No knock, ECU pulls timing - why?
Originally Posted by razorlab
Malibu,
Why is your timing totally flat?
Also, that one big knock event at the end. When it holds like that, I have found that is a real knock event. Usually the little spikes are ok but when the it holds like that it's bad news.
The voltage amount usually isn't a good indicator of knock, but more how long it takes for the spike to dissipate.
Can you post the actual log file?
Why is your timing totally flat?
Also, that one big knock event at the end. When it holds like that, I have found that is a real knock event. Usually the little spikes are ok but when the it holds like that it's bad news.
The voltage amount usually isn't a good indicator of knock, but more how long it takes for the spike to dissipate.
Can you post the actual log file?
The segment is from a log that consists of a long drive home, and not just a single run.. But I ran with an idle maf of around 50-60hz
FWIW, this is not how my car normally runs, this was an attempt to trace my long term fuel trims while driving home and find how much additional fuel I needed to get them in range.. I loaded a stock ECU map (but I raised the boost/maf cut limit)
And the timing being totally flat.. That is a direct result of intentionally hitting the 240-260% load sites on my stock map at those RPM ranges... THe cells in that range tend to be... Umm.. Flat..
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Those are the 260% cells from 3500-5500rpm which means at 1300-1500hz would end up squarely in that region..
It occurrs at the 180% column on the low octane map... but way more aggressive at higher load sites in that region.. (My car is hovering in the high octane map for the most part)
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Those are the 260% cells from 3500-5500rpm which means at 1300-1500hz would end up squarely in that region..
It occurrs at the 180% column on the low octane map... but way more aggressive at higher load sites in that region.. (My car is hovering in the high octane map for the most part)
Last edited by MalibuJack; Jun 8, 2006 at 11:54 AM.
If your car was mine, my eye would be 100% on that built engine to seek where the problem is. You ever listened to that motor with det cans?
We took the knock sensor out of the equation, so detonation or excessive engine noise is not a factor here.
MalibuJack, I understand what you are saying about high MAF reading putting you in the highest load cells but the question is why is the timing going lower than the highest load cells. Stock the timing is very low like you mentioned but I'm seeing timing lower than that at points and it's not following the low or high octane timing maps.
MalibuJack, I understand what you are saying about high MAF reading putting you in the highest load cells but the question is why is the timing going lower than the highest load cells. Stock the timing is very low like you mentioned but I'm seeing timing lower than that at points and it's not following the low or high octane timing maps.
Bad ECU?
Measure voltage with meter
Originally Posted by MalibuJack
If there is a way to get the MAF reading from the sensor during a pull, ..
Last edited by C6C6CH3vo; Jun 8, 2006 at 12:51 PM.
Originally Posted by AMS
We took the knock sensor out of the equation, so detonation or excessive engine noise is not a factor here.
MalibuJack, I understand what you are saying about high MAF reading putting you in the highest load cells but the question is why is the timing going lower than the highest load cells. Stock the timing is very low like you mentioned but I'm seeing timing lower than that at points and it's not following the low or high octane timing maps.
MalibuJack, I understand what you are saying about high MAF reading putting you in the highest load cells but the question is why is the timing going lower than the highest load cells. Stock the timing is very low like you mentioned but I'm seeing timing lower than that at points and it's not following the low or high octane timing maps.
It certainly must have a failsafe mode that pulls timing until some variable is satisfied..
Originally Posted by C6C6CH3vo
Bad ECU?
Measure voltage with meter
Measure voltage with meter
Originally Posted by AMS
Al is talking about putting an SAFC on a car which would trim MAF readings which would indicate a problem with MAF output. I'm not sure we're talking about the same thing because it has never been an issue, only on this particular modified car. I'll try to walk through the scenario so we can all learn and or figure this out.
Out of all the cars that I've seen/dynoed this is the second car that is doing this. The first was a bone stock car that was untouched and unflashed. It would pull random timing all over the place. We've built and tuned high hp flashed cars (500whp) with no issues at all. So if anything, this is an isolated issue to these two particular cars and one of them was untouched.
My timing logging is consistant and you can see the drop in horsepower on the dyno in sync with timing being pulled, so timining is being logged correctly..
