sorry guys, but I really need help

arnold · Post by **arnold** » Sat Mar 04, 2006 8:52 am

I have been putting a lot of effort in tuning my supercharged Austin Healey Sprite, but I need some more help now. I put in a WB (Innovative), I think I get good readings... Anyhow, the current situation is that I can drive the car, but mainly the acceleration from low RPM's results in dramatic 'bog'.

I modified the VE table just by looking at the logfile and modifying by hand. I tried to use MS tweak but I could not get any cross over points (2,5000 V is ego set point?).

Anyhow, I am not sure what and how. There are so many tools (Auto tune, MS Tweak, MSLVV, Log works), I need some help, what and how.

Thanks.

newtyres1 · Post by **newtyres1** » Sat Mar 04, 2006 4:41 pm

It certainly looks very lean every time you put your foot down on the accelerator, and very rich at idle/low rpm. Just keep adding or taking away fuel in the offending areas until it runs better. If you re-read the Megamanual's tuning section you might get some good ideas or directions there.

Ian.

arnold · Post by **arnold** » Sun Mar 05, 2006 12:04 pm

Well I choose to use the 'seat of pants' strategy, as far as possible. Modified some of the VE, got some improvement BUT also the engine started to run on 3 cyl, mainly at low rpm, little boost. I cleaned the plugs and narrowed the gap of the electrodes a bit. It helped (for a while).

Could this be caused by a too rich idle? Or is the boost (including extra fuel) casuing this?

PS I had no ign problems before

kanenas · Post by **kanenas** » Mon Mar 06, 2006 1:52 am

i had the same problem with mstweak, it could not find many crossover points in my logs. But VexMe did, it also let me make my own afr table before taking in a log and spitting out a corrected ve table (for the points found in the log).
i guess that's one more piece of software to play with:)
try it!
good luck
d.

arnold · Post by **arnold** » Mon Mar 06, 2006 2:18 am

VEXMe? Beats Me, I'll have to get into that. I run MS -I, V 2.2, MT latest version. I hope this is not the AutoTune...?

detcollector · Post by **detcollector** » Wed Mar 08, 2006 3:27 am

Youre data log makes it look as if you have a VE table from a NA engine.
In the VE table your top KPa row (around 100KPa or higher) should be set to around 105 (or higher).
The data shows your using VE values of 85% with a MAP of 124KPa. Clearly you must be running in boost to get that MAP so youre real VE should be approximately 100%. The VE in the table is set higher to get extra fuel in for max performance.
Re scale the part throttle points accordingly.
Hope this helps.

jonfx4com · Post by **jonfx4com** » Wed Mar 08, 2006 1:01 pm

is it it a stumble for a second or less or a permanent unrecoverable bog down. The differnce is that the first indicates an acceleration enrichment problem and the second a more general mixture lean problem. Your description of richening up and fouling the plugs leads me in the direction of an AE problem an upping the VE bins to pee more petrol in will not fix it.

On the AE side you can afford to be very heavy with the figures before you end up with a puff of black smoke each time you blip the gas pedal. Then just drop it until you have no stumble and no soot.

The percentage sin the VE table are not too critical (not to say they dont matter) but if your VE table spans 10% to 70% you just have the req fuel to high or vice versa. Ideally you tweak req fuel till your VE figures look good like 20% to 105%.

Jon