Dies, cranks but no start, then randomly starts.
03-25-2012, 07:03 PM
#1
Dies, cranks but no start, then randomly starts. I need ideas before I start just throwing parts at it.
Background: '02 T/A 6spd, bone stock with only skip shift, 125k miles. On occasion, while sitting at a stop light, the check gauage light will come on and the fuel level will drop to zero. Once you start to move, it jumps back up.
Cliff notes: It's randomly died/not start on me 4 times now. No codes.
Details: The first one I came home from work (30 minute) drive, parked, turned it off, waited 15 minutes, and when I went to go leave for an appt, it wouldn't start.
Checked the grounds, and went to checked fuel pressure (key on) which was fine, and when I went to check cranking f/p, it started and ran perfect (about 30 minutes after it first wouldn't start).
Next time, it was ~5 miles on the way to work, cuts out completely ~45mph and died. Cranked but wouldn't start. Trailered home, and it started on the trailer as we went to unload it, about an hour after it first died, so I couldn't even start to diagnose it. I did notice tho that the first few seconds the tach didn't work.
My wife and I took it on a few short trips (one of us staying home to play rescue) with no issues. One night (with my dad in his car) we went to go eat and again, about 5 miles after we left it died. AAA'd it home, still wouldn't start. My WAG is it *feels* like it's a fuel issue. The next day, it still didn't start, but as I was poking about and moving some wires by the PCM and it starts. Strip down the outer covers and search but don't find frayed wires. While moving wires around, it dies. Unplug PCM, and it cranks the same way it was when it didn't start. Plugged everything back up, still no start, then after relooming a section of wire it starts ARG!
Tonight, I drove it around for again about 7 miles around the neighborhood. Parked in driveway, while still running popped hood, and within a minute, it died. Put on a f/p guage, 55psi key on, didn't budge when cranking. So this tells me the injectors arn't firing. Cheapy code reader says no codes, reads the VIN and ready status's etc, so I'm guessing the PCM is at least getting power. It's currently no starting, I'm waiting an hour before I go try it again. It also is reading almost zero on the fuel guage, even tho it has 3/4 tank.
Each time, it doesn't stumble then die, it just straight up dies.
I don't think it's VATS related since it died while running. *If* it's a frayed wire, which of the eleventy billion wires from the PCM would cause this? Only other thing I can think of is a crank positioning sensor going bad, but why would that die after ~5 miles? How do PCM's typically fail?
TIA
Background: '02 T/A 6spd, bone stock with only skip shift, 125k miles. On occasion, while sitting at a stop light, the check gauage light will come on and the fuel level will drop to zero. Once you start to move, it jumps back up.
Cliff notes: It's randomly died/not start on me 4 times now. No codes.
Details: The first one I came home from work (30 minute) drive, parked, turned it off, waited 15 minutes, and when I went to go leave for an appt, it wouldn't start.
Checked the grounds, and went to checked fuel pressure (key on) which was fine, and when I went to check cranking f/p, it started and ran perfect (about 30 minutes after it first wouldn't start).
Next time, it was ~5 miles on the way to work, cuts out completely ~45mph and died. Cranked but wouldn't start. Trailered home, and it started on the trailer as we went to unload it, about an hour after it first died, so I couldn't even start to diagnose it. I did notice tho that the first few seconds the tach didn't work.
My wife and I took it on a few short trips (one of us staying home to play rescue) with no issues. One night (with my dad in his car) we went to go eat and again, about 5 miles after we left it died. AAA'd it home, still wouldn't start. My WAG is it *feels* like it's a fuel issue. The next day, it still didn't start, but as I was poking about and moving some wires by the PCM and it starts. Strip down the outer covers and search but don't find frayed wires. While moving wires around, it dies. Unplug PCM, and it cranks the same way it was when it didn't start. Plugged everything back up, still no start, then after relooming a section of wire it starts ARG!
Tonight, I drove it around for again about 7 miles around the neighborhood. Parked in driveway, while still running popped hood, and within a minute, it died. Put on a f/p guage, 55psi key on, didn't budge when cranking. So this tells me the injectors arn't firing. Cheapy code reader says no codes, reads the VIN and ready status's etc, so I'm guessing the PCM is at least getting power. It's currently no starting, I'm waiting an hour before I go try it again. It also is reading almost zero on the fuel guage, even tho it has 3/4 tank.
