Missing and popping.

[NA4NOW]

My buddy has a Nissan truck with a ka24de. Its all stock, and has 150K miles.

Yesterday, it started missing on him. Dead miss (misses all the time), ..and every few seconds or so, backfires through the intake. He already put plugs, wires, and dist. cap. So, its not ignition. Not with the backfiring, anyway.

Any idea what it could be? Is it possible it jump time, ...from a wore out timing chain? Would it have these symtoms?

Or maybe a messed up valve? Its missing on #4 cly.

[nissansrdub]

yeah check the timing...thats what i would do next...

[BoNyG515]

hook up an obd scanner or pull some codes...

[BoNyG515]

im sorry i forgot to add. use the scanner to determine if an ignition sensor is bad...

[NA4NOW]

The ignition timing hasnt moved. Distributor is tight, and has fresh tune up. Besides, how would anything ignition related cause a intake backfire?

I cant check the valve timing without pulling the front of the motor apart, and see if it jumped a tooth. Right?

We put a scanner on it first thing. It showed a code for the egr, and #4 cyl. miss.

[BoNyG515]

misfire can also be caused by bad injectors...take a look at #4 injector and see if it visually is good (connector, no debris, etc.). then if you have access to a noid light check if the ecu is properly allowing the injector to fire. if noid light passes. check for injector resistance and compare it to fsm specs. i hope this helps, and keep me updated!

[NA4NOW]

But would an injector make it backfire through the intake?

Im going to do a comprssion test, to see if it has a bad valve.

[BoNyG515]

your right but the computer only sees a misfiring cylinder. yeah run comp test next