Engine dies after warmup. no start.
08-11-2010, 01:10 AM
#1
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Engine dies after warmup. no start.
hey all! my name is logan, i made an account here and read through some posts, looked at some pictures, etcetera, but never got around to posting, really. now i'm in a panic.
what i have is a 1990 corvette with an l98 and a 6 speed manual. removable hard top, black with red interior. the envy of ever other 21 year old i know. i bought the car a few months ago, and i had a good time with it. she's quick, she gets decent gas mileage compared to what i'm used to (3rd gen camaro, 05 avalanche), and is absolutely stylish
. that's the good.
the bad: she's an electrical nightmare. half the interior sensors have intermittent issues, the power door locks don't work, and the theft deterrant system is throwing up errors. the switches (on the doors) to open the hatch don't work, and sometimes, randomly, the courtesy light will come on while i'm driving. uhg. but all of that's liveable, or can be remedied by removing a fuse.
the ugly. now she's taken to leaving me stranded on the side of the road. she'll run for about 20ish minutes, depending on if i'm actively driving (less time) or just idling (more time) but the end result is the same. engine dies. she dies idling. she dies in gear (turning drivetrain won't keep the engine running). she dies coasting. she dies in the rain. she dies in the sun. if it snows, i'm willing to bet she'll die in that too. when i try to start her up, she refuses. the engine turns, sometimes i get a hint of combustion, but she's a stubborn little gal. she'll crank all day, until the battery dies (yes i've done it, stopping only every few seconds to let the starter cool off a minute or so). starter turns strong (still!
) but she won't run again till i come out the next day.
everyone said it was the fuel pump. i tested it, and discovered it was within limits, but a little low. being how i am, i ripped it out, chucked it away, and used a brand new one from a project my dad was working on (he's so nice). fuel pressure is good. still dies. we checked spark, and that was good. she still dies
. after that, everyone was convinced it was the o2 sensor. heck, that's 20 bucks, right? swapped that out. no dice.
sooo i'm out of good ideas, really. i checked the egr valve. it seemed ok, although i didn't check the solinoid itself, having been driven mad by long working hours and little time to devote to diagnostics...
oh speaking of diagnostics. i plugged in my handy dandy obd1 tester, and discovered my system is throwing out nothing as far as trouble codes.
anyone ever experienced this? i spent the past couple hours looking all over the interwebz for similar cases, but most are different enough for me to move on. any help or suggestions on how to test other potential culprits would be appreciated, thanks in advance!
--logan
what i have is a 1990 corvette with an l98 and a 6 speed manual. removable hard top, black with red interior. the envy of ever other 21 year old i know. i bought the car a few months ago, and i had a good time with it. she's quick, she gets decent gas mileage compared to what i'm used to (3rd gen camaro, 05 avalanche), and is absolutely stylish
. that's the good.the bad: she's an electrical nightmare. half the interior sensors have intermittent issues, the power door locks don't work, and the theft deterrant system is throwing up errors. the switches (on the doors) to open the hatch don't work, and sometimes, randomly, the courtesy light will come on while i'm driving. uhg. but all of that's liveable, or can be remedied by removing a fuse.
the ugly. now she's taken to leaving me stranded on the side of the road. she'll run for about 20ish minutes, depending on if i'm actively driving (less time) or just idling (more time) but the end result is the same. engine dies. she dies idling. she dies in gear (turning drivetrain won't keep the engine running). she dies coasting. she dies in the rain. she dies in the sun. if it snows, i'm willing to bet she'll die in that too. when i try to start her up, she refuses. the engine turns, sometimes i get a hint of combustion, but she's a stubborn little gal. she'll crank all day, until the battery dies (yes i've done it, stopping only every few seconds to let the starter cool off a minute or so). starter turns strong (still!
) but she won't run again till i come out the next day.everyone said it was the fuel pump. i tested it, and discovered it was within limits, but a little low. being how i am, i ripped it out, chucked it away, and used a brand new one from a project my dad was working on (he's so nice). fuel pressure is good. still dies. we checked spark, and that was good. she still dies
. after that, everyone was convinced it was the o2 sensor. heck, that's 20 bucks, right? swapped that out. no dice.sooo i'm out of good ideas, really. i checked the egr valve. it seemed ok, although i didn't check the solinoid itself, having been driven mad by long working hours and little time to devote to diagnostics...
oh speaking of diagnostics. i plugged in my handy dandy obd1 tester, and discovered my system is throwing out nothing as far as trouble codes.
anyone ever experienced this? i spent the past couple hours looking all over the interwebz for similar cases, but most are different enough for me to move on. any help or suggestions on how to test other potential culprits would be appreciated, thanks in advance!
--logan
08-11-2010, 01:45 AM
#2
Le Mans Master
Logan, you are experiencing loss of spark or loss of fuel.
Determine what you are losing, and move in that direction.
1. forget smog devices like EGR and smog pump, etc.
2. focus on things like the module inside the dist., and fuel pump relay, oil pressure switch.
