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C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
Subscribed... as I also have some surging / bucking at low rpm. And a tendency for the rpms to drop to around 200 or even die when I let off gas and push in clutch after it has heat soaked for a short while, and I get in and go after it's been shut off for 10 minutes or longer. It was really bad until tuner drilled 1/8 hole in throttle plate. At least now it doesn't just die after I release gas and push in clutch .
Subscribed... as I also have some surging / bucking at low rpm. And a tendency for the rpms to drop to around 200 or even die when I let off gas and push in clutch after it has heat soaked for a short while, and I get in and go after it's been shut off for 10 minutes or longer. It was really bad until tuner drilled 1/8 hole in throttle plate. At least now it doesn't just die after I release gas and push in clutch .
Replace your maf sensor. Mine surged and got better after putting radiator shroud back on but still died occasionally. Replaced MAF and smooth as silk now. Just be sure to use OEM and not aftermarket.
I'm revisiting this thread again. So as Michael_D mentioned in one of his points I have a MAF tune instead of SD tune. Now from my old fox body 5.0 days when you modded those cars you wanted to switch to a Mass Air Flow sensor setup if you had a Speed Density car. Now it looks like on a Z06 it is the opposite??
I had an 89 5.0L Mustang when they were new and that was the first year they got MAF which was supposed to allow much greater ability to mod the car vs. if you had an earlier version Mustang which was SD. If you heavily modded a SD Mustang (cams and stuff) you would get that annoying revving and dropping idle cause the system couldn't figure out the airflow to the engine that a mass airflow sensor equipped car can.
Now our Z06's have a mass air sensor so I'm kinda confused about this.
You can unplug (or forget to plug back)😁the MAF and car will actually drive good under SD but lose power and break up under hard throttle. Ask me how I know. 🤪
Replace your maf sensor. Mine surged and got better after putting radiator shroud back on but still died occasionally. Replaced MAF and smooth as silk now. Just be sure to use OEM and not aftermarket.
I'm going to talk to my engine builder and suggest we try that. Car also now has Halltech CAI, which places the MAF forward of where it normally is.
Flyloe. I have a mf108 as well. Had to replace radiator shroud. My shop said he sees that issue with the halltech a lot where the direct air causes surging. So remedy is to put shroud back. You might lose minimal hp on top end but no big deal. I can tell zero difference. If that doesn’t fix your issue then you probably have a faulty MAF
Just curious, if the current tune has SD (VVE) disabled, is the intent to disable the MAF entirely and switch to full SD or to run them in blended mode (ie. tune them both) like it does stock? I'm still quite green when it comes to tuning so I'm just trying to learn something
Flyloe. I have a mf108 as well. Had to replace radiator shroud. My shop said he sees that issue with the halltech a lot where the direct air causes surging. So remedy is to put shroud back. You might lose minimal hp on top end but no big deal. I can tell zero difference. If that doesn’t fix your issue then you probably have a faulty MAF
I'll talk to my engine builder and see what he thinks. Thanks for the reply. Hope I can get it resolved.
My car has some surging which my tuner and I have tried about everything we can think of in HPT to get rid of it. It is most noticeable driving 30 mph around 1400 rpm. Looking at the logs, it appears the surging with my tune has timing spikes (negative direction) related to it. Looking at my log the during steady state cruising the timing will be at 40° then get a negative spike to 24° then right back up to 40°. This lines up with when I feel the surges while driving. My logs do show the typical O2 and fuel trim oscillations but they do not coincide with the surges felt when steady state cruising at 30 mph.
No one has mentioned timing spikes/oscillations yet so I'm not sure if this is unique to my tune. We have tried everything we can think of to get rid of the timing spikes/oscillation when steady driving at 30 mph about 1400 rpm range. I even experimented by making every timing chart I can find match the same amount of timing so corrections will not change the timing. That did not work. I'm not sure what could be causing these timing spikes to occur.
Sorry about jumping on your thread but I figured I'd add another dimension of surge into the mix.
