strange idle problem

[m3vxt]

Here is the full story I have built a mini with a suck through supercharge setup with a throttle body and injectors on the the inlet to the charger which has been proven to work by a certain company. I am using 2injectors alternating, 2squirts

I have basically copied the kit!!


I have got my ms up and running. I can get it to idle nicely until it gets warm then it will idle nicely for say 20secs @AFR 13:1 then the revs slowly drop off and afr rises.

Then it will suddenly pick up after nearly stalling and idle well for say 20secs and the whole cycle starts again.


What is happening??? I have turned off all enrichemnts and idle control.

I have tried increasing VE around the area that it idles in and around.

I am just in the process of moving the IAT to after the supercharger. Maybe heat soak in the inlet manifold etc causing a problem?

I am very new to this so it all a big leaning curve to me right now so bare with me if I say anything stupid.

[Matt Cramer]

Please post a data log of the problem happening, along with your MSQ file. This will help me see what the ECU "thinks" is happening and may provide additional clues.

[m3vxt]

Ok will do

I have added an IAT sensor between the outlet of the supercharger and the inlet ports.

As requested files attached.... I am execting there is some stupid I have done. It is only a short log as the engine was fairly warm already but this might help.

[m3vxt]

Can anyone help me??

From the log it looks to me as if the warmup enrichment is on.... but in Tunerstudio it is disabled

[m3vxt]

Problem solved!!

I had all the warm up enrichments set to 0% now set to 100% i guess this is correct? from my understanding that makes no enrichment
and anything over 100% adds more?

Run the engine up to around 95*c fully warmed and it ran fine and the log showed NO WUE or ASE.

Managed to take the revs up to around 3500 and boost of about 5psi no load but it was only just rich enough get on for around 15:1-16:1 in places but for first time running for any length of time not too bad I guess. I had a little tweak of the VE table leaned it off a little at idle and added alot else where. Doesn't smell rich like it would with a carb.

Idled nicely at 1300rpm +/-50 @12:1 which is too fast but easy to tweak back the idle stop screw later. I don't tthink it will idle much below 1000rpm due to the very lightweight internals (flywheel, crank and bottom pulley)


Well that is the story so far

[Matt Cramer]

Bingo, 100% enrichment on warmup = normal fueling. (Oddly enough, with ASE, 0% is normal fueling.)