Check engine light

[Alaskanredneck]

Have you checked to see if any of your plugs are fouled out? I think its defiantly a sensor telling the computer to advance the fuel in the a/f ratio the problem is just about every sensor in the truck as well as the tcm could be causing the extra fuel problem. Do you know any techs that could test each sensor or does the auto parts store near you test them?

 

[mehedgec]

I have a friend who just told me his Explorer overheated and cracked the block. So he's prolly gonna scrap it. I'm gonna try using his MAF and see if that solves the problem tomorrow *crosses fingers*

 

[mehedgec]

Have you checked to see if any of your plugs are fouled out? I think its defiantly a sensor telling the computer to advance the fuel in the a/f ratio the problem is just about every sensor in the truck as well as the tcm could be causing the extra fuel problem. Do you know any techs that could test each sensor or does the auto parts store near you test them?

I haven't checked those. I'll give the plugs a look.

 

[mehedgec]

I just took the front drivers side plug out, and its pretty fouled up. A decent bit of "white crust" all over the tip. Guess its time for new plugs.

What brand do you recommend for our model explorer? I know not to buy Bosch.

 

[Alaskanredneck]

I would say stay with motorcraft if not from the dealer there is a company called Factory Motor parts they are a dealer warehouse but most locations sell to the retail customer like us. Factory is also cheaper than the dealership. motorcraft is designed for your vehicle and has gone through more tests than aftermarket products because they are the oe plugs and have to stand up to federal testing which most other brands cant touch.
PS I DONT THINK THE PROBLEM IS WITH THE PLUGS i MAY BE WRONG BUT i THINK THE EXCESS FUEL FROM A BAD SENSOR CAUSED THE PLUGS TO FOUL OUT.

 

[Alan_V]

Sweet thanks.

Also, on the way home from work just now, The light and symptoms decided to go on and off a few times...This is ridiculous.

Okay, I got out there this evening. My 93 CA spec has 4 wires to the MAF. KOEO unplugged: Red at position A is B+, Black at position B is B- (mine read 37mv, good ground). This is he circuit that powers up the MAF. Brn with Blk at position C read 5.86 volts so thats v ref. This is the voltage that is the base voltage for the signal of the MAF. Blue with red at position D read 34 mv. That's ground for the signal. As air goes thru the MAF, the path to ground changes, and your voltage on pin C wil change accordingly. Backprobe pin c (brn/blk) using a t pin. Measure the voltage between that pin and a good ground. Accelerate the engine and your voltage should change at a consistant rate with throttle opening. If it stays at a constant voltage or varies up and down wildly, my money's on the MAF is hurt.

 

[mehedgec]

Okay, I got out there this evening. My 93 CA spec has 4 wires to the MAF. KOEO unplugged: Red at position A is B+, Black at position B is B- (mine read 37mv, good ground). This is he circuit that powers up the MAF. Brn with Blk at position C read 5.86 volts so thats v ref. This is the voltage that is the base voltage for the signal of the MAF. Blue with red at position D read 34 mv. That's ground for the signal. As air goes thru the MAF, the path to ground changes, and your voltage on pin C wil change accordingly. Backprobe pin c (brn/blk) using a t pin. Measure the voltage between that pin and a good ground. Accelerate the engine and your voltage should change at a consistant rate with throttle opening. If it stays at a constant voltage or varies up and down wildly, my money's on the MAF is hurt.

What is a t pin exactly? Is that something you pinch in from the outside so that you can measure the voltage while the harness is conected?

Edit: Nevermind, I got one from the electronics lab at my work.

 

[Alan_V]

What is a t pin exactly? Is that something you pinch in from the outside so that you can measure the voltage while the harness is conected?

Edit: Nevermind, I got one from the electronics lab at my work.

Exactly. There are 2 ways to use it. The recommended way is to slide it in the back of the connector until it makes contact with the actual pin. Other ham-fisted sorts just poke it thru the insulation.

 

[mehedgec]

Exactly. There are 2 ways to use it. The recommended way is to slide it in the back of the connector until it makes contact with the actual pin. Other ham-fisted sorts just poke it thru the insulation.

Ok, I did what you said, and here are the results. I got 14V at the +B, 0.09V at B-, 0.10V at Vref and when I revved it, the voltage slowly increased to like 0.15V. I'm gonna test it a little more extensively later on, I just did a quick test on my lunch break.

 

[Alan_V]

Ok, I did what you said, and here are the results. I got 14V at the +B, 0.09V at B-, 0.10V at Vref and when I revved it, the voltage slowly increased to like 0.15V. I'm gonna test it a little more extensively later on, I just did a quick test on my lunch break.

Read the vref @ pin C disconnected KOEO.

 

[mehedgec]

Read the vref @ pin C disconnected KOEO.

I actually checked that one last week, I recall it being around 6V.

 

[Alan_V]

I actually checked that one last week, I recall it being around 6V.

I checked my vref and got 0.237v (237 mv), BUT, I can't rely on it. The display on my DVOM went dark due to low battery. Don't have any spares so I'll have to try tomorrow. But from what you're telling me, I've a sneaky suspicion the maf is bad.

 

[mehedgec]

I checked my vref and got 0.237v (237 mv), BUT, I can't rely on it. The display on my DVOM went dark due to low battery. Don't have any spares so I'll have to try tomorrow. But from what you're telling me, I've a sneaky suspicion the maf is bad.

I was 99% sure it was MAF at that point. I finally just said "screw it" and spent the money on a new sensor last night and installed it.

Problem solved! No more check engine light. So its over

Thanks for all the help you've given me, I appreciate it man

 

[Alan_V]

Okay, cool.

So for the record, with the maf plugged in, B+ on the red wire, good ground (<50 mv) on both the black and blue/red, a known good vehicle reads 237 mv on the blk/brn wire, backprobed, at idle. Do us a favor and read that voltage and post it. Then we have 2 samples for future posters.