I have a 2001 z24 with the 2.4 in it with 86,000. The car died 1 day driving home from work. I orig thought it was the fuel pump because I didnt hear the pump humming. Checked all fuses, all good. Replaced pump but still nothing. Checked for fuel at the rails and have fuel. I can pour gas in throttle body and it starts. Iam guessing injectors arent working. Replaced both crank sensor and cam sensor. still nothing. You guys think its the pcm??

Check the ICM.

Also get some noid lights to see if the injectors are firing.







PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

what about the fuel pump relay? if its not priming when you turn the acc on, your fuse or relay may be bad. i believe you can use the ac or another relay to test it. i have 3 or 4 stock ecotec fuel pumps sitting around if you need another one


04 Cav. 2dr. 5spd. My DD. 'Nuff said.

The fuel pump is running. When you turn the key to acc I can here the pump hum. I also opened the fuel line off the rail and fuel does shoot out of it. Iam leaning towards the pcm. I dont thick the icm is bad because I can start the motor when i pour gas down the throttle body.

I wouldn't think PCM, and if it runs when u add fuel must b fuel related. How much fuel was available at the rail? Do u have way of checking fuel pressure? Checking fuel volume as it exits fuel rail can be useful info too. First I would check fuel injectors with stethoscope or u can use a hose to listen as someone cranks over. U can also check them electronically to c if being fired. Could b fuel pressure regulator, when mine was bad it would start but ran rough but suppose if it was not resisting at all fuel would just cycle back to tank without sufficient fuel to start. Can test this with fuel pressure gauge if does not maintain fuel pressure after key on this is prob bad.

I'm still thinking ICM, and check the 5V reference to each injector. If it is anything lower than 5V....they will not fire. 4.9V will not fire them.




PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

I have an update, but nothing good. I tried the PCM just because I had a known good 1 laying around. no difference, still no start. I pulled the fuel pump reg off the rail and replaced again with a known good one. Same results, still no start. Where is the ICM located?? I have a donor car for parts that ran well even after the front end crashed that totaled it so I can remove the ICM from that car and give it a whirl. I don't see any port on the fuel rail to check for the fuel pressure, but while I had the fuel line disconnected, I turned on the key and visually seen the fuel shoot several feet! I really don't think the pressure is bad because the car doesn't even begin to try to start.

Also doesn't the icm control just the spark? I googled the icm location and I know where that is now. I will try that when I get home tonight. Fingers crossed.

Check to make sure your crank sensor is good. Is your tach acting up at all?




PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

I replaced the crank sensor 2nd after replacing the fuel pump. The tach DOES NOT move while cranking. I compared that to both my 2009 cobalt and 2001 silver-ado which neither of them move while cranking either. They both run perfect, btw. LOL

ICM controls the ignition, if it starts when u put fuel in throttle body that would not b your problem. Did u check fuel injectors connectors for 5 volt power? Or listen to them while cranking to c if they r firing? Now if it did not actually run but just fired a time or two when u pored fuel in then could still b ignition or sensor related. Here is nice article for troubleshooting ICM and coil pack http://easyautodiagnostics.com/gm_2200_coilpack/coil_test_diagnostic_1.php. note there r wires that hook up to this that also go to crank and cam sensors.

Yes the car starts and runs for a 30-45 seconds until the fuel runs out. That's why I originally thought it was NOT the ignition system. I don't have anyone to crank the car while I'am under the hood, but I think I can pull the starter relay off and jump that out to crank it over while I'am under the hood. I used a test light on 1 of the injectors and had a light come on, but I didn't measure that with a volt meter. Also, if either the crank or cam sensor was bad, how would it start and run just by adding the fuel? I have replaced both of these sensors anyway already. I still think its the injectors that aren't working, I just don't know why.

That's w hat I thought, yeah nothing wrong with ignition side or sensors. You can test for voltage to injectors without cranking, just key on with multimeter. Cannot test firing, ie ground signal from computer without cranking. I bought a remote starter switch for those kind of situations.

