Help with 350 TBI timing advance

[WayneJ]

back a while ago my truck had that same exact issue. It would run like a top with the timing wire disconnected but the CEL would be on. I changed all kinds of BS trying to cure the issue. Come to find out, it was a loose ground for the ECM. May want to check that.

Where was the loose ground?

 

[redchevy914x4]

it was about 8 years ago but I believe it was behind the glovebox and one of the wires that goes to the ecm but I am not 100% sure on that

 

[streetperf]

Hey everyone. So my truck was my daily driver untill a random misfire turned into a stumble so bad that it would die, and not be able to restart untill hours later. I've changed out the following......map, 02, CTS, iac, distributor, TPS, egr/egr solenoid, and a throttle body I had sitting around. Nothing changed except the position of the cap with the replacement distributor. It had bad valve guide seals. Those were just replaced and now it fires more often and doesn't smoke. But the problem persisted before they were changed.

Through plugging and playing I came to realize that it only runs with the set timing wire disconnected. With it connected it only starts with wot and dies as soon as I let off the gas.....Any ideas? I'm not throwing any codes.

 

[streetperf]

I had a customers vehicle recently doing the same thing. Finally found and I don't know your case but, someone had removed the harness from the retainer by the distributor. After tightening the connector pins to the module, put the harness in the retainer and the vehicle ran and idled like it was supposed to. Connections on computer vehicles are very sensitive.
Take a look and good luck.

 

[WayneJ]

I had a customers vehicle recently doing the same thing. Finally found and I don't know your case but, someone had removed the harness from the retainer by the distributor. After tightening the connector pins to the module, put the harness in the retainer and the vehicle ran and idled like it was supposed to. Connections on computer vehicles are very sensitive.
Take a look and good luck.

Thank you, for the info I'll look into that because I do have a lot of broken, cracked, and half melted connectors. But my problem ended up being a clogged catalytic converter. I removed it on a hunch and hollowed it out. When I threw it all back together the truck ran better than I've ever seen it run. Smoother and stronget than I thought possible from a tbi!

 

[streetperf]

Thank you, for the info I'll look into that because I do have a lot of broken, cracked, and half melted connectors. But my problem ended up being a clogged catalytic converter. I removed it on a hunch and hollowed it out. When I threw it all back together the truck ran better than I've ever seen it run. Smoother and stronget than I thought possible from a tbi!

Wayne, a vacuum gauge should of showed you a clogged cat. A vacuum gauge can show you quite a bit of information in diagnosing a problem.

 

[WayneJ]

Wayne, a vacuum gauge should of showed you a clogged cat. A vacuum gauge can show you quite a bit of information in diagnosing a problem.

You are exactly right!! I ended up replacing my valve guide seals because they smoked on startup. I read somewhere that burning up oil can cause your cat to become clogged. So i pulled the y pipe out and started her up open headers, and by god she ran like a 76k mile tbi should!. So i gutted it out put it all back togethor and shes been my daily driver once again.....untill last weekend when the started broke and refused to do anything other than click the solenoid......I love this truck 1 disappointment at a time.