Motor Stumble "loop"
04-26-2011, 07:57 AM
#1
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Thread Starter
Motor Stumble "loop"
Got an interesting issue.
Built auto transmission (internals, cooler ,TC & shift kit), intake, plenum spacer & exhaust.
Initially tuned with Uprev (full license) with the bolt on mods. For about three weeks the car was obviously more peppy and fun but then what seems to be a computer glitch developed.
When I hit ~3650 on the tach, the needle "jumps" to ~4500. The rpms increase extremely rapidly. And yes, I hear the motor rev up. But then when it hits 4500, it seems to get caught in a loop where the rpms cycle between 4100 and 4500, quickly - maybe three times per second. The car actually feels that it is trying to accelerate on each rise of the tach and then it coasts during the fall of the tach. Again - quite quickly. I can maintain this "loop" by not changing throttle position. As soon as I let off the gas or push harder on the pedal, it moves past this range.
It's not possible for me to sneak up on 3650. I could be going 35mph and the tach slowly rises to 3650 and then the car accelerates (no throttle position change) to 4500 and does the Loop thing. If I'm accelerating quickly from a dig, I can "pass through" the loop area without experiencing the quirk. The motor will move through the rpm band without changing the rate of acceleration.
A video would be lovely but need a passenger to tape it so I can manipulate the motor.
In an effort to figure out what the hell is going on, I've swapped out the throttle body. When that didn't work, I flashed the ECU back to stock. Now the original tune is gone (feels like it did before the tune) but I STILL have this gremlin in the system! It has been more than a year and I'm sort stuck now with swapping out the ECU unless I get some better ideas. I might have a donor ECU that I can borrow to try out. Might at least help me rule out one more item.
Anybody experienced this? I have searched in every forum that runs a VQ35DE - no luck.
Built auto transmission (internals, cooler ,TC & shift kit), intake, plenum spacer & exhaust.
Initially tuned with Uprev (full license) with the bolt on mods. For about three weeks the car was obviously more peppy and fun but then what seems to be a computer glitch developed.
When I hit ~3650 on the tach, the needle "jumps" to ~4500. The rpms increase extremely rapidly. And yes, I hear the motor rev up. But then when it hits 4500, it seems to get caught in a loop where the rpms cycle between 4100 and 4500, quickly - maybe three times per second. The car actually feels that it is trying to accelerate on each rise of the tach and then it coasts during the fall of the tach. Again - quite quickly. I can maintain this "loop" by not changing throttle position. As soon as I let off the gas or push harder on the pedal, it moves past this range.
It's not possible for me to sneak up on 3650. I could be going 35mph and the tach slowly rises to 3650 and then the car accelerates (no throttle position change) to 4500 and does the Loop thing. If I'm accelerating quickly from a dig, I can "pass through" the loop area without experiencing the quirk. The motor will move through the rpm band without changing the rate of acceleration.
A video would be lovely but need a passenger to tape it so I can manipulate the motor.
In an effort to figure out what the hell is going on, I've swapped out the throttle body. When that didn't work, I flashed the ECU back to stock. Now the original tune is gone (feels like it did before the tune) but I STILL have this gremlin in the system! It has been more than a year and I'm sort stuck now with swapping out the ECU unless I get some better ideas. I might have a donor ECU that I can borrow to try out. Might at least help me rule out one more item.
Anybody experienced this? I have searched in every forum that runs a VQ35DE - no luck.
Last edited by jumbosrule; 04-26-2011 at 07:58 AM.
04-26-2011, 11:58 AM
#4
Registered User
Thread Starter
No I hadn't tried the TPS - will do the pedal dance. Just for kicks I copied it here along with two other learning procedures.
Accelerator Pedal Release Position Learning
Operation Procedure
1. Make sure that the accelerator pedal is fully released.
2. Turn ignition switch ?ON? and wait at least 2 seconds.
3. Turn ignition switch ?OFF? wait at least 10 seconds.
4. Turn ignition switch ?ON? and wait at least 2 seconds.
5. Turn ignition switch ?OFF? wait at least 10 seconds.
Throttle Valve Closed Position Learning
Operation Procedures
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch is ?ON?.
