VW 16V accel enrichments

turbotib2000 · Post by **turbotib2000** » Sun Jun 25, 2006 6:55 pm

Hey,

I am trying to get my buddy's 16V turbo rocco tuned and we are having a stumble problem which we are thinking maybe related to the accel enrichments map.

Now I don't have fuel VE table 100% tunned(the map is nice a smooth though) but the car runs good when just partial throttle driving and when WOT.

The problem is the transition from partial throttle to WOT. The engine stumbles with to much fuel. But if you slowly get into WOT the car is fine no hesitation.

Would this be the accel enrichments? I tried playing with them some but It just seemed to make it worst.

We are using the settings from another VW that is running a similar setup.

Does anybody have some accel settings I could try? Or some tips/advise on what to try?

Setup is 16V t3/04E .63 a/r, 42LB injectors with 42 si rail pressure anda walbro inline high flow pump. Ported head, Eurospeed IM, 70mmTB 3"exhaust....

Thanks,

turbotib2000 · Post by **turbotib2000** » Tue Jun 27, 2006 5:36 am

12125 Members and nobody can help?

jonfx4com · Post by **jonfx4com** » Tue Jun 27, 2006 7:56 am

A datalog would help plus an MSQ file.

Do you use a WB EGO, I seem to think that most of th VW's had a bosch as standard, mine is so quick to respond that with AE off it still grabs the lean spikes for me, although I dont recomend that as a real solution. The logs will tell folks when it goes lean, by how much and why. Without that info its hard to help much more.

Jon

turbotib2000 · Post by **turbotib2000** » Tue Jun 27, 2006 6:18 pm

jonfx4com,

Sorry I don't have a log.

But according to the LM1 the air fuel ratio is around 12.5 when the stumble takes place. The fuel map is nice and smooth in the area it stubles aswell.

Did some more tunning this evening and the car runs extremly well. Excellent start up, idle partial thorttle driving and even WOT throttle. Its just the transition from partial throttle to WOT when first crank the throttle all the ways open.

Could this be a setting? My buddy got some accel enrichments from another VW which were alot different then what we were using but it Made zero difference.

jonfx4com · Post by **jonfx4com** » Tue Jun 27, 2006 10:22 pm

I think I would move more towards MAPDOT enrichment than TPSDOT enrichment. Reason being that the air into the engine on a turbo car is not in proportion to the TPS position. If you are part throttle and the turbo is wound up a little and you then open the throttle you dump a huge amount more air in than if you openend it the same number of degrees with the turbo not wound up. By using TPS to define your accel enrichment you can never get this right as if it works without boost it will not work with it and vive versa. Move the slider over to the left so you make sure the mixture is tracking the MAP not just the TPS then place with the MAP enrichement figures. Better still look at the new betacode whcih uses Xtau and then you can forget the TPS and MAP enrichments totally.

Jon

turbotib2000 · Post by **turbotib2000** » Wed Jun 28, 2006 3:59 am

Jon,

Thanks for the replies.

The engine stumbles even without registering any boost in the transition from partial throttle to WOT. But it also stumbles when it is picking up boost aswell.

But The engine Breaths extremely well. Eurospeed intake manifold, 70mm throttle body,Ported head and 3" exhaust 2.5" very short intercooler piping.

Still feal its the TPS accel? and we should use MAP?

Can you give me some tips on what settings to try with the MAPDOT?

Also can you explain abit more about

"look at the new betacode whcih uses Xtau and then you can forget the TPS and MAP enrichments totally"

Where do I find this?

Sorry I am not real familiar with the Megasquirt program. I have been using Haltech for the past couple years.

Thanks

jonfx4com · Post by **jonfx4com** » Wed Jun 28, 2006 4:27 am

http://www.megamanual.com/ms2/betacode.htm

Please read all the warnings about this BETA code. Its untried and your call if you use it or not but the Xtau stuff will cure your AE problems, if that is what causes your stumble.

Or if you dont want to change the code, go here and read the section titled Setting the Acceleration Enrichments

http://www.megamanual.com/ms2/

I seem to remember seeing some really good posts on AE in turbo motors aound the tuning fuel and air section.
MAPDOT or Xtau are the way to go. TPS is not good for turbo motors as the air flow can change out of all proportion to the throttle movement.

Also beware that you are not stumbling through throwing in too much fuel, I had that problem. One more tip is be sure that the rate of change of MAP to force enrichment is not lower than the noise on top of your MAP signal due to individual cylinders inducing air from the manifold or you get continuous MAP enrichment. You really need to to do some data logs to get to the root of the problem. Its dead easy click file, datalogging, record then go for a drive. Download MegalogViewer

http://www.ideasandsolutions.biz/MegaLogViewer/

and point it at your log file and you can see every last detail of what your engine and squirt did and saw during your drive. It will save you hours or days of guess work, especially if you have a WB connected to MS. You will see the MAP signal, mixture, Timing, EGO, temps, everything. You can't tune without it on a MegaSquirt, give it a go.

Jon