2011 CTS-V Almost dies when coming to a Redlight. Just moved to warmer climate

[edcmat-l1]

The dumbest part of it all is how much is pulled from the low load area. 15+ degrees is just insane. That totally screws up mileage, emissions, etc. It's just dumb. There's no reason for it.

[sgod1100]

The dumbest part of it all is how much is pulled from the low load area. 15+ degrees is just insane. That totally screws up mileage, emissions, etc. It's just dumb. There's no reason for it.

Damn, I overlooked the low load areas...good lord. I don't get why he is so popular with the ctsv community when he is doing this shit..

[ctsv2011]

The "waterfall effect" effects both the main spark table and the ff table (since it getting added to the main table). You will have MORE power and it will be much more smooth when you accelerated into the moderate/high load areas. Mine is shown below.

Attachment 139201

Here is the timing difference between your tune and a stock tune. Granted at wot in the higher load areas you will be less than stock due to increased boost. But look at the mid rpm/load ranges. that doesn't even include the IAT timing adder that is pretty high in the stock tune as well.

Attachment 139202

What is a reasonable way to start to add back to those tables comparing my tune vs stock tune. All the blue area would it say be safe to multiply by 1.25 and log or would throwing all of it back in and logging be reasonable.

[sgod1100]

What is a reasonable way to start to add back to those tables comparing my tune vs stock tune. All the blue area would it say be safe to multiply by 1.25 and log or would throwing all of it back in and logging be reasonable.

I can help you out if you want. [email protected]

[edcmat-l1]

What is a reasonable way to start to add back to those tables comparing my tune vs stock tune. All the blue area would it say be safe to multiply by 1.25 and log or would throwing all of it back in and logging be reasonable.

Pull a stock file off the repository and put everything from 1.0 g down (numerically, or up in your graph) back to stock.

[ctsv2011]

Pull a stock file off the repository and put everything from 1.0 g down (numerically, or up in your graph) back to stock.

Will give it a shot and post back this evening. Will take a log of the car first for a base point.

[ctsv2011]

I can help you out if you want. [email protected]

Cool man i will send you a email later today once off work, appreciate it

[sgod1100]

Cool man i will send you a email later today once off work, appreciate it

Sure thing..include your phone # in the email

[ctsv2011]

here is some logs. car doesnt do it every single red light but it will do it every drive

[GHuggins]

Try tuning your VE and MAF. MAF is off about 10%, but boy that VE. You're off anywhere from 6% to 100% lean on the VE. Not to mention your tip temp just in the 4 cells you were hitting in that dip log was changing nearly 4% on it's own Good luck with fuel control like that.....

[edcmat-l1]

Looking through it in more detail there is ALOT of stuff that needs to be put back to stock. I see 3 or 4 tables that have been doinked with that shouldn't have that are most likely causing the dip.

Before the critiquing begins, this is NOT meant to be a complete tune or total redo this is specifically targeting the OPs issues.

[JayRolla]

From my understanding it's only a maf tune. Vve is disabled I believe please correct me if I'm wrong

From my understanding dynamic airflow is never truly disabled. Its still used for idle and transient fueling. Your fuel trim is off quite a bit idle and cruising. I would disable the maf and tune your VVE table up to 3-4k rpms off your STFT.

[edcmat-l1]

From my understanding dynamic airflow is never truly disabled. Its still used for idle and transient fueling. Your fuel trim is off quite a bit idle and cruising. I would disable the maf and tune your VVE table up to 3-4k rpms off your STFT.

That is true. Although in this guys' case he's got some other wonky shit going on that's the main cause of his idle issues.

[JayRolla]

Damn, I overlooked the low load areas...good lord. I don't get why he is so popular with the ctsv community when he is doing this shit..

I agree. He has this car hitting 27* in the flex fuel table. Maybe he is always thinking the user will be under 80% because he does not add max timing till 80% E and only 62% timing at 50% E content. His low octane table actually had 1* more in the high load area than his high octane table. The same raped low to mid timing that makes absolutely no sense. He adds a lot back in the low mid area with the flex table but that would only be okay if the person is always on E.

