Did overhaul on ATX and 2.0L engine. Before this, it was in running condition. Just did OBDII scan test and no codes present. Earlier today, swapped out old PCM with another used one, based on tests determining it as the culprit for why I'm getting no spark. Crank sensor tests prove it to be functional. Wiring harness taken apart, and crank sensor pigtail was replaced as well as bad/exposed wiring. New cam sensor, new plugs. Engine will crank, but no spark. Ignition coil tests good, and ASD relay tests good.

Sorry if this is jumbled, just trying to get it all out. Any and all help will be greatly appreciated, I'm at my wits end!

*EDIT* forgot to mention, the only change I made was replacing the camshaft (which had some wear) with another used one (had less wear). mine is a 2000 model base. the donor vehicle from which the cam came, i believe was a bit newer, I want to say an 03, but it could've been a little older. dunno if they changed the way the magnet reads from the sensor or not

 

Did you program the PCM,they are generally not plug and play like that. If you have a scantool you should be checking for things like CKP, CMP, Fuel pulse width.

Let me know what you got.

 

I guess I dont understand what there is to reprogram that would differentiate between vehicles (donor pcm came from 2000 plymouth neon with ATX, which is a direct fit for my 2000 dodge neon with ATX) the scan tool (rented from autozone) gave me an option to read codes. the extent of my knowledge is thats all scan tools did, unless it was a pricier model that had more features.

as far as checking crank and cam sensors, like i said, the cam sensor is new, and the crank sensor was tested to be good; its getting 8 volts, good ground, and signal wire shows varying voltage from .5 volts to 5 volts when crankshaft is turned by hand. fuel related issues i wont be bothering with as of yet (should there even exist a fuel problem) since im not even getting spark (power from ASD, but ground connections not being made in PCM to complete circuit) all evidence really does point to PCM being the culprit, which is unlikely getting a dud replacement, but if theres some programming involved that im unaware of, i'd love to hear about it.

 

Does your check engine light come on when you turn the key to the on position?

 

http://forums.neons.org/viewtopic.php?f=40&t=337431

Hopefully this helps you.

 

assuming the check engine light is that yellow symbol that kinda looks like an engine, then yes it shows up. i even get an initial charge to the coil during that time, but goes away after that 'priming moment' (dunno what its called).

crank sensor is good, based on test done. ive tried disconnecting cam sensor, and still no dice. my neon is a stripped down base model, so no chip in the key, so i cant see why i would need the PCM programmed.

i heard one thing that may be an issue. i was told that the crank and cam sensor are supposed to work in sync with each other, so if the timing belt is off a little, it will not allow spark to be created via coil...is this true? like most engines, the marks dont line up PERFECTLY, so i got it as close as i possibly could, i dont think there's much of a chance it's off, but id like to know if there's validity to this claim; sounds a little weird to me.

 

If the timing is off it probably won't start..

Is your ignition key grey or black?? My Neon is the base model but it still has the SKIM system.

 

This is my first post in the neon section, but I just a very similar problems with my girls car. We swapped out the camshaft and had a no start condition. And after a whole lot of hunting it turned out the cam magnet on the end of the used camshaft was different that the one originally on the car. We swapped the cam magnets out and the car cranked right up. hope this helps.

 

very appreciative of the responses guys.

well, after some inadvertent looking around in the 1st gen area, i read about the VSS causing problems. So i gave it a shot and unplugged it, and....BAM it fired! talk about relief! checked the pinout, and sure enough it shares the same power feed and ground wire. chances are excellent the sensor somehow shorted out, though it could be the wiring, i will need to check. it will only run for a split second after turning the key. if i push the accelerator down while cranking, it will rev up for about a second longer, the timing and compression seem to be fine, but im thinking the donor PCM i got may still be suspect. i understand that if you have the wrong PCM (with the key chip being the variant, and btw my key is black with no chip) it will allow a non-chipped system to run but only momentarily. can anyone confirm or deny this? also, does anyone happen to know how to tell which PCM is for which ignition system? thanks a bunch, this has been a monster! :P

 

Lol I should have known, I had that happen to a Ram once. VSS shorted the 5V reference down to 2V.