Can't get car to idle smooth what am i doing wrong?

Jon k · Post by **Jon k** » Tue Mar 07, 2006 5:12 pm

Ok so I hooked the injectors up to the MS tonight. This is a BMW M50 inline 6 with a supercharger running 30# injectors. I set the constants up (which seem to reset every now and then!?) 2495cc motor, 30# injectors and used the stock crank settings and ve table. The car started right up but the idle fluctuates 600 - 800 rpm, and i checked the wideband and it's going from like 10.5 - 11.5:1 at idle... i hit 'autotune' it complained that something is out of the window or out of range and the idle didn't change. We rev'd it up a little bit slowly, it starts to lean out to like 12.5 or so, but then the revs fall slow. The vacuum is 21" or so at idle but fluctuates a little bit, didn't use to on stock ECU.

Also, I get resets when starting, not everytime i don't think, but sometimes. I am on a MS-I V.3 running MSnS-E s19 (i believe) on MegaTune 2.25B717

Keithg · Post by **Keithg** » Tue Mar 07, 2006 5:20 pm

take the VE bins at 600-1000 and 30-50kpa and reduce them until you get AFR to about 14.7 when it is warmed up. Autotune is set to default to NOT adjust the idle bins. If you want it to do it for you (not recommended), you need to edit the ini file to allow adjustment.

KeithG

Jon k · Post by **Jon k** » Tue Mar 07, 2006 5:50 pm

Keithg wrote:take the VE bins at 600-1000 and 30-50kpa and reduce them until you get AFR to about 14.7 when it is warmed up. Autotune is set to default to NOT adjust the idle bins. If you want it to do it for you (not recommended), you need to edit the ini file to allow adjustment.

KeithG

We brought the VE bins down to like 25 at ~30kpA @ 500... should we go lower?

Keithg · Post by **Keithg** » Tue Mar 07, 2006 6:41 pm

well, if it is too lean, then yes. It does sound as though something is not quite right, though. Did you get the correct flow rate for the injectors? Which fuel pressure regulator? How about the coolant temp sensor. Are you using the GM sensor or another one? Did you get the proper values in? Is it cold when you are trying to get this all going? Timing? Is it correct? If you are getting resets, you probably do not have a good enough ground. Go at it one at a time. 1) review the ground issue, first. Make sure that the WB and the MS all use the same ground point. Make sure that this point (usually a bolt on the head) has a really good connection to the battery negative as well (battery cable). See if you can resolve the resets first. I never had a problem with resets, so this is probably in the mega manual, but I never went through it looking for this information. Once the grounds are known good and the MS runs consistently, then work on the fueling issue. You may find that it changes a bit if the ground reference is different. go through the manual and double check everything, you may have made a mistake when you set up the first page with the basic variables in it. Also, did you change the setting in the ini file for the WB you are using?

KeithG

Posted by email.

Jon k · Post by **Jon k** » Tue Mar 07, 2006 10:30 pm

Apparently my resets are normal - they occur when I shut the ECU off and back on via ignition. All is well with that. Using GM temp sensors, they function perfectly. The car logs all teh data correctly, I just can't seem to get it to idle nicely.

kanenas · Post by **kanenas** » Wed Mar 08, 2006 1:46 am

warm up your engine. make sure that there is no warm up compensation. Open up megatune and open tuning-ve. That's where Eric's 4 corners are. read about it in the manual. briefly you can move the location you are working on with the keyboard arrows, then you can either enrich ( press w) or lean out (press q) and the ve bin under the cursor will go up for richer, down for leaner. The change is instantaneous but does not get saved in the hardware until you press the "save" button.
one qualifier, i might have gotten w and q backwards, double check in the manual
good luck,
d.

Jon k · Post by **Jon k** » Wed Mar 08, 2006 7:35 am

Thank you! I didn't even know about the 3D VE Tuning until I was talking with a friend last night and he told me all about it. Going to try it today!

jonfx4com · Post by **jonfx4com** » Wed Mar 08, 2006 12:51 pm

Also try to get the VE vales around idle fairly consistent with no big jumps are you get cycling as it the idle moves around different VE bins. Same applies for timing bins. This smoothed out my idle very well.

Remember that the idle area is not an area you will drive in so you can afford to make it a wide plateau to get things smooth.

Jon

Jon k · Post by **Jon k** » Wed Mar 08, 2006 4:27 pm

Ok i have the idle smoothed - it doesn't surge anymore, but i feel like the RPM is too slow. I am using my stock DME for idle control

I may try to unplug idle control valve and crack the TB open to get it to idle a little higher... it sounds like a really cammed out big block. It idles at about 680 - 700 rpm... I am going to try and raise it.

So now that the idle is smoother, what do I do? whats the next step to tuning?

MicroSquirt.com read only forum (Jan.15,2018)