3. Turn ignition switch is ?OFF? wait at least 10 seconds.
Make sure that the throttle valve moves during above 10 seconds by confirming the operating sound.
Idle Air Volume Learning (Throttle Position Learning)
It is better to count the time accurately with a clock.
Operation Procedures
1. Perform Accelerator Pedal Released Position Learning.
2. Perform Throttle Valve Closed Position Learning.
3. DRIVE YOUR VEHICLE FOR AT LEAST 5 MINUTES FOR PROPER OPERATING TEMPS
4. Turn ignition switch "OFF" and wait at least 10 seconds.
5. Confirm that accelerator pedal is fully released, turn ignition switch "ON" and wait 3 seconds.
6. Repeat the following (steps 7a, 7b) procedures quickly five times within 5 seconds.
7a. Fully depress the accelerator pedal (HARD)
7b. Fully release the accelerator pedal.
8. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds until the Check Engine Light (CEL) stops blinking and turned ON.
9. Fully release the accelerator pedal within 3 seconds after the CEL is ON.
10. Start engine and let it idle. (START YOUR VEHICLE WITHIN THE 3 SECONDS OF STEP 9).
11. Wait 20 seconds.
12. Rev up the engine two or three times and make sure the idle speed and ignition timing are within the specifications.
Accelerator Pedal Release Position Learning
Operation Procedure
1. Make sure that the accelerator pedal is fully released.
2. Turn ignition switch ?ON? and wait at least 2 seconds.
3. Turn ignition switch ?OFF? wait at least 10 seconds.
4. Turn ignition switch ?ON? and wait at least 2 seconds.
5. Turn ignition switch ?OFF? wait at least 10 seconds.
Throttle Valve Closed Position Learning
Operation Procedures
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch is ?ON?.
3. Turn ignition switch is ?OFF? wait at least 10 seconds.
Make sure that the throttle valve moves during above 10 seconds by confirming the operating sound.
Idle Air Volume Learning (Throttle Position Learning)
It is better to count the time accurately with a clock.
Operation Procedures
1. Perform Accelerator Pedal Released Position Learning.
2. Perform Throttle Valve Closed Position Learning.
3. DRIVE YOUR VEHICLE FOR AT LEAST 5 MINUTES FOR PROPER OPERATING TEMPS
4. Turn ignition switch "OFF" and wait at least 10 seconds.
5. Confirm that accelerator pedal is fully released, turn ignition switch "ON" and wait 3 seconds.
6. Repeat the following (steps 7a, 7b) procedures quickly five times within 5 seconds.
7a. Fully depress the accelerator pedal (HARD)
7b. Fully release the accelerator pedal.
8. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds until the Check Engine Light (CEL) stops blinking and turned ON.
9. Fully release the accelerator pedal within 3 seconds after the CEL is ON.
10. Start engine and let it idle. (START YOUR VEHICLE WITHIN THE 3 SECONDS OF STEP 9).
11. Wait 20 seconds.
12. Rev up the engine two or three times and make sure the idle speed and ignition timing are within the specifications.
04-26-2011, 12:09 PM
#5
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yep thing to keep in mind on the Z is that not only do we have a TPS for the ecu, but the butterfly iteself is run off a motor since its fly by wire.. that motor goes bad, has brushes and contacts just like any motor.. remove, open up, electrical parts cleaner maybe?
Sounds like the machine takes over independant of the ECU.. id put money on it being the throttle butterfly motor.
Sounds like the machine takes over independant of the ECU.. id put money on it being the throttle butterfly motor.
04-26-2011, 03:21 PM
#6
If you changed the throttle body and took off the flash from the ECU and both failed to make a difference, then I guess you need to look elsewhere - the only thing else you changed is the transmission... Perhaps the TC is locking/unlocking - you might try adjusting the calculated load table or torque management in Osiris...
Last edited by rcdash; 04-26-2011 at 03:23 PM.
