# VR6 turbo MS2 Oscillation at idle going full lean randomly and gradually with quick throttle



## Will powered (May 30, 2014)

So As the title states I'm dealing with a VR6 turbo with a short ram intake. I was able to get the VE table just about spot on. The car drives perfect once moving. The issue I'm having is once the car cools down and tried to start back up it will fire off normally without issues. Then gradually you will see the AFR creep up from 12:50 all the way up to and bounce back and forth at 20:1. I have EGO correction off while its doing this so know that's not a factor. And like I said the car will fire off normally run fine for a bit then out of nowhere creep up lean and oscillate. This will also occur once its warmed up and out of warmup enrichment. It will also do it if the throttle is blipped up abruptly.
Some of the things I have tried,
I have tried turning the EAE correction off and it still does it
I checked and corrected my INJ Dead time from one to .695 based of #'s from the injectors manufacture specs (42lb Green Giants http://www.fiveomotorsport.com/bosch-gr ... 0280155968 )
tried changing the values in the EAE tables cause to me it seams as if its a fueling issue with it being stuck to the intake or sucked from but I am totally getting lost in that. 

Any help is greatly appreciated

Will


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## Will powered (May 30, 2014)

Anyone have some sort of idea?


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## need_a_VR6 (May 19, 1999)

You have a datalog and msq posted to look at? I have seen hot start issues caused by iat heatsoak. There are corrections you can implement.


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## Will powered (May 30, 2014)

I can not post attachments for some reason. But I can send you a PM of the data log and Current MSQ or it can be seen here http://www.msextra.com/forums/viewtopic.php?f=134&t=54442&p=403291#p403291


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## need_a_VR6 (May 19, 1999)

I sent Ed an email late last night with some thoughts. 

The short story is unless VE is *very* well tuned, don't try EAE. Also, unless you get good driving behavior from std AE, don't try EAE yet and make sure you can get that working. Only then turn EAE on and start off with VERY small throttle blips and only move on when the AFR is rock steady transitioning in/out of those.


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## Will powered (May 30, 2014)

Yeah, Ed just sent it to me. Thanks for the EAE info, I do still have a couple of questions. The main issue that I find we have having is once the car is warmed up and stable we were able to drive the car. I was able to get the VE table what I thought to be pretty spot on. The AFR was tuning in right where I wanted it and when stopped at traffic lights settled right in at 13:5 and idle was smooth as can be with no popping at all or oscillation. I then smoothed out the VE map with the 3D map and we drove again slowly getting into boosted areas and was able to get those areas far better. When we returned home we shut the car, it sat for about 5 mins, started back up and idled with no issues. 
Its not until the car goes absolutely cold that it starts to act like it has never been tuned. It will start normal start going in Warmup enrichment then within id say 20-30 sec ~ it slowly creeps up from about 10:5 to full lean and then starts to oscillate. No matter where I move the Warm up enrichment makes no difference unless I keep it very high corrections. The problem there is then I cant get it to return back to 100% so it shuts off correctly. 
This is what led me to believe that there was an issue with the wall fuel film. Like I said the VE table works great once the engine is hot and driving down the road. Not until you do abrupt changes of the throttle like Ed originally described while shifting into 5th. My thinking this and idle are similar in that they are very low RPM and load.

I also found from my search for a solution that Ed had never corrected the Injector Dead time for the Bosch Green Giants hes running. It was still set to the default of 1ms. I tried correcting this to what I calulated to be .695 at 13V. This just made matters worse with the oscillation. ( Note that I corrected this after already tuning the VE table so I know it needs to be increased now )

Sooo, This is why as you can see I'm getting a bit lost. So if you were me what would be your first place to look? and or adjust. You also mentioned tuning out AE only first. Are you referring to just the TPS Based AE? Is it just as simple as moving the rats of change to PW adder? Or does the TPSdot threshold also need to be adjusted? 