[edcmat-l1]

I agree. He has this car hitting 27* in the flex fuel table. Maybe he is always thinking the user will be under 80% because he does not add max timing till 80% E and only 62% timing at 50% E content. His low octane table actually had 1* more in the high load area than his high octane table. The same raped low to mid timing that makes absolutely no sense. He adds a lot back in the low mid area with the flex table but that would only be okay if the person is always on E.

I didn't even look through most of that. Was only looking at things that would pertain to idle quality, idle control and idle dip.

[RobZL1]

Wowsers. Yeah, screw VVE at this point. Just get a good MAF tune first with all the other wonky sh!t fixed. If people get paid for this nonsense, I should quit my day job. LOL

[GHuggins]

Problem is his VE is really off on top of his MAF and tip temp. Until fueling is right there is no point in chasing other idle concerns as fueling/airflow directly controls everything. In his log where the idle dip was taking place, look at his fueling. If the wideband is right (this will directly reflect the VE with sudden rpm changes) it's way off and his stft's are doing the opposite, but again showing fuel way off. I would address fueling before I did anything else besides possibly cutting the throttle pull a little. His other timing and idle issues need addressing no doubt, but I would get fueling for both models close first.

[ctsv2011]

the car was tuned with wideband in the tailpipe. the wideband is now in bank 1 sensor 2 location. b1 s2 is just ziptied up in engine compartment. not sure if wideband changing locations affect it but i moved the wideband well before the idle dipping starting.

[ctsv2011]

I agree. He has this car hitting 27* in the flex fuel table. Maybe he is always thinking the user will be under 80% because he does not add max timing till 80% E and only 62% timing at 50% E content. His low octane table actually had 1* more in the high load area than his high octane table. The same raped low to mid timing that makes absolutely no sense. He adds a lot back in the low mid area with the flex table but that would only be okay if the person is always on E.

i added stock timing tables back in today did a quick pull leaving work and saw max of 22.5 degrees on e48 thats about all my pump can handle without the help of a aux pump. i can see the lambda is off quite a bit target .79 and actual .83. i will tune the vve vs stft this weekend and see where it gets me.

[edcmat-l1]

Problem is his VE is really off on top of his MAF and tip temp. Until fueling is right there is no point in chasing other idle concerns as fueling/airflow directly controls everything. In his log where the idle dip was taking place, look at his fueling. If the wideband is right (this will directly reflect the VE with sudden rpm changes) it's way off and his stft's are doing the opposite, but again showing fuel way off. I would address fueling before I did anything else besides possibly cutting the throttle pull a little. His other timing and idle issues need addressing no doubt, but I would get fueling for both models close first.

I agree the airflow tables need dialing in. But I'm a "root cause" kinda guy. It's like detective work. What exactly is happening when it idle dips? It's pig rich. We know that. But it's way richer than it would be, same cell different throttle position, different load.

What else is happening? If you look through the log at several points you'll see it's closing the throttle blade more than it is at stationary idle.

What else is happening? Right before the stall the timing is drastically low to negative. Unusually low for an E38 or GEN4 control system in general.

So, what would cause this strange combination of events? VVE and MAF tuning aside.

Let's look at some screen shots.

First one is DFCO. Look at that it's disabled. Guarantee that's the +30% fuel trims on decel. No other reson for it being that rich at that time.

DFCO.jpg

Second screen shot is TPS at stationary idle. Granted it moves around but it is roughly 10%+.

TPS.jpg

Third screen shot is it right before the dip. Notice the TPS is below 9%. It's closed the blade FURTHER than idle speed trying to get it to idle speed.

TPS, fuel, timing.jpg

What table would most likely cause that? Throttle follower. When compared to a stock file it is more agressive in the 800 column, even more in the 600, and ridiculous in the 400. If it gets to that point it's going to make itself stall. Dumbest shit I've ever seen.

Throttle follower.jpg

And how about that timing dipping so low? Next screen shot is the idle overspeed coasting spark. Anything above 144 RPM over is MORE aggressive than stock, encouraging the engine to decelerate more rapidly.

idle overspeed spark.jpg

It's the combination of these 3 things that's causing the dips. You could change all these things and never touch the VVE or MAF table and it would fix it.