Have you tried locking IAC and adjusting your AFR up and down?

Lock you IAC into a position were it will stay idling and then lean or richen the AFR until it stops or gets better.

 

What is your minimum transient fuel set to? Stock it is .045. Bigger injectors, you need to drop it some. Try .016.

Might screw with your trims a bit, but that's easy to fix.

 

At one point I locked the IAC at 55 counts and then locked timing at 30* and it was still surging, I will try doing that again but see if it will take changes to the AFR with any positive results.

I'll have to look. Very likely set to stock unless it was mentioned needing to be changed in the injector data.

 

My guess would be that it's idling a bit lean.

 

have you tried drilling the TB ? this ones doing pretty much the exact deal, just pulled in shop going ck settings and go from there...thinking about the drilling

 

so I tried altering the commanded AFR while timing and IAC were locked and that didn't help the surging really anywhere between 13:1 and 17:1

for ***** n giggles I loaded my old closed loop tune but with the current VE table and the car idled fine...so I used the compare function and 1 at a time changed each table which was changed with the corrected injector data and/or idle airflow data

none of them would get it back to idling...so I just copied my VE, MAF, and timing adjustments from the open loop tune into the closed loop tune and everything was perfect for a bit, my thought process being maybe something in the file had become corrupted

drove the car around for about 10 minutes and it was still working nearly flawsless, one time coming to a light the idle dipped low but it recovered instantly

I was ready to call it good but then when I parked and put it in Park to save the log file it started surging again and adding 8-11% fuel to park idle with LTFT.

Saturday I'm buying a cigar and smoke testing the intake manifold and if that doesn't turn up anything I'm going to try adjusting the throttle blade open a touch. I'm just thinking that it seems since my IAC counts are already low that will just make it worse...but it's something to try.

 

No, don't do that... your IAC counts are low enough now.

I had a look at the tune and log you posted originally and your VE table looks really wild... there's something seriously wrong there. Try reducing your injection timing a bit... maybe to about 5.9 and redo your MAF and VE.

If you want to do anything with airflow, move your entire IAC Effective Area table down 4 cells and redo your rafig/rafpn.

 

I've redone the MAF and VE already and I did a LOT more smoothing on the VE this time. I'll check injection timing and if it changes redo them again.

I will also try the change to the IAC area as you note. I've seen mention it needs changing when going to a larger TB but never knew what to do with it.




I'll try to upload a more up to date look at what I'm working with as far as the tune and also some logs this weekend.

 

I feel your pain...all I can say, and I know probably catch flak for this but, to me the factory computer in a HP app is biggest POS out there, I have mega squirt on my turbo car, 1200 hp idles like a stocker, much easier to tune that this crap, just my rant..

 

Checked for vacuum leaks and have no signs of one. Tested by injecting smoke into the intake with an air pump with the throttle body taped off. Small amounts came out around the throttle blade shaft but that's it.

I went back to trying messing with the DVT functions and can't get it to idle right at all under 1100 rpms and even then it tries to surge a tiny bit.

The surge seems to start because the engine drops RPMs down to around 600rpm and then shoots back up and then gets stuck in a loop of 600-1200rpm idle.

If I rev the engine it will come down and idle fine for a few seconds before the surge returns.

Fuel pressure is solid.

I'm sure it's something basic but I can't figure it out at all.

On a cold start it will idle fine up until about 160-170*F engine temps. On a start after the first it will start surging lower at around 140*F.

 

Have you touched your IAC table at all? Also, are you SD or MAF?

 

Also just noticed fuel pressure bleeds off with key on engine off. Think that injector is trash.

I am MAF but tried unplugging the maf and plugging in a IAT sensor to rule out MAF issues.

Just wonder why the fuel trims aren't screwed bank to bank if it's the injector?

 

Not sure unless there's one on each bank? That's enough carbon to cook a burger! Wow! Certainly it will be difficult to correct until you get the leak fixed.

There's another thread where someone figured out how to calibrate the IAC counts. It's pretty cool. The short version is to plot IAC counts vs MAF air to figure out your IAC counts per G/Sec airflow. Then figure out your overall MAF vs commanded air error. Then adjust the table. So for instance, if you get 16 counts per g/sec and you're 2 g/sec lower commanded vs MAF, subtract 32 from the whole IAC table. Makes it easier to find the idle trims. Would also explain why you're logged RAF table wants you to drop it every time you log using the RussK config.

Their version is six pages and better written, but it's a great way to make your IAC quit moving around so much, but allow it to move some to hold idle.

 

yeah I printed his instructions but could barely keep the car running to log

borrowing an injector and getting a new plug and going from there...might get a whole set of 8 or send mine off to be cleaned

 

It does explain why locking in the AFR and the spark and the IAC would still allow it to surge. Glad you found something to explain it.

 

He hasn't implemented either of our suggestions.

 

I did try a tune with an adjusted IAC table (I likely loaded a dozen different tunes today) and it made no change (likely due to the mechanical issue) so I put it back how it was for the time being. The car was actually getting worse and was to the point it wasn't even driveable. I will revisit it once I have some control regained.

Perhaps it's not a perfect strategy but at one point the car was idling well so I was trying to narrow down the cause of the drastic change in behavior.

New plug and injector will be installed tomorrow and I'll see if I'm back to a good starting point or not.

 

to be fair he did find a very real mechanical issue that's impossible to tune around.

I've got a mental list of users whose opinions I rank higher than my own and TS is one of them, so I don't worry too much. When he posts what he found, he's just not posting the 27 things that didn't help.

 

Put in a known good injector and fresh plug. Car still doesn't run correctly but fuel pressure still bleeds off with key on engine off. Also now the ltft are vastly different, side with the known good injector is 13%leaner than the other bank

going to replace the whole set to rule out injectors and go from there

 

My opinion (which might be completely wrong) is that your injectors are fine. I think you've got a pig rich decel which is carbon fouling your plugs.

Try replacing all your plugs with a fresh set and implement Darth V8r's suggestion of reducing your minimum pulse (including minimum transient pulse) and redo your MAF and VE.