randomly dies while driving (3.8 v6)
Thread Starter
Joined: Apr 2005
Posts: 2,169
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From: Dallas, TX / Boston, MA
randomly dies while driving (3.8 v6) did some searches.... lots of people ask this question, but I never see anyone post their solution.
so i got a 3.8L v6 camaro for a DD... i've had a few incidences where it just randomly dies on me while driving. it always happens in the first 15 mins of driving, and so far its always happened while at a relatively low speed (under 30). like i'll be in traffic on the highway, just coasting, and i'll go to hit the gas and it'll be dead.
typically, i'll throw it in neutral and it'll start right back up, but then immediately dies again. on the 2nd time i restart it, its fine.
its happening more often now, so i'm getting concerned. i've seen people suggest that it could be the fuel pump, cam sensor, or crank sensor. no codes are being thrown. any way to test those components since the condition is not able to be reproduced at will?
so i got a 3.8L v6 camaro for a DD... i've had a few incidences where it just randomly dies on me while driving. it always happens in the first 15 mins of driving, and so far its always happened while at a relatively low speed (under 30). like i'll be in traffic on the highway, just coasting, and i'll go to hit the gas and it'll be dead.
typically, i'll throw it in neutral and it'll start right back up, but then immediately dies again. on the 2nd time i restart it, its fine.
its happening more often now, so i'm getting concerned. i've seen people suggest that it could be the fuel pump, cam sensor, or crank sensor. no codes are being thrown. any way to test those components since the condition is not able to be reproduced at will?
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Joined: Apr 2010
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From: Manchester , UK
Fuel filter.. had the same thing happen to me on my 97 mustang 3.8 ..
Didnt throw a code or anything , it would just die , and sputter when I started it up the first time or so .. Id wait a few minutes and start it again , drive off only until it would die on me again . Changing the fuel filter is the easiest and cheapest thing to do , try it , your problem might be an easy fix (compared to fuel pump , cam sensor etc )
Didnt throw a code or anything , it would just die , and sputter when I started it up the first time or so .. Id wait a few minutes and start it again , drive off only until it would die on me again . Changing the fuel filter is the easiest and cheapest thing to do , try it , your problem might be an easy fix (compared to fuel pump , cam sensor etc )
Check FuEl pressure at the rail. If this reads ok , the following items were the reason The same thing happened to me with 3.8l.
Ignition cOntrol module (sits under the coil packs).
Cam & or crank sensors replaced when I had to coast off a highway cuz the car shut off.
Sorry - typin from my phpone n it's sich lS
Ignition cOntrol module (sits under the coil packs).
Cam & or crank sensors replaced when I had to coast off a highway cuz the car shut off.
Sorry - typin from my phpone n it's sich lS
Thread Starter
Joined: Apr 2005
Posts: 2,169
Likes: 1
From: Dallas, TX / Boston, MA
ok, happened to me again, except this time it took me a good 5 mins before i could get the car started again. i've taken it off the road until i can figure this out.
i took the ignition control module to autozone, and it tested good. we ran it through the tester like 7 times (sometimes they dont fail until they heat up).
i checked the fuel pressure at the rail. it read a ~42 (should be 48), but i think its ok and my gauge is just reading low because i then tested my LS1 car and it read a ~50 (should be 55).
if the fuel pump is having an intermittent issue, is there even a way to test for that?
i looked at the ALLDATA software sections on the cam and crank sensors. while they cant be tested without a TECH2, the description of the operations of them says that if the cam sensor fails, the car will throw a code and still run based on a backup mapping.
however, for the crank sensor, it states that 'if the pcm receives no pulses on this circuit, no fuel injection pulses will occur and the engine will not run.' doesnt say anything about a related code.
so assuming that the fuel pump is not the issue, it looks like the crank sensor is the most likely culprit. (also appears to be a bitch to do). the cost of both sensors combined would be less than the cost of a diag scan from the stealership, so it looks like its worth a shot, unless i can get some additional guidance on the fuel system.
i took the ignition control module to autozone, and it tested good. we ran it through the tester like 7 times (sometimes they dont fail until they heat up).
i checked the fuel pressure at the rail. it read a ~42 (should be 48), but i think its ok and my gauge is just reading low because i then tested my LS1 car and it read a ~50 (should be 55).
if the fuel pump is having an intermittent issue, is there even a way to test for that?
i looked at the ALLDATA software sections on the cam and crank sensors. while they cant be tested without a TECH2, the description of the operations of them says that if the cam sensor fails, the car will throw a code and still run based on a backup mapping.
however, for the crank sensor, it states that 'if the pcm receives no pulses on this circuit, no fuel injection pulses will occur and the engine will not run.' doesnt say anything about a related code.
so assuming that the fuel pump is not the issue, it looks like the crank sensor is the most likely culprit. (also appears to be a bitch to do). the cost of both sensors combined would be less than the cost of a diag scan from the stealership, so it looks like its worth a shot, unless i can get some additional guidance on the fuel system.
