02 LS1 Bogging issue
Thread Starter
Teching In
Joined: Mar 2011
Posts: 15
Likes: 0
From: South of Atlanta GA
02 LS1 Bogging issue ok, i will try to describe this as perfectly as possible, hopefully someone can lend some insight to my problem.
CAR: 2002 Pontiac Trans AM Automatic transmission, LS1 with 75K miles, stock, engine, headers back exhaust. Stock tune, updated by GM 3 months ago.
PROBLEM: This started two days ago. has been running perfectly up until this. i filled up with gas, at a well known gas station, with 93 premium 3 days ago. problem did not immedatly start. started the next day. i go to start the car, runs perfectly. rev's perfectly. put in Drive, and drive away. about 80% of the time right now, the engine under moderate throttle or less, will start to bog... feels like its missing 2-3 cylinders. push it to the floor, it seems like it unclogs itself, or whatever, and wakes the hell up. i can't force it to do it at all, but it seems to do it pretty consistantly about 3/4 a mile give or take, from startup.
TROUBLESHOOTING: i have done the following to attempt to remedy this situation. check plug wires, initially. all are tight on coils and plugs. check all sensor connections. everything looks tight, i took a peek at the MAF sensor, and it looked clean, but i blasted it with some CRC maf cleaner anyway (while cold of course). gets solidly consistant fuel mpg, and i'm trying to see if anyone can point me int he right direction as far as where i should go next. i really do not want to take it back to the dealership to figure out. i thought it would probably be the fuel i put in... so i topped off today from a different station, about 3-4 gals, and put some water remover in (STP brand) just to see if it would help at all. pulled the fuel filter, gave it a good shake, and poured it out the IN side, into a glass, crystal clear. so doesn't feel cloged at all. i hooked up a scanner to it, to try and check the sensors, and this is what i got.
-MAP showing good 11 inches HG at idle.
-MAF seems like its good, showed 1.5 GPm ( i think was the unit of measure) at idle. seemed like it increased properly with rev.
-TPS showed at idle, .4% and increased properly with gas pedal (key on engine off for this test)
-02 sensors, seemed like they were reading properly at .750 volts, up and down a few, and switching to .2 volts then back to .7 ish.
-ignition advance, at idle, was 18 deg. advanced past 25 with throttle
i do NOT have a fuel pressure gauge to check pressure, and would not be surprised if the brand new pump died. Dealership would replace free of charge.
Work done in last 6 months:
New spark plugs, NGK iridiums
new plug wires, Duralast autozone brand
new fuel filter in last 30 days
new fuel pump (installed by GM, using GM parts) in last 90 days
New rear axle, (refurbished unit installed by GM)
Air filter cleaned (K&N)
new oxygen sensors (Bosch 13111 Corvette sensors)
i am completely stumped.... i haev NO clue where to go from here, except take it to the Stealership and let them "diagnose it". Thanks for taking the time to read my lengthy post, and i apreciate all assistance.
CAR: 2002 Pontiac Trans AM Automatic transmission, LS1 with 75K miles, stock, engine, headers back exhaust. Stock tune, updated by GM 3 months ago.
PROBLEM: This started two days ago. has been running perfectly up until this. i filled up with gas, at a well known gas station, with 93 premium 3 days ago. problem did not immedatly start. started the next day. i go to start the car, runs perfectly. rev's perfectly. put in Drive, and drive away. about 80% of the time right now, the engine under moderate throttle or less, will start to bog... feels like its missing 2-3 cylinders. push it to the floor, it seems like it unclogs itself, or whatever, and wakes the hell up. i can't force it to do it at all, but it seems to do it pretty consistantly about 3/4 a mile give or take, from startup.
TROUBLESHOOTING: i have done the following to attempt to remedy this situation. check plug wires, initially. all are tight on coils and plugs. check all sensor connections. everything looks tight, i took a peek at the MAF sensor, and it looked clean, but i blasted it with some CRC maf cleaner anyway (while cold of course). gets solidly consistant fuel mpg, and i'm trying to see if anyone can point me int he right direction as far as where i should go next. i really do not want to take it back to the dealership to figure out. i thought it would probably be the fuel i put in... so i topped off today from a different station, about 3-4 gals, and put some water remover in (STP brand) just to see if it would help at all. pulled the fuel filter, gave it a good shake, and poured it out the IN side, into a glass, crystal clear. so doesn't feel cloged at all. i hooked up a scanner to it, to try and check the sensors, and this is what i got.
-MAP showing good 11 inches HG at idle.
-MAF seems like its good, showed 1.5 GPm ( i think was the unit of measure) at idle. seemed like it increased properly with rev.
-TPS showed at idle, .4% and increased properly with gas pedal (key on engine off for this test)
-02 sensors, seemed like they were reading properly at .750 volts, up and down a few, and switching to .2 volts then back to .7 ish.
-ignition advance, at idle, was 18 deg. advanced past 25 with throttle
i do NOT have a fuel pressure gauge to check pressure, and would not be surprised if the brand new pump died. Dealership would replace free of charge.
Work done in last 6 months:
New spark plugs, NGK iridiums
new plug wires, Duralast autozone brand
new fuel filter in last 30 days
new fuel pump (installed by GM, using GM parts) in last 90 days
New rear axle, (refurbished unit installed by GM)
Air filter cleaned (K&N)
new oxygen sensors (Bosch 13111 Corvette sensors)
i am completely stumped.... i haev NO clue where to go from here, except take it to the Stealership and let them "diagnose it". Thanks for taking the time to read my lengthy post, and i apreciate all assistance.
Teching In
Joined: Mar 2008
Posts: 49
Likes: 0
From: Wilburton, Pennsylvania
I've been having a very similar issue, read my post in this section and it might help you a little. I would check all of the O2 connectors for any moisture. It seems that was the root of my problems but I had the same things happen to my car, about a minute after startup it would miss and run like s*** but once you put your foot in it, it clears out. I would definitely check the O2 connectors though.
Thread Starter
Teching In
Joined: Mar 2011
Posts: 15
Likes: 0
From: South of Atlanta GA
I've been having a very similar issue, read my post in this section and it might help you a little. I would check all of the O2 connectors for any moisture. It seems that was the root of my problems but I had the same things happen to my car, about a minute after startup it would miss and run like s*** but once you put your foot in it, it clears out. I would definitely check the O2 connectors though.
Man.....you nailed it right on the head. I swapped in a set of denso O2 sensors I have as a backup (brand new got them BOGO free so picked up a set for 45 dollars). Immediately ran better. Two days no malfunctions... I wonder what's up? I already warrentyd out the Bosch 13111 sensors so I have them on my desk brand new as well.
Thanks for the reply and I greatly appreciate the help.
Teching In
Joined: Mar 2008
Posts: 49
Likes: 0
From: Wilburton, Pennsylvania
That's great I'm glad it's running better for you and was a fairly simple fix! Did you try pulling the codes on the car yet since it's been running better? If not, I would definitely have the old ones cleared and have your car rescanned to see if those two O2 codes are still there.
