Trying to determine if I have a bad MAF

[edogg23]

My sho has gone from running 14's to really high 15s and has lost about 6 mph in its trap speed. 60k was done a little more than a year ago so my plugs are nice oil free. I have also just changed the O2 sensors. The engine runs smooth, doesn't seem to be missing at all so I'm puzzled why my sho has become slo.

Today I tried unplugging the MAF and trying some WOT runs and I really couldn't notice a difference between driving with my MAF connected and disconnected besides the check engine light that would come on when I unplugged it). Does this rule out a faulty maf or does the fact that the car doesn't run any better with the MAF connected indicate that maybe there is a MAF problem?

I am also ordering a new TPS any other suggestions?

 

[91 Plus]

I would just say tps..What about maybe your clutch..I think mine was giving me a loss of power but didnt fell like it was running bad at all!

 

[AutoSHO]

This is how I determined my MAF was bad: I was driving with the car in third around 3,000 rpms. I slowly opened the throttle. On mine, about 1/2 to 2/3 of the way to the floor, it felt like someone turned off the power switch, and the car was kinda doggy after that. I experienced the same 1/4 times as you (plus altitude correction) so its a likely possibility.

If the throttle response is good, and you don't have any holes in power (i.e. certain throttle positions feel slow, even though it is a fairly open position) then check your fuel pressure.

 

[Dave Kegel]

Make sure your crank bolt is nice and tight. If that loosens up, you end up with what is referred to (on the SHOtimes list) as "crank cancer". The woodruff key starts walking around the slot in the crank, which wears out. This causes the crank gear to have slop in it, which totally retards your timing, resulting in a loss of power.

It's happened to more people that you'd think, including Mr. SR71 himself.

Dave Kegel

 

[Mr Anonymous]

Diagnosis 101: Start with the Codes!

You're obviously going to have a MAF code now because of unplugging it, but clear the codes, spray the MAF element with ELECTRICAL CONTACT CLEANER (avoid brake or carb cleaner). After some driving, check the codes again (even if a CEL doesn't fire). You can also try the KOER test to see if anything looks fishy.

I seem to recall the guy at AutoZone mentioning to another customer that they could test his MAF, maybe you could try that...

 

[shojuan]

If you've cleaned the MAF and you don't have MAF codes then try swapping on a known good MAF from a friend and seeing if that makes a difference. When I thought my MAF was bad I swapped on Efren's MAF and it actually made things worse! eek! Saved me from spending $160 on a new Pro-Flow Bullet MAF (I really wanted that new MAF! )

 

[edogg23]

Thanks for the help guys. I do have a pretty tired clutch. If I shift hard from first to second my rpms just kind of float around 5k until the engine passes that, I haven't been able to chirp gears for a pretty long time So I imagine maybe I'm losing some power there. BTW I cleaned my MAF with carb cleaner a few months ago trying to fix the problem, hopefully that didn't make things worse. This may seem like a dumb question but can I just jack up the car and take off the wheel and plastic gaurd to check the crank bolt or do I have to take a buch of stuff apart?

 

[shojuan]

edogg23:
can I just jack up the car and take off the wheel and plastic gaurd to check the crank bolt or do I have to take a buch of stuff apart?

Yeah. That's all there is to it and you'll have good access to the crank bolt.