I have an 89 iroc with a 350 tpi. It has sat for a while here and there for the 12 years I have owned it. I have another car that is my daily driver. The car has always ran good and hasnt given me much problems. I've been wanting to drive it more lately but it had a bad battery. Got a brand new redtop to put in it and started to drive it sometimes. It had a rough idle but still ran fine. The SES light would come on and go out(did for a while) and found out that the O2 sensor lost its ground at the ecm. Fixed that and it ran better but the idle was still rough. Checked my injectors and found 4 that had low ohms. I bought the bosch III's from FIC then the problems started that it didnt have before. It would smoke out the tail pipe after it ran for a few minutes idling, and if you reved it up, it smoked like crazy. I could tell it had a dead miss when I tried to drive it down the road leaving a smoke screen and had to turn right around. Thought I might need a tune-up since it hasnt been done in a while, so I got new plugs, wires, cap, and rotor. Put those in and it ran even worse with smoke pouring out the exhaust. Checked my plug wire routing and everything seemed good. Talked to jon at FIC and he seemed to think that one or more of the injectors was stuck open, which he sent me a new set of injectors. Stuck those in and redid my plug wire routing. Started the engine and it ran alot better, but not right. Checked and set the timing at 6 degrees BTC and the engine idles good. Now, it starts right up and idles great for a while but all of a sudden, it stalls. It starts right back up and idles, but still stalls all of a sudden. If you try to rev it up or hold a higher idle, it spits, sputters, boggs, and backfires. I still get smoke out the tail pipe after it idles for a while. Checked the injector connector routing and it looks like I have the connectors going to the right injectors. Does it matter what connectors are going to each injector? Chiltons manual has a diagram and each bank are wired together and seems to pulse at the same time. Kinda strange. At a loss for what else to look for. Sorry for a long post.

 

you have to start at the beginning.. make sure you have constant fuel pressure at the rail. check tps, should be .57. egr valve could be leaking, you need to check the ignition module, coolant temp sensor, maf and relays, all grounds. at least you know its not injectors, nice of him to send another set. oh it does not matter which injector wire goes to to injectors since its batch fire.. I think. but the FSM will tell you what color goes where.

 

1 more thing.. make sure the IAC is working.. it could be stuck all open, take it apart and make sure you have full pintle travel

 

Thanks for the reply. I replaced the ign. mod when I did the tune-up. but with the problems I got, I put the old one back in with no changes. I know the tps volts are correct. Adjusted that with my scanner. Already checked the iac and its adjusted and working correctly. Have to check the egr system. havent done that yet. Could be an egr problem the more I think about it. Have to check fuel pressure again, but the last time I checked it, it was reading around 44 psi. Everything else seems fine, but I will do some more checking.

 

since you have a scan tool. is the timing being retarded due to a bad knock sensor. use a timing light and see if the timing is being pulled back. also check the voltage to the maf. also double check the three grounds on the ecu and the engine to chassis grounds. keep looking. but egr is still suspect

 

I will check the timing retard issue with my scanner tomorrow. I do have a spare egr valve thats been in my room in the closet. Its good so I will swap it out tomorrow. When I checked the timing, I set it to 6 degrees BTC which should be correct for my car. When I plugged the est bypass wire together, and started it back up, the timing degrees was bouncing around, but showing around 10 degrees BTC on the timing tab with my timing light. Is that normal or should it go advanced? When the est bypass wire is unplugged, it is dead nuts on 6 degrees BTC with no bouncing around. It also seems to idle a whole lot better with the est bypass wire unplugged, but still spits, sputters and wants to backfire when you try to rev it up.

 

the timing should only move with rpm. not bounce at idle. is it going to closed loop? then bouncing.. now the knock sensor is suspect. also is your dist. in good shape, no shaft wobble is the pick up good. the egr will cause the engine to suck air and stall out.. try propane and check for a vac leak.. that timing bounce, i don't like

 

The last time the engine was running ok and before I did any of this work, the ecm was going into closed loop. I havent checked it since doing this work. Before, it wasnt going into closed loop due to my O2 sensor not switching because it lost its gound at the ecm. The O2 sensor was reading .45 volts at all times and not switching from rich to lean. Checked the O2 ground at the ecm and there was none, so I made my own ground for now till I can fix it right. Did that and I got O2 sensor counts and switching from rich to lean on my scanner. Havent checked to knock sensor, but I do have a spare one and might try throwing it in to see if that helps, but I want to check it with my scanner first. The engine seems to run smooth when the engine cools off some, but after about a minute of running, it starts to run a little rough and stalls, like when the ecm goes into closed loop. Just need to check it out with my scanner tomorrow. Thanks for the help and I will keep you posted.

 

Your fuel system could be full of varnish/rust from setting, this can dirty a clean set of injectors.

Most injector cleaners have alcohol in them (also a lot of gasolines), it dissolves the varnish.

Water (from humid air) can condense in fuel line/tank over time and rust a bunch of stuff.

Talk to Jon at FIC again and see if he has any suggestions about what to use to clean the rest of the system.

 

Ok. I hooked up my scanner and looked at all the parameters. No knock signal detected. It is going into closed loop. O2 is switching. Block learn is 128. Intergrator is 128. IAC at 160. TPS at .55. About the timing bouncing around when running with the est bypass wire plugged in. I think I said it wrong. Like I said, with the est wire disconnected, the timing degrees is dead nuts on 6 degrees btc with no movement, since the engine is running smooth at idle. It idles great with the est wire disconnected and no stalling, but still cant rev it up without it spitting and sputtering and backfiring. When I plug the est wire back together, the timing jumps to 10 degrees btc(is the timing suppose to retard, advance or stay about the same with the est wire plugged in?), but starts to jump around as the engine starts to idle rough. It runs a little rough and smooths out(back and forth) but mainly runs smooth till it stalls at idle which doesnt take long. About a minute or so. The rough running part accounts for the timing jumping around. The fuel system is fine. No varnish or rust. The inside of the fuel rail is squeaky clean with no discoloration. Pretty sure its not a fuel problem. I still suspect the egr valve. Got to let the engine cool down so I can change it. I think it could be something with the distibutor. It didnt act up like this till did the tune-up. Maybe a problem with the pick-up coil. Could of damaged it when I changed the ign. mod. Will keep you posted.

 

Fixed it. Turns out that I had the ign. mod wires backwards where the two pick-up coil wires plug into the ign. mod inside the distributor. The plastic part of the connector was really brittle and there was not much left of it and I ended up plugging it in backwards. Looked in my chiltons manual and it showed what colors went to what pins and it was backwards. Plugged it in right, started it up, reset the timing and it idles nice and smooth and it revs up now. Great throttle response and no smoke coming out the tail pipes. Still, that doesnt explain the smoke out the tail pipes when I first changed the injectors. Must of had a bad injector. Doesnt smoke with the replacements jon sent me. I got to send the first set back to him and I will have him let me know if one was bad. Thanks irocuroc for all your help. You've been a real pal. Now I got to let it cool off so I can get my plug wires back in there holders and take it for a drive. Thanks again.