04-29-2011, 11:59 AM
#7
Registered User
Thread Starter
yep thing to keep in mind on the Z is that not only do we have a TPS for the ecu, but the butterfly iteself is run off a motor since its fly by wire.. that motor goes bad, has brushes and contacts just like any motor.. remove, open up, electrical parts cleaner maybe?
Sounds like the machine takes over independant of the ECU.. id put money on it being the throttle butterfly motor.
Sounds like the machine takes over independant of the ECU.. id put money on it being the throttle butterfly motor.
If you changed the throttle body and took off the flash from the ECU and both failed to make a difference, then I guess you need to look elsewhere - the only thing else you changed is the transmission... Perhaps the TC is locking/unlocking - you might try adjusting the calculated load table or torque management in Osiris...
I had been playing with the torque management settings before I reflashed, but assumed that all would be back to OEM levels at this point. haven't tried to modify the tables further until I know the ECU is functioning properly. Will try to swap out with a donor ECU to see if that takes care of it.
If not, then the transmission is the only thing left to really look at. A shift kit and new internals were installed and maybe there is a problem with that? I have been considering a valve body upgrade - as a last ditch attempt to fix this issue, does that make any sense whatsoever?
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05-02-2011, 08:01 PM
#10
Registered User
Thread Starter
Yeah, I guess that's not totally out of the question but it's just presenting in a strange way.
The transmission is by far the weak link. With the upgrades I have made to the 5AT I put the maximum power around 450 but I'm sure I'm stealing life from it with anything consistently over 400whp, which is about where I am at 12psi.
Can you think of a way I could test the, "slip theory"? What about any of the Osiris datalogging?
The transmission is by far the weak link. With the upgrades I have made to the 5AT I put the maximum power around 450 but I'm sure I'm stealing life from it with anything consistently over 400whp, which is about where I am at 12psi.
Can you think of a way I could test the, "slip theory"? What about any of the Osiris datalogging?
05-02-2011, 11:29 PM
#12
Yeah, I guess that's not totally out of the question but it's just presenting in a strange way.
The transmission is by far the weak link. With the upgrades I have made to the 5AT I put the maximum power around 450 but I'm sure I'm stealing life from it with anything consistently over 400whp, which is about where I am at 12psi.
Can you think of a way I could test the, "slip theory"? What about any of the Osiris datalogging?
The transmission is by far the weak link. With the upgrades I have made to the 5AT I put the maximum power around 450 but I'm sure I'm stealing life from it with anything consistently over 400whp, which is about where I am at 12psi.
Can you think of a way I could test the, "slip theory"? What about any of the Osiris datalogging?
05-12-2011, 02:10 PM
#13
Registered User
Thread Starter
Today I swapped in a G35 ECU to see if I still had the stumble - I did not. Seems like it is my original ECU - I remember getting it wet once....
Might have to check the junkyards for a properly coded 04 ECU.
Might have to check the junkyards for a properly coded 04 ECU.
05-13-2011, 07:10 AM
#18
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wow, i didn't know a flash could do that. Maybe i can get another ecu to see if any of my issues will be solved from a new ecu. When i talked to the dealership about this it was goign to cost a lot to have another used ecu flashed to match my car and security. Too much to just "test".
05-17-2011, 12:43 PM
#20
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Thread Starter
Yup, no problems just swapping in a new one. The donor ECU came from an 06 G35 so it didn't run everything on the dash, but ignition was plug & play. And yes, I am running a Haltech 350Z PnP. I did not mention that in my original post because I had this motor stumble loop issue both before and after the Haltech was installed. I'm relatively confident the ECU is the problem and I have been holding off buying a new one just because of the expense. Actually been looking at junkyards but it is really hit or miss.
@lgear - are you asking about who built the auto trans or the motor?
The 5AT was built by a local shop here in Houston. We used Level 10 internals, Transgo Shift kit, B&W cooler & a modified for higher stall torque converter. The TC was sent out locally for mods.
@lgear - are you asking about who built the auto trans or the motor?
The 5AT was built by a local shop here in Houston. We used Level 10 internals, Transgo Shift kit, B&W cooler & a modified for higher stall torque converter. The TC was sent out locally for mods.