Hey Guys Still Stumped..

[Makdaddymac]

My 91 GT is still acting weird a month later....
It bogs when you step on the gas and sometimes in the lower rpms,it pops,almost like a backfire but from the engine compartment...
Im lost the only codes i got worht while was a MAF code and a fuel pump relay..I put on a relay,and replaced the MAF,the Maf didnt do nothing so i returned it and put my old one back on....
Somebody told me EGR Valve is doing it.Is that possible...
Im still waiting on an ebay maf to try it again,,,but i think i got/getting scammed ive been waiting like 3+weeks.
My guess is MAF,but it works every once and a while fine....Ive cleaned religously,probaly why it messed up??....
Ps. to reset the ecu just diconnect the negative cable right?

 

[Makdaddymac]

Is the maf my problem???

 

[powertrax91]

sounds like it could be... I had the same problem early this summer...
I replaced my MAF and that solved my problem...

 

[Makdaddymac]

im also getting a huge amoujt of fuel smell.Like its running rucher than richie rich..I replaced my maf and it did the same thing,but i only gave it like a down the sreet test and didnt reset my ecu! so maybe i dint let it recalibrate...How do you reset the ecu,just disconnect the battery cable correct? Cause on my probe you have to pump the brake pedal for a minute,just making sure htere isnt something stupid like that to do????

 

[99FiveOh]

The computer reads the voltage the meter puts out as air passes through it. You shouldn't need to reset the computer because when a new meter is put in (if that's the problem) it's voltage will be back in range and the computer will adjust accordingly, right away.

But, your problem sounds alot like a stuck open EGR valve. Is the vacuum line running to the EGR the original setup, or have you changed it recently? You can try unplugging the vaccum line from the EGR valve and putting a screw or something in the hose and test drive the car. Bogging and rich fuel smell sounds just like a bad EGR. Unmetered air is getting into the engine while in low RPMs.

 

[powertrax91]

I used my scanner to reset my ECU... how are you pulling codes?

The fuel smell / rich condition (I'm assuming at idel) is most likely from the faulty MAF... The ECU cannot determine how much fuel to deliver. Because it can't see how much air is passing the MAF, the ECU goes into a fault loop and the ECU will deliver the same amount of fuel regardless of throttle position or MAF voltage.

 

[88-GT]

Although my car is speed density, and more reliant upone the 02's, I also had the exact symptoms you are describing, I chased it forever and couldnt find it. Turned out I had gotten a faulty set of bosche 02 sensors that were bad from day 1. Replaced them with a set of NGK's and runs like a top. Might be something to look into, even just borrow a buddy's for a quick rip.

 

[Makdaddymac]

Your the second person who said it was as stuck open egr,mine looks like it played hot potato with the devil and lost.As for the maf im stil waiting on one for almost a month from a ebay guy...If i dont get it soon, i'll buy a reman from the store...But i think im gonna replace the egr 1)its cheaper and might be the problem 2) its cheaper and might be the problem!

 

[68stang351]

I had the same prob, replaced the MAF and all was fine

 

[Makdaddymac]

did all you guys get the popping nosie? and powr loss during this sort of backfiring popping symptom..??

 

[powertrax91]

did all you guys get the popping nosie? and powr loss during this sort of backfiring popping symptom..??

yes sir...

 

[sunil6784]

I'm pretty sure a stuck EGR valve would give you a code. I would work through one code at a time.

SOunds like the MAF could be the problem. Driving it down the street wouldnt be enough time to let the computer reset. Did you unplug the battery while putting in the new MAF? If you disconnect the negative cable for 20 minutes or so it should clear the computer. I also like to step on the brake pedal a few times for reinsurance.


Edit: Even after disconnecting the battery, there's still some electricity stored in the system in capacitors and whatnot. Pressing the brake pedal just sends this electricty to the brake lights.