vpshockwave

Alright, first of all I'd like to point out that I'm not a tuner. I'm having my car worked on by a reputable tuner who has tried every trick in the tuner book and has yet to be able to fix my issue so I would like to pick the brains of the other tuners here to see if anyone knows what could cause my symptoms. First, here are mods I had installed before the issue started happening (all installed/tuned by the same guys):

K&N CAI
G5X3 Cam (112 LSA I think, don't have the paperwork on me at the moment)
LG Pro Long Tube Headers
LG Big 3 Catback Exhaust
Dynoed @ 420/391 before my newest set of upgrades

Here is my newest set of upgrades installed when the problem began happening:
Centerforce DYAD Clutch/Flywheel
Meziere Electric Water pump
AFR 210cc Heads
FAST 102mm Intake
90mm LS2 Throttlebody/102mm Throttlebody (started with the 102mm, thought maybe that was the issue, swapped to the 90mm but the issue still occurs)
42 lb injectors
New Fuel Rails
Dyno'ed @ 475/421 with my problem

Alright, here is what the car does. Sometimes when I put the car in a rolling neutral (read: push the clutch in or actually put it in neutral, either one) the RPMs drop and do not stop around where they should (AC or no AC, no difference). They drop to anywhere from 200-500 RPMs, then surge back to 1500-2000 RPMs. It will continuously surge to and from these RPM ranges, often times killing the car completely, until I bring the car to a complete stop, at which time the idle will return to a normal 900-1000 RPMs. Now, as for what conditions brings on these symptoms -- there is no exact rhyme or reason I can see. Usually it's in town driving when I'm stopping at traffic lights somewhat often. But it has done it when I simply depress the clutch while cruising at 65+ on the highway as well. Sometimes the surging isn't as as bad, and it will only drop to 600-700 rpms and only surge up to 1100-1200 or so. The car doesn't appear to have any issue when in gear (no lack of power or other weird symptoms when driving), JUST when in a rolling idle (specifically rolling, if I'm stopped the idle is fine). Oftentimes when I clutch it to a rolling stop it will idle just fine, it appears completely random. My tuner has exhausted his knowledge and we're searching outside the box now at what may be causing this issue outside of the tune (probably a bad, intermittent part, but one that only affects a rolling idle). He also pointed out to me that he was having to send 5x the amount of air flow commanded to get the proper air flow or something -- that doesn't mean much to me but he said that was way higher than normal to get the proper amount of airflow.

Does anyone have any ideas? I would really appreciate any input as this issue is driving both of us insane.

CTD

What you are asking is pretty vague, your description of mods is good & it should play nicely.

In order to get a good answer you need a good question. The best is to post a log of the problem & the tune otherwise any response is a guess at best.

Clarification of this " He also pointed out to me that he was having to send 5x the amount of air flow commanded to get the proper air flow or something -- that doesn't mean much to me but he said that was way higher than normal to get the proper amount of airflow."
is really important & maybe the source of the problem. You shouldn't be trying to tune around mechanical problems if that is what it is. Your tuner should know that?

I've an idea what he talking about, that is only a guess because I cannot see the tune file.

Do you have a problem with naming the tuner? Qualification's are important.

So I might as well guess at this point, based on answer to the question in Red. How is the scalar being calibrated to compensate for the increased size TB's?

kp1

Getting a soft landing coming off throttle and arriving at a stable idle is always a challenge when you get cammed up, change injectors, and or intake/throttle body. It's doubtful anyone can solve your issue w/o seeing some logged parameters and seeing what areas your tuner has adjusted/changed.

mowton

Many questions as there could be multiple causes. The secret is to find the cause and effect and this must be done through the Logging software. My gut feel is the idle has not been tuned properly (Desired Air, LTIT, STIT etc) and MAF/VE at those idle area's isnt correct.

I would start with tweaking the MAF/VE in the idle area's as a minimum, then cold start idle scan logging PIDS such as RPM, ECT, Desired Airflow, MAF (air and HZ), Dynamic airflow, LTIT, STIT (both ac/off and ac/on) and tune these trims to a final value like -.2/-.3 g/sec. Make the base idle and high octane spark tables equal from 400-1200 rpm and .08 to .24 g/cyl.

Posting tunes and logs in one of the other forums may not be a bad idea either or seek unbiased help.

Ed M

tblu92

Even with a computer controlled engine it still comes down to either spark timing or fuel
Most likely you need an adjustment to both
1st I would work on the timing
With any cam swap you need to ADD timing to the "base timing table" in both P/N and in gear--in the idle /start areas---Stock timing is usually about 18*---You should have at least 24-25* there ---These are NOT either the Hi or low oct spark tables
2nd If you know how to data log your timing--Look to see how much your actual idle timing is bouncing around---On a stock engine it can bounce from 5* to 18* at idle
With a can you need to narrow this down as much as you can---Go to the "minimal final timing table " Up to around 1200 RPM's the stock tune may show as low as -15* timing--this is the reason for the bouncing around----Change the Min final timing up to 1200 RPM's to like 7* after 1200 make the rest of the table 6*---If this helps try increasing the timing up to 1200 RPM by adding 1* at a time-----IF you add too much you will get a ping at start up---that tells you to back it back down some
If these timing changes don't help then try the fuel tables next
The most common fix is to ADD a % to the entire "desired airflow table" may be called something else in HP-----
Try adding 15% to both in gear and P/N---If you go to far you'll get the opposite affect--a hanging idle--then simply back off some % til OK
If you work with these tables it will correct 90% of all cars----If not let me know an I will show you some deeper changes that can help next--

mowton

Did you ever get this resolved. Rolling, closed throttle tuning is tricky with a big cam setup but can be done. Let us know if you got it fixed. If not, more help is available.