You can take the dist. module to Autozone, and they have a machine to test it.
Check things like injector volts at the injector plug when cranking, fuel pressure while cranking, spark when cranking.
The only difference between running on the starter, and running is combustion.
In order to have combustion, you need a few things:
1. spark
2. fuel
3. compression
4. all mechanical parts have to be functioning (valves, cam,etc.).
5. There can be no obstructions in the cylinders (water, oil,etc.).
Check all but the last one.
Your computer could be at fault. Your ignition switch could be at fault. The dist. coil could be at fault.
If it won't start for a long while, pick something that soaks up heat, like ignition coil, computer, dist. module, relays, etc.
The computer uses map sensor voltage as a reference, not an absolute.
your car is a MAP car (manifold Air Pressure)
The car feeds the computer parameters to enable it to make decisions to run the engine, power the fuel pump, control the timing, and adjust the fuel.
Parameters needed:
1. distributor module tells the computer that the engine is rotating, and at what speed.
2. the MAP sensor tells the computer the vacuum strength inside the manifold to give reference for what the car is actually doing, going up hills, decelerating, cruising, idling.
3. The throttle position sensor gives the computer the signal as to what you want to do, idle all the way to wide open throttle.
4. Manifold air temp sensor gives the relative air density for fuel mixture
5. The vehicle speed sensor tells the computer the vehicle's speed in relation to the engine speed that the distributor was telling it.
6. The distributor is controlled by the computer as to spark advance, and the Knock sensor tells the computer if it put too much spark advance in.
7. The Oxygen sensor tells the computer how well it is doing, and whether to cut back on the fuel, or add more fuel to come up with a fuel mixture that provides a combustion process that has a certain amount of oxygen left in the burned gasses that indicates lean or rich fuel mixture.
Since your car does not have a MASS Air Sensor, the computer has a look-up table that provides the computer the math necessary to power the injectors the proper pulse width that they need to provide the right amount of fuel.
That pulse width is how many pulses per second, and how long the injectors stay open in that precious second to accomplish the right amount of fuel.
None of the sensors will cause the engine to stop except the distributor module.
Loss of computer input to the injectors will cause it to stop.
Determine what you are losing, and move in that direction.
1. forget smog devices like EGR and smog pump, etc.
2. focus on things like the module inside the dist., and fuel pump relay, oil pressure switch.
You can take the dist. module to Autozone, and they have a machine to test it.
Check things like injector volts at the injector plug when cranking, fuel pressure while cranking, spark when cranking.
The only difference between running on the starter, and running is combustion.
In order to have combustion, you need a few things:
1. spark
2. fuel
3. compression
4. all mechanical parts have to be functioning (valves, cam,etc.).
5. There can be no obstructions in the cylinders (water, oil,etc.).
Check all but the last one.
Your computer could be at fault. Your ignition switch could be at fault. The dist. coil could be at fault.
If it won't start for a long while, pick something that soaks up heat, like ignition coil, computer, dist. module, relays, etc.
The computer uses map sensor voltage as a reference, not an absolute.
your car is a MAP car (manifold Air Pressure)
The car feeds the computer parameters to enable it to make decisions to run the engine, power the fuel pump, control the timing, and adjust the fuel.
Parameters needed:
1. distributor module tells the computer that the engine is rotating, and at what speed.
2. the MAP sensor tells the computer the vacuum strength inside the manifold to give reference for what the car is actually doing, going up hills, decelerating, cruising, idling.
3. The throttle position sensor gives the computer the signal as to what you want to do, idle all the way to wide open throttle.
4. Manifold air temp sensor gives the relative air density for fuel mixture
5. The vehicle speed sensor tells the computer the vehicle's speed in relation to the engine speed that the distributor was telling it.
6. The distributor is controlled by the computer as to spark advance, and the Knock sensor tells the computer if it put too much spark advance in.
7. The Oxygen sensor tells the computer how well it is doing, and whether to cut back on the fuel, or add more fuel to come up with a fuel mixture that provides a combustion process that has a certain amount of oxygen left in the burned gasses that indicates lean or rich fuel mixture.
Since your car does not have a MASS Air Sensor, the computer has a look-up table that provides the computer the math necessary to power the injectors the proper pulse width that they need to provide the right amount of fuel.
That pulse width is how many pulses per second, and how long the injectors stay open in that precious second to accomplish the right amount of fuel.
None of the sensors will cause the engine to stop except the distributor module.
Loss of computer input to the injectors will cause it to stop.
Last edited by coupeguy2001; 08-11-2010 at 02:19 AM.
08-11-2010, 08:47 PM
#3
6th Gear
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Update:
Thanks for the input, coupeguy! here's what i did: Changed the ignition module today, and i had a pleasent, albiet frustrating, suprise:
now, she still dies, but i can start her up again afterwards. (at least the two times i tried, it worked. no telling if i'll be able to do it on the way to work). takes about the same amount of time as before for her to quit on me, tho.
soo, we're on the right track. any more of those wonderful ideas? things i should look into, etcetera. .
