'94 Ex, MAF Sensor

[BeginnerXplorer]

I have a '94 Ex with about 190,000 miles on it. This morning the truck started kind of roughly, not much but just a little noticeable. I got in and drove a few miles and while sitting at a stop light, the check engine light came on and then it stalled. I started it back up, the light was still on. It idled a little high and then fine for a bit then tried to stall again. I gave it some gas and it would idle for a bit and do the same. While driving back home, the check engine light would come on and go off. I used a multimeter to read the codes when I got home and it came back with "Mass Air Flow Sensor below minimum voltage". Does anyone know:
Is this the cause of my problem, or something unrelated?

 

[BeginnerXplorer]

Sorry, accidentally hit return

Also, if this is the cause what can I do to fix it?

I am going to go down now and try to clean the MAF filaments like I read somewhere else on the board. Thanks for the help.

Dave

 

[MrShorty]

While you are cleaning the filaments, examine them closely to see if they have come loose from their posts. Also go over the wiring to the MAF and make sure there are no loose connections or broken wires.

 

[BeginnerXplorer]

Okay,...15 minutes of work (30 if you count the time I left the negative battery cable off to clear the PCMs memory) and my truck seems to be fixed.

I only took it for a short test drive but had no idle problems and no check engine light. I also noticed that it does seem to be idleing much smoother and I had slightly better throttle repsonse (maybe it's just my imagine, but who cares right?...lol)

I would highly recommen this little bit of maintenance to anyone. Why wait until the truck starts running roughly? Just clean it every so often and you'll be in good shape. I am amazed at how much effect such a small (almost unnoticeable except on the q-tips) amount of build up can have.

Thanks Mr Shorty for the advice. And thank you 'Serious Explorations' for the help!!!

 

[BeginnerXplorer]

It's happening again. The check engine light is coming off and going on. The problem is during hard acceleration (like pulling through an intersection) or when idling. It seems like it really starts having trouble when I am sitting at a light. Any ideas?

 

[ronnie mullins]

What did you use to clean the maf with?You should use a denatured alcohol or an oxygen sensor and fuel injector safe cleaner.You could also try cleaning the IAC and the throttle body.

 

[MrShorty]

Have you ran the self-tests again to see if it's the same code being triggered?

 

[BeginnerXplorer]

I used denatured alcohol to clean the MAF filaments. I haven't gotten a chance to rerun the codes again. If I get home early enough I will do it this evening. I just wasn't sure if anyone knew of a common cause of rough and stalling idle. I will also try cleaning the throttle body. I'm not familiar with IAC..any help there would be great. Thanks.

 

[MrShorty]

IAC=Idle Air Control valve. bolts to the side of the upper intake. Is known to get dirt and crud in the valve. I would also check the TPS (throttle position sensor) If it's reading wrong, then the computer thinks it at part throttle when it should be at idle. Easy to check with a volt/ohm meter.

 

[BeginnerXplorer]

Thank you. I read a very good article on the board somewhere about checking/adjusting the TPS, so I will try that. I will also check the IAC. Thank you again everyone for your help.

 

[410Fortune]

The only code you are getting is the MAS code?
No 02 sensor codes?

 

[Billy177]

with 190k seafoam will help a lot

 

[BeginnerXplorer]

I am not sure what 'seafoam' is....

The MAF code was the only one I was getting. I was actually surprised because I kind of expected the 02 sensor.

I noticed this afternoon that it appears to happen most when the RPMs drop to about 750. Once it hits 750 there is a sudden drop to 500 and a noticeable 'chug' in the engine.

I did not get a chance this afternoon to run the codes again. Hopefully tomorrow I will.

 

[Billy177]

www.seafoamsales.com it is an engine decarbonizer