Help with 350 TBI timing advance

[WayneJ]

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.

 

[Black_cirrus]

Is it a quality ignition module in the distributor? I prefer Ac delco but most important is that it is NOT a no name chip.

 

[Black_cirrus]

Also try to check fuel pressure, I know it's hard to do on tbi. But my first car acted like that when the fuel pump was dieing.

 

[magimerlin]

You didn't mention sparkplugs as being looked at or replaced... I need to do valve seals on my 94 but till then when it starts getting a pretty bad miss I know it's time to change the plugs..... they get pretty bad....

sent from what use to be a great country...

 

[WayneJ]

Plugs and wires have been changed, and the ignition module was changed when I swapped distributors. I attempted to check fuel pressure a few months ago because I a had a lean condition, but that ended up being a 02 that got ruined thanks to the bad valve guides. Thanks gauge that I used must have been broken though because it read in the high 20s and the glass was missing from the gauge. I'll try again with a different tool though. Do I just put it in line with the fuel filter? Also is there a way to put the ECM in learn mode?

 

[Black_cirrus]

You swapped tb's did you put your new iac into it? Is the passage clear for the iac?

Tbi computers don't have much to learn I've had several scan tools on several trucks and never seen a learn mode that I recall. There might be some adaptive for the trans on 94&95s. You can always disconnect the battery.

 

[sntrym]

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.

How does it run with the timing wire disconnected? Have you driven it with it disconnected? If it runs fine, it's probably not fuel pressure. My guess is you have a bad sensor, whether it's the new IAC, knock sensor, or anything else you replaced. It would not be EGR since you're not running in Closed Loop mode yet.

When you set the timing with the wire disconnected, are you setting it to 0*?

 

[WayneJ]

It was set to zero when the truck started having these issues, since I have replaced the distributor, I have not used a timing light to get 0 again, but that's only because nothing has changed as far as symptoms. When starting with the wire connected it will crank and have multiple sudden stops in cranking, then sputter for a second and die. It also seems to be flooding with it connected. But spray pattern looks much better with it disconnected.

 

[redchevy914x4]

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.

 

[WayneJ]

Hmm good idea, I did find a random black wire in my engine harness that was just hanging out of the harness. However there was no other side or cut wire. I'll ground it to the firewall and see what happens. Also I reset the computer and now I can get it to run, but it's a low idle and still has the misfire. Is there a way that I can upload videos?