Ok so I have a 1989 4.3 tbi. I recently/currently restored it. After I got it back on the road from completely tearing it down and rebuilding it back it drove great. Then the Ignition control module went out. Replaced it and it ran great again,then the pick up coil went out. Since I've removed the distributor its been a battle. I got the timing off in the process trying to rush because of always being to busy,Finally took it to a shady mechanic to fix. When I got it back it would crank but idling was up and down. I replaced the ECM upon his advice and it changed nothing. Today I finally got the time to work on it and replaced the TPS. Now it drives ok,and no longer cuts itself off but still idles up and down. Im at a loss now as to what I can do to smooth it out. I have a few ideas but any feedback would be greatly appreciated. I have brand new distributor,cap,rotor,plugs,wires,fuel pump,filter,TPI,ignition control module,pick up coil. Ive also timed it with a light.

 

If you adjusted timing as described in post #2, you shouldn't need to time it again, unless you move the distributor.

 

Timing seems to be fine now. It runs ok while driving down the road now,and it hasn't cut itself off,but its still not idling like it should. Any sugestions as to why?

 

Still no check engine light through all this work and trouble?
If you have had all that stuff bad you could look at the MAP sensor. Use a scanner and compare that to a vacuum gauge. It takes some learning but supposedly a vacuum gauge can tell a lot about how an engine is running.
TBI is a very forgiving form of EFI. As long as the distributor, TPS, MAP, and air/coolant temp sensors are good you should not have any problems.
You could also verify the EGR is working properly and not stuck open.

 

The check engine light has been on for a couple months,but yesterday was the first time it's actually flashed a code,and I replaced the TPS. When I replaced that yesterday it finally went away. The MAP sensor has been checked,and its fine. I've thought about the EGR and the IAC. I was told my timing chain was to worn to set properly,and a buddy came by with a timing light yesterday and I believe that it may actually be true.

 

Ok so I drove it today and it's driving me crazy. I crunk it up the first time and its hesitant but always fires,idles for maybe a minute and chokes out. I get in it and drive it and as long as im cruising at 50-55 it drives like a champ,but when im barely moving its acting like its starving for power and wanting to cut out. I took it to the park where I was just slowly getting around and it stalled twice. Got back on the highway and it ran great,even while idling at red light. Then got it home and through it in park and it idled fine until i cut it off. Crunk it back up and as usual a little off but fired right up and started out high idle and came down to normal until I cut it off. Any suggestions?

 

See what the Captain thinks, but it sounds like it's running rich and flooding out. Start by cleaning the Idle Air Motor in the side of the TBI. Follow that with checking coolant and air temp sensors and possibly O2 sensor. Next time you start it cold, try pulling a spark plug after it dies and let us know what it looks like.

If you don't have a scanner with realtime data, I use WinALDL which is a free download and they have diagrams for a homemade cable that connects to a laptop. If you don't feel like making one there are some for sale online for pretty cheap.

 

Well thats what gets me. When im driving down the road with acceleration it runs great,not a skip or mis. And it seems like the longer it drives the more consistent it is. Right now my philosophy is a vacuum leak. Which actually could be that the guy I had working on it unplugged something,which he's done to me before,an forgot to hook it back up. I also have issues with my AC not blowing like it should and I know that's vacuum related. Is there any place I can look for diagrams on the vacuum lines for it. My plan at this moment is to drive it the rest of the week and see if that works the kinks out. Im on vacation next week so if it doesn't I'll at least have a better idea and the time to get my hands dirty.

 

Well, it's easy to start by unplugging all non-esential vacuum lines (everything but the brakes). Then plug things in one at a time until the problem comes back.
Besides that I can't remember if you said you checked to make sure the EGR was not stuck open. That can cause a very rough idle almost to the point of dying.

 

Well drove it today and at this point im 100% sure its air related. I have an aftermarket k&n and when it starts skipping it sounds like its suCking air. It drives great while accelerating down the road,but when i have to let off it always starts skipping and even stahls out on occasion. At cold start its a struggle and everything fuel and fire is brand new so here I am at that point