A buddy of mine tuned my '02 Z06 with HP Tuners and at idle he had a difficult time leaning it out so it dumps fuel like crazy and it causes alot of smoke. He leaned it up and as soon as he did the car died. The car has a G5x3 cam in it...is there something he is doing wrong? The car made VERY impressive power on the dyno....461.5....this is with LTs, B&B exhaust, and the cam. It appears the smoke is getting worse over time but he said it is 100% fuel and he can't tune that out without the car dying....whats the deal?

Thanks in advance for any input.

Here is the dyno sheet from the original tune a while back:

 

Would need to see RAF, timing, LTIT/STIT etc. scans. The RAF is for baseline and idle airflow/fueling. There is a Russ K scan from HPTuner Forum that is used to tune this.

What injectors, part number etc. Is IFR set IAW with injector specifications? May need to tweak the injector slope with min pulse, adders etc. Again would need to know injectors and idle logs.

Not sure how he was leaning it out. You could possibly have a "leaky" injector. Don't rule out mechanical or vacum where you are trying to compensate with the tune.

If you could post a copy of the tune, it would be easier to evaluate your situation.

Thanks

Ed M

 

My guess is that the headers are your problem---i assume you are NOT running a speed density tune and are using your MAF& 02's--Typically the new 02 sensor locations will not allow them to heat up properly or make coreect readings--so the ECM bounces between open and closed loop or never goes into closed loop--At WOT you are in the PE mode so it runs fine there---I would 1st check to see what the 02's are doing---Are they oscilating quickly ? not at all & pegged at 450 or very slowly until you rev it up ?--many people will install the rear 02's onto the front as they are more sensitive and heat better--Also i would check to see at what KPA the engine is idling at--It has probably gone way up with your cam-Most ls1's have the PE MAP threshhold set stock at 55 KPA--but now you may be iding at 70 KPA--This will sometimes false trigger it into the PE/OL-DRI mode and dump duel--I'm sure your tuner adjusted the tune for things like larger injectors ,WOT AFR--etc.----The problem could be many other things but without having the car it would be tuff to resolve-but i would start here and do some data logging at idle and let us know what's happening---

PS:any codes ??? what are the LTFT's doing ??--beyond -25% ???

 

Ok, I will relay all this to him and see what he can come up with. I know the 02's had some issues for a bit. I bought the car tuned by this guy but it was only tuned for WOT so I took it to another local tuner that tuned Tostoes Camaros (they were the brothers that raced on Pinks a while back and ran 9's or something) anyway, I took it to that tuner who did a driveability tune by hooking to the 02's but after an entire tank of gas he couldn't seem to get it right. I would stop and the idle would jump to 2grand and sit there for about 20 seconds before returning to normal and so on. I then took it back to my current tuner and he hooked back up to the ECU inside the car and said that the other guy turned off 2 of the 02's and messed with a bunch of other things. He then got it back to his WOT tune and we did a driveablilty. He tried explaining how it all worked, unlike the other guy, but I only could grasp so much since I have never tuned before.

The day he tuned it I saw the chart that shows lean and rich or something and when in the red it is rich and in the green it is ok....am I correct? Anyway, at idle it was in the red and he turned it to green and *clunck* the car died. Now the big question is, would the smoking at idle burn up anything inside the motor? I had people tell me that it can ruin the rings and valve seats....I just don't want the motor popping. I have driven on this tune for 10k without it breaking anything yet. The Service Engine comes on every so often and so does the Service Active handling...don't know if that is related or not.

One last thing, is the surging when trying to accelerate quickly below 2,500 because it is loading up on fuel. The exhaust pops and sounds like a gun going off then the car comes alive and tears off. I have basically learned not to give it to much gas under 2,500.

 

Could be a number of things.A common thing is a leaking header pulling fresh air over the 02's on decel/idle.

A cam like that is not untunable and should run fairly good.

I tune off the L-terms to make it easy.Make sure idle timing is 24-28 degree's(fairly steady),02's are good and see how far the L-terms are correcting.

 

I agree with Slowhawk--the loud pop on excelleration is often an exhaust leak that will pull in fresh air and ignite the unburnt fuel in the exhaust---It also can be a misfire---What are the codes you are getting ? get your fuel trims in line--as mentioned---Also you didn't mention surging/hanging idle- before but did later--that is fixable as well---
A "hanging idle" as you describe can be corrected by :
subtracting a % to the 'desired airflow table" both in gear and in the P/N tables if needed---If you go to far it it hang --sound like he did
Also in the "throttle follower table" the same thing--remove a % from the P/N table or in gear (whichever is needed)--If you go too far it will hang- adding some will make it come down to idle faster
Also the "thottle cracker"--subtracting from the tables will make it idle down faster if it stalls you went to far--

 

The hanging idle and surging was a previous tune...this does not occur now. The only issue that I am having that I am worried about is the large amount of smoke at idle...none at WOT though.

 

Won't his cam want a bit more timing at idle?
Just trying to understand as I am new to this stuff too!

 

YES--I forgot to mention this as his tuner most likely added some in already the "base spark in P/N " and "base spark in gear" -typically depending on the LSA and duration of the cam you should add 2-3 *up to 800-1000 RPM's

 

I've got mine running in open loop at idle and closed loop everywhere else. Mine was dumping fuel at idle too. Not smoking, but way too rich. The idle would hunt a lot and stall pretty often. Now it's rock steady all the time, even with ac on.

To accomplish this you have to do the following:

- Set your PE Enable delay rpm to 0
- Set your PE EQ Ratio vs. RPM to 1.000 through the 1200 rpm column
- Set your PE Enable TPS to 0 through the 1200 column

Before you do this though, open your VCM Scanner and warm up the car. Go into VCM controls and command the AFR to 14.7 and slowly lean it out until you hit the cars sweet spot. This will be just before the idle starts to chop and surge. You don't need a WB for this. Once you find the AFR the car likes divide 14.7 into it. i.e. 14.7/16.0 = .91875 Then in your VE Table under airflow multiply the 400 through 1200 column by that number then do the PE enables listed above.

This should put the car into PE mode at idle (open loop) at the AFR you command. The car will idle tons better and eliminate the fuel smoking and smell.

Justin

 

Thanks a ton Skinny Kid

 

This might not apply, but doesn't the PCM select the richer of the available fueling parameters? Or is that for WOT (Power Enrichment) mode only? I like the idea though, will give it a shot

 

Yes it will pick the RICHER of the 2 commanded AFR's as a safety--BUT that only happens when in PE mode----