do. First crossfire injection I have ever worked on.
Melting Slicks
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From: Phoenix, AZ to Quakertown, PA.
C6 of Year Finalist (appearance mods) 2019
Racer
Joined: Aug 2015
Posts: 384
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From: Pine Ridge FL
Do you have a shop manual? You'll need it for diagnoses. You could have a coolant MAP sensor, a big vacuum, or stuck EGR just to name a few examples.
I assume no check engine light? Does it idle OK after it warms up?
Start with a visual inspection paying attention to the vacuum hoses and wires. Then you are going to have go through the process of elimination. The shop manual walks you through with flow diagrams.
I assume no check engine light? Does it idle OK after it warms up?
Start with a visual inspection paying attention to the vacuum hoses and wires. Then you are going to have go through the process of elimination. The shop manual walks you through with flow diagrams.
Thread Starter
7th Gear
Joined: Dec 2024
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I do have a shop manual and looked at everything. I was a mechanic when I was younger and usually fair at diagnostics. I’ll look at the EGR since I’ve pretty much exhausted everything else. Didn’t know if it was cross fire related or not. I can rebuild a quadrajet in the dark but this is a bit new to me. Thanks for the assist!
Safety Car
Joined: Nov 2005
Posts: 3,532
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From: Arizona - If you don’t know CFI, STOP proliferating the myths around it...
I do have a shop manual and looked at everything. I was a mechanic when I was younger and usually fair at diagnostics. I’ll look at the EGR since I’ve pretty much exhausted everything else. Didn’t know if it was cross fire related or not. I can rebuild a quadrajet in the dark but this is a bit new to me. Thanks for the assist!
Melting Slicks
Joined: Aug 2003
Posts: 3,416
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From: dayton oh
Idle surging is usually a sign of a vacuum leak. Most Xfire intakes eventually leak from the manifold top plate (the trapezoid piece the TBIs bolt to) -- reseal it with "Great stuff" gasket maker and call it a day
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Safety Car
Joined: Nov 2005
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From: Arizona - If you don’t know CFI, STOP proliferating the myths around it...
So, I was going to go with the vacuum leak like Dean had mentioned, but they always run like crap cold and warm at idle. Driving the car down the road with foot on gas you don't see that type of thing. So, does it seek idle up and down all the time or just cold idle? One other thing, did this happen out of nowhere or did you do something else and then it started idling funny? The NO CEL light means that the ECM is happy with the way it is running, which is a bit odd, but I've seen stranger things with CFI.
Thread Starter
7th Gear
Joined: Dec 2024
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The increase-decrease idle is usually when initially starting the car and letting it warm up. Checked once again and couldn’t find a vacuum leak. I could learn to live with it but I like everything to be 100%. I had an issue with high idle and fixed that with new idle controllers. Seems to have started after that or the issue was masked by the high idle.
Instructor
Joined: Aug 2023
Posts: 206
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From: San Antonio, TX
One thing that comes to my mind was balancing the throttle bodies. It would come down RPM wise to around 500 and then shoot back up to 1100+ and then back down. Sometimes it would seem like it was going to stall and then would rev back up. Once I balanced the throttle bodies it made a huge difference in RPMs. Now when I fire it up it shoots up to 1100 or so and then comes back down and its nice and happy. But I wouldn't rule out a vacuum leak either. As Fast81 mentioned, the gasket on the top plate could be bad. I found a leak on mine near the EGR. I also tracked down/isolated vacuum issues by plugging the source (found behind the rear throttle body). Once I found things leveled out I slowly added things back and ended up finding that one of the headlight actuators had a leak.
Racer
Joined: Aug 2015
Posts: 384
Likes: 144
From: Pine Ridge FL
The increase-decrease idle is usually when initially starting the car and letting it warm up. Checked once again and couldn’t find a vacuum leak. I could learn to live with it but I like everything to be 100%. I had an issue with high idle and fixed that with new idle controllers. Seems to have started after that or the issue was masked by the high idle.
Checking the TBI balance is a good idea. The process to check that takes the IAC out of the loop so would be interesting to see how it runs during that. It's possible that if you used aftermarket IACs one of them is not working right. Check this video out:
Safety Car
Joined: Nov 2005
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From: Arizona - If you don’t know CFI, STOP proliferating the myths around it...
OK, things to check are, but limited to and not in this order, CTS sensor, verify there is no vacuum leaks on the top plate or any place else, EGR and TB balance. How many miles are on the car?
Thread Starter
7th Gear
Joined: Dec 2024
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The 82 has 42,000 miles on it. Not sure what actually fixed it but after changing plugs, wires, cap, adjusted the timing and cleaned the EGR valve it seems to have settled down. BTW, I’m ordering a GM EGR valve today. Thank you all so much for the help with this issue, I’ll figure it out someday, meanwhile I will be following this forum religiously!!
