stalling problem 16v 2.0 84GTI MS2 3.57

[2vwjones]

So here is my issue;
I got my MS tuned great i am making sweet power, 183.5whp @ 6250rpm
My AFR is right were it should be, BUT when i am at a high rev like over 5500rpm and i let off the gas it just dies. It starts back up fine and idles great. However just reving it in the shop over like 5500rpm it just dies instead of dropping to idle. I am stumped on why. I put my MSQ on here so if any one can look at it and let me know if i F-ed something up that would be great.
O ya the motor is a built to the nuts 2.0 16v 9a block. I am running 300cc injectors and no IAC or stepper
I am running MS2 3.57
If any other info in needed on my Motor please let me know.

[Matt Cramer]

The MSQ is only part of the picture. Could you also please post a data log of this happening? This will give a better feel for what is going on here.

[2vwjones]

Ok here is 2 of them, One is driving and the other is in the shop just reving past 5k so i could show what is really going on.

[Matt Cramer]

It looks like when you lift off the throttle, you land in a VE cell so lean that it drops the pulse width below the injector dead time - and it stays that way until below 1000 RPM, at which point the RPM is falling so fast the engine can't catch itself when it restarts. Fatten up the VE cells in the low kPa range at 2000 RPM and below.

On an unrelated note, you've got a problem with false triggering acceleration enrichment in the 1111.msl log. This isn't causing the stall but you will need to address it to get the car tuned properly.

[2vwjones]

Thank you for the input, how do i fix that problem?

[Matt Cramer]

The false triggering? Increase the Threshold values in Acceleration Wizard.

[2vwjones]

So i raised the MAPdot Threshold up from 100 to 208, my TPSdot is at 208 I have it set to 100% MAP. Question: would it be better to run this at 50%map & 50%tps?? I will be trying this out later today if the rain stops. I have to make the changes to the 2k VE bins as well.
Thanks For the tips. Any More??

[2vwjones]

Ok so i made some changes and still have the same problem. I would like to know why, in my data logs that my dwell jumps? it seems to happen when my car stumbles, or it making it stumble. here are 3 new data logs..

[Matt Cramer]

I would like to know why, in my data logs that my dwell jumps?

Because your battery voltage is dropping at high RPM. Are you running high impedance injectors, or low?

[2vwjones]

I am running low impedance injectors. I have so High but their a lot smaller. the ones i am running are 300cc and i like them. Is my PWM wrong?

[Matt Cramer]

No, but low impedance injectors mean you need to be extra careful that your grounds and power wires are up to snuff.

[2vwjones]

as for as i know they are all good, Why is it so important with low Impedance injectors? all my grounds go to one spot on the frame. I am running a mk3 power disturber for all my power. The one that mounts on top the battery with all the fuses.
My battery is in the back of my car. Not sure if that makes a difference?

[Matt Cramer]

Try rerouting the ground to the engine block or negative terminal of the battery. Frame grounds can often have to go through spot welds and other points that have surprisingly high amounts of resistance.

[2vwjones]

Ok i will try that. I am going to be doing some work on it today so i will change the grounds around and maybe ad a few just to be sure. Thanks for all the help..

[2vwjones]

well did some changes today, redid some grounds and ran a new one from the battery to my main ground point on the body and then over to the motor. I hope this will help with the dwell jumping. Its been raining here the last few days but its going to be nice this weekend so i will be doing more dataloging. i will post up the new one as soon as i get it. Thanks for all the help.

[jonnyphenomenon]

I am running an engine very close to this setup and I am having all sorts of problems too. intermittent stumbling issues under acceleration. Im looking at your msq file and found it is considerably different from mine.

one thing I do not have trouble with is with it dying when I decelerate rapidly. I would like to compare my low rpm settings with yours...

have you made any progress with yours? do you have a newer MSQ file I could take a look at?

[2vwjones]

I am running an engine very close to this setup and I am having all sorts of problems too. intermittent stumbling issues under acceleration. Im looking at your msq file and found it is considerably different from mine.

one thing I do not have trouble with is with it dying when I decelerate rapidly. I would like to compare my low rpm settings with yours...

have you made any progress with yours? do you have a newer MSQ file I could take a look at?

I would like to to see your MSQ so that i can compare the two.

[2vwjones]

So i did some work to the rabbit today and found that one of my fuel lines was leaking on my 255lp. I fixed it and am hoping that fixes my issue.. I have not had a chance to drive it yet but i will tomorrow. If this did fix it i will be verry happy.
If you think about it when i need the fuel, like at WOT under a load, if i was getting air or just dropping FP it could have made it stumble of miss.
Please tell me if i am out of my mind or if i am on to somthing

[jonnyphenomenon]

Hey there, Sorry I never got back to you about my MSQ files. I have been avoiding my car lately because its been running so badly.

a little off topic: BUT
This Saturday I decided to crack open my head and replace the lifters. All 16 of them... something about the way it was running made me think I had a lifter(or lifterS) that was collapsing and preventing my car from breathing. New lifters in, car fires right up first turn of the key. even while I have all startup and warmup enrichments disabled, no ISV, etc. normally it would take 4 tries to get it to startup.

all of this time I have been fighting with my tune, while blaming megasquirt for being garbage. Now I know that my problem was mechanical and not software. of course, now I need to completely retune the engine so it will actually have some power.

Back ON TOPIC:
I just looked at your logs, and wow. your figures are ALLL over the place. First of all, you should calibrate your TPS so it is between 0 and 100%. I see it dips below 0, (-5) in the log. Also, something is certainly happening with the battery voltage where it is slipping down to as lot as 8.2v. this can happen due to bad grounds like someone mentioned previously, or by a short somewhere, or bad ignition settings. - and possibly bad configuration of those injectors... I see spikes all over the place in your "Shop" log. the Coolant temp (CLT) spikes and your RPMs read a max of 17,286... thats not right.

also, for starters, try to do your logging and tuning on a warmed up engine. do some wide open throttle pulls in 2nd or 3rd gear... thats all for now. I have to get back to work.

[jonnyphenomenon]

OK, so here is my Latest MSQ file. this fires right up in the rocco, and after 10 seconds or so I can roll right out of the garage without stalling. Its a mess really, because of all the things we were trying to get it to run at all.

BUT IT LIVES!!!!

http://www.angrymods.com/projects/megas ... s_good.msq

please note that my ignition settings are peculiar. compare mine to yours OFFLINE before you try to just drop this in and use it.