Well i had my buddy come out and tune the car. It ran beautifully! The next day i was driving to work the car started bucking and my wideband would go from my normal cruising AFRs to about 17-18:1 afrs. I thought maybe it was raw fuel causing the reading so i pulled the plugs to visually inspect them. Cylinder 1 and 4 were white (cyl 4 was definitely leaner then 1) and cylinder 2 and 3 looked about normal. When i drive the car it seems like it goes rich then lean causing it to break up itermittently. When the car does this it wont start without me flooring the gas pedal (even after flood clear) it also will not idle. Idle afr's are around 18:1 when it acts up. The next day i go for a drive..... it runs fine, just like it did when he tuned it. My tuner thinks it is something mechanical, I on the other hand think it is something to do with the MS. I am completely lost! I did get 2 logs of when it was acting up, one highway and one on my street. If someone is interested in looking at my msq and logs I will gladly email it to them since I have no idea how to post them. Any help would be greatly appreciated!
#4305, "RE: random lean condition" In response to Reply # 4
I was kinda wonderin, because I have the AEM UEGO and it's a piece of junk. If you have the same one I have, the output mode changes at random times, switching it from 0-5V output to MS to 0-1V, effectively trickin MS into thinking it's runnin super rich and MS leans it way out to correct it. My voltage output, even in the correct mode, still doesn't match AFR between the gauge and MS, as 14.7 reading on the gauge will have to be input around 15.8 or so on me AFR tables to keep it correct. Just some thought.
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'95 GS w/ t3/t4b FMIC, diy piping & RFL BOV MS2-Extra Fuel&Spark 50 lb/hr Holley injectors w/ 1:1 RRFPR JE 8.8:1 dish w/ Hastings Rings Eagle Rods w/ ARP bolts ARP Head studs Mild port/polish head 3" custom DP/cat section, 3" PIT catback dual MBC - 12 psi / 20psi
#4307, "RE: random lean condition" In response to Reply # 6
Another trick to try - is to adjust the closed-loop behavior of how wide of a range and the rate it updates the "fuel trims". How often the MS is allowed to adjust your injector pulsewidth, the percentage step, and the absolute limit, strongly affects driveability and fuel economy in closed-loop conditions. When I had my MS 5+ years ago I eventually got it down to +/- 5% at 1% steps. I'm not saying that's the exact value that you should be trying to hit; every car is different. But, under ideal conditions, your VE table should be so perfect that you shouldn't be needing any kind of EGO correction. That is, however, virtually impossible to achieve, but it's a good place to shoot for.
Bottom line - the VE table is where it's at, EGO correction is for fine tuning.
#4309, "RE: random lean condition" In response to Reply # 7
well I finally broke the motor in and decided to go for some WOT street tuning. Got the car running great on 10 psi creeping to approximately 14. After about an 1 hour and a half of street tuning (WOT, partial throttle and dd conditions) the car would run like a tugboat/subaru hybrid. The AFR's would go very lean...about 18-19 afrs. The car basically runs exactly like it did when I had vb921s and they overheated. I am currently running the IGBTs that rs-autosport offers. I am running with EGO correction disabled and open/closed loop off). Do you guys think I could have overheated the IGBTs? I am running 7.0 cranking dwell and 5.0 running. I checked Fuel pressure and its fine. The plugs look lean. This car is killing me!
#4314, "RE: random lean condition" In response to Reply # 9 Jan-26-09 08:02 PM by Corbin
V3.0 board does not have a flyback board (that is reserved for V2.2). V3.0 does have a flyback circuit for PWM control of peak & hold injectors. If you had the wrong settings for the injectors, you could have overheated components in the flyback circuit or injectors. It might be wise to run through my old MSQ. Click "save target as".
At that time, I was running MSI, V3.0 board, 029Q code, LC-1 WB, VB921s driving 4G63 transistor, and PWM control of 780 cc P&H injectors. The car ran well with those settings up to 15 psi. I eventually switched to the MSII and opened up a new world of problems that I am still working through. If you want, E-mail your MSQ (use the link by my profile)
