Ok, So my car was running pretty good this Saturday. Then on sunday, It starts up fine as usual, and about 10min into my 2hr drive home, It starts missing really bad and backfiring through what sounded like the throttlebody and exhaust. I had HPTuners with me so I scanned it while driving. the only code was a P0300 Random/multiple cyl misfire. I limped it to autozone and pulled the sparkplugs out to investigate. the sparkplugs from cylinders 1 and 3 were heavily carbon fouled (dry not wet) while cyls 2 & 4 were fine. I changed the plugs, gapped them correctly and it still ran like crap. Triple A for the win. So, I get the car home and do some more diagnosing. I attempt to reflash my pcm back to stock with the vats disabled in that tune as well (never had a problem with my tune, but I figured its one less thing to rule out) At first, HPtuners doesn't recognize my pcm (I have the vehicle license to tune it too) I believe it said something about the OS ID not matching. I try it again and get it to work, but it takes like 7 mins to reflash instead of the normal 2mins. So I go to start it and now I get the ol' cranks but no run issue. Also,when I go to scan the car, hptuners say "cannot connect with VCM. make sure key is on run." I tried using my little handheld code reader and it wont connect either. It's like there's no power going to it. All fuses are good, I switched the fp relay out with other relays and still nothing.
Here's a few symptoms that its having-
Fuel pump relay clicking rapidly when the key is on (never did that before lol)
Tries to run when I spray starting fluid in the tb. (Got spark)
If I jump the relay, the pump runs just fine and I have strong, steady fuel pressure at the rail. I disconnected the fuel line and turned the key on to check.
if I check the voltage at the relay while the key is switched on, it reads 12 volts on one point, nothing on the other (a ground?) and then the other 2 points read 7volts and about 5.5-6 volts on the other.
Is it possible that my pcm is corrupt? I was going to take a ride to the junkyard today and buy a PCM/BCM from a 2000-2002 cavalier z24 and reflash it. $21 for a pcm, figured its worth a shot lol
2000 Cavalier Z24 5spd CRM
Eibach Anti Roll kit, Poly motor/trans mounts, custom made CAI, Header, cutout, tuned by me with HPtuners
14.81 @ 91.09 mph 2.06 60'
97 Saturn SC1 with DOHC swap. 13.7@98mph on motor. +75 shot 12.8 @107mph
Also. I meant to add, I found a lot of threads from different forums with this issue but nobody every posts about how or if they resolved the problem(s)
2000 Cavalier Z24 5spd CRM
Eibach Anti Roll kit, Poly motor/trans mounts, custom made CAI, Header, cutout, tuned by me with HPtuners
14.81 @ 91.09 mph 2.06 60'
97 Saturn SC1 with DOHC swap. 13.7@98mph on motor. +75 shot 12.8 @107mph
Swap the AC relay with the fuel pump relay.
Then check the grey wire that goes to the ICM? Does it have voltage?
Then find another ICM and IDI housing. Swap both of those out.
I assume the PCM is dead, and so is the ICM.
Edited 1 time(s). Last edited Tuesday, March 18, 2014 11:40 AM
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
-MD- Enforcer wrote:Swap the AC relay with the fuel pump relay.
Then check the grey wire that goes to the ICM? Does it have voltage?
Then find another ICM and IDI housing. Swap both of those out.
I assume the PCM is dead, and so is the ICM.
Your assumption would be correct lol. Right after I posted, I headed to a junkyard which was chocked full of j bodies lol. I picked up a complete ignition setup(ICM,coils, coil housing, plug boots, aluminum cover), a couple of pcms and bcm from a 2000 and 2001 2.4 cavalier. replaced the pcm, bcm, reflashed with hptuners and did a vats disable. it ran rough. Hptuners showed a cyl 1& 3 misfire. replaced the ignition setup and it ran better, with only a cyl 3 misfire after that. suspected the plug was fouled. cleaned it up, didn't misfire as much. swapped it with cyl 4 plug. and cyl 4 was showing misfires. replaced plug and its 100%
Thanks for your reply. hopefully this will be helpful to those who end up in the same boat as I did.
2000 Cavalier Z24 5spd CRM
Eibach Anti Roll kit, Poly motor/trans mounts, custom made CAI, Header, cutout, tuned by me with HPtuners
14.81 @ 91.09 mph 2.06 60'
97 Saturn SC1 with DOHC swap. 13.7@98mph on motor. +75 shot 12.8 @107mph
I almost guaranty if you swap the original icm and pcm back in.....they will work now, and no it doesn't make sense to me either.
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
-MD- Enforcer wrote:I almost guaranty if you swap the original icm and pcm back in.....they will work now, and no it doesn't make sense to me either.
It's funny you say that, because I tried that yesterday, just for the heck of it and it didn't work. If I had to take a guess, I would say the pcm is corrupt/damaged. It doesn't happen often, but it can. HpTuners reads/connects to the "new" pcm just fine. But It doesn't recognize/connect to my old pcm.
2000 Cavalier Z24 5spd CRM
Eibach Anti Roll kit, Poly motor/trans mounts, custom made CAI, Header, cutout, tuned by me with HPtuners
14.81 @ 91.09 mph 2.06 60'
97 Saturn SC1 with DOHC swap. 13.7@98mph on motor. +75 shot 12.8 @107mph
When I had this issue...I did a write entire on my original pcm, and it seems fine....
That being said, I'm running another PCM lol.
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
-MD- Enforcer wrote:When I had this issue...I did a write entire on my original pcm, and it seems fine....
That being said, I'm running another PCM lol.
I couldn't even do a write entire because it wouldn't even read it lol. I scooped up a few pcms that day. At 21 bucks a piece, I couldn't go wrong ha
2000 Cavalier Z24 5spd CRM
Eibach Anti Roll kit, Poly motor/trans mounts, custom made CAI, Header, cutout, tuned by me with HPtuners
14.81 @ 91.09 mph 2.06 60'
97 Saturn SC1 with DOHC swap. 13.7@98mph on motor. +75 shot 12.8 @107mph
98tadriver wrote:-MD- Enforcer wrote:When I had this issue...I did a write entire on my original pcm, and it seems fine....
That being said, I'm running another PCM lol.
I couldn't even do a write entire because it wouldn't even read it lol. I scooped up a few pcms that day. At 21 bucks a piece, I couldn't go wrong ha
when you put the new pcm in did it work like plug and play or did you have to flash the pcm?