Running rich when cool and Lean when hot !?!? | Ford Explorer Forums - Serious Explorations

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Running rich when cool and Lean when hot !?!?

Joined
November 19, 2017
Messages
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City, State
Mobile, AL
Year, Model & Trim Level
1999 Explorer XLT AWD
So I've been having trouble running lean lately and everytime I think I have it licked.... it rears its ugly head a little differently. As of the last 2 days it predictably runs slightly rich in the morning when it's cool outside, and super lean right about noon when it's in the 80s. Just recently: new maf sensor, 02 sensors, throttle body gaskets, upper and lower manifold gaskets, and egr gaskets. I'm about to lose my mind..... also the car seems to run ok...although when it's hot there is a noticeable loss in power/acceleration. Thanks in advance for any advice.
 



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I am now getting CEL for lean on banks 1 and 2........fml
 






That list of changes you have may be enough now, that it needs some new programming. I'd finish doing anything else affecting over all airflow through the engine, swap the K&N filter for an Amsoil EA filter of some kind, and get the PCM programmed. That should pick up a decent amount of power you can feel, after the tuning.

Check the plugs occasionally too, be sure the gap is not eating the plugs at all. Regards,
 






So Ive waited a few days to post this..... I wanted to be relatively sure. Saturday evening I tried something.....I put the oem MAF sensor back in and removed the Walker aftermarket one I bought. It instantly fixed my fuel trim problem. 3 days later and the short term trims are fine and I have yet to get a CEL. It also noticeable improved performance in hot weather. Seems Bizarre......
 












Ford has a great fuel injection system. There is no gain in power or upgrade in a MAF sensor. A larger MAF is not necessary unless you have enough upgrades that the engine is out flowing what the MAF will read. The Walker MAF is obviously sending a different voltage to the EEC than the stock one does at different flows. The curve is off/reading differently than the stock one.

I ran the stock MAF in a Ranger with 6lbs of boost, no problem.
 






I didn't see the Walker maf sensor as an upgrade but more of a replacement seeing as the housing stayed the same size. Am I missing something??
 






It reads like it should be a replacement part. But there are some differences in quality of MAF brands. Some have good reputations, some do not. I'd lean to an OEM MAF, or SCT or a couple of other big names, and avoid the rest.
 






Basically you do not have enough in power adders to need a tune and there is no reason to replace the Ford MAF unless it is not working or you need something that will read more flow and housing that will allow more flow..........

If you want a tune you would get a bit more power with running high octane and a high octane tune, and tuning the transmission, but that is not worth the price of a tune and tuning equipment to me.
 






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