Each time, it doesn't stumble then die, it just straight up dies.
I don't think it's VATS related since it died while running. *If* it's a frayed wire, which of the eleventy billion wires from the PCM would cause this? Only other thing I can think of is a crank positioning sensor going bad, but why would that die after ~5 miles? How do PCM's typically fail?
TIA
Last edited by Alien; 03-25-2012 at 07:13 PM.
03-25-2012, 07:31 PM
#2
Man, I'm happy to say I had a 80% identical issue. I spent over $1000 hunting down. I was 300 miles in to a 1000 mile road trip and it cut out. Cranks and cranks and cranks and nothing. Later, starts up. On a whim, the fuel pump and PCM were replaced. Ran great for a few months. I was backing out of the driveway and it just dies. Cranks and restarts fine. Then a couple days later it starts running terribly when it's cold and PIG rich. And a CEL comes on for the crank position sensor. Condition got worse and worse and the PCM was replaced AGAIN. Ran okay for another few months. Conditions started AGAIN. This time they were IDENTICAL to yours. I was so frustrated. I went and pulled another PCM and (this time I was home from college and actually had my hands on the car, not my dad) when I pulled the old PCM it was COVERED in corrosion. *BINGO* I realized the rain channel next to the PCM was clogged with leaves and the plastic trim that seals the hood was MISSING A $1 SCREW TO HOLD IT IN PLACE! #$^%!!! So I repaired the trim piece and checked sealing. To do this, rub oil on the rubber weather sealing, close your hood, reopen. You should see a healthy line of oil. Then, as a final measure, I used hot glue to glue the mating edges of the PCM case. The glue doesn't get too hot, easy to remove, and is cheap insurance. I am running over a year strong with zero issues.
Long story short, remove your PCM. If there is corrosion, replace the PCM and make SURE your hood seals and the rain channel is clear. My PCM read PERFECTLY when it was 'sick' and then it would just 'hiccup' and cause these bizarre issues.
Hope this helps, if you need any more direction on this, just shoot me a PM.
Kyle
Long story short, remove your PCM. If there is corrosion, replace the PCM and make SURE your hood seals and the rain channel is clear. My PCM read PERFECTLY when it was 'sick' and then it would just 'hiccup' and cause these bizarre issues.
Hope this helps, if you need any more direction on this, just shoot me a PM.
Kyle
03-26-2012, 11:48 AM
#3
Waited a few hours last night for everything to cool down, still won't start.
I did pull the PCM (the third time it died) and it looked good, no corrosion on it or the connectors. Thanks for the idea tho.
I didn't realize the ground were on the drivers side head, I'll check those tonight. I have a feeling it's wiring related, since I can't imagine anything else being intermittant.
I did pull the PCM (the third time it died) and it looked good, no corrosion on it or the connectors. Thanks for the idea tho.
I didn't realize the ground were on the drivers side head, I'll check those tonight. I have a feeling it's wiring related, since I can't imagine anything else being intermittant.
03-26-2012, 12:13 PM
#4
Waited a few hours last night for everything to cool down, still won't start.
I did pull the PCM (the third time it died) and it looked good, no corrosion on it or the connectors. Thanks for the idea tho.
I didn't realize the ground were on the drivers side head, I'll check those tonight. I have a feeling it's wiring related, since I can't imagine anything else being intermittant.
I did pull the PCM (the third time it died) and it looked good, no corrosion on it or the connectors. Thanks for the idea tho.
I didn't realize the ground were on the drivers side head, I'll check those tonight. I have a feeling it's wiring related, since I can't imagine anything else being intermittant.
03-27-2012, 11:58 AM
#6
That's what I was leaning towards, but then it was running when the tach read zero.
Update: I did get it to start again last night. Tried to clean (wipe with blue towel) the grounds at the back of the heads. Could barely get my hand on the bolt, couldn't even get a wrench on it, but then it started. There's two bolts with grounds on the head, correct? I felt the wires on one bolt, could feel any on the other. What a PITA 4th gens are. Give me my third gen engine bay any day of the week. Is it any easier to jack the car up and come in from below?
Update: I did get it to start again last night. Tried to clean (wipe with blue towel) the grounds at the back of the heads. Could barely get my hand on the bolt, couldn't even get a wrench on it, but then it started. There's two bolts with grounds on the head, correct? I felt the wires on one bolt, could feel any on the other. What a PITA 4th gens are. Give me my third gen engine bay any day of the week. Is it any easier to jack the car up and come in from below?
