First crack at tuning. Need some help!...bigtime.

[Toni]

A bit of background...The car was finally working great! Trims were perfect, o2s were both cycling nicely. SO I was finally able to put in some bigger injectors and start tuning...

So I have 450s@43psi and maft gen II to tune -20 mainscale. Dual widebands and logging going. The car starts and idles and sits pretty around 100 o2 trim. So I'm happy about that!

From reading jeff's site about tuning I just start tuning low load up to about 5 just sitting there at idle. So I give that a crack, once I get past ~900/1000rpm the car kinda stumbles and then once I let go the ecu goes into freak mode no longer cycling.

The rear and front widebands are acting very differently.

here is the initial throttle blip


So what gives with the rear?

~2k


Then after that the car starts reving up/down and the rear o2 was cycling on the wideband?....urka durk?


Any thoughts guys?

[Toni]

Hmm I'm wondering if one of the injectors on the rear isn't sealing properly creating a vac leak that is getting bigger on some throttle...

[lawdogg]

That is very strange that one wideband leans out so much more than the other.

You didn't happen to log throttle did you?

[Toni]

black is rpm red is tps

well I sealed up the injectors and that didn't change anything. It seems as if the rear wideband is more sensitve to changes in afr. Once I riched it up it settled to 14.7. There was one point where I could get the car to idle at 2k with perfect cycling nb, and money widebands.

The ecu seems to be going into limp mode pretty quick on me. I pulled the o2s and reset the ecu and tried to tune via wideband. I can get it to 14.7 up to 3k rpm with some pretty heavy rich correction

base mainscale -20

1200 +3
1600 +7.5
2200 +7.5
2800 +6

I dunno, it feels like I'm putting in too much fuel but the widebands were all 14.7s in those ranges.

Then I plugged the o2s back in, the ecu imediatly didn't like it and limped home.

-Antoni

[Toni]

Just leak tested, nothing not even the throttle body (resealed that puppy recently).

[lawdogg]

Can you swap the stock injectors in and zero out your correction, see what happens? I'm thinking fuel delivery issue ... maybe.

[Toni]

I can...

I have 43.5 psi at the rail and a fuel loop. I guess there is a chance one of the injectors is bad in the rear...Although they just came out of a working car.

-Antoni

[niterydr]

I am also leaning towards an injector problem. check your electrical connections and the injectors themselves (sounds like you already verified the install ruleing out a vac leak).

[Toni]

At the moment that seems like the cause. I put back the 360s and turned up my base pressure so I'm now running 388s. I set a -7 correction and it runs perfect. The ecu does not go into limp mode.

[Toni]

Alright mystery solved!

looks like my lm1 sensor(rear) went bad. I swapped the sensors and the lc1 throws an error code with the lm1's sensor. Weird that the lm1 didn't throw an error.

When I went to the track with the cranked 360s I noticed the rear was reading SUPER rich, like 8s compared to the front at ~11. I made the assumption that it might be bad and was right.

I put the 450s back in and just tuned by the good sensor. After a few tries I was able to dial the low rpms to like 3krpm without the ecu limping. Looks like these 450s have different flow characteristics than the "388s" I had in.

-Antoni