This is not related to intake air temps as I watched them vary from 95deg to 140deg and it would not correlate to timing, same with coolant temps.
We eliminated the knock sensor as the culprit as we basically removed it out of the block and had it hanging and isolated. To corect Markus, when we unplugged the knock sensor and it threw the code, then the ECU pulled extra timing (limp mode)
Also for experimentation purposes only, we set the low and high octane maps the same and the timing is still going lower (at random) than the highest load level timing we have specified. Meaning even if it was on the highest load level it should still follow that load line. Unless....
What we know
1. Swaped MAF sensors to make sure nothing in there wasn't goofed (BAP).
2. Not knock sensor related
3. Not Intake temp related
4. Not coolant temp related
5.
What I'm still thinking it could be related to
1. Manifold Pressure diff sensor ?? not likely but I'll look into it.
2. Maf reading. For example we could be on the highest load cells in the map. The O3 goes to 260 on the map but for calculaton purposes the ECU might have an algorithom to remove more timing if the load goes higher than that. The only thing that doesn't make sense is that I've run many cars to way beyond this power level and maxing out the load cells and this has never happened before.
I've got a nice 8 hour drive each way to BeaveRun this weekend (Time trials) so I'll think about this some more.
-Martin
Out of all the cars that I've seen/dynoed this is the second car that is doing this. The first was a bone stock car that was untouched and unflashed. It would pull random timing all over the place. We've built and tuned high hp flashed cars (500whp) with no issues at all. So if anything, this is an isolated issue to these two particular cars and one of them was untouched.
My timing logging is consistant and you can see the drop in horsepower on the dyno in sync with timing being pulled, so timining is being logged correctly..
This is not related to intake air temps as I watched them vary from 95deg to 140deg and it would not correlate to timing, same with coolant temps.
We eliminated the knock sensor as the culprit as we basically removed it out of the block and had it hanging and isolated. To corect Markus, when we unplugged the knock sensor and it threw the code, then the ECU pulled extra timing (limp mode)
Also for experimentation purposes only, we set the low and high octane maps the same and the timing is still going lower (at random) than the highest load level timing we have specified. Meaning even if it was on the highest load level it should still follow that load line. Unless....
What we know
1. Swaped MAF sensors to make sure nothing in there wasn't goofed (BAP).
2. Not knock sensor related
3. Not Intake temp related
4. Not coolant temp related
5.
What I'm still thinking it could be related to
1. Manifold Pressure diff sensor ?? not likely but I'll look into it.
2. Maf reading. For example we could be on the highest load cells in the map. The O3 goes to 260 on the map but for calculaton purposes the ECU might have an algorithom to remove more timing if the load goes higher than that. The only thing that doesn't make sense is that I've run many cars to way beyond this power level and maxing out the load cells and this has never happened before.
I've got a nice 8 hour drive each way to BeaveRun this weekend (Time trials) so I'll think about this some more.
-Martin
I have been using my AEM now for over 2 years on my own car and also tuning AEM on various customer cars.
I was "trained" at AEM and feel I know my way around the softwear very well.
Still, there are certain "bugs" or "issues" which I have come across with that softwear and had to either plug away at it or ask for help to resolve the problem.
Interestingly, it was this very issue which lead me to take out the stock ecu from my own Evo. I first purchased evo flashing equipment for my own evo and it was only therefater I started to do tuning for others and start doing it professionally. Sadly, I never took the time to resolve this timing issue on my own car with the reflash equipment as the much easier path seemed to be just put a AEM in it.
Ironically, when I first proposed a colaberation with Buschur I was forced to confront this timing problem and it was Buschur who assisted me in solving the puzzle along with Tadashi of Techno Sqaure also offering pieces of the puzzle.
Originally Posted by MalibuJack
Actually you'd have to use an Oscilliscope if you don't have something installed inline like I do.. The MAF output is Karmann Frequency, its a square wave signal.. measuring Voltage won't represent anything other than a carrier voltage..
Heres the list of possible ignition limiting culprits:
- Airflow sensor
- intake temp sensor
- barometric press sensor
- Coolant temp sensor
- cam pos sensor
- crank pos sensor
- vehicle speed sensor
- ignition switch-st (duh)
- knockers sensor
