Idle fluctuations

joosdawg · Jun 23, 2007, 12:14 AM

So i got my maftpro all installed tonight using speed density on my 03 evo 8. First time starting it the idle was real rough and wanted to die but didnt. Made many many changes to the VE table, fuel ect til after cruising around it was staying around 14.5-15.0 AFR at idle. When i got home the idle fluctuation thing started in again at random. The AFRs go from 11.0-18.0 the idle falls on its face and catches itself but its not a steady pace or anything like a surge its more like every 3-8 sec it will do it but it again wont stay set anymore. I had 4.40 and im going to be upgrading to 4.80 when i get back outside again to rid of some lean tip in conditions ect. The idle thing is the only thing holding me back right now as ive got my WOT, and mids all dialed in pretty well it drives almost like stock again besides the lean tip in's. No matter what i change or how much, it seems to keep pulsating back and forth between rich and lean. All my sensors seem to be in check and as i said my mids and WOT are dead on the money its just the idle once i have it sit there for more than a min or so, or on startup. What can i change to hopfullys stabilize my idle?

PVD04 · Jun 23, 2007, 05:14 AM

Just start playing with the VE table around idle. Small changes can make a huge difference there. Also, look at your logs and figure out what happens just before the RPMs start to fluctuate. You may find that your manifold pressure drops a little or raises a little. Adjust the VE cell that it moves into and see if that helps.

-Paul

Tuner@Swift · Jun 23, 2007, 06:33 AM

Sounds like you're running into the exact same problems that I was having. Are you only tuning with the MAFT or are you making adjustments to the ECU as well?

You need to see where your fuel trims are and get them in check if they aren't.

Do you have cold start enrichment enabled?

I was never able to get rid of the lean tip in condition, but I think that if I had adjusted the accel enrichment table in the ECU, I could have seen an improvement.

joosdawg · Jun 23, 2007, 03:51 PM

well just got back in from like 4 hours are trying to tune the damn thing in again. Somthing must be having a strange reading because the only way i can minimalize the hesitation on tip in is to set the tps enrichment to 2.00! and decay to .60 boost enrichment to 0 and map enrichment to .45 and thats with trying a million combos and thats all that would work for some reason.

After upgrading to 4.80 keeping the same settings my car went to **** and i couldnt even drive it, it would die, ect ect when i got it tuned in perfect lastnight with 4.40. That in itself confused the **** out of me plus the idle is still searching for some stupid reason the RPM is stable but AFR fluctuates and hits as rich as 10.9 and as lean as to max out my UEGO and then stumble and return to rich after a few seconds.

I guess i dont understand what i should be adjusting from here as i tryed everything to stabalize the idle AFR but its not working. Again though WOT is fine. While cruising if i let the throttle get down to about 1V while staying steady on it at 1v it will buck intermintantly, but it doesnt do this at anything above 1 volt on the TPS. It bucks the worst at between idle and 3000rpm with that ****ty hesitation i keep getting and thats what makes it hard to drive. If it wasent there itd be perfect. Any help is greatly appreciated!

Tuner@Swift · Jun 23, 2007, 07:35 PM

I was never able to get speed/density to work correctly. I did the exact same things you did and had the exact same problems. I got sick of messing with it and picked up a GM MAF for $30 and I am having much better success with that setup.

joosdawg · Jun 23, 2007, 08:12 PM

well i figured it out! my map sensor wasent close enough to the intake manifold and i wasent using the 5v power from the 6pin on the maftpro i was using the AEM power source from the digital gauge. Swapped em around and grounded to the pro, mounted it with a vaccum line of like 1 inch in length to a T then 1/2" to the map sensor all from the port on the passenger side of the intake where the line goes normally to that sensor then to the FPR. Only thing ive done so far is start it and check out the idle and tuned the idle to 14.7 and it actually stays! its about time but im gonna head out and finish tuning this beast and see where i wind up. Track day tomorrow but i doubt ill be ready unless i stay out til like 5am doing this **** lol

KawRider · Jun 26, 2007, 07:37 AM

Could you take a few pics of the setup?

Thanks,