Thanks for the input, coupeguy! here's what i did: Changed the ignition module today, and i had a pleasent, albiet frustrating, suprise:
now, she still dies, but i can start her up again afterwards. (at least the two times i tried, it worked. no telling if i'll be able to do it on the way to work). takes about the same amount of time as before for her to quit on me, tho.
soo, we're on the right track. any more of those wonderful ideas? things i should look into, etcetera. .
08-11-2010, 09:41 PM
#4
Pro
Your problem maybe your ECM. Last summer my 90 started doing the same thing. Almost left me stranded a couple of times. Once she sat for a while and cooled off she would run fine. During the winter months I never had a problem until the summer came around again and the problem reoccurred. I bought another ECM at Autozone and have driven the car multiple time now in the blazing heat without any problems.
08-11-2010, 11:08 PM
#6
Pro
08-11-2010, 11:22 PM
#7
Pro
When I was having the problem and was pulled over on the side of the road with the hood up and the ignition still in the run position I could hear multiple different relays clicking on and off. Does yours do that?
Last edited by esham; 08-11-2010 at 11:25 PM. Reason: spelling
08-11-2010, 11:55 PM
#8
6th Gear
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nope, i don't remember hearing any relays. it's kind of like i had turned the key 'off' except of course everything stays on like its running, and the check engine light comes on (still no codes. that's just what pops up when the key is 'on' without the engine running)
08-14-2010, 04:37 PM
#9
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Update.
replaced ECM, problem remains.
not the ecm, ignition module, fuel filter, fuel pump, o2 sensor, throttle postition sensor. any more ideas anyone?
replaced ECM, problem remains.
not the ecm, ignition module, fuel filter, fuel pump, o2 sensor, throttle postition sensor. any more ideas anyone?
08-15-2010, 10:05 AM
#10
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sounds like you are putting a lot of money into unknowns. are you actually testing these items? if you have a fsm there are plenty of flow charts that help tremendously for narrowing down what the actual problem is.
08-15-2010, 10:40 AM
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Ok, try this one (cheap).
Take a voltmeter and switch it to 200 ohm.
Take off the connectors of each injector and put the voltmeter leads on the injector pins (engine off, will be off when you disconnect the connectors anyway).
Check the resistance on each injector (cold and warm-if possible).
Post what you get...
Take a voltmeter and switch it to 200 ohm.
Take off the connectors of each injector and put the voltmeter leads on the injector pins (engine off, will be off when you disconnect the connectors anyway).
Check the resistance on each injector (cold and warm-if possible).
Post what you get...
08-16-2010, 07:48 PM
#12
6th Gear
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Ok, try this one (cheap).
Take a voltmeter and switch it to 200 ohm.
Take off the connectors of each injector and put the voltmeter leads on the injector pins (engine off, will be off when you disconnect the connectors anyway).
Check the resistance on each injector (cold and warm-if possible).
Post what you get...
Take a voltmeter and switch it to 200 ohm.
Take off the connectors of each injector and put the voltmeter leads on the injector pins (engine off, will be off when you disconnect the connectors anyway).
Check the resistance on each injector (cold and warm-if possible).
Post what you get...
08-17-2010, 09:19 AM
#13
Burning Brakes
keep replacing random stuff, it will ALWAYS eventually fix the problem...after you replace the last OEM part left on the car. 
Since you're 21 and are asking for help instead of telling someone else to fix it, its likely you are like the rest of us and funds are tight sooo...
Get a FSM and start troubleshooting properly.
previous poster has shown what these things need to run. You are missing one of those.
Air
Fuel
Spark
troubleshoot when the problem exists. after it has stalled and wont start.
Its not likely you are not getting air sooo...
I would start by checking fuel pressure with key on, off, and after at least 10 minutes off.
then measure the injectors. you did this so I would replace them all with new ones (call Jon @ FIC). Be prepared as I understand these are not easy on an L98. The Lt1 takes about 1 beer and 30 minutes.
Get a noid and check to see if plugs are getting fire.
One of those sets of instructions will put you on the correct path.
Since you're 21 and are asking for help instead of telling someone else to fix it, its likely you are like the rest of us and funds are tight sooo...
Get a FSM and start troubleshooting properly.
previous poster has shown what these things need to run. You are missing one of those.
Air
Fuel
Spark
troubleshoot when the problem exists. after it has stalled and wont start.
Its not likely you are not getting air sooo...
I would start by checking fuel pressure with key on, off, and after at least 10 minutes off.
then measure the injectors. you did this so I would replace them all with new ones (call Jon @ FIC). Be prepared as I understand these are not easy on an L98. The Lt1 takes about 1 beer and 30 minutes.
Get a noid and check to see if plugs are getting fire.
One of those sets of instructions will put you on the correct path.
Last edited by jnealg; 08-17-2010 at 09:21 AM.
08-17-2010, 04:28 PM
#14
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