Well i replaced the ICM with the donor cars ICM and got the same results of NOTHING. I thought maybe the car just had a bad tank of fuel or maybe somebody tampered with the fuel with sugar or something, but after taking loose the fuel line and pumping out some fuel, then pouring that down the TB, it started, ran for 30-40 seconds, then died. Fuel is good. Is there a fuel injection computer? I know the injectors aren't working, but I don't know why. I haven't actually tested them while cranking with a test light or volt meter, but I think its obvious.

There is no fuel injector computer. It is controlled by the PCM, but other things like crank sensor and cam sensor data help tell the computer when to send fuel. It is possible that you have a break in the wiring for the crank sensor or you got a faulty new one. I would swap over donor car parts and see if that is the case. Also making sure your fuel injector harness is getting power as well. (wires, relays and fuses) Fuel pressure and voltage to the injectors in important as well.

I tried to get the crank sensor off the donor car, but they are a mother father to get out of the hole. They appear to get stuck in the hole from getting hot, then cold, etc. I broke the original 1 off the broken car, and the donor car also. I haven't tried to trouble shoot the wiring yet, due to the fact I live in md (AKA ARCTIC CIRCLE) where the temps have been 40-18 degrees NOT INCLUDING THE CHILL the past few months, and I'am working outside after work. I HATE the cold, btw.

This is the same thing my car was doing. I'm telling you it is either the Crank Sensor, ICM, and the wiring to and from the ICM.

Read this LONG ASS TREND.
http://www.j-body.org/forums/read.php?f=11&i=145548&t=145548&p=1




PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

I have read most of the long a$$ thread, but My car DOES start when I pour gas into the throttle body, which means I do have spark. I guess I do have a bad cps, but it's too cold out to mess with it now. I will start from scratch and go 1 wire at a time from injector to the damn ground on the battery!! LOL

I did throw a test light on #1 injector and it lit up when the fuel pump primed. I would guess the injectors are at least getting power, but I haven't checked the other wire coming off the injector to see if it pulsates while cranking yet. I NEED a garage bad. Working outside in 30" weather sucks.

Just curious, when I plugged in the new (donor) pcm, I did not do a relearn or pass lock relearn. How is that performed? I just plugged in the pcm and cranked it. Will the security light be flashing in the dash? After putting the org pcm back in, the security light DOES NOT flash, BUT I don't remember if the light flashing or not flashing with the donor pcm.

OOPS, I found the pass lock procedure just after my last post.

I read part of that long thread but I keep coming back like you do to but it starts when u put fuel in, r they not reading that part? When I had pass lock problems it would start initially, then die always same length of time iirc 1 or 2 minutes. The light on dash either flashed or stayed on , its been a while. My problem was cause I replaced the ignition switch, my new O'Reilly s part was bad so every time I went thru relearn process it didn't take. Finally towed to dealer where they did same thing I did with new part to fix. IIRC it communicates with BCM which is separate from PCM. Again mine was not a no start but a very brief start, and didn't yours do it with orig PCM also?

I noticed when I sent that one link to u I forgot u have 2.4 which is way different than 2200 - sorry but troubleshooting basics still remain same although ICM and coil packs r way different.

[quote=Bob Raffety]I read part of that long thread but I keep coming back like you do to but it starts when u put fuel in, r they not reading that part? When I had pass lock problems it would start initially, then die always same length of time iirc 1 or 2 minutes. The light on dash either flashed or stayed on , its been a while. My problem was cause I replaced the ignition switch, my new O'Reilly s part was bad so every time I went thru relearn process it didn't take. Finally towed to dealer where they did same thing I did with new part to fix. IIRC it communicates with BCM which is separate from PCM. Again mine was not a no start but a very brief start, and didn't yours do it with orig PCM also?
Mine does NOT start at all unless I pour gas down the throttle body.I know my injectors aren't firing, I just cant figure out why. I believe I have a bad wire somewhere. just haven't had time to find out where due to time, and the fact it"s 30' outside! Lol

Yeah I know but u asked about the PCM and pass lock also