MAF Problems???

Thomas A

Registered User
I've been working on my friends SC the past couple of days, and am having a problem with the MAF. The car wouldn't keep running more then about 3 seconds unless I was on the gas. I figured it was a problem with the MAF. Sure enough, I unplug the MAF and it runs great. So, I'm think bad sensor. So I swap sensor's with an extra one I had laying around from a '90 SC. Same thing; won't run with it plugged in. Okay, maybe somehow it doesn't like the housing, so swap the sensor and housing with the extra one I had. Same thing happens.

So, appreantly it is something to do with the MAF signal, but not the MAF it's self. Does anyone have any idea what it might be, or how I can test the sensor to make sure that I don't have two bad ones. Thanks!

Thomas
 
No, I'm sure it's related directly to the MAF. When it is plugged in, it runs bad and dies. When I unplug it, it runs perfectly. That's obviously a MAF issue. I'm going to go pull codes again and see if it spits out anything new.

Thomas
 
Hey Thomas A

I just unpluged my B/map sensor and maf sensor. Tried to start motor it would just sputter and die wouldn't rev up. Got codes 22c and 66c. Hooked Them up cleared codes . Ran codes again got pass 11 for on demand and continuous. I seem to have just the oppisite problem with it unhooked it runs like crap but with it pluged in it runs better.

If something is wrong with the maf it should be showing up as code 66c voltage MAF to low.
 
You need to clear the codes if you don't

The kam memory chip will keep on cycling with the problem therefore it will keep running bad. The car has to be running good / fresh start by clearing the codes in order for the Kam to learn to run good again.
 
Ive also had similar maf problems, my car would run very rich at idle and idle like crap. There wasnt any codes that came up either. I got another maf off another car and it still did the same thing. I just bought a pro-m 87mm unit and it has completely fixed my problem.
 
Thomas A said:
No, I'm sure it's related directly to the MAF. When it is plugged in, it runs bad and dies. When I unplug it, it runs perfectly. That's obviously a MAF issue. I'm going to go pull codes again and see if it spits out anything new.

Thomas
Well Thomas I hate to say it....but thats not the way to troubleshoot the EEC-IV system. That method creats more problems than it solves.
When you unplug the MAF that throws the comp into open loop and it starts applying preprogramed fuel and spark tables that are set up to keep the engine running safely.
The fact that you are getting no codes for the MAF means one of 2 things.
1. The comp tested the MAF and electricaly its fine, but mechanicaly it could still have a problem. The comp cannot check for mechanical problems with that sensor.
2. The MAF is electricaly bad but the comp was reset with the bad MAF on it and now the comp thinks the bad MAF is good even though it may read out of spec.

If in fact the MAF is good but the engine is running bad then you probably do have vac leaks. My reasoning for that is when you unplugged the MAF the comp went to open loop and that will richen the fuel mixtures up which would cover up small vac leaks, it would also use a different ignition timing to help the engine run.
 
I went out and cleared the EEC, started the car and let it die, then pulled codes again. This is what I got this time:

C21: DIS fault problems with Crank Position Sensor circuit

C24: DIS fault failure in coil 1 primary circuit

C66: MAF sensor voltage signal too low.

Thomas :confused:
 
Where did you get those code explinations from? This is whats in the "Ford Fuel Injection & Electronic Control" manual.

C21: ECT out of test range.
C24: ACT (IAT) or VAT input out of test range.
C66: MAF or VAF circuit below minimum voltage.

1 outa 3 aint bad. LOL!!
#66 could be a bad MAF, but it also could have something to do with the wireing so eliminate that as a problem first so you dont end up buying a MAF that you may end up finding out you dont need.
 
The book I have listed them as this actually:

C21: ECT out of test range OR DIS fault problems with Crank Position Sensor circuit

C24: ACT (IAT) or VAT input out of test range. OR DIS fault failure in coil 1 primary circuit

Seeing how one of the explantions for each dealt with the DIS, I assumed that was the ones I should be looking at.

Thomas
 
The scanner is a Sunpro that is made by Actron. Ford Code Scanner, CP9015 Car Computer Code Reader - Domestic: Ford, Lincoln, Mercury 1981 & Newer with EEC-IV or MCU Engine Computer Control Systems. 1994

Thomas
 
Thomas I'm using the above mentioned manual, it is sold through Ford Motorsport and is reffered to by them as the Bible on the EEC IV system.
I've already told you what the manual says about the code #'s you posted.
Now I'll post whats in the manual relating to the problems your book gave as code explinations.

C21: ECT out of test range OR DIS fault problems with Crank Position Sensor circuit
Your manual talks of problems with the crank posistion circuit. My manual says you need a code 14 PIP circuit failure.

C24: ACT (IAT) or VAT input out of test range. OR DIS fault failure in coil 1 primary circuit Your manual mentions failure in coil 1 primary cicuit. My manual says you need a code of 45 "DIS coil pack 3 circuit failure or coil 1 primary circuit failure.

As you can see there is a big difference. I dont know what to tell you. Are you sure youre using the reader properly and have read all the instructions on the reader?
You can look the code up yourself at www.fordfuelinjection.com and check them out for yourself. That site will also teach you alot about the EEC IV. Hope this helps you.
 
As you can see there is a big difference. I dont know what to tell you. Are you sure youre using the reader properly and have read all the instructions on the reader?
Yes, I know how to use a code reader.

At any rate, this seems to be a problem relating to the MAF, thus throwing the 66 code. So, is there a voltage I can get from the MAF Sensor to see if the sensor is bad? If I can determine that the sensor is okay, I can then start looking for corrided wires and such. Thanks.

Thomas
 
Hey Tom, where are you working on this car at? Your place? Let me know. I may be able to swing out and take a look. Maybe swap a couple part off mine to trouble shoot. Let me know. I've got drill this weekend so I won't be available until around 4:00pm. Just drop me an email or reply here.
 
Yeah, that would be cool. Yes, I'm working on it at my place. It would be nice to be able to swap in a MAF that we know is good and see what happens. It's real possible that my other one isn't any good. It's been bouncing around in a box of parts for quite awhile. I'll be around tonite, and don't know about tommorow night. Might be over at my brother's house. I'll shoot you an e-mail when I find out. Thanks.

Thomas
 
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