Cascade Crew

90droptoproc · Posted: Sat Dec 13, 2008 2:31 am Post subject: injector fun

I saw alot of talk in another persons post about injectors not firing and it has me thinking about a nother car I have here right now I have been fighting with

the car is an 89 2.0L auto cavalier
there is no injector pulse, and no 5V reference from the ecm
I have been trying to find out whatwould cause the lack of 5V reference
I have tried a new computer with no change
also the past owner had a system in this car and had one of those huge possitive battery terminal clamps and has grounded it badly on the hood (there is welding burns on the hood) Laughing

am I reading it right in that other post that the ignition module can cause the lack of 5V at the computer??

the only reason I ask before trying a new one is that I have done one this month on another cavlier and they are a pain in the butt

I need to get this car outta my hair Embarassed

I have 9 cars right now

chevymad · Posted: Sat Dec 13, 2008 9:28 am Post subject:

Are you talking about the 5v sensor supply? or the 5volt signal to the module that switches the timing from module to computer. They're different. If you're not getting the sensor supply voltage, I too would be looking at the ecm. It's possible that whatever fried the first ecm is still there.. and you fry the new ecm as soon as you plug it in. If thats the case you have to take your dvom and measure every power/ground/sensor/relay that connects to the ecm and make sure none are shorted to power or ground.. tedious.

Brings up a story, had a plymouth laser with a fried computer. Found about 6 old key tags under the seat from various shops in portland. So the car had been around.. then sold at auction.. and I ended up getting to try to fix it. So I replace the ecm.. the car is running nicely for about 20min.. then fills with smoke and quits.. fried ecm. At the time the ecm's were $$ too. Well I can't find anything to cause this, so I call our tech line. Dude tells me to unplug such and such, then try a new ecm. If it fries then unplug something else and try again.. I think we paid $350 for the used ecm then, and a new one was $1k. So that option was definatly out. Sent that baby to the local college to work on. They had it almost a year before they got it figured out. Never did find out what it was though.

blue89 · Posted: Sat Dec 13, 2008 10:38 am Post subject:

Is this the engine with the waste spark ignition module on the block near the firewall? There is a crank position sensor directly beneath the ignition module that could be the culprit. I think I remember someone saying they will go out and cause a no run/spark condition.

90droptoproc · Posted: Sun Dec 14, 2008 11:20 pm Post subject:

ya, wasted spark, odd thing is, I have spark

and paul, it is the 5V grey wire (W11) that has no voltage

dlp · Posted: Mon Jan 19, 2009 4:15 pm Post subject:

I know this sounds to simple, but have you checked the fuses in the fuse block? I know each bank of injectors on V8 cars have a fuse in there...bad fuse, injectors dont work.

90droptoproc · Posted: Wed Jan 21, 2009 12:18 am Post subject:

I have checked all the fuses, but thanks for the idea

blue89 · Posted: Wed Jan 21, 2009 8:32 am Post subject:

If the sensors have no 5V reference and changing the ECM changed nothing, then I would suspect that you have a short somewhere. I would definetly work on this part first.

Do the injectors have a power source? The ECM controls the ground, so if the injectors have no power they won't work. Fix the 5V source from the ECM first then check the injector power.

90droptoproc · Posted: Fri Jan 23, 2009 3:25 pm Post subject:

will the coil pack and ignition module failing cause there to be no 5V?
also, I have checked, there is power to the injectors, but no ground like you say

blue89 · Posted: Sun Jan 25, 2009 8:44 pm Post subject:

You might want to unplug all the sensors to eliminate a possible sensor short. I think it's important that you get that 5V source back. No point in doing anything else till that is accomplished. I'm pretty sure that the ignition module will work independant of the ecm so it makes sense that you can have spark without fuel. And the only way you would have a ground at the fuel injector is if the ecm tells it to open.