Stalling and bouncing idle (after fixing idle switch)

**Toni** · 04-28-2014, 09:39 PM

So apparently my tps was turned just a hair too far and it wasn't always triggering the idle switch. Now it is. Idle settled down in the garage. ISC was adjusting and target idle rpm was being reached. Tested the operation by adjusting the idle screw and the ISC moved to compensate.

However, when I went out for a cruise. It wasn't catching the idle after stopping and would even bounce from stalling to high rpm and back again. Here is a graph of what is going on.

Any thoughts?

**RealMcCoy** · 04-28-2014, 11:00 PM

Why is the ISC at 46 counts at idle...? Is that warmed up, no load? That's about 40 counts too high...

**Toni** · 04-28-2014, 11:14 PM

I think it's actually around 25 when it's not about to start bouncing. I'll try to put it in idle adjustment again and set the screw and see where it ends up.

**Greg E** · 04-29-2014, 07:22 AM

Blowthru MAFT nuisances. I've never gotten a car to run stock smooth setup that way. Draw thru, no problem. Blow thru hates life.

I think its a result of having the BOV and TB too close to the MAF.

**Toni** · 04-29-2014, 08:36 AM

See that's the thing, I could have sworn it was working fine when I got the MAFT. I guess it's easy enough to confirm for sure, I still have the draw through setup so I'll have to see. Shit, actually I can just block the bov, this even happens just driving back and forth in my driveway.

**Greg E** · 04-29-2014, 09:59 AM

Good way to test!

**Toni** · 04-29-2014, 10:08 AM

So noticed something else odd. Apparently all of my fuel trims are zeroed out. This is after a few hour drive from the dyno, I would have expected some adjustments.

Something related perhaps? My AFRs on the wideband were bouncing around 14.7 as usual but I'll have to check to see if my o2s ever cycle.

**Greg E** · 04-29-2014, 10:19 AM

Originally Posted by Toni

So noticed something else odd. Apparently all of my fuel trims are zeroed out. This is after a few hour drive from the dyno, I would have expected some adjustments.

Something related perhaps? My AFRs on the wideband were bouncing around 14.7 as usual but I'll have to check to see if my o2s ever cycle.

Ah yeah. That might have something to do with it.

Fuel trims not updating are a sign that the ECU loses battery power after tuning off the ignition. This isn't good. It would also means the idle trims would be reset every time you walked away from the car too which would also cause this issue.