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03-27-2012, 08:24 PM
#9
I may take you up on that!
Update: Started it up tonight and just let it idle in the driveway. Pulled and wiggled some wires especially the one down to the cps (didn't see any signs of fraying), loosen or UNDO a few grounds (not the PITA on at the back of the head), still runs fine. Then, sure enough, about 10 minutes later it da da dadadada dies. Ok, so it has to be something heatish related, right? Like fuel pump dying, but not since it's still got pressure. I think maybe fuel pump relay... hmmm, there's a big ignition relay and a starter relay. Pull ign relay (maybe it's bad) and put in starter relay spot. Attempt to start, sounds weird, but then again, the ign relay isn't in at all. Ok, put in ign relay (formerly starter relay). BAM starts.
Too late for the Borla to be idleing and annoying neighbors. Will repeat test tomorrow. Would be awesome if it's just a bad IGN relay.
Update: Started it up tonight and just let it idle in the driveway. Pulled and wiggled some wires especially the one down to the cps (didn't see any signs of fraying), loosen or UNDO a few grounds (not the PITA on at the back of the head), still runs fine. Then, sure enough, about 10 minutes later it da da dadadada dies. Ok, so it has to be something heatish related, right? Like fuel pump dying, but not since it's still got pressure. I think maybe fuel pump relay... hmmm, there's a big ignition relay and a starter relay. Pull ign relay (maybe it's bad) and put in starter relay spot. Attempt to start, sounds weird, but then again, the ign relay isn't in at all. Ok, put in ign relay (formerly starter relay). BAM starts.
Too late for the Borla to be idleing and annoying neighbors. Will repeat test tomorrow. Would be awesome if it's just a bad IGN relay.
03-27-2012, 09:25 PM
#11
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I had problems with my 01 z28 until a few weeks ago. the tach would stop working and she ran like crap. no codes were thrown for the longest time. I replaced the fuel filter and maf, without fixing the problem. Then I baught a crank sensor, took my starter out and within 20 minutes i fired her up. she has been running great since.
03-31-2012, 02:18 PM
#12
Update: All the same issues, tried to recreate all the same things. Relay swap didn't work, but hey, I can dream it's a $3 fix. Other night, let it idle with fuel pressure guage hooked up and a timing light to see which died first. After exactly 20 minutes, no spark and died. I wanted to rule out CPS since it never ran bad when it was running and also really hoping it wasn't because I didn't want to pay for a crank relearn. Didn't know the CPS only really took affect in closed loop (after 10-20 minutes), so went ahead and replaced it.
Started, drove as expected after having battery disconnected, and idled for over 20 minutes. I think that's it resolved. No codes yet either, so maybe a CPS relearn isn't needed.
Thanks everyone!
Started, drove as expected after having battery disconnected, and idled for over 20 minutes. I think that's it resolved. No codes yet either, so maybe a CPS relearn isn't needed.
Thanks everyone!
Last edited by Alien; 03-31-2012 at 02:48 PM.
04-29-2013, 03:23 PM
#13
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Any Updates? I am having to same problem out of the blue.
Checked Relays, changed Crank sensor did a case relearn when running,
checked pcm wires then changed pcm, changed fuel filter, good pressure. Still runs for 15 minutes cold then dies.
Checked Relays, changed Crank sensor did a case relearn when running,
checked pcm wires then changed pcm, changed fuel filter, good pressure. Still runs for 15 minutes cold then dies.
04-29-2013, 03:38 PM
#14
Update: All the same issues, tried to recreate all the same things. Relay swap didn't work, but hey, I can dream it's a $3 fix. Other night, let it idle with fuel pressure guage hooked up and a timing light to see which died first. After exactly 20 minutes, no spark and died. I wanted to rule out CPS since it never ran bad when it was running and also really hoping it wasn't because I didn't want to pay for a crank relearn. Didn't know the CPS only really took affect in closed loop (after 10-20 minutes), so went ahead and replaced it.
Started, drove as expected after having battery disconnected, and idled for over 20 minutes. I think that's it resolved. No codes yet either, so maybe a CPS relearn isn't needed.
Thanks everyone!
Started, drove as expected after having battery disconnected, and idled for over 20 minutes. I think that's it resolved. No codes yet either, so maybe a CPS relearn isn't needed.
Thanks everyone!