Paul thanks for all your help with this. I hope I made as clear as possible. Thanks for your time.

Will


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## need_a_VR6 (May 19, 1999)

*VR6 turbo MS2 Oscillation at idle going full lean randomly and gradually with...*

How did you calc the deadtime? If you did it by changing n squirts to get equal afr on both settings it should be very close. 

To get the fuel tables nailed now that you have changed the deadtime, turn eae off. You will have to change the tps and mapdot thresholds low enough to trigger, the default should otherwise be reasonable. Make sure the lowest map bin is a little below full decel vacuum, your low bin looks a touch high. Also lowest rpm bin needs to be near cranking rpm. Tune the fuel table. 

Once thats all working turn the eae back on. I would start with the clt tables flat. Going back to default with eae wall map ans rpm defaults and restart the process.

Also make sure all the logging fields are enabled it seemed like some were missing.


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## Will powered (May 30, 2014)

Paul that makes perfect sense. Can you just clarify when I get back into EAE with the Coolant tables all set to 100, what should I concentrate on. I guess what I'm saying is I'm a bit confused with what EAE constant and EAE RPM is and when and where it should be adjusted. For instance what should be adjust first, Is it done at idle or while driving? do you adjust them by going back and forth between the two? Thanks again.


Will


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## Will powered (May 30, 2014)

Also, Ive been reading about this changing squirts too but don't know where or how, I changed the Dead time from the injector constants menu. I could not change the squirts in this menu because its batch fired, I kept giving an error message.


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## Will powered (May 30, 2014)

Paul,
So we made the changes to the VE table X and Y axis and it seams to help out a lot. We also turned off the EAE for now so that everything can be better tuned out. It runs through warmup without issues now and you can goose the throttle any way and it will not oscillate ( still goes a bit lean but quickly recovers) . The issue now is that after its shut down to cool off a bit and then restarted it goes crazy again. It will go lean and start to oscillate. after about 2 mins it stops and then there are no issues until its shut off again? Is there something staying on that is causing this? Where or what should I check? Thanks again for all your help. 


Will


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## need_a_VR6 (May 19, 1999)

Look at the datalog for the gamma values, that will tell you the contributors of the individual components (VE, ae, ego, etc) there is something amiss that you will likely spot if you look at those values. 

Also, make sure timing in the region/temp around idle is stable. 

Another thing to check is make sure decel fuel cut isn't cutting in around idle. Usually I'll have the kpa cutoff well under idle, and turn off at 1500rpm or so to avoid issues.


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## Will powered (May 30, 2014)

need_a_VR6 said:


> Look at the datalog for the gamma values, that will tell you the contributors of the individual components (VE, ae, ego, etc) there is something amiss that you will likely spot if you look at those values.
> 
> *Forgive me Paul but I never quite understood what Gamma Values were. Can you explain what they are and control?*
> Also, make sure timing in the region/temp around idle is stable.
> ...


*This is one thing I was curious about all along and believed it to be the root of the cause. I'm still learning Megasquirt and am more Familiar with DFI from my own car and it there is a setting for decel fuel when using a manual transmission. Is there a table in megasquirt specifically for this? I see Decel Fuel Amount in the AE wizard but that is set to 100 meaning no cut, right? The AE low RPM threshold (RPM) is set to 1500 and the high 5000. Should these be changed? And the VE table numbers below idle where I now have set to 14KPA are just slightly lower than the cell above them for a smooth VE map? Are you saying these need to be changed as well? *


Once again, thanks for all your help. Ed was beginning to loose faith, and now that its running much better hes excited to drive it with all the warm weather coming. 

Will


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## need_a_VR6 (May 19, 1999)

There are a few places that you need to watch

- ve table lowest map bin needs to below hard decel kpa value
- accel decel % I leave at 100% and use afr or ve table to set deaired behavior
- decel ful cut is a separate feature (in advanced or extended) and needs to be disabled (for now) or set properly for map and rpm limits.


