issues after AOS replacement, could use some help...

[Chris_in_NH]

hi guys,

i just replaced my AOS yesterday with the help of a friend. the install went well and relatively smoothly.

i was experiencing some throttle hesitation for a while, i thought it might be the MAF. but it eventually got worse, and about a week ago i got huge clouds of smoke when starting the car. it got to the point over 2 or 3 days that the car would start and then stall, and finally would not start at all.

i checked the throttle body and found a pretty good amount of oil in there, and decided the AOS was toast. so i had the car towed to my friend's house (he has a lift which made things MUCH easier) and we replaced the AOS and spark plugs, and sopped up as much oil from the throttle body and plenum as we could. i don't think the engine ate that much oil, as the oil level had not dropped significantly.

we fired up the car after replacing everything and it ran like a champ. very smooth idle, engine sounded 'normal' and smooth. there was a ton of smoke as the remaining oil that made it to the engine burned off. i let it warm up for a few minutes and then drove 30 minutes home without incident.

i went inside for a couple hours (had to watch Sopranos and Big Love!) and then went back out to the car with a PST2 to see if i was getting any new codes, and to erase the previous codes. started the car, it was running fine. but when i gave the order to reset the codes, suddenly the car started running badly and eventually stalled. I checked the codes again with the engine off. I got codes for the MAF (was still unplugged) and an air temp sensor. I figured they were both MAF-related. I plugged in the MAF and started the car. The car did not run well. It tried to stall a few times but I pressed the gas to keep it running.

After a few minutes I decided to take it just around the block. I got about 500 feet away and the check engine light started flashing. I quickly pulled over and shut down the engine. I thought the MAF was probably sending crazy signals to the ECU, so I unplugged it again. Got back in the car, it would start but was very rough. I tried getting the revs up - I just wanted to get it back in the driveway. But it wouldn't go. I did hear a distinct 'pop' when I tried to start it the last time (misfires i'm guessing). At that point, I got out and walked home.

the codes i pulled before walking home were:

P0102 MAF unplugged

P1313 Misfire, Cylinder 1, Emission Relevant

P1314 Misfire, Cylinder 2, Emission Relevant

P1315 Misfire, Cylinder 3, Emission Relevant

P0306 cylinder 6 misfire

P0305 cylinder 5 misfire

P0304 cylinder 4 misfire

P1319 Misfire, Emission Relevant

P0112 Intake Air Temperature Sensor - Below Lower Limit

P0300 random/multiple cylinder misfire detected

i also noticed that the oil level had dropped considerably from the time i left my friend's house up to this point. when i left, the dash gauge indicated FULL, but after all of this happened, the gauge now read at the bottom level of the dash gauge. i looked underneath the car, and checked the new AOS and related connections and did not see any oil. so i started thinking that the only other place it could be going is back into the engine.

i did notice when changing the spark plugs that a few of the coils are cracked. (car is a 97). but it seems very odd that the car would run SO well for over 30 minutes, but then suddenly act up a bit later (and upon clearing the codes - i don't know if this was the cause or if it's completely coincidental.)

the plugs i used were Bosch Platinum 2 (4303's) which i had used previously with great success.

i was planning on checking:

-look at spark plugs for oil fouling

-make sure spark plug tubes are securely connected and 'snapped' on to plugs.

-check TB again for oil

-check AOS hoses for leaks

-check that TB and air tube are securely fastened

-check for vacuum leaks (oil dipstick, oil and coolant caps seem air tight - maybe oil filler tube? we had to move it around quite a bit to get the AOS in - but again, the car ran fine right after the swap.)

thanks in advance! i'm really hoping to get to the bottom of this.

[Chris_in_NH]

i read a post here that said that disconnecting the battery would reset the ECU. it did. car works fine now.

we'll see how long it lasts...

after the repair yesterday, i drove it home with the MAF unplugged. then just to test the MAF i plugged it back in. that's when i started having problems. even though i disconnected the MAF again after the problems, the ECU must have had the 'crazy signals' still in memory or something. i just unhooked the neg terminal of the battery for 30 seconds or so, reconnected it and drove away! :D

new MAF will be here before the weekend...