I have the same problem as you. I get a random misfire and when the car is hot sometimes it won't start back up. It's really annoying. But I have a lot of miles on mine as well.
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I'll just save you some time of having to hear my response later haha. If you are getting that light, and it seems like there are several people in here that might be, it is most likely your throttle body position sensor. Since the 3.8Lt don't use throttle cables, they rely on sensors. When those go bad, then it can cause a world of hurt-but the fix can be easy!
Here is what used to happen to me:
While the engine was cold-full operation temperature, if I were to raise the RPMs more than just a couple grand (I had he 5spd manual), probably 95+% of all of my engine power would suddenly be lost and I'd immediately get the "Engine Power Decrease" light come on. I'd have to pull over, turn the car off, turn it back on, sit and let it fully warm up, then it would drive just fine. It took me FOREVER and $1,000 to figure out the problem. Now, I know it should've been a quick and cheap fix. You shouldn't even need a new throttle body-just the 2 sensors.
But OP, if you got a new throttle body I am worried that my advice doesn't apply to your problem. Then again, it's possible you got another bad set of sensors with that throttle body. Good luck, guys!
Here is what used to happen to me:
While the engine was cold-full operation temperature, if I were to raise the RPMs more than just a couple grand (I had he 5spd manual), probably 95+% of all of my engine power would suddenly be lost and I'd immediately get the "Engine Power Decrease" light come on. I'd have to pull over, turn the car off, turn it back on, sit and let it fully warm up, then it would drive just fine. It took me FOREVER and $1,000 to figure out the problem. Now, I know it should've been a quick and cheap fix. You shouldn't even need a new throttle body-just the 2 sensors.
But OP, if you got a new throttle body I am worried that my advice doesn't apply to your problem. Then again, it's possible you got another bad set of sensors with that throttle body. Good luck, guys!
Thread Starter
Joined: Apr 2005
Posts: 2,169
Likes: 1
From: Dallas, TX / Boston, MA
ok, just replaced the crank sensor and now it wont start at all.
i see there is a crank learn procedure, but it requires a tech2 or other system scanner (which of course i dont have). i'm not about to tow this thing to a dealership... will it perform the relearn if i unplug the battery to reset the computer?
i see there is a crank learn procedure, but it requires a tech2 or other system scanner (which of course i dont have). i'm not about to tow this thing to a dealership... will it perform the relearn if i unplug the battery to reset the computer?
Probably because it's missing two cylinder 
:engird:
Seriously though, have you considering the coils or the fuel pressure regulator? Coils do run hot on the 3.8 sixes, so if there is no heat sink grease under the coil it could cause it to fail.
It's weird no code is being thrown.
:engird:Seriously though, have you considering the coils or the fuel pressure regulator? Coils do run hot on the 3.8 sixes, so if there is no heat sink grease under the coil it could cause it to fail.
It's weird no code is being thrown.
Thread Starter
Joined: Apr 2005
Posts: 2,169
Likes: 1
From: Dallas, TX / Boston, MA
i double checked that the crank sensor was plugged in. nothing else was unplugged that would affect starting. i also checked out the ignition relay (swapped in a known good one), and reset the ECM by unhooking the battery. i'm smelling fuel after trying to start it, so i know its getting gas.
@blackgazguzzler: i could try checking the resistance on the coils tomorrow. even if one coil was bad (2cyls), i coudlnt imagine that preventing the car from starting. i would think it would just cause it to run rough since it would only be on 4cyls. and the crank sensor does not throw a code, only the cam sensor does.
i never had an issue with just no starting whatsoever, just with randomly dying. the only thing i can think of is that i didnt tighten down the crank pulley enough, and maybe the crank sensor isnt reading the interrupter ring properly? i was deathly afraid of snapping the crank bolt from oil on the threads or something like that... its tight enough that the pulley ribs line up with the other pulleys, just didnt torque to spec. based on the way that ring is shaped, i cant imagine the difference being enough to not let the sensor read correctly.