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## Will powered (May 30, 2014)

Paul,
Was able to try and get some tuning done this afternoon. I saved the MSQ and a Datalog from it while driving back. Ill have to PM them too you. Here is a quick explanation of what has been changed. 

the lower KPA values in the VE, Spark, and AFR tables have been lowered to 15KPA. I then Increased the VE table in those lower areas to increase the Decel fueling. 
In the Accel wizard I set the TPS dot to 200, and the decel fuel to 97
The EGO is still off ( set to be active above 240deg) 
While driving it with the EAE off ( after a stumbling and lean start) I was able to verify the VE table and get numbers that are just about spot on. 
I adjusted the TPS graph in the accel wizard to get rid of the bogg the best I could before realizing that this car just wont stay static without EAE, in my opinion because of the short ram intake and turbo
I turned the EAE back on and began to make changes while Ed was driving, Watching the AFR as he would tip in a various RPM and MAP ranges and seam to get it much batter. 
The problem is after doing this the car now seams to run at a much richer level ( 10.5 or so). To make matters worse the car at times gets stuck lean between gear shifts. If driven at constant speed and very light load it will slowly return back down to about 12.0 AFR, Or when it happens you let off the accelerator for a moment and then get back on it will return to normal. 
Also just as we were packing it in, it was idling for a few minutes, when Ed went to pull it in it shot right up lean. He had to tap the throttle a few times to return it to normal. It then was fine. 

If you could spare some time to look at the DataLog and the MSQ and tell us what looks strange, may need adjustments, or what it is I'm missing with this It would be very helpful and much appreciated. 

Thanks,
Will


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## najort32 (Sep 8, 2004)

*bump*

bump


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## Will powered (May 30, 2014)

Paul, ed sent me this. Is this part of my problem? When I look at the data logs I can see how the PW drops the AFR goes lean for a while . The PW then comes back and slowly stabilizes. 


Over Run Fuel Cutoff
This is used to cut fuel off during deceleration to aid engine braking and reduce fuel use. The RPM setpoint will need to be a bit higher than your tickover speed, I would suggest it was around 800rpm higher than the tickover RPM so as the fuel and engine has time to settle down again once fuel is switched back in.
The KPa should be set to slightly above the vacuum value pulled when decelerating, e.g. 20KPa. 
A typical delay time of 1-2S is best to ensure it doesn't hunt. 
To find your TPS setting value, go to Tools, Calibrate TPS, and with your foot completely OFF the throttle hit Get Current. Remember this value and hit CANCEL on the Calibrate TPS dialog. Add 2-3 to this value and enter it, so if you had a value of 20 enter 22 in the setting.


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## need_a_VR6 (May 19, 1999)

It could be and I explained that above or in an email. I havent been near a pc lately to check the last msq and log yet.


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## Will powered (May 30, 2014)

*Going full lean during long decel or when first tring to take off after cool down Turbo VR6*

So after much discussion I went back and began tuning out the VE table from practically scratch. Some of the changes that led to this were,
Setting the correct injector dead time and required fuel
Adding lower Map cells to stop Oscillation
Turning off EAE correction
Setting the AFR table to 13.0 across the board, turning off EGO correction

I then set out to streat tune the Turbo VR6 Beetle starting in the lower cruise cells and slowly working my way up to the mid range and then into the higher RPM mid Vac areas. Eventually made it into some of the high map and then into light boost. All was going well, the car was running smooth and for the first time I was able to run the car with EGO correction on. I drove the car around the usual loop under various driving conditions. all seams well. 

Now to the quirks, When driving down the road if you let off the Accelerator for a few seconds, say like coming up to a traffic light that then turns green. In the 1900 to 2500 RPM range getting back on the accelerator suddenly causes the car to go full lean and hang up there. You have to let off again, free rev the motor quick and then can get back on and it all is fine. 

