Hi All,

I own a 1982 Corvette with the Crossfire injection, I have owned it for 18 years with zero issues. But the engine was in need of an overhaul. Lucky me, I found a complete rebuild 1982 Corvette engine/tranny combo for a decent price, less expensive that rebuilding my own. Fresh rebuild with all new parts, including the throttle bodies that were rebuilt by DCS and other new parts. Not being mechanical minded, I found a local auto shop that claimed to have experience with Crossfire Corvettes to do the swap. Well it took much longer for the swap than I was told, and they finally got it running again, if you can call it running. The engine starts and runs, idles fine. But drivability is terrible, will not shift correctly, seems to lose power, and it is not repeatable, sometimes it seem fine, others terrible.

So I have a few questions. If the Crossfire injection is way out of whack/balance, would that make the transmission shifting out of whack? Seems to me I read that is all controlled by the computer bases on feedback. They also removed some "smog" parts that they said were not necessarily needed, would that have an affect on computer function related to engine and transmission performance?

The car is basically undriveable currently, it will not shift properly, I don't think it ever shifted to Drive when I test drove it. The owner is blaming it on the engine and transmission, saying I got taken, but I have confidence in the seller as have has been nothing but standup and all of his references are top notch, he has been in the engine rebuilding business for 30 years and the transmission and throttle bodies were sent to experts for their rebuilds.

I just don't know how bad the Crossfire being out of sync affects the rest of the performance of the car, transmission shifting specifically.

Thanks for any input, it is greatly appreciated.

 

Has anyone checked the computer for error codes?

 

I think you may have several problems.one may be a vac leak .two the trany cable is not adj right.three I would check the balance of the tbs. four check timing .five check fuel pressure.i don't think you have a bad motor or trany ,you need someone to do some checking.

 

the trans is most likely the TV cable adjustment. Remember , you'd rather be too tight (delayed up shifts) than too loose.
Your car is definitely in a learn mode. So crazy idle and and surging will happen but should get better with time. You should not be experiencing any major bogging, popping or misfires.
Timing is always an issue on these cars because the timing mark moves on the balancer. This means you have to time it by ear and feel. If wide open throttle WOT runs are up and down, I would install a remote fuel pressure gauge. If the regulator is sticking, it will cause all kinds of crazy driving issues

 

The mechanic I hired went on and on about his experience with '82, '84 and '85 Vette's and the Crossfire injection intake system, that's why I went to him in the first place. But after 3 months, and now seeing how the car is running after the replacement, I am having major concerns on his shops abilities. I assumed he would know all the things you guys have already stated.

Apparently he has a Corvette restoration expert working on the car today, who said he will have it tuned and working perfectly by the end of the day. Fingers crossed.

Just don't know how far I let this mechanic go before I have to pull the plug and find a better mechanic, or take all the advice on these forum boards and become an at home mechanic on my own. Everything that I have read on the Crossfire seems fairly basic, its just knowing what to do and in what order.

Thanks for the input to this point, very educating.

 

This type of thing ....situation is going to get get worse ....all these sensor , computer , electronic cars will die and there will be no cost effective rebuild s for those not able to completely disassemble and reassemble and tune up their C4 C7 engines.

One poor guy at the local gym took his Late C4 to 6 may be 10 different so called corvette mechanics before he got his car straight . About 6 months ...finally after replacing half the parts on the motor it ran ok once again. They all were guessing , none really knew how to make it run correctly.....bleak outlook.
The Chevy dealers won't touch these old cars . Unless you are specifically into racing and building these engines as a hobby ....most guys in 15 years will be priced right out of fixing up any of these computer motors.

Buy old school and drive.

 

One issue that is often overlooks by "mechanics" is the cleanliness of the connections on the ECM....particularly the grounding point[s]. You need to remove all the connections and use Q-Tips and alcohol to clean every conductor; then put some dielectric grease on those contacts, reinstall the connectors, and make sure that all are tight.

For a ground wire from the ECM, you need to trace it back to the 'chassis ground' point, remove any screw/lug, clean it all very well (ScotchBrite, etc), reattach, and put a bit of dielectric grease on places where air/water/moisture can seep in.

Then, operate the car for a few more days to see how it's doing. If you still have troubles, use the OBD system to spit-out any error codes [do internet search on how to do this on your '82] and also find an error code table for it. If your ECM is working properly, it should help you diagnose any electric-related problems that exist.

 

The ECM should be working fine, as it was running very good with the original engine and tranny in it, it was just tired and had leaks all over and needed a good overhaul, but I found these freshly/professionally rebuilt engine and tranny for a much better price. So unless connections got messed up during the replacement, my guess is that should not be an issue. I do have an OBD reader in the car, if he chooses to use it or not?!? From reading the replies here and researching the suggestions further, I believe the tranny issues are related to the TV cable at least it sound familiar to that. And the engine noise I believe is just timing and valve train adjustment. Just not sure why the mechanic is having so much trouble with it as the descriptions online sound so basic and easy to follow, was expecting this mechanic to be pretty good, starting to question it now though.

 

Just curious here... did they tell you what "unnecessary" "smog parts" they removed?

 

I was going to ask the same question - the ECM is looking for several signals. Could be a BIG deal if the guy arbitrarily started removing stuff Also, what codes is it throwing?? The shop manual will point you, at least to the basics.

 

No they didn't tell me what smog parts they removed, just that they have done this many times before without any issues. Last word, the engine is purring like a kitten and running perfect.

But the tranny is a mess, at least the shifting is. It starts out in low gear, but jumps to overdrive very quickly, and bogs down, and will not down shift. Supposedly 2 tranny experts have looked at it and cannot get it to shift correctly.

Have no idea where to go from here, other than taking it to someone else. What a mess.

 

so the shop owner said that you got taken on the motor and trany deal but.. .Now the motor is running like a kitten.Sounds like It took them a little bit to learn about cross-fires.The trany could have a valve body change or the cable still not right but I would check does your ecm have the correct prom?The factory had a recall on the proms and the aftermarket has one that delays the up shift.