@blackgazguzzler: i could try checking the resistance on the coils tomorrow. even if one coil was bad (2cyls), i coudlnt imagine that preventing the car from starting. i would think it would just cause it to run rough since it would only be on 4cyls. and the crank sensor does not throw a code, only the cam sensor does.
i never had an issue with just no starting whatsoever, just with randomly dying. the only thing i can think of is that i didnt tighten down the crank pulley enough, and maybe the crank sensor isnt reading the interrupter ring properly? i was deathly afraid of snapping the crank bolt from oil on the threads or something like that... its tight enough that the pulley ribs line up with the other pulleys, just didnt torque to spec. based on the way that ring is shaped, i cant imagine the difference being enough to not let the sensor read correctly.
Last edited by slayer_taunu; May 8, 2011 at 11:00 PM.
Thread Starter
Joined: Apr 2005
Posts: 2,169
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From: Dallas, TX / Boston, MA
i torqued down the crank bolt, still no start. i put the old crank sensor back in, and now it starts but dies after like 15-20 seconds. i think the new sensor is DOA. as far as it dying now... i cracked the plastic cover behind the pulley, and its rattling like crazy... i'm hoping thats just messing with the crank sensor. i'm gluing it back together and we'll see if it runs after that and a new sensor.
Thread Starter
Joined: Apr 2005
Posts: 2,169
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From: Dallas, TX / Boston, MA
ok, i am at a loss.
put in a new crank sensor, still wont start, but sometimes it will continue to rotate real slow for another 5 seconds or so after i stop cranking it... so it must be getting SOME spark. either that, or its just dieseling from all the built up compression from cranking it.
i checked the continuity of all 4 wires from the crank sensor to the ICM, and they all appear to be ok. i checked the resistance of the coolant sensor, and its normal.
the wires on the back of the starter are tight, and the car is cranking fast, so it doesnt appear that i yanked any grounds when unbolting the starter.
i double checked that i have the coil packs and plug wires on in the right order.
what else can i possibly do? its just boggling to me that it would run with the old sensor back in, but not a new one. the interrupter ring on the back of the crank pulley appeared to be fine... so i dunno if its just random chance that it has an alignment issue and it just happened to line up correctly on that attempt?
put in a new crank sensor, still wont start, but sometimes it will continue to rotate real slow for another 5 seconds or so after i stop cranking it... so it must be getting SOME spark. either that, or its just dieseling from all the built up compression from cranking it.
i checked the continuity of all 4 wires from the crank sensor to the ICM, and they all appear to be ok. i checked the resistance of the coolant sensor, and its normal.
the wires on the back of the starter are tight, and the car is cranking fast, so it doesnt appear that i yanked any grounds when unbolting the starter.
i double checked that i have the coil packs and plug wires on in the right order.
what else can i possibly do? its just boggling to me that it would run with the old sensor back in, but not a new one. the interrupter ring on the back of the crank pulley appeared to be fine... so i dunno if its just random chance that it has an alignment issue and it just happened to line up correctly on that attempt?
Thread Starter
Joined: Apr 2005
Posts: 2,169
Likes: 1
From: Dallas, TX / Boston, MA
you have to get the car started to even do a crank relearn, so it cant be that.
and now i cant get it to start with the old sensor in.... its gotta be a loose/broken wire somewhere. there's not a lot of play on the crank sensor wire.
other possibility is that i got a spark when i was re-installing the starter and touched it against the frame or exhaust by accident... so i wonder if i burnt one of those cables. the starter is turning fine, but maybe its affecting voltage elsewhere in the car.
and now i cant get it to start with the old sensor in.... its gotta be a loose/broken wire somewhere. there's not a lot of play on the crank sensor wire.
other possibility is that i got a spark when i was re-installing the starter and touched it against the frame or exhaust by accident... so i wonder if i burnt one of those cables. the starter is turning fine, but maybe its affecting voltage elsewhere in the car.
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I'm having the same problem with my 2000 firebird 3.8l. Just randomly dies, no codes. I've changed the coil packs, plugs, plug wires, ignition module, caddie convertor, and had the fuel pump checked. The next item on the list is the crank shaft sensor.
Do you think the crank shaft sensor you got was just bad? I know that happens from time to time.
All in all I think the problem is eletrical, and I hope one of us has answers soon. I'll keep checking this forum, and if I get anywhere with mine I'll post about it.
Do you think the crank shaft sensor you got was just bad? I know that happens from time to time.
All in all I think the problem is eletrical, and I hope one of us has answers soon. I'll keep checking this forum, and if I get anywhere with mine I'll post about it.
I had a problem very similar to this on my old 3.8 Firebird, it turned out to be the fuel pump. It would prime fine and get the car running but after running for a moment it would lean out so when we tested the fuel pressure on crank it was strong but it would slowly lean out until it finally gave up.