Failed MAF?

driller

driller

El Presidente
Here's the deal... these headers don't owe me anything. They've had a lot of abuse over the years. But they have been repaired/welded once and I'm not sure they could be repaired this time. Even if so, how long would it last? The leak is very small... I would've never suspected any leak without doing the OBD2 swap and logging STFT's and having the issues I am currently having. I was only able to confirm the leak by charging the exhaust system with compressed air.

I only hope once replaced, the STFT's line up as they should and we can progress from here. If they do not, I am still left with a problem. I still need to get the converter question and intake question answered, but to do so I need to get past this problem first.

The only thread of hope I'm hanging onto is the STFT's did seem to line up once the RPM's were over 2500 or so. That appears to be the classic symptom of a small upstream leak. At lower RPM's, air is induced into the exhaust stream upsetting the affected O2 sensor. At higher RPM's the percentage of fresh air is insignificant to the overall flow across the O2 sensor.

I'm leaning towards a set of long tubes if I can convince one of the local hotrod shops to fab up a set from some Mustang full length headers and install them. :cool:

I'm also seriously considering a short flex pipe in each downpipe to take some of the engine torque strain off the headers.
 
tixer

tixer

Lincoln Evangelist
I should note that 97MarkJA is local to me, so if you go this route, I'd be happy to provide "free shipping" to Carlisle..
 
driller

driller

El Presidente
I was turned away rather quickly when I asked about fabbing up long tubes for the Blue Flame. :p

We did discuss the STFT problem for quite a while. It seems to be not so an uncommon issue with big cams on heavily modified vehicles. Some just run open loop full time and others just ignore it. It was suggested that if I was set on replacing the headers to just go with another set of Kooks. I'm not sure how I feel about that.

I may just put in the new O2s with a new IACV, double check for any vacuum leaks and see what happens. :(
 
tixer

tixer

Lincoln Evangelist
Maybe only a short-term fix, but if you can get in there with a Q-tip or something, I know JB-Weld makes a "high heat" variant which specifically lists "Exhaust Manifolds" as a potential use..

Even if it only holds for a while, it might allow you to determine if that leak is significant enough to be causing your problems.

http://www.jbweld.com/product/j-b-highheat/
 
driller

driller

El Presidente
I actually used some high temp epoxy last year when I first ran across this problem. I just tried to put it where I could. I think to get it where it needs to be I need a u shaped piece of flexible tubing (copper?) and a syringe or caulk gun or something to that effect. But it could be worth a try.
 
driller

driller

El Presidente
Wow... two months have come and gone and I am no further ahead than I was. :mad-tilt:

This last couple days I spent in and out of the garage. First day was literally wasted trying to install drivers on the new Lenovo laptop to allow the XCal3 to datalog the car with new O2 sensors.

New O2s showed little difference than before. Bank 1 still not switching as Bank 2. STFT's goofy as ever. OK, next task at hand... the dreaded IAC valve. :eek:

Off with the intake tube, throttle body, passenger wiper cowl and whatever else that was in the way. Two hours later the old IAC valve was out. Couple more hours and the new IAC valve was in. After a supper break I put everything but the wiper cowl back in place and started the car. Pretty much little to no difference. Datalogs still show the same symptoms.

I think I'll probably just clean it up for a car show next weekend and run it open loop for a while. Not sure what the next step will be. :embarrassed:
 
M

MustangChris

New member
driller said:
So what symptoms does a failed MAF produce?

There's a story behind this but I want to hear what others have experienced first. :frown-blue:
Click to expand...
mustang wont throw a code; just wont idle properly, dies at stoplights, sputters during acceleration.

Try cleaning it before replacement and check your engine+battery grounds.
 
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