Engine shuts down after hitting rev limiter?
02-09-2010, 04:17 PM
#1
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Join Date: Jul 2002
Location: Phoenix, AZ
Posts: 1,277
Engine shuts down after hitting rev limiter?
Car hits it, dies and I roll to a stop. Turn off ignition and back on and all is fine.
OK, I have separate datamaster files I referenced to try and find some correlation. Here is what I found...per what datamaster says:
1. Both banks of injectors stay consistently open to some random BPW close to the final BPW before shutdown. Note however one run the right bank locked closed because I had just hit the rev limiter.
2. 02's go lean on both banks even with the injectors being told to be open and throttle does not respond thus indicating a loss of spark.
3. Spark advance goes to some random number. On the 1st run, it is 34 degrees and the 2nd, it is 39 degrees. It stays like this until the ignition is shut off.
4. At shutoff, speed indicates 0 until the engine stop rotating then it will immediately again show the correct speed.
WTF is going on? Could I have a short? No voltage loss or spike during the episodes.
On the 1st run I did get DTC 41 (Ignition coil short). I bypassed the regular routing and went directly to the main fusebox for voltage. This eliminated the DTC 41 from occuring on the 2nd run but still the car shut off. Rev limiter is set for 6500 and the car shows it bypasses it by a few hundred RPM before it gets hit (again per Datamaster)
I tried duplicating the results by pulling only the battery connections to the PCM and leaving ignition hot. Datamaster did not read the same way so I am uncertain if it is an intermittent battery connection loss.
Thanks,
Ben
OK, I have separate datamaster files I referenced to try and find some correlation. Here is what I found...per what datamaster says:
1. Both banks of injectors stay consistently open to some random BPW close to the final BPW before shutdown. Note however one run the right bank locked closed because I had just hit the rev limiter.
2. 02's go lean on both banks even with the injectors being told to be open and throttle does not respond thus indicating a loss of spark.
3. Spark advance goes to some random number. On the 1st run, it is 34 degrees and the 2nd, it is 39 degrees. It stays like this until the ignition is shut off.
4. At shutoff, speed indicates 0 until the engine stop rotating then it will immediately again show the correct speed.
WTF is going on? Could I have a short? No voltage loss or spike during the episodes.
On the 1st run I did get DTC 41 (Ignition coil short). I bypassed the regular routing and went directly to the main fusebox for voltage. This eliminated the DTC 41 from occuring on the 2nd run but still the car shut off. Rev limiter is set for 6500 and the car shows it bypasses it by a few hundred RPM before it gets hit (again per Datamaster)
I tried duplicating the results by pulling only the battery connections to the PCM and leaving ignition hot. Datamaster did not read the same way so I am uncertain if it is an intermittent battery connection loss.
Thanks,
Ben
Last edited by 95Blackhawk; 02-09-2010 at 06:14 PM.
02-10-2010, 11:32 AM
#2
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Join Date: Jul 2002
Location: Phoenix, AZ
Posts: 1,277
Ok a quick update:
I tested it again by hitting the rev limiter with the same results of engine shutdown.
About 1.5 seconds after engine stops getting spark, I get DTC 41 (IC open circuit) and 36 (high resolution failure) then about 0.5 seconds later, I got the dreaded DTC 51 (EPROM failure).
What do people think about this? I put in a new PCM after the 1st episode because of DTC 51 and now it is happening again.
Battery as well as ignition are both good connections.
I tested it again by hitting the rev limiter with the same results of engine shutdown.
About 1.5 seconds after engine stops getting spark, I get DTC 41 (IC open circuit) and 36 (high resolution failure) then about 0.5 seconds later, I got the dreaded DTC 51 (EPROM failure).
What do people think about this? I put in a new PCM after the 1st episode because of DTC 51 and now it is happening again.
Battery as well as ignition are both good connections.
02-10-2010, 02:20 PM
#4
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Join Date: Jul 2002
Location: Phoenix, AZ
Posts: 1,277
6525, 1st gear...like the computer knows when a 6 speed is in 1st...
6554, 2-6th
Fuel resume for both is 6482.
