PDA

View Full Version : If only it could idle...


Roger-Dee
08-24-2008, 05:45 PM
I could call it done. The car runs fine and pull great, much more power than lh with much less boost. but...

It's been 3 weeks now that I'm messing with my idle setting. It's going to drive me crazy, at this point I'm thinking about a throttle stop and a GM on/off idle motor. I tried the setting of boris wich seems to be working for a lot of other poeple with no luck. I tried 500dollar740ti setting, kenny setting and even The aspirator setting and nothing will get me a good idle. I'm starting to think the problem is me, not ms or the 3 different iac valve i've cleaned/tried. The engine will start down to 60*f (coldest I have seen thus far) and won't stall in the traffic. It just never regulate to the same rpm.

When I first start it the morning, it will start at about 2500 rpm, drop quickly to 1000 then back up to 2200, and do the same thing like 4/5 times but reving a bit lower everytime until it settle at ~1100. It will do it with almost every setting I've tried, just a bit slower with some setting. The odd thing is... For a minute it could idle well at 950rpm with a given frequecy and idle dc, then I drove a bit it will be 150~200rpm higher or lower. Another odd thing; sometimes it will idle at 950 really well and the idle dc is moving by no much than +-1%. Then after a min the engine will slowly rev dowm and the idle dc goes up to compensate but as the idle valve is finally open enough for the rpm to catch up, it revs up fast to 2500+ then start to do the same thing it does in the morning... Could it be underhood temp getting too hot ?

When the engine do his drop from high to low rpm, the afr shows 19.9 so I assume fuel is being cut, could it be the ASE that make it too rich ? Edit #2; probably not since my ase is set to 10 second...

A little rundown of the setup (the important thing):
MS1 v3.0 with extra board / Plug'n'play kit for lh2.4
550cc high imp. injector
A cam 6* advanced
Plx wideband
IAT in the bumper

Please give me some input, anything to look for...
Edit: here's my msq.

Roger-Dee
08-24-2008, 10:38 PM
Well i'm gonna update this thread right now.

I unplugged the iac valve, did 2 datalog of my idle afr and the no load afr so now it got perfect afr. I started the car, idle at 1200 for a few second, then start to go up & down... No big change in afr, the engine just rise then fall flat as fuel is being cut then rise back again.

Helllllp !

Here is the log along with the current msq, i played with the req_fuel to give me some more resolution. At this point i'm so tired, I mean how can I have so much problem to get it to idle properly...

linuxman51
08-24-2008, 10:44 PM
a nice silky smooth idle is the hardest part. turn your EGO correction off at rpms below about 2000 and then start working on it.

Roger-Dee
08-24-2008, 11:05 PM
Yeah I noticed that ego correction will change the idle condition a lot.

With the idle valve disconected, what need to be tuned to stop this up/down situation? Both fuel&spark ? I mean there's no way my idle setting will work well if the car can't even stay at a steady low rpm.

linuxman51
08-25-2008, 09:06 AM
yeah adjust fuel and timing until its fairly stable, and then start playing with the idle valve. Idle is relative, what are you trying to get it to idle at? my car idles rock solid at 1000rpm's in neutral, at about 11.9:1

spe1983
08-25-2008, 12:24 PM
I was having trouble with my PNP when I had it but i never worked with it as much as you. With the valve plugged once I started the car up the idle would shoot up to about 2.2K RPM and stay, I figured it was just open all the way. Couldn't ever get to run properly, and with it unplugged it would idle fairly steady at 1.2K RPM when warm.

I never got around to messing with it, but over the past weekend I had a question. I am building a MS1 V3 as a d-jet replacement for my 142, I was going to install the PWM idle valve set up. I noticed in the instructions to leave out D8, and on my PNP board D8 was installed. Does this Diode need to be removed for proper idle valve operation?? Thanks

linuxman51
08-25-2008, 02:23 PM
on a v2.2 or v3.0?

Roger-Dee
08-25-2008, 04:38 PM
Yeah me think it's my problem.. I try to idle at 14.0 wich is way leaner than most other poeple I've seen here. Using the spark map you posted a while, the one you rocked on your 60/63, the idle was at is worse. Seem like my car don't like to idle at 18-20*.

I also shoot for 950, wich i think should be okay. I'll play with it tonight as much as I can, I've wasted so much fuel trying to get a good idle, it's not even funny. But i was only changing the idle setting, never really played with the maps.

Am i the only one who don't sleep well when I spent too much time on something that don't work the way I want ? I even got a hard time to concentrate at the job today, trying to figure out what I'll try tonight.

Damn MS... I hate to love it.

spe1983
08-25-2008, 04:48 PM
on a v2.2 or v3.0?

V3.0, on both accounts. I noted everything else the assembly manual said on the PNP board except for D8 is still there. I have a very similar set up to Roger here. I don't know if it has anything to do with it or not. Just asking.

linuxman51
08-25-2008, 06:08 PM
clip one of the leads on d8 and see if that fixes the issue.