i just had heads and cam install and after one day of driving went out the next morning and wont start. ive checked all of the grounds on the engine and the pcm is coming up, because my lt1 scanmaster is reading my 02's and everything else. i was pulling a trouble code 42,& 83 but now after unhooking the pcm, looking at the connections, and plugging it back in, no codes and car still not running. im thinking for some reason either no fuel, but the injectors are getting voltage, no spark, but we put a tester on one of the plug wires and it was firing.yet i cant tell if its firing in the correct order. any ideas? maybe bad pcm?
thanks
mike

 

First thing to do is see if you have fuel pressure. either with a gage or the no cost way.

Also what type of spark tester did you use? The ones with the gap between 2 electrodes work better than the type with the neon bulb. I've seen the bulb light up but there still be insufficient spark to jump the gap of a plug under compression.

Incidentally the cause of the 42 would not allow you to have spark. This code is for the ignition control signal from the PCM to the ICM.

It's good you have voltage to the injectors but you also need pulses (going to ground) from the PCM.

 

i have 40 psi to the fuel rail. i used a gauge. i used the spark tester with a bulb. this does make sense, because i pulled one of the plugs and it was kind of black, but ive seen much worse still run.so maybe its not jumping the gap. yet i dont smell any gas while trying to start it. and your saying that a 42 would stop the spark? and how do you test to see if the pcm is pulsing to ground?

 

This is getting confusing. Drop this thread and stick with the other thread that deals with the 42 code since you have more information there.

Stay with one thread when ever possible.

As far as the spark tester, get one with the 2 electrodes and recheck it inline with the plug in between the plug and wire.

 

what is it doing when u r cranking it? does it want to start or is it just turning over not even trying to start?

 

the car is turning over and not even trying to crank. its not even dieseling. which makes me think that either its not sparking enough to ignite the fuel or its not getting fuel. since it only needs three things to run, spark fuel and air. i just had the computer tuned 2 days before with an overnight shipment from pcm4less. so the only other thing i can think is the computer.

 

as mr.gonzales says, look at thread urgent!!!dtc 42. it will explain everything there, i will continue on with that thread. so reply there. thank you, sorry for the confusion.

 

one thing, you cant tell how fouled, fouled is by eye, sometimes it'll look new and still be fouled, i'd throw a new set of plugs in or ground the plug to the block and turn it over and see if it's doing anything at all

 

THE THREAD IS CONTINUING ON URGENT DTC 42. but anyways the plugs were defouled when i had the heads installed since their not that old. but even if they were fouled completely it would still try to start. right now its just turning over and over by the starter. like its not getting fuel or spark. but like i said continue on thread urgent dtc42