Mass Air Sensor failure?

TXHusker · Sep 19, 2011

My 74 (with '93 swap) sat most of the summer while I worked on it. Saturday, I drove it around the block to the house to pick up the boy, then to wally world. Total about 3 miles. When we started to leave Wal-Mart, it sputtered and acted like it was low on fuel. Added 10 gallons, wouldn't even idle (may be a result of my jackin' with the timing trying to get it running again) I had to be towed home.

After getting it in the garage, I finally got it to idle, barely and removed the K&N filter to check if it needed cleaning, it could but wasn't blocking air flow, removed the mass air and the idle improved a bit but basically stayed the same (chugging along struggling to stay running). When I disconnected the sensor, the idle smoothed out after several seconds.

Is this coincidence or has my mass air sensor failed?

Broncobowsher · Sep 19, 2011

If the intake duct between the MAF and the throttle body is still hooked up, and it was working just fine and suddenly went bad. Then I would say it was a bad MAF. Before tossing it for a new one, take it out and hose it out with a can of brake clean and let it dry well. Put it back in and try again. IF it is happy, it was just dirty (K&N's are known for sometimes oiling up the MAF and making them go bad). IF that don't do it, then I would find a new MAF

barronj · Sep 19, 2011

Broncobowsher said:
(K&N's are known for sometimes oiling up the MAF and making them go bad)

Especially if you've cleaned it w/a degreaser & re-applied the oil.

Also, brake cleaner might work, but I'm positive that there's an alternative designed to be sprayed on that little element. So little is needed, you would think it would be sold in eye-dropper form, but alas no, you buy enough for an entire metropolis worth of dirty MAF sensors.

jw0747 · Sep 20, 2011

brake cleaner on MAF sensor might destroy it. use MAF cleaner.

CJ who??? · Sep 20, 2011

I've recently bought a can of MAF cleaner at NAPA. Before I started getting into this EFI stuff I've never heard or seen it before. It's usually around the brake cleaner isle and I think I paid around $8.00 or $9.00 for a can.
I have a Mustang and Explorer MAF, and both of them have a factory caution sticker on them warning about cleaning, especially the inside.

Broncobowsher · Sep 20, 2011

Don't clean them while they are powered up.
If the sensor is already bad, what do you have to loose (besides $8 for the can) in trying to clean them up?

TXHusker · Sep 20, 2011

I'll grab a can today at lunch then spray the inside.

I'm going out on a limb and using my logic, (uncharted territory for me) I would think spraying in the opposite direction of the air flow would be the best procedure in this case. What I mean is, I would spray from the opposite direction of air flow.

TXHusker · Sep 20, 2011

confused....

cleaned the MAF with the cleaner at noon and allowed it to dry all afternoon (5+ hours).

I am not sure why it was idling couple days ago, but it isn't idling now. just chugs and chugs.

I'll check plugs and fuel filter tomorrow. any suggestions are welcome.

markperry · Sep 20, 2011

I was told by a mechanic that after spraying the MAF with the cleaner you also need to take a toothbrush and lightly brush the thin wire, then spray again?

Viperwolf1 · Sep 20, 2011

markperry said:
i was told by a mechanic that after spraying the maf with the cleaner you also need to take a toothbrush and lightly brush the thin wire, then spray again?

do not touch the wires!!!!

TXHusker · Sep 20, 2011

more info

I am following the thread started by PK8950(?).

he was asked about backfire/misfire

something I didn't mention previously: I have had an issue with backfiring in the upper intake, it would stop after warming up...and Saturday it was particularly worse...sounded like popcorn.

markperry · Sep 20, 2011

Viperwolf1 said:
do not touch the wires!!!!

Good advise, I won't listen too him anymore!

Broncobowsher · Sep 20, 2011

markperry said:
I was told by a mechanic that after spraying the MAF with the cleaner you also need to take a toothbrush and lightly brush the thin wire, then spray again?

And don't even bother putting that back in the car after treatment like that. MAFs are very sensitive, much more so then a toothbrush. I won't even use high pressure compressed air on them. Shop vac on blow or what a can of cleaner and spray is as hard as you should ever abuse the innards of a MAF.

ransil · Sep 21, 2011

TXHusker said:
I am following the thread started by PK8950(?).

he was asked about backfire/misfire

something I didn't mention previously: I have had an issue with backfiring in the upper intake, it would stop after warming up...and Saturday it was particularly worse...sounded like popcorn.

Vacuum leak...

TXHusker · Sep 21, 2011

ransil said:
Vacuum leak...

great....now if you could pinpoint that for me, I'll be on my way.. haha

I didn't even consider a vacuum leak

TXHusker · Sep 25, 2011

searched vacuum hoses and connections, can't locate an issue.

Discovered a cracked distributor cap. replaced it and rotor...it idles pretty good now.

MAF appears to be bad, engine dies every time I connect it. I haven't replaced it yet.

I started another thread (http://classicbroncos.com/forums/showthread.php?t=192646) on this part but I'll ask here as well.

I put a fuel pressure gauge in today and it's showing only 10-12psi while running. That seems low especially after reading other articles which state I should see 40-45psi.

what do you think?

Viperwolf1 · Sep 25, 2011

10-12 psi is too low. 30-40 psi is correct. Fix the fuel pressure before messing with the MAF.

Mass Air Sensor failure?

TXHusker

Sr. Member

Broncobowsher

Total hack

barronj

Bronco Guru

jw0747

Bronco Guru

CJ who???

Full Member

Broncobowsher

Total hack

TXHusker

Sr. Member

TXHusker

Sr. Member

markperry

Bronco Guru

Viperwolf1

electron whisperer

TXHusker

Sr. Member

markperry

Bronco Guru

Broncobowsher

Total hack

ransil

Bronco Guru

TXHusker

Sr. Member

TXHusker

Sr. Member

Viperwolf1

electron whisperer

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