The other is after the car is allowed to cool off, say below 165. the car is already out of Warm up idle is smooth, but as soon as you go to take off the car goes full lean and hangs up there. Same thing, blip the throttle causes it to come back to normal. It will continue to do this when shifting until the car gets over 170 then it is some what normal aside from the condition I described above. 

I now don't know where or what I should adjust, To me it seams that its not getting enough initial transiate fuel, and when in Decel its pulling all the fuel off the wall and that's why its going full lean. Any help here would be greatly appreciated.


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## najort32 (Sep 8, 2004)

*bump*

Paul?


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## PapioGXL (Jun 3, 2008)

I responded over there with an msq to try.


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## a1ABA (May 23, 2011)

i was having the same problem with my ms2 aba-t, make sure your coolant temp on your laptop is reading FULL operating temp before you get all crazy with changing the fuel ve table, fixed my problem.


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## Will powered (May 30, 2014)

a1ABA said:


> i was having the same problem with my ms2 aba-t, make sure your coolant temp on your laptop is reading FULL operating temp before you get all crazy with changing the fuel ve table, fixed my problem.


Forgive my Lack of MS2 knowledge but What is aba-t not sure what it is or means? As for full operating temp I always wait until we have been driving a bit before any changes are made. Other wise things do indeed go nuts.


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## Will powered (May 30, 2014)

*Full lean after low RPM high vac decel and back on throttle*

So I did massive VE table changes once again. IT is getting better and better each time we drive the car, and tweak out or ignore the annoying full lean spikes. I wish I could attach the latest MSQ so everyone can see it but still cannot attach anything here. So here are a list of some of the changes I made

With help from elutionsdesign from MSextra I adjust my timing map, not exactly like factory or but a combination of his and mine. The timing map is now smother and responds well. I deff noticed a loss of power but that is expected when cutting timing by almost 8deg.

Set the AFR table a bit closer to realistic numbers and once again used elutionsdesign table and combined them to mine.

Finally made adjustments to the Accel wizard I lowered the TPS DOT down to 85% and set decel fuel to 100. I was not finally seeing the car go rich with throttle changes and lower the accel enrichment to a more reasonable m/s addition.

All these changes made the car run smoother and stayed almost spot on 13.1 afr with the EGO correction on. I still get a full lean condition while driving in the 1800-2100 rpm range. If i am in decel ( lower vac cells in that RPM range and then hit the accelerator to accelerate again the car will spike up to 16.1 and beyond . I immediately let off the throttle and it will resume normally. Like it never even happened. I just have no clue what I could be. The other thing is , it does not always do it. Its like the throttle has to be hit just right. Then it goes nuts.

Any and all help is always great. Thanks


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## need_a_VR6 (May 19, 1999)

The tip in issues are accel related. Likely tps dot threshold is too low or the lower values arent big enough. 

Intermittent lean conditions are usually the indications of misfiring. Check over the ignition. 

Feel free to post the msq to msextra and link it. Might have time this weekend to finally look it over again.


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## PapioGXL (Jun 3, 2008)

What are your accel time, accel taper, and end pw in the wizard? The msq I saw had issues in that area. I have always had good results with .2 for time, and 0 for taper and end. You may also try adjusting the accel enrich RPM scaling lower limit to around 2500 RPM, this will keep the same accel enrichment at all speeds below that value. :thumbup:


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## Will powered (May 30, 2014)

*MSextra link*

http://www.msextra.com/forums/viewtopic.php?f=134&t=54901&p=408661#p408661


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## PapioGXL (Jun 3, 2008)

That's gonna be DUMPING fuel when you accel. And you can see it in the attached screen shot.

Change to the settings I recommended and I guarantee it will be better. :thumbup:


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## PapioGXL (Jun 3, 2008)

Also, your bottom row of VE is still too fat, you're basically just wasting gas for no reason. You should be around the 15's or higher for AFR's in that region, but you're currently seeing 12's.


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