Here's the issue (I've searched but can't find the same problem). I've got an 89 formula. 350 w/ 305 intake/tb. The motor and ignition is brand new. On start up, the engine does 1 of 2 things. 1) completely dies or 2) drops to 300 rpm and catches itself. If it stays running the rpm ranges from about 450-700/750, the whole time the exhaust wreaks of gas. Under light acceleration (like backing out of a driveway) the engine power surges. With the air cleaner assembly off, I can see gas building up on the throttle plates and going down around the edges. If I tap the gas the engine dies. Going down the road it doesn't run that bad however. I've replaced the iac with a brand new one, switched the tps with one off of a leftover tbi unit, and I've got an o2 sensor waiting to be put in. I've also had the fuel pressure regulator suggested to me. Does anyone have any suggestions or has had the same problem? If the problem doesn't go away after the o2 sensor I'll probably just switch the tb with my leftover one.

 

fuel pressure regulator, bad injectors. could even be a faulty coolant temp sensor, telling the computer to dump more fuel than is really needed.

 

hmmm, ill put a new regulator in the old unit and just swap the whole thing. ive heard a lot of different fixes from a lot of different people. people have told me the tbs cause a similar problem on theirs so i switched it and nothing. there are no vacuum leaks, i used a can of carb cleaner to make sure

if it was a coolant temp sensor, would that show on the gauge? my car apparently only runs at 155-165 degrees.

 

no the coolant temp sensor sends a signal to the computer its about 15 bucks. its located on the intake manifold by the thermostat housing.

 

well now something new happened. i got bored and decided to go for a drive. drove around for about an hour and a half. parked. left again and got the "Service Engine Soon". checked the codes and nothing came up. kept flashing 12. finally i got a 44, which is lean exhaust. is it possible that my whole ecm is just shot? ive talked to a guy that had an iroc tbi and had to replace the whole ecm. if thats the case, ill probably just switch to tpi.

 

iac: replaced
tps: swapped
o2 sensor: replaced
coolant temp sensor: replaced
fuel pressure regulator: replaced

what else could it be? i switched the regulator with one for a 91 caprice since they had 350 tbi. is it possible that the computer is just shot?

 

anyone have a similar problem?

 

Is the ign. timing set right? Did you unhook the timing conector while setting it? Maybe the balancer has slipped, try different dist. postions.
These engines are really sensitive to engine vacuum (map sensor), needs to have over 17.5" at idle(could be timing or map on the wrong vacuum connection), get a gauge & check the different ports for the highest reading. Hook the map sensor to that one.
Maybe the ecm grounds are loose or dirty, they are on the back of the heads. You can also check the ecm grounds at the ecm connector pin outs, try tapping the ecm while its running to see if it runs better or worse.

 

alright, ill check all of that out. is it possible that the computer is just shot? im confused as to why the computer is telling me the exhaust is lean when its obviously not

 

What is history of car? New purchase? 350 swap apparently. 305 injectors? Did you obtain a corrected chip?

 

at 125k miles the 305 was swapped for a new 350 gopher motor. everything else was kept 305. im not sure what all he did to make it correct. after replacing everything i did and the randomly listed codes from the computer, and the lean exhaust code when its burning way too rich, i was told that the com is junk today. ill just replace it and the memcal.

 

Key on engine off the CE light will blink once then steady on. That will validate car is running off a good prom/ECU....Key on engine off if it radidly flashes then prom is culprit. If key on engine off and a solid on CE with no blink the ECU could be suspect. There is a code for bad ECU.

 

well im getting a blink and a solid. everyone else is telling me the ecu is bad though. after everything thats been replaced it shouldnt be running so rich. ive also talked to a few people that have told me they had the same problem and it went away after they replaced the ecu. at this point, im not sure. all i know is im getting a lean exhaust code with extremely rich exhaust and everything ive been told to replace hasnt helped except for easier start ups