engine cutting out - at the end of my rope (long)
11-06-2008, 08:37 PM
#32
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fuel pump relay/wiring? Check that fuel pump wiring and pressure!!!
I had a cutout which drove me absolutely nuts for months. It was exactly like the vid you show. I replaced wiring , ecu, engine, fuel pump, everything up front...I could have sworn it was electrical, but turns out to be a piece of crap floating aound in the gas tank blocking the fuel out hole on turns.
I had a cutout which drove me absolutely nuts for months. It was exactly like the vid you show. I replaced wiring , ecu, engine, fuel pump, everything up front...I could have sworn it was electrical, but turns out to be a piece of crap floating aound in the gas tank blocking the fuel out hole on turns.
11-07-2008, 06:41 AM
#33
Drifting
Thread Starter
Yeah, still slowly fighting it. I only did a couple track events this year and it's not my daily driver, so it's become a driveway ornament of sorts. As the thread title states, I'm at the end of my rope so there's nothing left to hang myself with. ;-)
xrad, while I haven't been able to eliminate fuel pickup/pressure as the issue (I sat watching a fuel press gauge for ~1 hr at idle and it wouldn't hiccup) I have confirmed the -primary coil signal wire (pin #1 on the DME connector) is losing juice, so it's definitely electrical. If a different wiring harness doesn't solve it, though, I'll start looking harder at fuel delivery.
xrad, while I haven't been able to eliminate fuel pickup/pressure as the issue (I sat watching a fuel press gauge for ~1 hr at idle and it wouldn't hiccup) I have confirmed the -primary coil signal wire (pin #1 on the DME connector) is losing juice, so it's definitely electrical. If a different wiring harness doesn't solve it, though, I'll start looking harder at fuel delivery.
11-07-2008, 08:53 AM
#34
Rennlist Member
Does it only happen when the G forces apply in a certain direction? For my on-board video, I made a splice for the microphone - and found that it shorted out while turning one direction, but worked fine turning the other...
If your wiring harness is OK, you have to determine: is the DME working correctly, but receiving an erroneous signal; or are all the input correct and the DME is falsely interpreting them?
Is it possible that you're missing a tooth on the ring gear or something? Something that would cause a skipped RPM signal? There's a way to put an oscilloscope on those sensors.
Ya know - I just had another idea, could you have a faulty ignition switch? I have seen that on other cars. (I also once saw a fellow that had such a large and heavy key chain that every time he turned left the car would shut off because the key chain swung like a pendulum and turned the key...)
The more I think about it (because you've tried another DME) - that part of the system is working properly. Something else is the culprit - and I bet it's something silly and stupid.
If you take the car out on the street, can you replicate the problem? You could wire a little buzzer inline with the main power source to the DME. If the buzzer stops buzzing when you lose power, you know the DME has lost voltage.
If the buzzer keeps buzzing, then you know it's DME or post-DME related.
In fact, the more I think about it - I'm guessing it might be something like the ignition switch. Not only is the engine coasting, but your dash is losing power - it looks like the tach drops faster than when you shift gears (which should be the engine's natural "coast down" speed due to inertia.) When the power comes back on, the tach jumps up because the engine is still spinning faster than the tach was reading (because the tach lost electricity).
Let me know your thoughts on this theory.
If your wiring harness is OK, you have to determine: is the DME working correctly, but receiving an erroneous signal; or are all the input correct and the DME is falsely interpreting them?
Is it possible that you're missing a tooth on the ring gear or something? Something that would cause a skipped RPM signal? There's a way to put an oscilloscope on those sensors.
Ya know - I just had another idea, could you have a faulty ignition switch? I have seen that on other cars. (I also once saw a fellow that had such a large and heavy key chain that every time he turned left the car would shut off because the key chain swung like a pendulum and turned the key...)
The more I think about it (because you've tried another DME) - that part of the system is working properly. Something else is the culprit - and I bet it's something silly and stupid.
If you take the car out on the street, can you replicate the problem? You could wire a little buzzer inline with the main power source to the DME. If the buzzer stops buzzing when you lose power, you know the DME has lost voltage.
If the buzzer keeps buzzing, then you know it's DME or post-DME related.
In fact, the more I think about it - I'm guessing it might be something like the ignition switch. Not only is the engine coasting, but your dash is losing power - it looks like the tach drops faster than when you shift gears (which should be the engine's natural "coast down" speed due to inertia.) When the power comes back on, the tach jumps up because the engine is still spinning faster than the tach was reading (because the tach lost electricity).
Let me know your thoughts on this theory.
11-07-2008, 09:41 AM
#35
Drifting
Thread Starter
Does it only happen when the G forces apply in a certain direction? For my on-board video, I made a splice for the microphone - and found that it shorted out while turning one direction, but worked fine turning the other...
If your wiring harness is OK, you have to determine: is the DME working correctly, but receiving an erroneous signal; or are all the input correct and the DME is falsely interpreting them?
Is it possible that you're missing a tooth on the ring gear or something? Something that would cause a skipped RPM signal? There's a way to put an oscilloscope on those sensors.
Ya know - I just had another idea, could you have a faulty ignition switch? I have seen that on other cars. (I also once saw a fellow that had such a large and heavy key chain that every time he turned left the car would shut off because the key chain swung like a pendulum and turned the key...)
The more I think about it (because you've tried another DME) - that part of the system is working properly. Something else is the culprit - and I bet it's something silly and stupid.
