Mass air sensor below minimum voltage, rough cold idle.

Tickler

Registered User
Anyone ever have this happen before?
Often my bird idles rough when cold, but idles fine when hot. Whenever I unplug the IAC it idles great. Occasionally when I'm at a red light the CEL will come on, and only throw a code 66. So far I've replaced the iac, maf & cam sensor to no avail.


66 O,C Mass air flow sensor fault, below minimum voltage
 
Check for leaks

Hello.
Your statement that it runs rough when cold sound like a possible vacuum leak. I had the same CEL code before and it was from a loose intake coupling (vacuum leak after the MAF). Check the main rubber inlet hose for any cracks or loose clamps. Check the hose mounted at the bottom of the rubber inlet tube for any damage or loose fittings. Also go through the intake and return tubes to see if there are any loose joints. For sealing the tubes to the intercooler and the supercharger top I highly recommend the teflon gaskets that are sold by a few of the members and vendors here through the club. I would also re-seal the top to the supercharger using a very thin layer of ultra copper rtv sealer. From there go through all of the vacuum lines and see if there are any that are loose or damaged. If they are hard or if they appear to be "iffy" replace them.
One last area to look at are the intake bolts and gaskets. Check to see if all of the bolts are tightened to the correct torque.
Hope this info helps.
Good luck!
Bill
 
I just finished a top-end rebuild with my own two hands..... It's not a vacuum leak, too intermittent. I forgot to mention the thing will stall after idleing anywhere for 5 min (10 cold), But runs like a raped ape on a motorbike otherwise.
 
Are you sure about the code # you are listing? 66 is for a trans oil temp sensor code, 26 is for MAF voltage. Have you verified the voltage at the MAF?
 
Are you sure about the code # you are listing? 66 is for a trans oil temp sensor code, 26 is for MAF voltage. Have you verified the voltage at the MAF?
66 Vane Air Flow (VAF) or Mass Air Flow (MAF) signal low -
Transmission Oil Temperature (TOT) signal low (possibly grounded) -
 
I checked the 89 PCED Ford manual, and 66 is a code for the MAF. I was looking at a 92 PCED before. It is a continuous memory code. Did you check for any KOER codes? Sounds to me like you have a wire harness problem. In order to check it correctly you will need the procedure and a DVOM to check the wire harness.
 
After I installed the maf yesterday, i forgot to do the re-learn procedure for the ecm. Problem solved.
 
There's several ways to do it, but the simplest is to unplug the battery for about 15 minutes. This wipes out any fuel trims stored in the computer that helps to keep the car fuel mixture optimal for less than WOT situations.

It also affects idle.
 
Back
Top