crookedbowtie

Been having hot starting problems. Blew grey/black smoke out the intake. right when it started. Backfired slightly before starting the time before that. What does this mean? I am afraid to try and start it again.
This happened right after replacing the ICM and coil. Did it just get flooded and "cough" the exhaust out the intake?WTF it almost seemed like the motor ran backwards!

daniel6718

iTrader: (36)

you mixed up plug wire i bet...

robsquikz28

iTrader: (246)

what made u change the icm and coil????

crookedbowtie

Uh,oh I was hoping that word wouldn't come up! It looks bone dry and the truck is under cover. It hasn't done that before, although I did pressure was the heck out of the motor before I put it in 2 months ago, but it hasn't displayed this exact problem (the smoke) ever before and it runs and revs really good when it starts, just idles a bit high. It also has no problem staring cold. Timing?? flooded?? I was starting it several times in a row close together. Please anything, but the opti.

crookedbowtie

Plug wires are unchanged from running it previously and it had no misses.

crookedbowtie

After I would run it and get the motor warm, the motor would just crank and crank, but no fire. I did however have spark it just looked a little week. I thought the ICM might be suffering from heat soak, because it tested good several times. I spaced the coil an ICM from the head and put new diectric grease between it and its sink, warmed it up and shut her down, started several times. I walked away came back 5 minutes later and crank,crank,crank...no fire. Tested the coil before this and while it was having the problem warm...both times within spec..matched the new coil. Out of desperation replaced it anyway (cheaper than the ICM) no hot start, replaced the ICM. She started with a little gas almost like it was flooded from cranking (the motor was still warm at this point). Shut it down started it again, little backfire pop and...started. Revved it a little, shut it down, tried to start it again (can't remember if I used the gas or not) and poof black smoke right our of the K&N, almost sounded like it started to run backwards.

daniel6718

iTrader: (36)

sounds like its getting too much gas...you check fuel pressure?

crookedbowtie

Have a gauge on the schrader valve, 40-43.5 psi. Also pulled the rail and checked for leaky injectors under pressure..none. Checked injectors with a 9 volt batt. and they all click. Checked the signal from the PCM with a noid light...pulses on all 8 even when it won't start. I am running a Walbro 255 pump, is that too much pressure to run with it?

LS1Z28-00

iTrader: (8)

could be coolant temp sensor if it is running really rich.

crookedbowtie

It doesn't seem to smell like it is running too rich when it is running. Wouldn't the idle be lower and rough if it was running too rich? It was idling high and smooth. I am afraid to start it now. If that is what we decide on I will give it a shot though. Maybe this is why it won't idle down and it starts fine when it is cold, but acts flooded when it is warm. Current performance did lower the temp in the PCM if that helps figure anything out. What do you think?

I should add that the electric fan is coming on which would I think mean that the temp sensor is good. Right? I don't however have fan #2 power hooked up to anything, but was told that this wouldn't be a problem.

camar0corey

iTrader: (22)

Is the fan coming on when the vehicle is cold though? Do you have the diagnostic port and SES stuff hooked up, can you tell if its popping a code? Wondering as it sounds like you swapped this into a truck?

Curious if the fan comes on when cold, as that would mean the computer is probably in limp mode, may have other sensor issues.

crookedbowtie

WTF I got ballsy and started it again, fired right up. Still high idle but sounded good. Ran it for a while, acted almost as if it was going to idle down (I was thinking finally woohhoo!it is doing what it is supposed to), but then it idled up and stayed there. Fuel pressure was still 40-43.5psi. I didn't want to let it rev high so I shut it down. I went to start it up again and it literally sounds like it starts up backwards and sends the black smoke right out the intake and dies!

crookedbowtie

No, I do not have a diagnostic port hooked up. I also don't have a scanner to check for codes unfortunately. Yes, it seems like the fan may be coming on before my Autometer temp gauge registers 160 , but I am not sure. Would limp mode make it idle high? Also if it was in limp mode I should be able to pull the MAF plug and it would run the same, right? If I pull the MAF it will die, and if I start it without the MAF it starts for a sec then dies. What other sensors are you suspecting? I will check them with a multi meter if possible.I have no emissions or rear O2 sensors and they were deleted from the PCM. The front O2s are old though and they are mounted in a mid length header collector.

camar0corey

iTrader: (22)

Hard to say, any sensor the PCM uses to determine how the engine runs could be bad, setting a code and tripping limp mode. Won't matter if you unplug your MAF, that's only to see if the MAF is bad or not.

If in limp mode the fan will be running all the time, even when its cold, and the motor will run really rich.

crookedbowtie

Just got back from the wrecking yard with an ODBII port from a Firebird and a Suburban (just in case I needed extra pins). Now I have to figure out how to wire it in. What scanner should I buy my options are from AZ, Knect's, Schuck's, maybe NAPA. Looks like a cheapo is around a $100 and a better one is almost double...is it worth it? I need to get this fingered out!

crookedbowtie

Yes!!, Autozone has a loaner scan tool I'm on my way. Hopefully I'll have some codes in a little while.

strokin93z

iTrader: (1)

Sounds like maybe a Timing issue?(not sure, ima newb?)

crookedbowtie

Code P0123 throttle position sensor A circuit high input. Yes, finally some closure or at least hope. I guess I just replace it and see what happens, right?

crookedbowtie

Stumped! Replaced it....same code, same high idle. pulled connector off and tried to test for a 5v reference from the PCM between the black and grey wire. I didn't get 5v. not sure if I am supposed to check with the plug attached and poke through the wire though. I tried it with the key on and were the sensor prongs go into the plug. It will not let me delete the P0123 code.
After I replaced the sensor it threw a p0122 TPS low circuit and a p0118 coolent temp something or other. Deleted those two and it hasn't thrown them again, but won't let me delete the P0123.
Started it up and pulled the TPS sensor off the motor to see if it was being held open, ran the same. Pulled the plug off the TPS idle changed very slightly and returned to high idle threw the P0122 again ( put plug back on and deleted it). I am guessing it is not getting the reference signal and just plain not working. Only thing I can think of is to run a new wire after testing the pins at the PCM. GRRRR, so close but not there yet. What if the PCM is not putting out the reference?

ORedRoc4

iTrader: (15)

Ohm out the wires (2 i think) from the end of the connector to the pin on the ECM, both should have little to no resistance. if resistance is high or is differed from the other, check schematics to see if there is a resitor in line (Which i HIGHLY doubt). If there is no resistor, you have a bad wire.

Hope it helps.

-justin