Popping, backfiring at 3 psi and above?

[DCEPTCN]

Well, I was supposed to go dyno this morning and, true to form, my haunted car developed a new problem overnight. At about 3 psi and up (basically if you give it any gas) it will start popping, like a cluster of little backfires. Needless to say, when this is happening the car loses all 'pull' and is basically bogging out. It will usually stop as soon as you let off of the gas, but sometimes continues on for a moment. It's got new plugs and wires, new MAF, fp has been checked and is fine, new chip, etc. etc. I thought for sure that this was a coilpack problem, so I just put a new one on and there is no improvement.....I just had to cancel on the dyno and they didn't sound really happy with me. Anybody have a problem like this before.....and WTF is it? TIA

 

[Reaper]

will it clear up if you keep on the gas? is it still there at higher RPMs? or just at lowe RPMs?

my guess would have been the coil pack. but since you have already tried a new one. i would not look at the connection to the coil pack and other fuel and spark related items. how is your FP across the powerband? does the FP track with boost?

thats all i can tthink of.

 

[DCEPTCN]

Unfortunately, it continues if I keep on the gas....but I've not spent too much time pushing it, all that popping and stuff scares the hell outta me.

 

[John Larkin]

Really need some scan tool data here. Watch for voltage dropout, MAF dropout, knock. As was asked before does fuel pressure rise with the little bit of boost you've been making? Also check your intercooler connections and MAF pipe connections. Squeeze the connector hoses and make sure they're on there good.

 

[TT/Ameasap]

By new MAF, do you mean it is a reman MAF?

If so, that could very well be your problem. unplug the MAF sensor and see if it is any better or any different.



HTH
Bi

 

[EdMacKenzie]

I know it may be way off, but check the alternator voltage, I just had a similar problem when my alternator died, hit 2000 rpm and die out, was only pushing 12.4 volts and was causing a whole wack of problems... just a suggestion..

 

[Otto J]

Make wure the vacuum line on the fuel regulator is hooked up tight and not leaking, If oyur fuel pressure doesnt rise it will do that

 

[bogie1]

I had the same problem early last year, Thought for sure it was plugs or coil pack- would start to buck and pop over 5 # boost--installed a new ignition module and never poped again.--Good luck!

 

[Slo86GN]

That's exactly what happened to an 86 GN I had a while back....ignition module wasn't able to keep up and was dropping out above 2000-2500 rpm. Changed out the module and no more popping/spitting.

 

[NJTurbo]

Originally posted by DCEPTCN
Unfortunately, it continues if I keep on the gas....but I've not spent too much time pushing it, all that popping and stuff scares the hell outta me.

May sound stupid but I know you just had motor in and out. Make sure all your vacuum lines are on and on right and tight. Intercooler hoses on and tight. Did you install the Mass Air Flow in backward, I did once. Drove me nuts for days check it. Possible bad ignition module, did you mess up the firing order. Keep us posted.

 

[HellOnWheels]

Have someone help you....start the engine then UNplug the cam sensor, if problems go away you've found the culprit.


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