Mine might be an electrical issue. Ordered a shroud and I'll put that on tonight, but when trying to do some logging last night, when I hit that speed where the car starts surging the HPTuners logger stopped and started and stopped and started. It were as if someone were slapping the space bar on the laptop in time with the car surging. Ground or something I don't know. I'll have to find it though. Mine also gets much better when it is warmer in the afternoon than when it is cool in the morning on my way to work, which also makes me feel like it could be a ground somewhere.
I take it that we have to disconnect and remove the oil cooler to replace the shroud?
And we're sure the MF103 will fit in there without the shroud cut and still be able to the shut the hood? I'm not sure how the MAF plug doesn't rub on the shroud if the shroud isn't cut.
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16-'17-'18-‘19-'20-'21
I had a stock Z with a KillerB. After I installed a VetteAir I got a surg at full throttle. I had it tuned out.
Later after a cam and head work I assumed it wasn't a problem with a tune. I feel nothing.
My car has some surging which my tuner and I have tried about everything we can think of in HPT to get rid of it. It is most noticeable driving 30 mph around 1400 rpm. Looking at the logs, it appears the surging with my tune has timing spikes (negative direction) related to it. Looking at my log the during steady state cruising the timing will be at 40° then get a negative spike to 24° then right back up to 40°. This lines up with when I feel the surges while driving. My logs do show the typical O2 and fuel trim oscillations but they do not coincide with the surges felt when steady state cruising at 30 mph.
No one has mentioned timing spikes/oscillations yet so I'm not sure if this is unique to my tune. We have tried everything we can think of to get rid of the timing spikes/oscillation when steady driving at 30 mph about 1400 rpm range. I even experimented by making every timing chart I can find match the same amount of timing so corrections will not change the timing. That did not work. I'm not sure what could be causing these timing spikes to occur.
Sorry about jumping on your thread but I figured I'd add another dimension of surge into the mix.
If you log "spark state", you can zero in on what spark table the ECM is looking at during the dips. I have seen spark smoothing cause dips before. I usually dissable it with cars that have manual transmissions.
If you log "spark state", you can zero in on what spark table the ECM is looking at during the dips. I have seen spark smoothing cause dips before. I usually dissable it with cars that have manual transmissions.
Thank you. I will look into this. I haven't played with the tune on over a year so it might be time to get back in there and see what is going on.
My car has some surging which my tuner and I have tried about everything we can think of in HPT to get rid of it. It is most noticeable driving 30 mph around 1400 rpm. Looking at the logs, it appears the surging with my tune has timing spikes (negative direction) related to it. Looking at my log the during steady state cruising the timing will be at 40° then get a negative spike to 24° then right back up to 40°. This lines up with when I feel the surges while driving. My logs do show the typical O2 and fuel trim oscillations but they do not coincide with the surges felt when steady state cruising at 30 mph.
No one has mentioned timing spikes/oscillations yet so I'm not sure if this is unique to my tune. We have tried everything we can think of to get rid of the timing spikes/oscillation when steady driving at 30 mph about 1400 rpm range. I even experimented by making every timing chart I can find match the same amount of timing so corrections will not change the timing. That did not work. I'm not sure what could be causing these timing spikes to occur.
Sorry about jumping on your thread but I figured I'd add another dimension of surge into the mix.
Something you may want to try is changing the 20 amp fuses for the injectors there are 2 up to 30 amp it has changed the tune on my car. Speculation is there is oscillations in the injectors due to the current draw and the 20 amp fuse acts like a variable resistor. Easy enough to try anyway.
Something you may want to try is changing the 20 amp fuses for the injectors there are 2 up to 30 amp it has changed the tune on my car. Speculation is there is oscillations in the injectors due to the current draw and the 20 amp fuse acts like a variable resistor. Easy enough to try anyway.
Very interesting. I haven't heard of that before and definitely easy to try with no risks.
Subscribed... as I also have some surging / bucking at low rpm. And a tendency for the rpms to drop to around 200 or even die when I let off gas and push in clutch after it has heat soaked for a short while, and I get in and go after it's been shut off for 10 minutes or longer. It was really bad until tuner drilled 1/8 hole in throttle plate. At least now it doesn't just die after I release gas and push in clutch .
Drilling a hole in throttle plate? Has anyone else done or heard of this?
08-16-2018, 02:43 PM
