Car dies when push in clutch while driving

[93camaro_zzz]

Hey guys,

Ok, so I finally figured I would post on here to see if you guys have some ideas about this. The vehicle is a 2005 Cadillac CTS-v LS6 6 speed with factory DBW throttle body. I recently performed a heads and cam on the car, and am just tuning it now. I would say everything with the tune has been great except one part. When you are driving at lets say 2200rpm, and then you push in the clutch to let the car go to idle as you approach a stop sign, the rpms will go down until it pretty much dies. The only reason it doesn't die is because I have implemented stall saver until I get this figured out. I have attached my current tune and a log of the car on what it is doing. You can see in the logs where it will go down to about 350 rpm and then stall saver spikes up the rpms. I am keeping my foot off the peddle during these times as to show what the car is actually doing. I am pretty much out of ideas on this thing. I tried messing with rolling idle a little, but not too much, and also I tried to increase the integral and proprtional LOW values by quite a bit, as I figured it was being able to correct and ramp in tps fast enough before it dies. But these have basically done nothing as well. Anyone have any ideas? Thanks in advance.

starting again.hpt
Dying after push in clutch.hpl

EDIT: cam is a 227/235, 110+3, and heads are TFS as cast 220s.

[GHuggins]

Base Running Airflow appears to be way too low for your application...

[93camaro_zzz]

I just tried to put in all stock value for everything but running airflow, and idle rpm, and the car still idles fine, but does the same thing on dying when pushing in clutch. Looking at the logs, it idles at a certain tps. Lets say that it is 5.1%. Well when the idle is coming down, the tps doesnt even increase from 5.1% to a higher value until the car is at like 300rpm (Way too late). Also, I have a very wierd thing going on where it is trying to add in quite a bit of STFT right at the point in which it is dying. I dont know why it would be doing that, but I wonder if it is somehow related.

[93camaro_zzz]

Base Running Airflow appears to be way too low for your application...

Thx for the reply. Yeah I would have thought the same thing. I started this all out by initially adding in the 4g/s to the RAF and started to work from there, but after the logs, it wanted me to go back down. On the log I just did with the stock values (minus RAF), at idle I was getting 0 STIT and only have -0.6g/s of LTIT (Hardly a concern). Any more ideas?

[GHuggins]

Your VE table needs work - this is why it's adding the 15 to 20 percent on deceleration - could also be why the engine goes to stall... You can also mess with the throttle follower and your iac tables to help keep the throttle from closing so quickly by increasing the follower settings on all of the speeds before the vehicle is stopped and by shifting the iac table to the right by 3 to 5 cells... I would put all of the idle corrective tables back to stock and then dial in the ve table before messing with anything else...

[93camaro_zzz]

Hmm, I have the car tuned to run on MAF only right now. VE table disabled. Do you still think that is a concern? Also, this is a DBW car, so I don't think it uses any of the IAC tables. I could be wrong though. Also, throttle follower only goes off of tps, not vehicle speed. So I am not quite sure it is that. I can rev the car to 3k, and it comes down fine, but for some reason, it is just when the clutch is in, and the car falls to idle by itself. I appreciate the responses, just trying to reason this out.

[GHuggins]

VE is always used during transients "change in rpms"...

Throttle Follower Decay Gear - off of vehicle speed

[93camaro_zzz]

VE is always used during transients "change in rpms"...

Throttle Follower Decay Gear - off of vehicle speed

Well I guess I could have solved that mystery by logging dynamic airflow and comparing it to the MAF airflow value.

Good catch on the throttle follower, I thought it was just off of tps %. I will modify up these two things and report back. Thanks for talkin it over with me.

[93camaro_zzz]

Updating this thread. I made the changes to the VE, and then I also started messing with Throttle Follower. I am just at about wit's end with this car. It has been a curse to me. I go out to tune, and I started adding some throttle follower, decreasing decay, adding in some delay, etc, to make the throttle come down better. Well I was surprised that it started responding better. It would come down to idle fairly well about 9 times out of 10. The times that I couldnt get it to come down nice, was when let's say you were driving the car at 3000rpm, and then you let off the throttle completely at that point, waited a couple of seconds, and THEN pushed in the clutch to let it come down, it would just come down to fast, then dip down, and stall saver would kick in. It's like the few seconds that you are off throttle but still high in rpms, it decays away the follower at those points, and then when it comes down, theres none left of it.

