-LS1-

iTrader: (4)

I just finished up a transmission rebuild/install and havent driven the car in a few months before this week. During those 2 months I had the battery removed from the car. When I took it for the first drive around the block, it idled and ran fine for the first few minutes of driving, but then started bogging/choking in any gear with a severe loss of power under load, while idling, etc. After 45-60 seconds of this it "cleared out" and ran fine for as long as 30 minutes (that's the longest I've driven it on one start-up since then anyway). If I turned the key off even when it had been driven (ie, it was warmed up) it would still do the exact same thing as if it were still stone cold.

I have long-tube headers, ORY, catback, !AIR, untouched MAF (intact screen), ported throttle body. It only started acting up this year; it always ran fine before now. Is there a sensor or something that I might have forgotten to hook up around the trans that would cause this to happen? (I wouldnt think so, but it's the only thing I messed with since it was stored for the winter). I was thinking O2 sensors (I have a SES code for them but I'm assuming that's for the rears) but if that was the case Id think it would be doing the opposite (running fine the first few minutes and then like crap the rest of the time). I can't hear any odd noises at idle or under load, other than the obvious sound from the motor chugging. I obviously also have SES lights for multiple cylinder misfire. Any insight would be much appreciated.

RsSean

iTrader: (27)

It may have been moister in the fuel tank from sitting some where. Did it throw a SES light? If so what is the code. I could probally help you if there were a code.

-LS1-

iTrader: (4)

Old gas/water in the tank had crossed my mind, but it literally does it at almost the exact same place every time driving down the road, and then stops at about the same time/place afterwords and then runs perfectly fine, which would make me think it's some sort of sensor malfunctioning. I don't have the exact codes since autozone didn't give me a printout or anything (they did last year), but I had 2 random misfire codes and 2 O2 sensor codes.

blade2222

sounds like a o2 failure. I had one giving a false lean condition the pcm would enrichen so much it started fouling out giving random misfire.

chavez885

iTrader: (12)

Replace your front o2's.

blade2222

also reason it runs good after a min. or so is the pcm is going back to open loop.

-LS1-

iTrader: (4)

Gotcha, I didn't realize it would go back to open loop, that makes sense.

-LS1-

iTrader: (4)

Dropped in some Bosch OE style front O2's (click). Took it for a spin around the block afterwords and it didn't change the issue one bit. Anything else it could be? (Should I keep these incase they go out in the future or put the stockers back in and get the $150 back?)

loyolacub68

iTrader: (16)

Depends how many miles you have on your car. Its nice to have new O2's after a while because they start going bad and then your mpg starts to suffer.

blade2222

disconnect MAF and take it for a spin.

99camaromike

iTrader: (1)

my car was doing the same thing,,,change the o2's and the spark plugs,,,,the o2's will kill them,,,,,,put in ngk tr 55,,,

-LS1-

iTrader: (4)

I possibly (hopefully?) may have found my problem while checking something unrelated to this. I was uninstalling my ported throttle body to remove the epoxy from it (the epoxy'd part was starting to flake away) and while I was taking off the hoses going to the TB I noticed one was already off and hanging to the side; the one in this pic, courtesy of installuniversity.com:



I'm going to finish uninstalling the TB and remove the epoxy before I go ahead and re-hook that line up and take it for a test drive, but hopefully that would be something that could cause a problem like this. ::fingers crossed::

By the way, I have no idea how that might have come unhooked; I haven't touched anything to do with the throttle body since *way* last year.

-LS1-

iTrader: (4)

Well, of *course* that couldn't be it, because obviously that would be too easy. Got everything back together with that line hooked up, and it still does the same thing.

-LS1-

iTrader: (4)

I took it to Autozone again and got the following codes:

PO102
PO132
PO131 (twice)
P0141 (twice)
P0152 (twice)
P0300 (twice)

I had gotten all of those before, aside from the first one (PO102, MAF low voltage code).

-After doing some reading on that code from what I could find on this site, I took the MAF apart, cleaned the sensors with a can of MAF cleaner, let it sit for a day and took it for a drive. Negative.
-I replaced the PCV valve as someone suggested for that code. Negative.
-I made sure there were no exhaust leaks around the front O2's and checked to make sure the Y-pipe and all fittings were securely tightened. Negative.
-I checked the ENG SEN fuse again (had already checked every single fuse in the fuse boxes a few days before that) and it was fine.
-I checked the volts on the 3 prongs for the MAF clip and they were all normal from what I had read (one was 5 volts, one was 12, one was 0). The prongs looked perfectly straight and not bent or damaged.
-I got under the car and took off the wire loom for all of the O2 sensors; all wires are mint all the way up away from the LT's/oil pan (no burned wires).

And of course I had already replaced both front O2's with absolutely no results. The only thing I really havent done is actually replace the MAF, which I will do soon with a donor MAF from a friend's f-body sometime this week to test. If that's not it (and I highly doubt that's going to be the fix since I just replaced this last year) what else should I check?? I'm running out of ideas here, and wishing I hadn't brought this thing out of storage and put insurance on it since it's almost been a month and I haven't even got to drive it once yet other than for troubleshooting runs.

BeachZ

iTrader: (2)

Check the clip on your knock sensor. Sounds like it's broken.

-LS1-

iTrader: (4)

I checked that clip, it looks fine and is still firmly attached. Seems like if that was the case it'd pull timing the entire time instead of going away after a fuel minutes and reverting back to normal.

I swapped my MAF out with a friend's MAF today, and it still does the same thing. It seems to be getting worse as well. Before, it would only last a few minutes before going away, now it lasts 5-10 minutes before going away (usually I'll just turn off the car and start it back up to get it running normal again instead of waiting for it to work itself out, because it's almost impossible to get moving from a stop when it's chugging like that). I'm ready to throw in the towel and bring it in to a shop to get this diagnosed. Is there any last things I should check/replace before I do that? I'm going to pick up a fuel pressure gauge and check that before I take it in, just incase it's the fuel filter/fuel pump (but again...I highly doubt that since this problem goes away and runs PERFECTLY normal if you let it bitch and moan through it's misfires for long enough). I feel like a complete fool for rushing to get this out for the summer since I've wasted 1/6th of my paid insurance period with it just sitting in the garage.

BeachZ

iTrader: (2)

:shrug: Then maybe it's the knock sensor itself. My car had pretty much the same symtoms as yours, and it my case it was the clip, but a bad knock sensor would work the same way, I think.

1FST-Z

iTrader: (6)

Check your Crank Position Sensor. Located above the starter.