I’ve got a 99 Silverado 1500 with about 400 000 km on her.
About a year ago I had a check engine code come up related to the MAF sensor.
I put off replacing it because I don’t drive the truck very often.
I finally got around to picking up a new one last week; ( a brand new one from NAPA) I swapped it out for the old one, and at the same time I swapped out my very old K&N air filter for a paper one. Since I swapped out the the MAF sensor and the air filter the truck has been running like absolute garbage. I had another check engine light come up about the MAF sensor.
P0174 and P0102 both came on after a day or so. I did some reading and discovered that after swapping out the MAF sensor you are supposed to unhook the battery for a short while to remove the codes, and to get the truck to relearn the new MAF sensor. I sorted that part and on my drive to work in the morning the truck seemed to be running at least a little bit better.
I’m having rough starts in the morning (it’s not cold yet, it’s only September)
The truck is shifting really rough from first to second, and a little less rough from second to third.
(It’s an automatic)
At this stage I am considering if maybe the part that I bought is faulty. I had a friend come by with an OBDII reader to check the codes and do some tests. The tests showed that one of if not both of the catalytic converters are shot as well, I’m not sure exactly how badly. I’m thinking the issue could be with the O2 sensors as well. I don’t know what to do moving forward and the truck isn’t really worth the money to pay a garage to poke around in there and start fixing all of the damn issues. I just want it to get back to running smoothly without spending an arm and a leg.
A faulty MAF could produce O2 sensor and cat codes, but the O2 sensors and cats could still be ok. Since the engine ran ok before the MAF replacement, suggest to focus on getting the MAF system checked out as first priority. Is there a reason you don’t want to just install the old MAF sensor and drive on as before? It could actually be working fine, and the MAF code you were getting is related to something else.
I had a bad MAF from NAPA way back on my Buick. It ran OK but too rich. The only way I could really test was by swapping it with another MAF from a 3800 I had. They replaced it but said parts like that are best to be OEM. No idea if that’s that problem but bad ones happen from time to time. Proving it without a code reader though is a problem.
I’m not a true mechanic. I try to work on old stuff cheap. I’m kind of a parts changer at best. But, it looks like you want to take the cheap route. So here’s what I’d do:
Unplug the MAF and see how it runs. I have done this with GM’s, and they’ll typically idle and run pretty darn well with the MAF unplugged, although you will get a check engine light. It might idle a little funky at first, but should level out. Drive it a few miles, enough to get the engine all the way up to temp. If it still runs like crap with the MAF unplugged, I do not think the MAF sensor is the issue. If it perks up and runs pretty decent, I would suspect the MAF. I have had bad luck with aftermarket sensors (not necessarily Napa brand), and I’d prefer to stick to an oem maf sensor. I would try cleaning the original MAF sensor and reinstalling it. Use only the MAF sensor cleaner (they make a spray for just this purpose, sold at every parts place and probably wal mart). There’s a pretty big possibility that oil off of the k&n filter has gotten onto the MAF sensor. While you’ve gotten the air filter duct off, go ahead and clean the throttle body real well with throttle body cleaner. May as well while you’re in there. See what that does and we can go from there.
“It’s Me” mentioned vacuum leaks. These trucks are pretty prone to vacuum leaks at the intake manifold. So that would be on my list of things to check next.
You mentioned that testing revealed bad cats. Do you know how they are “bad”? If they are plugged and restricting exhaust flow, you’ll need to address that. If they are just not doing their job like they once did but are still free flowing, it will not affect the way the engine runs and we can put that on the back burner for later.
