Backfire Sputter Bucking and Hesitation.....

[nytescion]

My car is doing all the above at 4500rpm. I originally thought I was overruning my fpr untill I installed the aeromotive fpr and I'm still getting the same situation. So far to try and fix the problem i have done:

Aeromotive Fpr
installed new spark plugs (ngk's)
installed ngk plug wires
Boost leak test (holding 35 psi have small leak at throttle body shaft seals.)

For some reason I can't get my logger to log but it's probably user error. I do get a check engine light for code 24. which I'm looking into. I recieved my shop manual (on cd) yesterday night so I'm going to try and get that worked out. I'm at wits end with this car now and I need some help. Thanks in advance.

 

[1gDSM4g63]

It's probably a fuel cut. Assuming that your EPROM is not damage make sure your FPR set to 37-39 psi and change your fuel filter too or it could be your spark plugs aren't gap properly. Another thing make sure your MAF or MAS is connected.

 

[nytescion]

ok bout to go check plugs again. Maf is connected. I am running an eprom ecu but it is not socketed or chipped yet. I got the logger to log while idleing and revving now I just need to take her on the quick drive up the street to get a log while driving. Quick question in just free revving I logged 38 degrees in timing is that a bit high?

edit: actually looking at the log the highest I see is 42 degrees and that was at 3700rpm

 

[1gDSM4g63]

Update your profile, you're not very clear on what you've done to your car. If you're running a AFPR, upgraded fuel pump and bigger injection you need to have an afc and chipped EPROM or DSM Link to stop the fuel cut.

 

[nytescion]

everything has already been updated. running stock 450's and 14b (i have 880's and the hx40 on a tubular mani and open dump to slap on but i wanted to figure out my problem first) Other than fuel cut, in which i will have to get a safc now? what else could be affecting the car likes this. One guy local heard me talking to a friend about it and he said to check me map sensor? hmm......

 

[Stainbox12]

Our cars don´t use map sensor. As said above, replace fuel filter, make sure the pump is installed correctly. Timing seems to be a very high, check it and make sure its at 5 degress. Also check injectors they may be clogged, i would take them to an fuel injection shop and have them cleaned for the sake of it. Also try swapping with another ECU. When the cam angle sensor, is all the way advanced, it would cause backfires and popping sounds due to excessive spark.

 

[nytescion]

I'll try the fuel filter,and check timing when i get home. I've tried using a different ecu also. My cam angle sensor is dead in the middle of adjustment.

What I have noticed is that while driving and I floor it it will go up to 4000rpm-ish then the will like immediately stop pulling. kinda hits a wall . At this point the car is non-responsive to the accelerator. then when the rpm drop back down to around 2700iish, backfires then (if i still have the peddle down) it will try to pull again with the same results.

 

[Stainbox12]

I'll try the fuel filter,and check timing when i get home. I've tried using a different ecu also. My cam angle sensor is dead in the middle of adjustment.

What I have noticed is that while driving and I floor it it will go up to 4000rpm-ish then the will like immediately stop pulling. kinda hits a wall . At this point the car is non-responsive to the accelerator. then when the rpm drop back down to around 2700iish, backfires then (if i still have the peddle down) it will try to pull again with the same results.

Do you have a logger? you may find a lot of useful information with one. You may check your fuel trims, monitor knock, timing advance and/or retard. You may be able to diagnose your problems. I would say, that right now, you are just blind trying stuff. Start with the cheapest things, and go up with the most expensive ones. But definatly get a logger it will save you time and money. Good luck.

 

[nytescion]

ok bout to go check plugs again. Maf is connected. I am running an eprom ecu but it is not socketed or chipped yet. I got the logger to log while idleing and revving now I just need to take her on the quick drive up the street to get a log while driving. Quick question in just free revving I logged 38 degrees in timing is that a bit high?

edit: actually looking at the log the highest I see is 42 degrees and that was at 3700rpm

yes I have a logger I'm just having a problem getting it to work while driving. But so far on the logger the only thing i see wierd is the timing and my o2 sensor reading. I'm getting 2.5v and it doesn't fluctuate at all. that's from 900 rpm all the way to around 3400rpm.

 

[dale187]

My car was doing the same thing. Do you have a aftermarket boost gauge? If so what are you pulling as far as psi? My problem ended up being a failed MBC. Running the car off the wastegate for now and car runs fine.

 

[EvansF]

maybe you are creeping and then knocking. when you are creeping, its usually higher on 4th and 5th gears.

 

[nytescion]

I'm running the car off wastegate pressure. I'm only getting to 8 or 9 psi max before this starts to happen.