I guess that I don't totally understand the reading of the codes as outlined in the factory service manual for my '82 cross fire. Intermittently, my "check engine" light comes on, and goes out after a few minutes. When it is on, the idle surges from about 400rpm to 800rpm back and forth (in neutral or park), and the engine stalls when putting it in gear. If I keep the rpm up and put it in gear to get moving, I spin the wheels (of course) and it seems to run fine even with the light on. After stalling, when firing up the engine again, I can see a hint of smoke coming out of the exhaust indicating a rich fuel condition. By the time I get home and check the codes, the light is alway out. I do get a 12 reading indicating the self diagnosis is activated and working properly. I then get a reading of 21 (in sequences) followed by 22, indicating throtle position sensor voltage abnormalities. If code 21 is signal voltage high and 22 is signal voltage low, what is going on here? I did check the voltage at the TPS and it reads .515, well within the limits, but then again, the CE light is off. The car has 72K original miles on it and it is, what I believe, the original TPS. This sporadic problem leads me to believe that I either have a weak ground somewhere or possibly some corrosion in a wire harness connector, or even a faulty ECU. Visually, I cannot see any problem when checking the wiring. Anybody have any similar issues or have an idea of where else to check? I know from past experiences that intermittent problems can lead a person to drink excessively. Not than any of us need an excuse, but it helps! HELP!!!!!!!

 

One of the biggest causes of problems on the '82's are vacuum leaks.
I had a bad connector at the ECU and it shut down the whole electrical system. They don't make them anymore so I took it out and hard wired it instead. Try that connector (big one at the ECU on the firewall, just to the pass. side of the distributer) check for corrosion, & etc.
It could be the temp. sensor, if the computer get variouis signals it thinks the engine is cold, then hot, then cold, and trys to compensate.
The list gos on and on. That's why I put a ZZ4 crate engine in mine, got tired of getting stuck out on the road.
Good luck with it.
Dave

 

Hmmm....never thought of a vacuum problem at the ECU or even a temp sensor malfunction. I thought the ECU was in the battery compartment behind the driver's seat. This is my first encounter with injection problems, but I am not afraid to tackle this one. I'll check it out this afternoon when it warms up a bit and see what I can see.Thanks for the thoughts, Dave, and hopefully it will be something minor and not a faulty ECU. I'd like to keep the ole '82 CE as original looking as possible and still be reliable. But I can appreciate the ZZ4 power that you installed in yours. It is to be envied.

 

The computer is in the Battery compartment, the Engine control unit is on the firewall.

 

Oops! Thank you for the correction. My Faux pas!!!!!
I didn't get a chance to check it out the other day, as my wife had plans for me that I wasn't aware of. Can anybody relate to that????

 

Andy, tps should be closer to 500ma . I have found the first thing to do with a CFI w/ many miles is bump the timing up. Drive it for a day and then see if there is any improvement. Also check the EGR valve by lifting up the plunger underneath. The engine should stumble then recover once you let go of the plunger.

 

The computer wants to see a TPS signal that compares favorably with the other sensor readings that it sees. If the TPS signal is out of range, it sets a code. This might be why you get both codes. You need to check the TPS as you open the throttle for a smooth imput up through the range. It could be that the signal is not steady as it moves up. The repair manuals have detailed flow charts for checking all systems.

 

I'll give that a shot too, the first chance I get. Thanks!!!

 

Hmmmm....I think that I have read the factory manual on the chapter dealing with the injection system over and over, and I don't recall seeing a flow chart like that. However, I may be wrong. I have some downtime this weekend and will go through the manual again. The pages are getting pretty dog eared in that section and the charts are flooding my dreams at night.....all to no avail. What you say makes sense to me, but it is strange that I have an intermittent CE light that comes and goes. Some local gearheads take the stance that a TPS either works or not at all. Kinda like virginity.....no inbetweens!

Yesterday, I popped the hood, cleaned and checked all the wire harness connectors, checked the tightening of the throttle bodies, water temp sensor connector, and replaced a somewhat cracked EGR vacuum line off of the intake. Everything was fine for 30 minutes of driving, and when I returned home to jockey the car into its parking spot, the CE light came on again. I was too frustrated and it was getting dark to fool with it any more.

I thought I was on the down home stretch with this car after fighting brake issues for nearly 5 months, only to have this ugly dragon rear its ugly head.

I'll do some more checking and testing once I can devote an entire day or weekend just on this one problem. But again, thanks so much for the tip.

Andy, The Intermittent!!!!

 

Its most likely the connection to the TPS. I have had this happen to me. The plug in a new TPS would not seat right. I put the old one back in and the problem solved it self. I guess the new TPS could also have been faulty who knows.

But I would first check the connector....I was able to recreate the problem by gently moving the wires. make sure the pins and plugs inside the connector and TPS are moisture free and create a firm connection.

There is also one other not commonly know connection. Its inside the box on your fire wall. Follow the harness around from the TPS to where it enters into the firewall. Remove the box...its actually just a cover. You will find several large connectors there. I found visible corrosion on the pins in mine. Clean them up good.

Hope this helps.

Jim

 

Thanks, Jim. Already been there and done that on the connectors at the firewall. Everything looked good and clean with no moister or corrosion. I blew the contacts with an air hose and plugged/unplugged the connectors several times to assure a good contact. I have a new TPS on order now. Let's see what that creates and/or solves. Thanks for the input.