PontiacBonnevilleClub.com

recently bought a 2001 bonnie sle. car starts right up when cold and runs great. Once the car heats up it starts to miss as you rev it. the miss usually starts around 2200 rpm. and then will get progessivly worse to were it wont even stay running. it almost bogs out like it doesn't have enough air. ive replaced plugs, plug wires, tps, maf,iac,icm and coil packs. ive checked fuel psi and fuel pump is not an issue . car will not throw any check engine light im stumped ...

you nee to have it scanned. the car will tell you if its a "Misfire" it will tell you what cylinder it is and go from there. have you replaced the fuel filter and checked fuel pressure.. if it bogs it sounds to me like its starving for fuel.. which would not click a CEL. might be a plugged injector (would probably give a Lean code), plugged filter or bad fuel pump.

S

yea it does need tobe scanned. im trying to get my hands on one right now. all I have is a cheap code scanner and nothing comes up. I replaced the fuel filter and I have checked fuel pressure. I get 44psi and when it begins to miss I still have 44-50 psi of fuel pressure. I started to check injectors before it started dieing by using a screw driver and my ear to make sure injectors were working. but then it started dieing . waiting for the car to cool down and start again.

did you unplug the MAF and see if the problem stops? NEW MAFS are defective more often then they work.

I have yet to try that again. ive been waiting for the car too cool. seems weird to me that it only does this after the engine has reached operating temp. but when the car is cool has all the power with no miss or bogging. ill try un pluggingthe maf here in a few

so I think I may have found the problem. I just replaced the crank position sensor. seems to have fixed it. ran the car in the driveway till it reached op temp and reved it for a good 20 min. drove it around about 20 min and no miss fire or bogging or anything. so we shall see

Hopefully that fixed it for you!

sadly it didn't . after about an hour of letting the car set, started it up and back to the way it was. tried unplugging the maf and made no difference. now im getting two codes p1361 and p1362. im still hitting my head against the wall.

http://easyautodiagnostics.com/gm_ignit ... dule_3.php

Run through that and see if you have any issues there, could be a bad / corroded connection somewhere.

crash93ssei thank you for the link. ive read it and it will be very useful. ill get back and let you know what the outcome is. does anyone by chance know how to upload a video? I took video last night of the car at 2500rpm and then reving it to give everyone an idea of what its exactly doing

I always upload to YouTube then link it here.

alrighty thank you. ill do that tonight after work. also what does this harness control? found a few spots on it were it is down to bare wire on the black wire going into the male end weather pack terminal

When did the misfire start? Can you post a further out pic, looks like the plug wire routing is really odd. That black wire should just be a ground.

I guess a few weeks ago. we bought the car off of the original owners last week. the old man was getting tired of the car stalling out and miss firing. so I picked the car up for 500 bucks hoping it would be an easy fix . I don't know if this is important but this miss fire and the car losing power only happens after the car has reached operating temp

I also don't know if this helps but when the miss firing occurs all the interior lights go crazy and the gauges all start tripping out

Plug wire routing is crazy but they are right.

Pull the battery cables off and make sure they are clean, even if a little corroded or dirty clean them very good and put them back on making sure they are good and tight.

When it is running bad, is there any smoke out the exhaust? If so, what color is it? You say the misfire doesn't occur until it reaches operating temp, does it start as soon as the gauge reads 200 or slightly before, a few minutes after?

I'll defiantly clean the terminals tomorrow . We've noticed a little black smoke at first but recently no smoke when back firing and missing I defiantly need to get that video uploaded . I'd say it happens a couple min after hitting 200 degrees . But it only miss fires when warm. When it's dead cold car runs amazing .

Oxygen sensor?

Sounds like the car is running right when it's in open loop and the PCM is just dumping fuel until the car warms up, then it goes to closed loop and uses the MAF and Oxygen Sensor to figure out the fueling.

sorry guys for the long period with no update. I replaced the upstream o2 sensor. but what I have found is when I wiggle the plug at the icm it runs worse and dies. im finding that a lot of the haresses are brittle and have wire exposed so im in the process of inspecting every connection and replaceing wiring harness ends. the one going to the icm was in horrible shape so at this point it seems like im chasing an electrical issue