backfire

[turbojitsu85]

I have an 85 GN that has all the necessary mods. It started to backfire on me when the boost gets to about 5 pounds but then it will keep going to about 10 pounds. The chip in it pulls timing when this happens the car goes nowhere. I've turned down the boost and this still happens. I know it's not the cam sensor beause it's not getting any bad codes off the scan tool. The ignition and coil pack was upgraded to an 86-87 when the old one went bad the wires are 10mm magnecore. I'm putting in a bigger fuel pump and cleaning the injectors next week. If anyone has had this problem or any suggestions please post a message or email me at turbojitsu110@ameitech.net.

 

[owlpond]

I had the same problem and all it turned out to be was a plug wire arcing off the downpipe. It came loose from the cradle and melted against it causing the arc. Might be too simple but worth looking at. good luck

 

[crazygn]

Check the wires real good. make sure your cam sensor is set good i think you said it was ok tho, and one more, check to make sure all the injector plugs on the injectors are tight. One might just be setting on the top but not on, i had this happen and it did the same thing.

good luck

 

[turbojitsu85]

Thanks for the reply but thats what happened to my last wires I'm 99% sure that its not the wires but I'm going to check them anyway.

 

[turbojitsu85]

I'm going to check the injectors when I clean them next week. The injetors are still stock I'm not sure how long before they start to go bad but that might be it. Thanks for the help

 

[crazygn]

what chip are you running and is it for the stock injectors. Did you tap on the maf to see if it stumbles. Do you have any vac leaks , did you spray to find any yet.

 

[turbojitsu85]

The chip is a Poston 93 octane chip that is for the stock injectors. I don't think Postons makes there own chips but there name was on it. They say the chip can push 16 to 18 pounds of boost on pump gas but when this started to happen i was only pushing 12. At first I thought it might be a bad tank of gas but I've gone thru 3 tanks of 110 and still the same backfire happens and then the chip pulls timing. I haven't checked for vacum leaks or the maf but now that you mention it I will.