MAF issue (maybe more?) & pulling codes, 94 explorer (manual)

[cgyleather]

Howdy,

I'm having a MAF issue... Occasionally, it hops while I'm accelerating; I recently had a mechanic replace brakes for me and he was nice enough to pull codes. He said that I needed a new MAF. No biggie, I'm picking one up later today.

I pulled the codes myself this afternoon, and KOEO is fine, my CM codes show up as 157 and 158, and when I try the KOER test, instead of blinking 3 times to show that I'm on a V6, I immediately get 2 codes:

998, and 157.

They repeat twice, the engine revs up to 1000rpm, and then the check engine light comes on and stays on.

Is the issue I'm having with pulling these codes in the way that is outlined on guides on this site due to my MAF problem?

Anyway, I do have another issue, which may be due to my MAF needing to be replaced or may be another issue alltogether: When I'm in 3rd, 4th, and 5th gear, I will sometimes hear something like a pinging/knocking noise when accelerating (most prominently in 3rd gear). What else could be causing this, in case I install a new MAF and I have the same issue with the noise.

 

[Roadrunner777]

I'm a cheapskate, I would try cleaning the maf first. Whatever you do, be sure to look at the screws that hold it in, they are special security screws... may need to hit a hardware store. Cleaning takes an electronic sovent, a good car place will sell you a can of MAF cleaner. Otherwise, an electronic connector cleaner will suffice. It must be clean to the point of magnification. Junk gets on it and the MAF gets hot and chars it on. The MAF is quite close to the air filter on the Ex. If you ever switch to an oiled filter, oil very very lightly. Oil film will burn on the MAF and all the money you are saving on filters will be spent on MAFs.

There is another thread here where someone re-seated the MAF connector and fixed both a 157, and a 998. I'd say fix the maf, reset the computer, and you should be good.

Yes, a bad maf can lead to ping and knock. You will get a little bit of this anyway, it even says so in the owners manual. Tightening the lower intake might help. Check for leaks in the cross tube from the MAF to throttle body. Check for vacuum leaks in general.

For today, I'd get the MAF working, disconnect the battery for 30 minutes to reset codes, and go for a drive.

 

[cgyleather]

Looks like I had to replace the MAF completely. Cleaning it didn't help.

Oh well, for $8 it was worth a shot at least. I'm pulling 111's all around now

 

[Roadrunner777]

Great! Well, you probably have a lot of the can left too, it's special because it is non-residual. If you ever need to clean out something fine, like a clock mechanism, it would be the thing. Anyway, all 111's all good. How is it driving?

 

[cgyleather]

Driving great as of this morning. I'm going on a big drive (Calgary down to Seattle and back) soon. Looks like it should survive the trip easy.