High RPM (5100+ RPMS) WOT Hesitation!!!!! - Saturn Sky Forums: Saturn Sky Forum
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post #1 of 7 (permalink) Old 06-18-2019, 12:23 PM Thread Starter
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High RPM (5100+ RPMS) WOT Hesitation!!!!!

So....As the title says......I'm still dealing with a high RPM hesitation above 5100rpms in third and fourth gear (prolly in 1st and 2nd but too quick to feel it). I have the Trifecta base tune....

The wierd thing is.....I've changed the plugs to the stock AC Delco 108s I gapped them to between .026 and .028 (can't fully tell because my feeler guage only has from .026 to .030 which is stupid) and changed the air filter to a stock AC Delco Air filter. Still getting it.

I logged the events and tried to look at misfires....NONE!!!!!!! It's starting to piss me OFF!!!!!!!

So here is what it feels like.....regardless of whether I'm flooring it from 1st through 2nd and into 3rd Always at around 5100 rpms or sitting in 3rd at 3000rpms and flooring it to redline the nice torquey pull feel I was getting sort of "lets off" (as if I let off the gas a bit) then quickly gets going again. Sometimes it does it more than once. Like I said, I checked the datalogs for cylinder misfires and nothing! In some cases the Air Fuel goes to low 11s but not lower. This happens regardless of KR as well!!!!! I can't understand what could be happening.

Also I should say that once it gets above 5100 rpms boost goes from 23psi to 20.5 psi or so, but that doesn't seem to be enough to sort of "interrupt" the torque pull (as I'm feeling) and it doesn't go back up to 23psi when it starts pulling again. Anybody else have this issue and fix it?
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post #2 of 7 (permalink) Old 06-22-2019, 04:19 PM
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Are you "pending" any codes? This sounds like you might be.
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post #3 of 7 (permalink) Old 06-24-2019, 09:57 AM
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Along with codes, are you seeing any Knock Retard (KR) at that range? Since KR will pull timing to fight the knock, a drastic reduction in timing would definitely be noticeable. Something else to look at. Since you say it drops off then comes back this would also sound like a possible knock issue.

If you're unfamiliar with it, KR works this way. When knock (...and it may not be true pre-ignition but we're going to lump all the possible events under knock since that's the way the ECM logic deals with them...) is detected, the ECM retards timing a certain percentage to get rid of the knock. This is called Knock Retard. Now, KR is a very eager beaver and the ECM tends to error on the side of caution (which isn't bad when you're talking about knock because it's one of the things that can throw a rod through a block which IS a really bad thing) and pulls more timing than is probably necessary to eliminate the knock.

Now KR will hang around for a while and slowly decay to make sure the knock conditions don't come back...so as you continue, the amount of KR applied and thus the amount of timing that is being pulled gets less and less until the KR is back at 0 and you're running the timing the tune is asking for. If knock comes back, the decay may be interrupted or the amount of KR increased depending on the severity of the knock.

So I would data log what is going on with your car as you drive and as you are experiencing this. Be sure to record boost and KR (along with RPM, speed, throttle position, timing, coolant temp, and current gear if you're an automatic) to see what's going on when it occurs. Also, if you're using a Bluetooth dongle and the Torque app (or Apple device equivalent) if the dongle is a cheap one it may not have the band width to data log all those parameters at a high enough rate to get a good log. I recommend either a more robust dongle or HP Tuners if you know someone that has it and is willing to log your car.


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Last edited by Robotech; 06-24-2019 at 09:59 AM.
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post #4 of 7 (permalink) Old 06-24-2019, 12:13 PM Thread Starter
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Originally Posted by The_Ghost View Post
Are you "pending" any codes? This sounds like you might be.
Nope, nothing to do with the hesitation. The only pending code I have is a p2271 which (I think) has to do with the O2 extender I put on that has a 90degree elbow.
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post #5 of 7 (permalink) Old 06-24-2019, 12:18 PM Thread Starter
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Originally Posted by Robotech View Post
Along with codes, are you seeing any Knock Retard (KR) at that range? Since KR will pull timing to fight the knock, a drastic reduction in timing would definitely be noticeable. Something else to look at. Since you say it drops off then comes back this would also sound like a possible knock issue.

If you're unfamiliar with it, KR works this way. When knock (...and it may not be true pre-ignition but we're going to lump all the possible events under knock since that's the way the ECM logic deals with them...) is detected, the ECM retards timing a certain percentage to get rid of the knock. This is called Knock Retard. Now, KR is a very eager beaver and the ECM tends to error on the side of caution (which isn't bad when you're talking about knock because it's one of the things that can throw a rod through a block which IS a really bad thing) and pulls more timing than is probably necessary to eliminate the knock.

Now KR will hang around for a while and slowly decay to make sure the knock conditions don't come back...so as you continue, the amount of KR applied and thus the amount of timing that is being pulled gets less and less until the KR is back at 0 and you're running the timing the tune is asking for. If knock comes back, the decay may be interrupted or the amount of KR increased depending on the severity of the knock.

So I would data log what is going on with your car as you drive and as you are experiencing this. Be sure to record boost and KR (along with RPM, speed, throttle position, timing, coolant temp, and current gear if you're an automatic) to see what's going on when it occurs. Also, if you're using a Bluetooth dongle and the Torque app (or Apple device equivalent) if the dongle is a cheap one it may not have the band width to data log all those parameters at a high enough rate to get a good log. I recommend either a more robust dongle or HP Tuners if you know someone that has it and is willing to log your car.
Hey Robotech I am datalogging it. I have the expensive dongle you recommended I buy two years ago. I'll upload the datalog when I get home tonight. It's stupid that I have to change it to a windows notes file before I can upload it though.

Anyway, there is no more KR than I got before I put the downpipe on it in December. It also wasn't doing this before I put the downpipe on. I took it to the track and ran a 13.6 at 102. The one thing I did notice is that the AFRs seem to get richer from 5100+. In that range I'm looking at anywhere from 11.6 to 11.1. I'd think that's a little rich in a direct injection car.
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post #6 of 7 (permalink) Old 06-24-2019, 12:20 PM
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P2271 is a post cat O2 sensor so it shouldn't be affecting anything with how the engine runs. This O2 just checks to make sure the cat is working.


V.A.L. (#1108)
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Max (#1547)
2007 TURBO 2.4
Too much to list here. See my Garage for details.
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post #7 of 7 (permalink) Old 06-24-2019, 12:23 PM
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Originally Posted by MattM View Post
Hey Robotech I am datalogging it. I have the expensive dongle you recommended I buy two years ago. I'll upload the datalog when I get home tonight. It's stupid that I have to change it to a windows notes file before I can upload it though.

Anyway, there is no more KR than I got before I put the downpipe on it in December. It also wasn't doing this before I put the downpipe on. I took it to the track and ran a 13.6 at 102. The one thing I did notice is that the AFRs seem to get richer from 5100+. In that range I'm looking at anywhere from 11.6 to 11.1. I'd think that's a little rich in a direct injection car.
Saw this AFTER I posted. LOL

Yea 11.6 is not too bad but 11.1 seems pretty rich for a DI car like you mention. Running overly rich would make it bog a bit. What's your fuel trims look like at that point? (And I totally forgot you had the high speed dongle...hard to keep track of who has what. LOL)


V.A.L. (#1108)
2007 2.4 Base
MagnaFlow dual outlet, quad tip exhaust test car
**Sold**

Max (#1547)
2007 TURBO 2.4
Too much to list here. See my Garage for details.
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