Racer
Joined: Aug 2015
Posts: 384
Likes: 144
From: Pine Ridge FL
The 82 has 42,000 miles on it. Not sure what actually fixed it but after changing plugs, wires, cap, adjusted the timing and cleaned the EGR valve it seems to have settled down. BTW, I’m ordering a GM EGR valve today. Thank you all so much for the help with this issue, I’ll figure it out someday, meanwhile I will be following this forum religiously!!
Instructor
Joined: Nov 2020
Posts: 128
Likes: 37
From: Brentwood, Tennessee
82 idle problem
Didn’t really find anything in the threads but here’s my issue. At one time my idle wouldn’t come down below 1200 rpm’s. I replaced both idle controls and fixed it. Now, when warming up the rpm’s drop to about 550 and then the engine states to “lope”. Rpm’s will go from 500 to 1500 repeatedly. Up down, up down. Seems fine on the road but the initial warm up sucks, not knowing if it’s going to die or what. Any ideas? I have removed the battery cables numerous times to make it relearn what it’s supposed to do. First crossfire injection I have ever worked on.
Safety Car
Joined: Nov 2005
Posts: 3,532
Likes: 1,185
From: Arizona - If you don’t know CFI, STOP proliferating the myths around it...
Had the same problem on an 82 I had. Turned out to be split hose on the fuel pump. Would idle wildly until the computer compensated and would run fine. Do not know if this is your problem but you might want to check if it has been a while since the sending unit has been out.
Advanced
Joined: Oct 2024
Posts: 80
Likes: 21
From: Michigan
Check for an ECM code anyway. The baud rate (data sampling) is very slow on this ECM. The idle drop could be caused by a condition that would set a a code, but as the idle goes up, the condition changes and may be in expected parameters. A code may set without an SEL illuminating. Sometimes not, but I check anyway.
At engine shut off, the ECM cycles the Idle Air Control solenoid(s) by moving the pintels out to full stop, keeps track of the step counts, then moves the pintels to start position using the base step count data stored in the prom (ROM). If you disconnect battery before the next start, consider doing this after battery is reconnected: 1. Turn key to "ON" (do not start). 2. Turn key to "OFF" and wait 1 minute (not an exact time, but sufficient to allow ECM to cycle the the IACs). 3. Then turn key to start engine. This may not change engine idle performance, but it may exclude some clues.
At engine shut off, the ECM cycles the Idle Air Control solenoid(s) by moving the pintels out to full stop, keeps track of the step counts, then moves the pintels to start position using the base step count data stored in the prom (ROM). If you disconnect battery before the next start, consider doing this after battery is reconnected: 1. Turn key to "ON" (do not start). 2. Turn key to "OFF" and wait 1 minute (not an exact time, but sufficient to allow ECM to cycle the the IACs). 3. Then turn key to start engine. This may not change engine idle performance, but it may exclude some clues.
Safety Car
Joined: Nov 2005
Posts: 3,532
Likes: 1,185
From: Arizona - If you don’t know CFI, STOP proliferating the myths around it...
Check for an ECM code anyway. The baud rate (data sampling) is very slow on this ECM. The idle drop could be caused by a condition that would set a a code, but as the idle goes up, the condition changes and may be in expected parameters. A code may set without an SEL illuminating. Sometimes not, but I check anyway.
At engine shut off, the ECM cycles the Idle Air Control solenoid(s) by moving the pintels out to full stop, keeps track of the step counts, then moves the pintels to start position using the base step count data stored in the prom (ROM). If you disconnect battery before the next start, consider doing this after battery is reconnected: 1. Turn key to "ON" (do not start). 2. Turn key to "OFF" and wait 1 minute (not an exact time, but sufficient to allow ECM to cycle the the IACs). 3. Then turn key to start engine. This may not change engine idle performance, but it may exclude some clues.
At engine shut off, the ECM cycles the Idle Air Control solenoid(s) by moving the pintels out to full stop, keeps track of the step counts, then moves the pintels to start position using the base step count data stored in the prom (ROM). If you disconnect battery before the next start, consider doing this after battery is reconnected: 1. Turn key to "ON" (do not start). 2. Turn key to "OFF" and wait 1 minute (not an exact time, but sufficient to allow ECM to cycle the the IACs). 3. Then turn key to start engine. This may not change engine idle performance, but it may exclude some clues.
Instructor
Joined: Nov 2020
Posts: 128
Likes: 37
From: Brentwood, Tennessee
82 Crossfire idle
OK, this is very odd to me on the fix. I've seen a fair share of these types of issues over the years. However, when this happens, it isn't just happening on a cold start/warmup type of thing, it is always happening which makes sense, since your fuel pressure would be affected 100% of the time. I don't see how the ECM comes into play with type of issue, your fuel pressure would suffer and if anything it would run lean or not at all. Typically, a wild surging or high idle in from a vacuum leak, but can be other things as well. You got it fixed, so that's a good thing.