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Sat for a couple months. Now multi-codes pending.

T

toof

New member
IAC, Throttle position sensor, MAF, transmission pressure valve. All were pending codes after the below incident.

Haven't driven it for in while and it started poorly and idled rough. Stalled several times. Surging idle. But worse, while driving it on the interstate after 10 minutes it down shifted and revved to about 4k steady RPMs. I got off the interstate and it was shifting hard. Temperature (coolant) was normal the whole time. Parked it for a few hours and drove it again and it behaved better, but rough-ish idle still. Thoughts?
 


check for damaged wires from critters while it sat. you might find a nest in the air filter box and chewed wires around the engine.

mice are good like that.
 


no the actual codes. not that i dont trust your definitions. but we like to see the code its self. as theres more then one code per item.

abs wont affect the tranny or how hit runs. thats a separate system.
 
Now set are: P0121 TP Sensor Range/Performance, and P0101 MAF Sensor Signal Range/Performance.

Just started and drove it for a code read. The car stalled at the 3rd STOP sign. Ran fairly well (maybe a little stumbling on the interstate) but was uneventful until I came back to gas up from Autozone. It stalled coming off the interstate. Gassed up with 93 then shook it down. It ran well. No stalling.
 
that maf code is for bad currant to some degree. it could be a bad maf, or fuse #21 blew marked ign in the under hod fuse box.

a messed up maf can screw with the tranny. if the fuse is good try unplugging the maf, car off, then start it, if it runs better the maf is typically bad.

the tps can go bad but its kinda rare. what year car you got?

if the car was cold on your last drive, it runs off the pcm when cold, once warmed up it will want to use the maf, faulty maf and she will act up on ya.
 
It's a 2000. The #21 fuse, a 15A is good. The car stalled cold and I think was stuttering a bit on the way to A-zone, but not on the way back from code reading. But it stalled coming off the interstate on the way back. Tank was nearing empty and the LOW fuel light has been on. Didn't drive it long after some fresh gas but it didn't stall or behave weird. Going to try it again in a little while on a longer trip.
 


another trick is to tap the maf while the car idles. if its running poorly it might perk up and run nice when tapped on. maf is the square flat thing a top the tb. the tps is on the rad side of the tb.

all them wires bake in the exhaust heat and can become damaged, cracks in the insulation or missing insulation. if you see bare wire the pig tail needs to be replaced.

if it comes down to the maf is bad, best to hit a junk yard and snag one. be much cheaper then new, and oem mafs work best, aftermarket suck in these cars. aka your car will hate it pretty fast. pretty sure thats the same maf from 99-01. its the same part na or sc'ed. part # is on top the maf, so you know what one is right while searching the yard. they are in a lot of gm cars, regals, park avs, impalas and so on. any one with a 3800 engine.
 
Swapped MAF; same problem. No difference. After several minutes of driving it does it again, then acts in a normal manner for a while. When it does it the car smells as though it's starving for fuel when under the hood, but I can rev it to keep it running when at a stop.
 
Well it tried to burn itself up. On the interstate is where this happens. This time I decided to keep driving and see if it would clear up again Nope. It went to 2nd gear and stuck there. Popping and choking, then the exhaust got very loud, and then louder still and by the time I got to the exit? Smoke. Pulled into a gas station, popped the hood and flames were down low on the pass side between the firewall and trans. Grabbed the station fire extinguisher and that's that. Trailer home. No more problem.
 


Could a clogged exhaust cause something like this? Vandalized gas, like sugar? cracked heads? It had decent power when I threw the pedal down though. Even when it was stuck in 2nd, it was sneezing some but would go pretty good. Just wouldn't shift.
 
Okay, found out what caused the fire. At the rear of the car the exhaust came off the rear hangers at the very back (left side), tweaking the exhaust coupling right behind the engine at the rear manifold. It caused a leak which got progressively worse over several minutes until it completely detached. That pipe (head pipe?) is just laying on the power steering lines which are above the rack. The high revving exhaust dumping straight out the rear flange ignited the foil/mat heat shielding and oil against the fire wall. The O2 wiring is cooked too. So, it's gonna take a few hours to repair the wiring and exhaust.
But what is the coupling supposed to look like back there? Meaning the manifold to the head(?) pipe. Anybody have a pic? Stopped by the parts store but we couldn't find an image of what it looks like. Or maybe mine just broke free?
 
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