Just for the record, the reason it recovers after you come to a stop is because that is when the PCM transitions to its Adaptive Idle feature and takes over both air and timing control to maintain your desired idle RPM. While rolling you are in the "normal" PCM control which requires special attention

In your setup, clutch depressed vs not results in different airflow models being applied so you need to make sure all of them are tuned stand alone. Also with big cam setups, you need to apply so much air in the idle/RAF that you need to reduce (or sometimes even zero out) the throttle cracker table. The Throttle Follower table is tuned to handle your 0 mph throttle blips that can also fall/sag/surge on their return.

Ed M

chrisgo

I have a H&C full bolt on 02 z06. I have the same problem, but only when the AC is on. I feel like the driveability portion of the tune was done with the AC off possibly(tuned before I owned it). When the AC is on and you begin to coast in neutral, the AC compressor pulls the idle RPM below the set point initially and the computer tries to compensate for that initial drop. Or am I way offbase here?

mowton

Try zeroing the AC Bump retard table (Torque Management>Engine>AC Torque>Max Retard)...don't understand why the AC would want to request spark retard, but seems to help when the table is zero'd.

After that you will have to log the pids i recommended above in AC on and tune accordingly...

Ed M

dagon138

While I don't have any suggestions, I had this issue, a 2nd tuner did a quick pass and fixed most of it. It then only reoccurred with ac on.. After about an hour of driving data logging etc, it got resolved. this is with the setup in my profile which is smaller cammed then yours but similar.

vpshockwave

Sorry for the late response guys. The car has been through hell and back and I won't go into details (you can check a couple other of my topics if you want, it's pretty long winded). Long story short, went on a road trip, began noticing some really bad knocking. Had it retuned in Cali by a reputable tuner, seemed OK initially then knocking/surging started back again. I got home and decided to try a few fixes myself before I gave it back to LG. I rerouted the valley cover PCV line (the PCV lines and my catch can were setup incorrectly). I put some RTV around the FAST 102 shell as I read that vac leaks in the rear were pretty common. I RTVed around the gaskets where the intake seals against the heads. I put a PCV valve back in when I rearranged the lines as well just in case (LG had removed it). That probably didn't make a difference but it gave me peace of mind. Once I did these fixes (and other ones I don't recall) the car started behaving differently after it relearned idle. Check out my video below. Now the issue is that it revs and surge super high on its own, but it doesn't really sag and die. The tuner in Cali suggested that perhaps I fixed the leak or issue and now the tune just needed to be fixed to account for the fixed leak. Currently LG has it as they needed to put the 102 TB back on (we took it off before my roadtrip thinking perhaps it was the issue) as well as putting on the 100mm MAF for me. Hopefully I'll know something by Wednesday or so this week and it'll be resolved. If not... back to the drawing board. Here's the video of what it's doing now:

tblu92

There are tables in your tune that are changeable that compensate for A/C load when turned on---often needed with major mods as yours

myredhead1

OP, were you able to resolve the surging issue?

lewislgZ06

I had many of the same mods done to my 03 Z06 and i too am having idle issues. Mine is just unstable at idle all together, but it runs great otherwise. Sometimes it overshoots target idle and sometimes it undershoots to the point of dying. I've been doing a lot of research online and talking with mechanics and it seems I am always brought back to the issue of manifold vacuum being low with the G5X3 cam. I'm not a mechanic or tuner, but I've read some articles that seem to make sense on how to deal with this issue, and it's all in setting the idle tuning so the PCM can compensate for the instability. Here are a couple of links that may be helpful. I too am taking my car back to LG, and I have great confidence that Anthony will get it dialed in. Hope this is helpful...

http://www.masterenginetuner.com/ls-big-cam-idle.html

http://www.hptuners.com/forum/showth...de-(w-pictures)

chrisgo

Did you adjust any of the tables when swapping around MAF units?

tblu92

You don't seem to respond to nay of my suggestions--
Your tuner must add 3-4 * to tour base spark timing tables-- and also add at least 15-20% to your Desired Airflow tables--- With your cam I would also DELETE the DFCO deceleration fuel cut-off tables---and finally remove at least 15% to your "throttle Follower table" which will eliminate the dying when coming to a stop--Adding a % to your desired airflow table will eliminate the idle hunting and surging---
Before your tuner attempts any of these changes he must 1st get all your LTFT fuel trims as close to "0" or slightly negative---These corrections can be done using your MAF HZ table

0Anthony @ LGMotorsports

Thanks Larry. Glad to see you again and get the car fixed up with the new heads and correct the hiccup in the tune. Glad to see she is up running in tip top on both car's accounts now!

lewislgZ06

Thank you Anthony for getting my tune dialed in. My car is running great! All the mods I had done at LG have really woke up the beast under the hood, and I get compliments everywhere I go about how great it sounds. I sincerely appreciate you and Bobby working with me and getting the car back in so quickly to install the heads and tweak the tune to perfection.

NemesisC5

I don't recall you mentioning the 100mm MAF, was this installed when you dynoed 475/421 ?

If not did you dyno again after install of the 100mm MAF? Gains?