Throttle hang. E38 from an automatic now on a manual T-56

[DRTHVDR]

Hello to all. I am brand new to EFILive and also 'tuning'. I have friends that are professional tuners and I have been using them as crutches for a long time now. I am enjoying using EFILive and all the various abilities it contains. I look forward to using this forum to unlock my cars full potential. Here goes my first question/issue:
I have an E38 PCM and L92 from a 2007 Cadillac EXT mated up with a T-56 from a 2001 Camaro. Since this engine was originally tuned for an automatic car there is a throttle hang (I don't know what else to call it) when I lift off the accelerator pedal to shift. This isn't an issue when street driving but it is disconcerting during my frequent auto-x and open track days. What can I do to remove this throttle behavior?

[DRTHVDR]

Am I explaining the phenomenon correctly? Does anyone have an idea of what I'm talking about?

[ScarabEpic22]

I'm going to bet you need to use a manual ECM OS, if you're running an auto OS without an auto behind it, weird stuff happens.

[swingtan]

Post a log and the current tune. It's a bit hard to diagnose just from a description.

Simon.

[DRTHVDR]

I have an L92 and I want to keep the vvt. If I was to use say a 2008 LS3 tune I'm afraid I would lose that feature.

[swingtan]

I have an L92 and I want to keep the vvt. If I was to use say a 2008 LS3 tune I'm afraid I would lose that feature.

I'm guessing you quote the wrong post.....

It's probably just commanded air flow but as said, without the data it's very difficult to help out.

[DRTHVDR]

15159 Here's the tune...

[swingtan]

OK, I've had a look at this. Nothing looks overly out of the ordinary and as ScarabEpic22 says, the missing trans could be causing some weirdness. However, here's something you could try....

Firstly, set {B1851} to all "0". There's no need for any shift into gear compensation.

I'm also wondering if the VVT is coming into play a bit and messing up the desired torque prediction. Also, does this engine have forced induction or Nitros ? The spark map looks like it's got FI of some sort so perhaps there is a pressure build up that's causing additional air to be forced past the throttle.

If possible, get a log file with at least the following PIDs selected (if they work on your OS)


ECM.IAT,
ECM.SPARKADV,
ECM.MAP,
ECM.VSS,
ECM.ETCTP,
ECM.INVLVTMP_M,
ECM.ECT,
ECM.KNKRET,
ECM.OCTSCL_M,
ECM.MAFFREQ2,
ECM.AIRPERSEC,
ECM.APCYL_M,
ECM.RPM,
ECM.APP,
ECM.INPHAB1,


Post up the log so I can see if the throttle is hanging, or if the ECM is commanding it open.

Simon

[DRTHVDR]

Firstly, set {B1851} to all "0". There's no need for any shift into gear compensation.

I'm also wondering if the VVT is coming into play a bit and messing up the desired torque prediction. Also, does this engine have forced induction or Nitros ? The spark map looks like it's got FI of some sort so perhaps there is a pressure build up that's causing additional air to be forced past the throttle.


Hmmm, the gear compensation sure sounds like the culprit.

Regarding the spark map, the motor is currently NA (I might add 100 hp shot later). No forced induction. Could the map look somewhat retarded because this is allowing the cam phaser more control? This is how VVT is given the freedom to adjust timing?

On another note: I need to buy a wideband so I can start datalogging and get AFRs. I will be doing this shortly. I had the pleasure of driving this car at an open track day last weekend. There is a misfire or hesitation around 4800-5400 rpm. After 5400 the engine revs like a rocket and feels very powerful.

Does everyone think I should work out the bugs on my base map THEN install my cam and springs? Or should I install the cam and springs and worry about the tune afterwards?

[ScarabEpic22]

Id personally get the bugs worked out as-is, especially if you havent been using a WBO2 it's going to need some work.

[swingtan]

Correct, get the stock setup optimised and then make changes. The stock system will be easier to tune than a cammed setup so you the current gear to learn.

RE: timing, yes it's probably cam phaser timing. Just remember when you change cams, you'l need to check the cam phasing to ensure the advance isn't going to cause PTV issues. It'll be interesting to see how the cam phasing impacts this motor. In the SIDI V6, advancing the intake cams earlier works quite well.

Simon.