tr87386

So I have read through many, many of the related threads on this topic. I just want someone with more knowledge about these cars to set me strait. I have had the car about 6 months. Halls ***, no complaints about power/shifting/how it runs when going through the gears. Car has a cam/long tubes/air lid/exhaust. 2000 M6 Formula. Since I have owned this, it has not idled well. I did all the normal stuff and didn't find much. New plugs/O2's/fuel filter/removed EGR/installed catch can. Did research on the best tuner in my area, consulted with a few people here that had him tune their cars. Brought the car to him for a tune. Found a vac leak while on the dyno. Brought car home running terrible. Fixed leak and verified by watching LTFT's on a hand held scanner/still won't idle. Brought back to tuner, tuner did his thing. Still running like crap at idle. Occasionally stalling but the idle was just surging up and down. Talked to tuner again. He had me drop the car off for a few days so he could duplicate cold starts etc. Said he spent "quite a bit of time working on it" and it is better....but not great. So my question is it seems like these cars are tough to get dialed in at idle? I don't want to keep bugging this guy but I am not happy with the way this thing runs. When warm it runs OK in 98% of driving situations. When cold (closed loop) runs rough and stalls at idle but as open loop driving starts it very rarely stalls. With AC on runs ok but in city driving situations it will stall out of the blue. I have learned to manipulate/anticipate the issues with the car, but I let a buddy try to drive it and it was ugly (dude knows how to drive). What advise can you guys give a very frustrated F-body owner?? I have considered throwing parts at it (IAC) but the tuner said all sensors "seem normal". Please help, thanks -Patrick

tr87386

This is the cam in the car.

G Atsma

A cam like that is NOT going to idle smoothly. It's called cam lope. Surprised you didn't know that

tr87386

Smoothly... no should it be stalling though? I mean rolling to a stop sign push clutch in and idle drops like a stone to like 300 RPM and spikes back to 1300 RPM and revs back an forth several times and finally settles into an idle. Maybe this is the nature of these cars I don't know.

JakeFusion

iTrader: (7)

It's not cam lope. Tuner should be able to fix that pretty easily. That's not a big cam. But it shouldn't be doing that. Can you post the tune?

tr87386

I don't have a way to post the tune, sorry.

tr87386

Tuner has a good reputation and reviews. Mainly tunes LS platforms. Lots of boosted set-ups go through this shop. I would imagine what I have should not be as complicated as tuning something boosted. I am wondering if I may have another underlying issue he is not seeing.

2xLS1

iTrader: (25)

That's just it. Good tuners find underlying issues.

tr87386

Something that I can see with my little hand held scanner is that when I push the clutch in coming to a stop the LTFT on both banks is pulling a ton of fuel. I have seen as much as 28%. Is that normal to see?

tr87386

I guess what I am getting at is is there anything you guys can think of mechanically that would cause that issue? Dirty/sticky fuel injectors maybe?

tr87386

Those really high trim numbers are only seen for a second at the lowest point the idle gets to by the way. once it bounces back up into a normal range eight or 900 RPM I am not seeing that happen.

JakeFusion

iTrader: (7)

The better question is why does your tuner have LTFTs enabled anyway? Or why is the car even in CL at idle? The O2s are not in a good positions in longtubes and a cam with any healthy overlap is going to eventually look "lean" and the O2s are going to command more fueling. And more fueling will make the car's idle unstable. Cammed cars want to idle lean.

subeone

iTrader: (5)

Post the file ill fix it in 5 mins

tr87386

So Jake, if it were you, would you bite the bullet and take it to another tuner? It certainly doesn't sound like you think it is something outside of the tune.

tr87386

What is needed to interface with the car so that I can post the tune? I assumed I would need HP tuners or something along those lines

JakeFusion

iTrader: (7)

Well it could be mechanical. A blown head gasket could do that but would present other problems.

But I agree, it would take 5 mins to fix the tune...

smokeshow

iTrader: (17)

Sounds like the surging is allowing it to bounce between fuel trim cells and cause stalling. Fixing the surging would prevent too many FTC transitions, however the transitions shouldn't be that extreme if the fueling is properly dialed in.