Anyways, so the customer wanted to pick up the car, so he swings by, and I tell him let's take it for a test drive, and make sure things are at least 90% ok. At least he has been a very understanding customer. Anyways, we go out on a drive, and what do you know..... it's like I never adjusted follower at all. Completely back to square 1 with the car not coming back down to idle well. I don't even know what to do anymore. I have SO much follower in the car, and from my simple math, with the decay rate, it should take like 5 seconds to decay away the follower, which it seems like it is decaying instantly.

Last but not least, is that Im not sure if there is something up with the scanner, but when I log Idle follower, it may be in error. It will show the idle follower to decay away instantly. So I figured it was wrong, since the changes I was making were actually helping. I dont know what to do now, anybody have any more ideas? I will post tune a little later, I am at work.

[GHuggins]

Have you tried disabling ltit's yet? The fact that it came back after "learning" makes me wonder if it's just learning something wrong... The only other time I've seen something like this is when the ecm was corrupt and a junk TB was compounding things... New ECM, TB and very minor tweaks and no more issues...

[93camaro_zzz]

Yeah, I started to think about if it had any kind of issues with the hardware. I did the heads, cam, lifters, springs, pushrods, fuel injectors, and head gasket install. Everything went fine. I am starting to think if it is the injectors. Because down low where it is stumbling (between 400 and 800rpm) it is REALLY sluggish. Like Im talking you are trying to blip the throttle to have it jump back up, and it is really lazy. So I started thinking if maybe these injectors just perform very poorly at short pulsewidth performance. Here are the injectors:

http://www.tickperformance.com/racet...n#write_review

But next time I go to work on it, I will try disabling the LTIT's and see what happens.

[NJ_Phil]

Check out your injector pulse width on bank 1.

I'd pull the plugs and see if any cylinders are running hot, maybe a plugged injector

[GHuggins]

Not sure how I missed that, but yeah - bank 1's pw is normal to begin with then goes up into the 100's by the end of the log where it starts having it's problems... This can be injectors or controller...

[NJ_Phil]

Always helps to have a second set of eyes look at things...

[93camaro_zzz]

Hey NJ_Phil, I was going to mention that when I posted the file. I think something was wrong with my scanner, because the car was running PERFECT during those times. With a commanded IPW of that high, it should have been flooding the engine to where it would kill itself instantly. I mean, I have tried to drive a car where it was Donald Trump rich, and they drive horrible. But good catch though.

On a side note, I hope it is just something with the scanner. Like I said, car was running perfect, but I hope that doesnt mean a bad ECU or something. I have other logs where the IPW is completely normal.

[93camaro_zzz]

Would anyone have some insight into maybe why the follower decays so quickly? My calculations show that it should take roughly 3-4 solid seconds AFTER the 1.2 second delay for all follower to decay away, but the log shows it decay instantly. Does the Throttle Follower value in hptuners actually correlate to the follower that is in the car? Or is it something else? I think the car needs follower, but for some reason it just is not getting it.

[GHuggins]

You mind posting the latest tune and log - in the above log this is what I see happening - this also goes back to what I originally saw - when your coming down in throttle - it cuts or lacks fuel (O2's are below 100mv) - from the looks of the tune you have dfco killed? - It starts adding a ton of air with (+20some) stit's / fuel still lazy and O2mv below 100 - after it hits about 300rpms fuel is added / O2's shoot way rich (900mv) - fuel + throttle = rpm's jump back up...

Now with that being said - bank 1 with it's 100some pw does get fuel added much quicker - still makes me wonder if there's a ecm issue - also possibly why your follower changes aren't showing up in the logs?

[93camaro_zzz]

Good observations GHuggins. Man, it is so hard to tell a customer that they have a bad ecm. It is a very expensive thing to try out. but I know what you mean. If it's bad, then it's bad. That's the problem. I have been doing a bunch of research, because I need to find the answer to this situation, not only to have a happy customer, but so I can finish the car, and free up my time again. lol. I found this thread:

http://www.hptuners.com/forum/showth...onix-injectors

And it seemed very interesting to me. If I recall, I think I maybe have used to wrong injector data for these injectors. I used "42lb injector" data from Greg's spreadsheet, and come to find out, that might have been a grave error. I think the problem is that I am using data from a Pintle style injector and the injectors that are in the car are disc type injectors. The difference between these two are enormous. Because they are completely different types of injectors, you could imagine that the Short pulse tables and Minimum IPW values would be completely different. This may be my problem. I am going to try these changes (Knowing that I will probably have to redo the full VE and the MAF ahead of me), and hopefully I have some good news to report back to you guys.

[GHuggins]

Hopefully it's just the injectors - injector calibrations can do some really funky things - chased my tail for a few days trying to figure out why one was surging - input correct injector data - problem gone....

[93camaro_zzz]

Man, I hope so too. I am way past due for figuring this one out.