I am having some issues with my APS TT when doing some WOT runs and fast shifting. Here is my setup:

2004 G35 Coupe

APS TT Uni chip tuned by Brainstorm
Conservative tune rich and conservative timing.
~9PSI ~390whp

Custom HKS Single outlet exhaust 2.5in Y to a single 3in, 2.5in Testpipes


THE ISSUE:

Started last night doing some runs, around 60 degrees F outside the car felt like there was a rev limiter around 4k then it lets go.

Basically a good WOT it pulls to 4K then stops for a second then boost kicks back in.

Really hard to explain I thought it was due to the cold weather. But today it was a nice day here in So cal and it still does it. If i dont shift fast or easy the throttle it wont do it.

BUT under quick WOT and fasts shifting (race conditions) it "bogs" in the midrange then kicks back in sometimes for just a quick second. Sometimes for a second or two.

Has any had this issue before? What could this be? Its very odd.

-George

 

are you monitoring your A/F during that point? Maybe your tuning is off and you are running too rich in that area causing your motor to bog. im talkin real rich, 9:1

maybe you are knocking, and ecu is pulling timing in that area. This can feel like what you described above..

 

When the car bogs down does it backfire too? Does it feel like it shut off and then comes back? I've had a similar problem lately. I'm running 9 psi as well. My a/f is in the 11-11.6. The only difference is the weather it's hot and humid here. Does this only happen at wot or does this happen at part throttle also?

 

I'm confused. If this occurring when you shift? If so, sounds like a slipping clutch.

 

Take it in to have the tune checked out/cleaned up.

 

Lemme guess. The car pulls strongly at WOT, but stutters/hesistates between shifts??

If so, we had the same issue with another APS TT car, and spent COUNTLESS hours trying to figure it out. Changed crank, cam sensors, knock sensor...troubleshot this one to death. Swapped throttle bodies...everything. We eventually removed the Unichip and installed an EU...no change.

For us, at least...we just switched to the UTEC and it doesnt hesitate at all now.
When I logged timing, the timing was actually going negative on our scanner in between shifts, and we could never figure out why.

With the UTEC, and full control over timing, the problem dissappeared.

Oh, and this issue appeared after about 3000 miles with the Unichip. The car drove perfectly for a while, and then the hesitation between shifts occured.

 

Intresting, As some of you know I recently purchased this car from another forum member. He had the APS kit on there since august of 2004 with the unichip since day one. I have had the car for about 2 weeks now and have been driving it everyday.

A better way to describe it is it feels like when you tires loose traction at speed and it just maintains the rpms then you get traction and it goes.

Basically I shift, it goes for a second, then hesitates for another second, then goes fine all the way to 6K.

I do plan on changing the EMS soon but dont have the funds for it right now. ( want to get a full FCON setup )

 

Sharif in my case I had 10-12k on the kit. The problem is intermitant at best. Friday I'm having the unichip reprogramed with my old map. 2 weeks ago the car started to go into safe mode. I replaced the maf this seemed to fix that problem. I wonder if the unichip or the harness is going bad. Any help or suggestions would be appreciated.

 

ok, stupid question but do you have the traction control on?

 

vdc on or off doesn't make a difference. I wonder if it has to do with the transition between open and closed loop.

 

Did it with VDC on and off, off course first thing i do when i drive the car is turn the vdc OFF, it still does it.

Any other tests I should do too help determine the issue?

 

Put it on the dyno and see what the car is doing.I think it is timing related, like the stock ECU is picking up knock and trying to pull timing.The problem with a set up like the Uni-chip and EU, it they piggyback the timing of the ECU.So if the ECU is in an aggressive timing map like say 26 degres, and the Unichip is pulling 6 degrees, your running 20 degrees of timing. Now say the stock ECU picks up some knock and pulls the timing to 24 degrees, now your running 18 degres after the correction.This makes a big difference.What I love about the utec is that you can log your stock ecu timing against your utec timing to see what the stock ecu wants to do..I have seen some stock ecu's pull timing to 10 degres!! So I would look at knock being a factor based on what your describing and my past experience.

 

I appreciate the post MRC, would a easy way to test this be putting 100octane in it again ( ran 100oct 2 weeks ago about 3-4 fill ups) and see if it stops doing it. Which would be knock related since there shouldnt be any with 100 octane.

 

I've had the car on the dyno numerous times and it didn't do it there. 10 minutes after I'm off it on my way home it shows its ugly head. The only thing the car did on the dyno was go into safe mode. That was corrected with a new maf.

 

that is because as he states it only happens if he shifts real fast, when doing dyno runs they usually never do any fast shifts
You need to make sure that you'll create the actual driving condition on the dyno to recreate this.

 

Thomas,

Are you still running the unichip for EMS? Wondering if you ever had any of these issues.

BTW ive met you before when you had the celica, Im Jasons freind that had the White 350z with nitrous at irwindale. Now I picked up this APD TT G35, got bored of the Z

P.S. Jason has a EVO9 now and we are going to irwindale this thursday along with some other friends if you want to go, just PM me.

Now back on topic

 

Sounds like the MAF voltage is not clamped correctly, that will certainly cause a problem like you describe.

 

I would try that..
It also can be MAF issues, but Im leaning towards the tune more..Has the climate and weather changed where you are recently?

 

I understand it happens when he shifts fast. I have a similar problem. I've even driven my car on the dyno to try and reproduce the problem. There were times that it happened so severe that my car shut down and chirped the tires and came back to life all within 1000 rpms.

 

Hey man, I was wondering what happened to you.
My car is at GTM right now for a full engine build and I'm changning from the unichip to the FCon. I had the APS TT with unichip for over 20k miles tuned and installed by Brainstorm and not one problem. Ed is one of the best tuners around and very **** about doing everything correctly, that's why it suprises me that it could be a bad tune.

Hopefully I'm getting my car back this coming weekend and then I'm planing on running the street legals in fontana on the 23rd. Most of the Controlled Innertia guys will be there as well, you should stop by