I have a 1985corvette popping out of the intake when I try to accelerate,bogs down and pops loudly,car is undriveable and gives code 41 cylinder select error. It has a new computer with the old prom switched over. I installed by the directions appears to be installed correctly. Also can't get the egr to work, manifold vacuum is present but seems like not enough ,not sure. I bypassed the solenoid straight vacuum to egr ,still doesn't open when throttle s down. I pressed up on the egr and held the vacuum hole closed with my finger, it held vacuum until I released it. Any help would be greatly appreciated. Thanks!


jec327

 

It sounds very much like it's radically out of time. Has the distributor been rotated somehow? Could the wires have been put on the cap wrong?
Ron

 

no, the distributor has been checked and is sitting on number one cylinder on the compression stroke and firing order is correct.

 

The other possibilities could be the timing chain has jumped a tooth or there is a thing called ESC(electronic spark control) that adjusts the timing when the knock sensor triggers it,could it be that?
Ron

 

not getting codes for ESC but what are the possibilities of a burned valve?

 

Yeah,that's a good possibility,a compression check,or better yet,a leakdown test would show that. It would also show jumped time, they would all be uniformly low.
Did this just start happening? Was there some work done on something?
Ron

 

This has been a project car for a couple of years now. I bought it cheap to restore. I work alot and workon it when I can. It was non-running when I bought it and I got it to run with a squirt of brake-kleen in the intake for a few seconds. I new it had a fuel problem right away, I pulled the injectors and they were full of water and gunk, so I bought used injectors from a junkyard and installed them ,got it to run but runs rough and pops,not so sure that they are all functioning correctly. Fuel pressure is good and strong, new fuel pump. I'm Considering replacing the injectors with new ones. Thanks for the help and It's awesome to see Jesus is Lord on your reply.

 

Possibly a worn cam lobe. You can check this by removing the valve covers, run the engine, watch and see if all the rocker arms have the same amount of travel. If you find one that's not, it's more than likely the culprit.

 

Hi JEC,

Before you drive yourself crazy with the diagnosis - pick up a VACUUM GAUGE.

If the valves are leaking - it will have a violently swinging needle.

If the vacuum is low - it will point towards valve timing.

Much easier to use than a compression test or leakdown - although they both have their merits.....