[sullyman86]

I am having an issue with lag after shifting. It happens on upshifts and downshifts, low or high rpm and little or wide open throttle. Everytime I shift the engine feels and sounds like I am not hitting the gas pedal even though I could have it at 3/4 throttle. Then, depending on how far I am pressing the accel pedal, it suddenly wakes up and starts pulling. The same things happens on downshifts. Ita not turbo lag as the engine feels completely dead and isn't making any noise like it's trying for a second and then bam loud engine noise like it should be and the car goes. Here is a datalog picture. I can link the datazap as well if needed This was a 1st to 3rd gear regular light driving datalog to try and see what's going on. As you can see the engine rpm continues to drop after I push the accel pedal. Boost is building like it should but the rpms drop until suddenly they slam upward.

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[sullyman86]

In the picture the green line is the accelerator position, the grey is rpms and the line toward the bottom is boost pressure.

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[dilat3d]

You should be able to direct link the datazap page .. it'll make it much easier to decode

 

[sullyman86]

@dilat3d Here's the datazap link
http://www.datazap.me/u/sullyman86/boost-leak-check?log=0&data=4-8

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[dilat3d]

It'd odd but the logs indicate you're getting somewhat on the gas before the car reads the gear as a new gear .. basically it looks like you're gassing the car while the gears are still in neutral

Has anything changed recently on the car?

 

[sullyman86]

E30 custom tune. I got under the car again and cannot find anything out of the ordinary. All pipes are tight, symposer delete looks good. Intake looks good. I swapped back to the paper filter to listen for leaks. No audible leaks and boost holds as it should. Turbo looks good.
It's such a strange issue.

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[sullyman86]

This happens during upshifts, downshifts, normal driving, aggressive driving, it doesn't matter it happens every time I shift. It just feels worse when I am driving aggressively obviously. It literally feels like I'm cruising at 2k rpms and then I am instantly at 3k rpms and wot. The engine sounds the same way. Shift, clutch out, give it gas and nothing just a nice engine whir, after a second goes by...bam full power slams in.

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[dilat3d]

Try flashing to your 93 tune, if it's OK then it's the tune as we discussed

 

[sullyman86]

Will do. I'll be driving the rest of my e30 tank off the next couple of days and will fill and flash to 93 afterwards

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[FiddyKing]

I've been having the same issue when taking the car anywhere close to redline. I read somewhere that getting a tune fixed the issue so I got an AP3 and loaded the stage 1 OTS and it still does it. Not sure how to fix the issue but it really sucks when racing and I lose because of this stupid lag when shifting.

 

[Bryman13]

Are you set up for FFS? If so, does that eliminate or reduce the lag between gears? I know when I went back to stock tune for a few days it felt super sluggish between gears, but that was simply turbo lag.

 

[FiddyKing]

Are you set up for FFS? If so, does that eliminate or reduce the lag between gears? I know when I went back to stock tune for a few days it felt super sluggish between gears, but that was simply turbo lag.

No. not that I'm aware of. I just loaded to map off the AP. Played around tonight with and without TC on and it does it either way. Seems worst the closer I shift to redline.


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[Bryman13]

No. not that I'm aware of. I just loaded to map off the AP. Played around tonight with and without TC on and it does it either way. Seems worst the closer I shift to redline.


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How long have you had the car? Maybe it's just you getting used to the ST losing power as you approach redline. Everybody will tell you there's really no point going over 5500 rpm with the stock turbo, so that combined with the actual turbo lag you get when you shift could make it feel wrong to you if you aren't used to a turbo car. I don't know though, it's hard to say anything for sure without being there and feeling it myself.

 

[JrST]

From what I've experienced, this happens when I am driving aggressively...I think what is going on is after the clutch is pushed in the accelerator is still pushed down telling the car to accelerate. The computer sees this and is keeping the car from free revving. I think this is a safety feature built into the computer to keep the free revving from damaging the engine. This happens to me when I'm power shifting or "flat foot shifting" if I am too slow at getting the car into the next gear and releasing the clutch.


Jr.

 

[Unfitproduct]

Would a light weight flywheel and new clutch pressure plate (clutch set up) correct this abnormality>?

 

[Jstump2490]

Did you remove your clutch spring?

 

[Bryman13]

From what I've experienced, this happens when I am driving aggressively...I think what is going on is after the clutch is pushed in the accelerator is still pushed down telling the car to accelerate. The computer sees this and is keeping the car from free revving. I think this is a safety feature built into the computer to keep the free revving from damaging the engine. This happens to me when I'm power shifting or "flat foot shifting" if I am too slow at getting the car into the next gear and releasing the clutch.


Jr.

He doesn't have FFS since he's just running the Cobb map, so that's not it. What you are seeing is rev hang, and I don't know how you FFS but if you're doing it so slow that the ecu thinks you made a mistake then you are doing it wrong. I use it all the time and I have never seen what you described.

Would a light weight flywheel and new clutch pressure plate (clutch set up) correct this abnormality>?

A lightweight flywheel would make it build revs faster but I don't think that would have any affect on what he's seeing.

 

[FiddyKing]

How long have you had the car? Maybe it's just you getting used to the ST losing power as you approach redline. Everybody will tell you there's really no point going over 5500 rpm with the stock turbo, so that combined with the actual turbo lag you get when you shift could make it feel wrong to you if you aren't used to a turbo car. I don't know though, it's hard to say anything for sure without being there and feeling it myself.

The car has 12k on it now and it is my first turbo car (my supercharged B18 had no lag lol). And it is worse when I shift close to redline. I'll work on shifting earlier to see if that makes a difference. Lately I've actually been avoiding getting into races thinking something is wrong with the car.

Oh, and thanks for all the input!!!

 

[JrST]

He doesn't have FFS since he's just running the Cobb map, so that's not it. What you are seeing is rev hang, and I don't know how you FFS but if you're doing it so slow that the ecu thinks you made a mistake then you are doing it wrong. I use it all the time and I have never seen what you described.



A lightweight flywheel would make it build revs faster but I don't think that would have any affect on what he's seeing.

I'm not saying he has a problem with the FFS in the tune. I realize that the OTS tunes do not come with that feature. I do not have a tune at all and do not rely on a FFS feature...so when I do Flat Foot Shift or "power shift" the engine does rev when the clutch is pushed in. I'm saying that may be his issue. When he is shifting he may not have his foot all the way off of the accelerator and causing the engine to rev. I think the computer has some safe-guard built in that keeps the power from being applied when it detects a free rev between shifts.

Hopefully that clears things up about what I was trying to explain....the addition of a lightweight flywheel will most likely worsen the problem if that is truly what is going on.


Jr.