I just bought this 87 C4 about a month ago. it was missing before the test drive but that was corrected with a tune up of plugs and wires and I bought the car. Its been missing badly for about 3 days after 2 weeks of running good. I replaced both maf relays and that made the ses light go away but still missing. Today I replaced the cap, rotor, plugs which all 8 plugs looked good and waiting for the oem factory wires tomorrow. If that doesn't fix it then is there anything else that I should check or take it to a pro as I try to learn this car?
Thanks for your help.

 

well, first thing, Congrats on your purchase !

Next and probaly the most important, locate and BUY a real FSM set. 2 books that will pay for themselves before summer.

If there are no longer any codes, no SES lite, and your description is accurate, a miS-fire at random? all the time? only certain speeds? Or is it coughing and stumbling likes its dying....pretty much all the time? have trouble keeping it running? That bad? or just a minor misfire sometimes..?

Gut says worn out injectors. These are throw aways. If they are stock, toss 'em and call Jon. $250 with all the gaskets and o-rings.

Yu really cannot do much without the FSM and some basic testing..

1st for THIS car would be Ohms test the fuel injectors.

2nd is fuel pressure test and leakdown time.

ICM test and heat/grease bedding.

EGR test. leaking EGR causes coughing, heavy misfiring.

Check ALL electrical plugs and wire.
The C4 is ALL ABOUT its grounds in the harness, NOT hot wires to anything. The work is done thru the ECM and the grounds that the ECM completes or d/c. Thats why you need the FSM electrical book. Solid drawings...very necessary.
Go to the battery and look behind it for a stack of several wires on a post. Thats the jumper post. Clean all those contacts. I've seen that get results like a tune up.

Then go look by the oil filter. See the stack of grounds on a bolt there. Those are the most important of all the ground wires. Clean and reassemble.

Forget the plugs and wires for now. This is HEI. If the plugs are not fouled and the wires not throwing arcs to a ground, its ok. The magic is in the ICM and the injection.
There is a link here somewhere to order NEW FSM copies. You can buy from fleabay for about $75 used for the 2 books.
Good luck !

ps
fuel filter & pump can cause trouble and not set ANY form of code. Thats the only system that CAN cause the car to stall or not start and NOT have a code. Fuel pressure or pump wear.

 

Thank you, I will get the FSM asap. If I am going at a steady speed fast or slow its kinda ok but from there if I slowly give it gas it begins to misfire, shake and shutter and it cant find the low gear for power. It starts fine, doesnt stall out just no power and very ruff running and its like my gosh, it was great just last week. I just got to learn the car and follow the advise given to me by the experts here.
LEESVET, thank you. I am going to get myself ready to perform those test this weekend to see whats going on.

 

After cleaning the grounding connections behind the battery and installing the new ac delco wires since I had already bought them, she was back to running fine again.

Thanks