hey all, forgive me if this has been posted, but I can't find answer, at least not for how it happened.
I have a 99 expy with the 5.4 triton. I went to get the oil changed, and while I was at it had the air filter changed. about 50 miles later, CEL came on.
I noticed when I hit on ramps and reach a speed of about 50 and the tac is still under 2000, it misfires. At first I thought it was in my head, but it started progressively getting worse. While idling at rest, it's fine.
I went to Autozone and got a code reading of PO171 and PO174.
came here and followed some advice and cleaned the MAF sensor. That didn't work, so I changed the MAF sensor. still didn't work. I have checked the hoses for vacuum leaks, all good.
Now, I know I can change the o2 sensors, but I don't buy it. doesn't make sense, because it was working fine, until I changed the airfilter and had the oil changed. Of course, I've seen freaky things happen before.
Check to see if all the electrical connections are in place on your air filter housing. Also check the PVC elbow located at the back of the intake to see if its cracked.
You could've knocked something else loose in the area when you changed the air filter, so that's something to look into. But I'd be more inclined to think that the air intake duct from the air filter housing to the throttle body has a leak. Either it cracked or it's loose at one of it's ends. Any air that enters this duct after the MAF will cause a lean condition in both banks 1 & 2.
problem solved; albeit wasn't a crack in the housing and tubes after the MAF.
I finally had enough of the problem that I took it to the mechanic. according to him, 3 coils were shot. I felt it to be too coincidental, but honestly, my patience ran out and I had him replace them along with the spark plugs and wires.... $500, but whatever. small price to pay for peace of mind.
hmmm! Not that I'm trying to protect the integrity of the mechanic, but I did have major misfires.
When I went to autozone, like a dummy, I had the codes erased. I went to one mechanic and he said its better I wait until the codes come back. After another 100 miles of driving, they never came back. (yes I purposely drove around trying to get those codes back). So, not only did those codes not come back, but the misfiring was starting to get worse.
I stopped in at the mechanics yesterday afternoon and finally got it fixed.
coincidence that changing the air filter and coils go out? hmmm! I find it highly suspect. Did I get taken? I don't know considering the codes never came back after a hundred miles of driving, aimlessly
hmmm! Not that I'm trying to protect the integrity of the mechanic, but I did have major misfires.
Well, you didn't state that..
Quote:
When I went to autozone, like a dummy, I had the codes erased. I went to one mechanic and he said its better I wait until the codes come back. After another 100 miles of driving, they never came back. (yes I purposely drove around trying to get those codes back). So, not only did those codes not come back, but the misfiring was starting to get worse.
I stopped in at the mechanics yesterday afternoon and finally got it fixed.
coincidence that changing the air filter and coils go out? hmmm! I find it highly suspect. Did I get taken? I don't know considering the codes never came back after a hundred miles of driving, aimlessly
It's far more likely that the replacing of the air filter triggered the "lean" codes and that that particular problem has not been directly addressed (may come back).
Steve
__________________
Think about it: Ignorance can be addressed through education but you can't fix stupid! ...apologies to Ron White
I noticed when I hit on ramps and reach a speed of about 50 and the tac is still under 2000, it misfires. At first I thought it was in my head, but it started progressively getting worse. While idling at rest, it's fine.
Project, I do feel a little more confident about my decision, after reading your post, thanks
Join Our Site - Its free, quick and easy!