I have hit the rev limiter many times in the past racing without this issue and is only just recently it showed up but I will go ahead and reprogram the limiter a slight bit lower to see if it makes a difference.
6554, 2-6th
Fuel resume for both is 6482.
I have hit the rev limiter many times in the past racing without this issue and is only just recently it showed up but I will go ahead and reprogram the limiter a slight bit lower to see if it makes a difference.
02-20-2010, 01:05 AM
#6
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Join Date: Aug 2007
Posts: 573
"On the 1st run I did get DTC 41 (Ignition coil short). I bypassed the regular routing and went directly to the main fusebox for voltage."
You probably have a bad Ingition coil, by re-routing power the PCM cant sense something wrong since it has certain algorithms it uses to check sensors and by cutting wires that run it it thinks everything is fine.
Also, if you actually have a shorting coil the last thing you want to do is wire it directly to a power source since the PCM is telling you it's shorting out (an actual short is a serious problem, if it's a short). Short circuit is the same thing as shoving a paper clip in the top two slots of a 120v plug, laying a wrench across the + and - terminals of a battery. Not good. I think often a short is interpreted as an "open", which is ok.
If you short out a PCM, or any of it's power outputs it will/should shut down until reset as a safety measure.
I would borrow or buy another coil and see what happens then start checking wires.
You probably have a bad Ingition coil, by re-routing power the PCM cant sense something wrong since it has certain algorithms it uses to check sensors and by cutting wires that run it it thinks everything is fine.
Also, if you actually have a shorting coil the last thing you want to do is wire it directly to a power source since the PCM is telling you it's shorting out (an actual short is a serious problem, if it's a short). Short circuit is the same thing as shoving a paper clip in the top two slots of a 120v plug, laying a wrench across the + and - terminals of a battery. Not good. I think often a short is interpreted as an "open", which is ok.
If you short out a PCM, or any of it's power outputs it will/should shut down until reset as a safety measure.
I would borrow or buy another coil and see what happens then start checking wires.
Last edited by dookie454; 02-20-2010 at 01:07 AM.
02-21-2010, 08:38 AM
#7
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Thread Starter
Join Date: Jul 2002
Location: Phoenix, AZ
Posts: 1,277
"On the 1st run I did get DTC 41 (Ignition coil short). I bypassed the regular routing and went directly to the main fusebox for voltage."
You probably have a bad Ingition coil, by re-routing power the PCM cant sense something wrong since it has certain algorithms it uses to check sensors and by cutting wires that run it it thinks everything is fine.
Also, if you actually have a shorting coil the last thing you want to do is wire it directly to a power source since the PCM is telling you it's shorting out (an actual short is a serious problem, if it's a short). Short circuit is the same thing as shoving a paper clip in the top two slots of a 120v plug, laying a wrench across the + and - terminals of a battery. Not good. I think often a short is interpreted as an "open", which is ok.
If you short out a PCM, or any of it's power outputs it will/should shut down until reset as a safety measure.
I would borrow or buy another coil and see what happens then start checking wires.
You probably have a bad Ingition coil, by re-routing power the PCM cant sense something wrong since it has certain algorithms it uses to check sensors and by cutting wires that run it it thinks everything is fine.
Also, if you actually have a shorting coil the last thing you want to do is wire it directly to a power source since the PCM is telling you it's shorting out (an actual short is a serious problem, if it's a short). Short circuit is the same thing as shoving a paper clip in the top two slots of a 120v plug, laying a wrench across the + and - terminals of a battery. Not good. I think often a short is interpreted as an "open", which is ok.
If you short out a PCM, or any of it's power outputs it will/should shut down until reset as a safety measure.
I would borrow or buy another coil and see what happens then start checking wires.
I have not figured this out yet and have chose to completely rewire the car. the reason being, the original wiring of the car pulls power directly from the alternator. NOW I find out this is bad and can cause problems with voltage irreguarities since an alternator does not put out perfectly smooth DC voltage.
I am wiring it to look more like F-Body wiring with all power coming from the battery. We will see if this solves my problem.
Looks as if I burnt up an ICM, PCM and maybe a coil with all this BS I have gone through.
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