If you take the car out on the street, can you replicate the problem? You could wire a little buzzer inline with the main power source to the DME. If the buzzer stops buzzing when you lose power, you know the DME has lost voltage.
If the buzzer keeps buzzing, then you know it's DME or post-DME related.
In fact, the more I think about it - I'm guessing it might be something like the ignition switch. Not only is the engine coasting, but your dash is losing power - it looks like the tach drops faster than when you shift gears (which should be the engine's natural "coast down" speed due to inertia.) When the power comes back on, the tach jumps up because the engine is still spinning faster than the tach was reading (because the tach lost electricity).
Let me know your thoughts on this theory.
If your wiring harness is OK, you have to determine: is the DME working correctly, but receiving an erroneous signal; or are all the input correct and the DME is falsely interpreting them?
Is it possible that you're missing a tooth on the ring gear or something? Something that would cause a skipped RPM signal? There's a way to put an oscilloscope on those sensors.
Ya know - I just had another idea, could you have a faulty ignition switch? I have seen that on other cars. (I also once saw a fellow that had such a large and heavy key chain that every time he turned left the car would shut off because the key chain swung like a pendulum and turned the key...)
The more I think about it (because you've tried another DME) - that part of the system is working properly. Something else is the culprit - and I bet it's something silly and stupid.
If you take the car out on the street, can you replicate the problem? You could wire a little buzzer inline with the main power source to the DME. If the buzzer stops buzzing when you lose power, you know the DME has lost voltage.
If the buzzer keeps buzzing, then you know it's DME or post-DME related.
In fact, the more I think about it - I'm guessing it might be something like the ignition switch. Not only is the engine coasting, but your dash is losing power - it looks like the tach drops faster than when you shift gears (which should be the engine's natural "coast down" speed due to inertia.) When the power comes back on, the tach jumps up because the engine is still spinning faster than the tach was reading (because the tach lost electricity).
Let me know your thoughts on this theory.
Initially the issue started only occasionally under heavy acceleration, but lately has become more frequent and now happens sometimes when cruising or idle.
I bought 3 small indicator lights and have hooked them to just about everything imaginable on the DME. I confirmed the DME is staying powered when the engine cuts out. I think the dash power is fine because the oil, volt, coolant, etc. gauges stay rock steady when this happens. I went as far as cutting the wire to the tach in case it had a short, but that didn't do anything (except make the tach inoperable). Yes, the tach bounces around wildly when the issue occurs, so it's getting some funky signal that corresponds to the coil signal being cut.
I haven't visually inspected the ring gear for damage but will do that now that the intake manifold is off. It's possible, but I would think a missing tooth would cause a miss everytime the missing tooth interrupts the signal. I haven't put an oscilloscope on them yet but did install new sensors, reset the depth, and put in the LR sensor harness with no change. If it continues I'll have it tested w/ an O scope to verify these aren't causing the problem.
I should know this weekend if the engine harness has corrected the issue. I'll let you know.
11-07-2008, 11:10 AM
#36
+1 on the ignition switch. I had a similar problem (sorry I didn't catch this thread earlier) and resolved it with a new switch.
Regards,
Regards,
11-07-2008, 12:07 PM
#37
Drifting
Thread Starter
11-08-2008, 06:14 PM
#38
Drifting
Thread Starter
Well, put in the new (used) wiring harness and took it for a 20 mile drive. No hiccups, even with several WOT blasts that would have caused stumbling in the past. Fingers crossed it's finally fixed.
11-08-2008, 07:20 PM
#39
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PLease check the heavy leads to the battery and the battery ground. They get old and the insulation wears off. It will arc to various metal areas under acceleration. I had precisely the same symtoms and ran through most of what you have. It was as simple as new battery lead from the starter and new grounds.
11-09-2008, 09:48 AM
#40
Drifting
Thread Starter
Thanks ehall.
I did check the voltage drop across the grounds (engine, firewall, and DME/KLR) and they were minimal. If the situation continues I'll certainly check the starter wiring while I'm checking the ring gear for missing teeth.
I did check the voltage drop across the grounds (engine, firewall, and DME/KLR) and they were minimal. If the situation continues I'll certainly check the starter wiring while I'm checking the ring gear for missing teeth.
11-09-2008, 10:39 PM
#43
Jerome,
I'm sacrificing a couple of virgins [and a goat for good luck] in the hope that this is finally cleared.
This might be the most painful and slippery electrical bug I've seen for a while. Having sat in the right seat watching it happen, then seeing it happen again sitting in the paddock at idle, it sure looked like it was going to be a diagnostic nightmare.
Props for sticking with it, Jerome.
I'm sacrificing a couple of virgins [and a goat for good luck] in the hope that this is finally cleared.
This might be the most painful and slippery electrical bug I've seen for a while. Having sat in the right seat watching it happen, then seeing it happen again sitting in the paddock at idle, it sure looked like it was going to be a diagnostic nightmare.
Props for sticking with it, Jerome.
11-10-2008, 12:44 AM
#45
I had similar cut out that occured only with hard driving on boost .searched forever checking usual culprits then finally found some slightly torn boots on my essentially new magnecors. They were made of pretty soft rubber easily torn while pulling off the plugs. Speculation was that during the extra load on boost the coil ouput would short to the block causing real abrupt cut in power. may be worth checking on your older wires. Could also try looking for spark under the hood at night. Put on Berus no problem since HTH