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prj
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« on: August 20, 2012, 01:52:05 AM »
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I have a car I am working on with a sinter clutch and a flywheel, that is 2x lighter than stock.
This is a ME7.5...
What I have done so far, is increased KFMRES and KFMRESK. This helped in that the clutch can be let off carefully without the car stalling.
However, what I have not fixed yet, is rev oscillation when releasing the clutch and giving the car some throttle.
Because the clutch barely slips at all, it will catch and then release, the revs will overshoot then undershoot, and it goes into a resonance loop. Eventually the engine stalls unless you push the clutch in. I lowered the sensitivity of KFPED and that helped. Because the engine is almost rigidly bolted to the chassis, I increased the idle to 1000 rpm, as any lower there is very strong vibration through the chassis.
I wonder what I should be attacking next. The idle itself is good now, but taking off from a start and especially reverse gear could be significantly improved.
This is not technically idle, it is very low load and engaging-disengaging clutch and revs oscillating.
One thing I should probably look at is ARMD (I have just disabled this on WOT), but any pointers would be appreciated.
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silentbob
Full Member
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Posts: 141
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« Reply #1 on: August 20, 2012, 02:20:20 AM »
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Is bit b_llrein set?
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prj
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« Reply #2 on: August 20, 2012, 05:08:48 AM »
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Is bit b_llrein set?
Good point. The car needs some work on the fuel system, this work will be finished tomorrow. After that I will log and check this. I guess if it is set I need to work on the PID and if it is not set, then something else. |
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userpike
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« Reply #3 on: August 20, 2012, 10:22:33 AM »
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I have a Spec stage 3+ sintered clutch disc and pressure plate, along with a Spec 7.5lb flywheel installed on my '02 gti 1.8t The tune I have which is way underpowered for my bolt ons is from Nuespeed, stage 1.
The ONLY time I ever had clutch engagement problems was during the initial break in period which lasted about 1500 city miles. after that, engagment has been smooth as butter with very close to stock like drivability.
I have never messed with the tune, but again the tune is only a stage 1 Nuespeed. I'll send it to you for observation if you' like but Im pretty sure anything you are trying to change up, prolly is still stock on this tune. As far as I can tell with the def files I have Nuespeed only changed like 8 maps.
I've never had issue with stalling unless I let the clutch out too fast while at a low rpm. Good luck!
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userpike
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« Reply #4 on: August 20, 2012, 10:27:22 AM »
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Oh ya! I also wanted to say during break in the clutch was very "on/off", no slippage and I also have 034 motorsport 85% durometer tranny and engine pendulum motor mounts and the dogbone mount is fully polyurathane 85% durometer even the front bushing in the dogbone, so I have as close to solid mounting as possible without actually having solid mounts.
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« Last Edit: August 20, 2012, 10:30:30 AM by userpike »
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prj
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« Reply #5 on: August 20, 2012, 02:56:13 PM »
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I have a Spec stage 3+ sintered clutch disc and pressure plate, along with a Spec 7.5lb flywheel installed on my '02 gti 1.8t The tune I have which is way underpowered for my bolt ons is from Nuespeed, stage 1.
The ONLY time I ever had clutch engagement problems was during the initial break in period which lasted about 1500 city miles. after that, engagment has been smooth as butter with very close to stock like drivability.
I have never messed with the tune, but again the tune is only a stage 1 Nuespeed. I'll send it to you for observation if you' like but Im pretty sure anything you are trying to change up, prolly is still stock on this tune. As far as I can tell with the def files I have Nuespeed only changed like 8 maps.
I've never had issue with stalling unless I let the clutch out too fast while at a low rpm. Good luck!
This car is far beyond Stage 3, never mind Stage 1. The flywheel is I believe lighter than yours, and the clutch is a LOT more heavy duty than yours. It is broken in, and it is almost completely on/off. I don't have problems with clutch engagement, I probably have problems with idle PID, but I will confirm after I log the flag silentbob mentioned. Thanks for offering your file, but I'll pass. |
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userpike
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« Reply #6 on: August 20, 2012, 04:16:53 PM »
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WoW a Spec stage 3+ clutch and pressure plate is good for 525 ft/lbs torque. I'm still writing the tune I will replace the Nuespeed tune with...slowly learning between homework assignments for college.
Does your clutch disc have a solid hub or is it sprung? If its solid, I understand engagement will be nothing but on/off. Mine is double sprung. Please post your fingings when you get the chance after you've figured it out. would be greatly appreciated! Much thanks!
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prj
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« Reply #7 on: August 20, 2012, 11:15:07 PM »
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WoW a Spec stage 3+ clutch and pressure plate is good for 525 ft/lbs torque. I'm still writing the tune I will replace the Nuespeed tune with...slowly learning between homework assignments for college.
Does your clutch disc have a solid hub or is it sprung? If its solid, I understand engagement will be nothing but on/off. Mine is double sprung. Please post your fingings when you get the chance after you've figured it out. would be greatly appreciated! Much thanks!
It is a multi plate clutch and it is good for over 750 ft lb. As on off as it gets. I consider myself quite used to heavy clutches, but I still manage to stall this thing almost all the time. There's just absolutely no inertia carried by the flywheel. I don't know much more details about the clutch, since I did not build this car. And sure, I will let you know the details. |
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prj
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« Reply #8 on: August 22, 2012, 11:51:48 AM »
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Okay, I had a chance to log this now.
This is 100% some sort of PID controller going nuts, because the graph is perfect in shape.
I just pushed the throttle to a certain RPM and then slowly released the clutch.
I could not log b_llrein, because I don't have that defined in my .ecu file, and I would need to search the disassembly for it first.
What I could log was b_ll. The problem happens the moment it gets turned off.
Please see attached image.
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prj
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« Reply #9 on: August 22, 2012, 11:55:04 AM »
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In this image you can see that requested load does the same oscillation and throttle plate angle follows, even though I am holding the throttle in exactly the same position.
I also attached the log.
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prj
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« Reply #10 on: August 22, 2012, 01:59:49 PM »
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Both mifa_w and mrfa_w follow req load as well.
I must log wped_w, I think the problem might be coming from mrfgr_w.
Will verify tomorrow.
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phila_dot
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« Reply #11 on: August 22, 2012, 02:54:49 PM »
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How does ignition angle look? Have you logged zwout?
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prj
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« Reply #12 on: August 22, 2012, 11:25:44 PM »
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Sure, download the log file.
Has exactly the same swings as everything else.
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prj
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« Reply #13 on: August 23, 2012, 03:04:02 AM »
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I solved the problem.
I significantly increased PVDNV and everything is OK now.
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nyet
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« Reply #14 on: August 23, 2012, 09:57:24 AM »
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Can you summarize what PVDNV does?
I see that it is the P constant for the idle control PID, but how does that affect letting the clutch out?
I thought there was a different anti-stall system unrelated to idle control in ME7?
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« Last Edit: August 23, 2012, 09:59:40 AM by nyet »
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