Problem code 66
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Problem code 66
I'm curious why the voltage to my maf could be low? I checked the archives and didn't see it mentioned specifically. I didn't see how to read resistance or voltage values at maf plug in haynes bood? Truck runs perfect, just annoying CEL comes on a couple seconds after starting. Any input appreciated.
91 ford ranger 4.0 5 speed.
91 ford ranger 4.0 5 speed.
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One detail a lot of people miss when reporting a trouble code is which part of the test it's from: KOEO hard fault, continuous memory, or KOER. If it's a continuous memory code, did it pass the KOEO and KOER parts of the test?
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Thanks for reply. I reread the EECIV article a couple times and think I am testing correctly? The koeo test comes up as 11 11 1(seperator?) then 66 66. The koer test came up as 98 66, 98 66. The throttle goosed itself then no more codes came out. I erased all previous codes prior to warming up the truck and registering above codes.
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From: UT
The codes output before the separator pulse in the KOEO test are the KOEO hard fault codes. 11 = pass
The codes output after the separator pulse in the KOEO test are continuous memory codes.
And, of course, you have listed the KOER codes.
Next thing I'd do is do a thorough visual inspection of the MAF. Make sure the intake tube is hooked up and intact. Check for vacuum leaks or any other way for air to get into the intake without going through the MAF. Inspect the wiring from the MAF to the computer. Make sure that everything is plugged in and that there are no obvious breaks. You'll probably eventually want a good wiring diagram that shows the MAF wiring. If you don't have one, try your local library. They often carry professional repair manuals in the reference section, which can have good wiring diagrams, application specific code lists, and pinpoint tests for each code. Can be a very useful resource.
If you don't see anything obvious, then check for battery voltage across the MAF at the Vpower and Vground pins (KOEO). You can check the MAF output by measuring the voltage between the MAF return pin and ground. (Should be ~.4 V KOEO and be between 0.4 and 1.5 V KOER).
The codes output after the separator pulse in the KOEO test are continuous memory codes.
And, of course, you have listed the KOER codes.
Next thing I'd do is do a thorough visual inspection of the MAF. Make sure the intake tube is hooked up and intact. Check for vacuum leaks or any other way for air to get into the intake without going through the MAF. Inspect the wiring from the MAF to the computer. Make sure that everything is plugged in and that there are no obvious breaks. You'll probably eventually want a good wiring diagram that shows the MAF wiring. If you don't have one, try your local library. They often carry professional repair manuals in the reference section, which can have good wiring diagrams, application specific code lists, and pinpoint tests for each code. Can be a very useful resource.
If you don't see anything obvious, then check for battery voltage across the MAF at the Vpower and Vground pins (KOEO). You can check the MAF output by measuring the voltage between the MAF return pin and ground. (Should be ~.4 V KOEO and be between 0.4 and 1.5 V KOER).
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Thanks for help mrshorty. I checked air inlet and all good. Removed and plugged line for blowby to intake air tube in case it was getting too much blowby? Same codes. Didn't see any physical damage to wiring or sensor. Then I remembered I had mitchell on demand, and searched for a wiring diagram. Then found all the info on diagnostics. Totally alien to me, but will start on maf chapter. Could you describe what a "breakout box" is?
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Breakout box is an expensive gadget ($400 - 500 new) that plugs into the computer and/or vehicle harness. Provides a safe way to hook up a DVOM to the computer's harness and test/monitor the various EEC-IV components. Run a quick google search or search on ebay (seems they usually go for ~$150 to 200), and you should be able to find people trying to sell them, as well as pictures and descriptions.
As a DIY'er, though, I haven't been able to convince myself to spend that much on such a piece of diagnostic equipment. I recognize that, "by the book" it's a no-no, but I just take a small straight pin and back-probe the 60 pin connector at the computer. There is the possibility of damaging something, so be real careful not to short anything or accidently try to measure the resistance of the computer or physically damage the connectors and you would be fine.
As a DIY'er, though, I haven't been able to convince myself to spend that much on such a piece of diagnostic equipment. I recognize that, "by the book" it's a no-no, but I just take a small straight pin and back-probe the 60 pin connector at the computer. There is the possibility of damaging something, so be real careful not to short anything or accidently try to measure the resistance of the computer or physically damage the connectors and you would be fine.
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Thanks, I was wondering if there was a way around the box, I was going to check harness for for open circuits. Makes me nervous poking around computer. At least I can't screw a hard drive. What do you think of making some sort of box out of an old harness plug???
I figured things were going to easy on maf. Fixed bad ground, but still getting same codes.
I figured things were going to easy on maf. Fixed bad ground, but still getting same codes.
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It turned out maf was bad (I think). Replaced it with one from a 4 cylinder ranger of same year and it works great, no check engine light. Now I don't mind going out and buying correct maf unit. $$$$$$
Thanks for the help.
Thanks for the help.
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