I have a 93 Sunbird MPFI 3.1 V6 coupe/auto...it has an extremely bad problem with burning fuel...the ICM, coil packs, plugs, and wires are all new, has a new map sensor, IAC valve, intake has been thoroughly cleaned, etc....at start up it blows black smoke and idles rough and cuts off quite a bit at stop and go idle...the codes thrown through the ECM are system over voltage and ESC knock sensor circuit...i would replace the knock sensor (if i could find it), but considering that the ECM can't seem to keep the engine from pinging under any load, it has to be some other fuel or wiring/charging(???) problem...it has no vacuum leaks, previously had no problems whatsoever, and the plugs have been changed numerous times...each time, all 6 are covered in "black carbonized gas"...i have let it sit up for a week or so at a time a few times and had trouble getting it to start until i hooked a jump starting battery charger up to it...within seconds, it started...the battery has been checked for proper voltage a few times at autozone and was over 12 volts or whatever they said...now, it won't even run at all....i tried to switch the ECMs and that changed nothing...the car would not even take a jump off from a 95 V8 Ram...something is real screwy...any help, please!!!!!!!

open circuit on the knock sensor maybe or low voltage on the O2 sensor

thanks for the reply, trevor...two things...on the knock sensor, if the knock sensor is not operating the spark advance for the ignition timing like it is supposed to, supposedly from what i've read in the Haynes manual is that the ECM reads the knock sensor circuit error and adjusts the spark advance to return driving performance somewhat-it immediately gurgles and pings and blows raw black fuel out the tail pipe and sputters like it is drowning in gas...i've tried another computer (with the original PROM installed) and nothing changed...and supposedly the ecm doesn't even look for the O2 sensor signal until the car has reached operating temperature...on a cold start, it starts up and runs rich right of the gate...anyone that has had this problem or knows what is going on, please reply.

http://www.wellsmfgcorp.com/counterpoints/counterp_v4_i4_2000.pdf

This might help you out.


you snooze you lose!
keep working, millions on welfare depend on you!

http://www.v6z24.com/howto/locations

Scroll down, there is a pic of knock sensor location.


you snooze you lose!
keep working, millions on welfare depend on you!

Has anyone ever known of/had a vacuum leak cause their car, especially a MPFI 3.1L, to run rich and spray black clouds...I'm gonna check the MAP sensor's vacuum line this weekend when I buy a new battery to throw in this bucket so I can hopefully get it started again....it seems loads of people are having problems with their j-body's running like spit just like mine (though properly maintained), but I've yet to really hear of anyone finding a vacuum leak to be the cause of it all. My brother, a tranny mechanic and gearhead muscle car racer, suggested this to me.

and by the way, i'm theoretically believing it is a vacuum leak because the ECM/PCM can't correct and better adjust a vacuum leak like it can a low or high voltage sensor reading, correct anybody??? plus i like the sound of it...it's an easy fix! what about the coolant temperature sensor? does it give outside air temperature readings to the ECM when the key is turned on and adjust fuel delivery in bypass and on, causing a rich mixture if the reading is very low (cold)? this was also a suggested check, for this reason. i had no idea the coolant temp sensor did this (i thought it was the IAT sensor's job)

my old roommate had that prob and it was his fuel injectors
they had wore out and were leaking as the engine was running (inj were stuck open)

Mitch

here's one statement of how it works

http://autorepair.about.com/cs/fuelinjection/a/aa030301a_2.htm


Alont

When you changed the coils packs out did you put in a new module ?
You need to make sure that the voltage is at around 13.5 volts when the car is running.
When you changed the computer did you use your prom or a diff. prom.
It really sounds as if you have a stuck fuel injector which the computer will not be able to compensate for and will set diff. codes. If you can get ahold of a stethiscope and listen to the injectors and see which one(s) are not working. Mine was number one cyl.
If it is stuck, put screwdriver on the injector body and tap it with a hammer. This should free it up temporarily until you can get a new one(s).
Hope this helps.



brien
89 Z24

his is running rich on all cylinders. Let us know how that battery works. Also see if any current is being drawn while the car is off. I wouldnt guess this right from the start, but what about the timing chain? Possibly the chain jumped a sprocket and its off a bit?


http://www.cardomain.com/id/nocho
there are 10 types of people in the world, those who understand binary, and those who dont.

Have you checked your fuel pressure? If its running extremely rich the fuel pressure regulator could be bad. Pull the vacuum line to the regulator off and check for gas if you don't have a pressure gauge. I have seen a few of these regulators go bad its worth checking.

i've had this problem also and still do as a matter of fact. i've changed the entire ignition system except the ECM. And the only cylinder that wasnt fouled out was the #4 one. So i decided to rebuild my engine after i got an "family" vehile for temporary purposes. while draining the oil, it reeked heavily of gas, roughly speaking there was about 1 gallon of gas in my engine block. last week i noticed (with the valve covers and manifold's off) that my hydraulic lifters are screwed. as in coming apart. extremely loose rocker arms, though everything is tighted down like it should be.

but thats just my experiance

i should note that after i did the last tune up, everything was fine for a few miles, then all hell broke loose in my 2.8

I had that same problem with a 3.1 before, the can would barely run at idle and sometimes when I hit the gas from a stop it would stall. ESC knock sensor circuit was the code I had. I replaced the knock sensor and the ESC module (under the coil packs.) I think it was the knock sensor that fixed it but I'm not sure.





You can't outrun the radio.

My car didnt show any codes, but i did replace the knock sensor, crank shaft postion sensor, ignition module, coil packs, plugs, fuel filter. after all this it never made a difference. and that's roughly the time i found out that the valve train was screwed up.

If you know anyone with a scantool have them put it on the car and run it while watching the engine data. That would be a big help in diagnosing your problem. I know when I have a problem I hook mine up and log data for 10 miles or so, and am able to catch stuff that doesn't even show up on the CEL light yet.