Nintastio

I am having quite a few issues with my V and getting it tuned properly. Originally when I got the car it would run great most of the time except when you push in the clutch while there was load on the motor either from applying the brakes or turning the steering wheel and causing the power steering to put load on the motor.

The tuner originally told me he thinks there is a ground issue or a vacuum leak. I have not been able to locate any ground or vacuum issues and don't think this is the problem.

Few weeks later and him changing all sorts of parameters the car now runs much worse.

I am getting quite a few engine codes that are putting the car in limp mode or causing it to just shut off completely:

P0068 MAP/MAF - Throttle Position Correlation
P0103 Mass or Volume Air Flow A Circuit High
P0120 Throttle/Pedal Position Sensor/Switch A circuit
P0220 Throttle/Pedal Position Sensor/Switch B circuit
P1516 Command vs Actual Throttle Position Performance (TAC Module)

I am going to inspect the MAF and TB like the tuner is asking, but I really think he is what is causing all these issues. The person that installed the motor is saying the tuner is an idiot and there is nothing wrong with the car itself. Does anyone have any input on this situation? I am running out of ideas beyond taking it to a different tuner, but before I do I want to try to verify it is the tune and not the build if possible.

Few things about the build that may be relevant:

Thompson Motorsports 416CI LS3
Fast 102 intake
Nick Williams 102MM throttle body
Stock MAF
Injector Dynamics 850CC

If there is any other info needed about the build let me know and thanks for any input that may help me solve this issue!

jclayc

iTrader: (8)

for me on my LS6 H/C/I car, the issue you describe - when you push in the clutch while there was load on the motor either from applying the brakes or turning the steering wheel and causing the power steering to put load on the motor - was caused by too light a flywheel. Others with a big cam, a FAST and heads have a similar issue. (Some have not had this issue, though.) I went through three tuners and chased everything from a MAF issue, TB issue, ground issue, vacuum issue and more before I went with a stroker LS3 and a 28lb flywheel. No issue now.

How heavy is your flywheel?

Sssnake

I concur with the engine builder. It sounds like the tuner is not correctly accounting for the NW 102. All of the errors except P0103 are likely due to improper tuning of the new TB. P0103 could be caused by this as well but there are a LOT of things that can cause this error. My guess is that your VE input data needs work as well. If the ECM is not estimating the airflow required for return to idle properly you run into issues when you add load (power steering and AC on/off).

Sssnake

jayclayc lightweight flywheels do contribute to this as well. I am still willing to bet that the issue is the high vacuum portion of the VE data around idle. For light weight flywheels you can reduce the risk of stalling by slowing the return to idle and adding a little more to the AC tables. I am running a Mc Cloud 13.5 and maybe stall once in a couple of weeks when the engine is cold. Before doing a LOT of work on the VE data below 40 KPA it would happen multiple times daily (usually when cold).

serik21

Sounds like a issue with the tune. I have a procharger which puts more load on the engine at low rpms before my tune I had issues of it stalling at low rpm so I always had to hold the gas at stop lights(driving out of boost to dinner) after the tune I have no issues with stalling and I have a 12lb Aluminium flywheel so the guys that are saying it's your flywheel are grasping at straws

jclayc

iTrader: (8)

generally speaking, since the codes didn't exist before the tuner, it seems like the codes are 100% attributable to the tuner's work and not a mechanical problem or leak, right?

as for the pre-tuner symptoms with the clutch in and turning - I totally agree there are many with light flywheels that have not had this issue and totally agree that there are tuners out there willing to spend the time to solve the issue if they allocate a good bit of time to getting things perfect but there does seem to be a correlation between a light flywheel and the symptoms.

Whether the "fix" is going to a heavier flywheel or getting a better tune is a matter of which straw you'd rather grasp.

For issues relating to the precise tune parameters/causes, I'd definitely listen to sssnake and serik. I'm approaching it from a general cause/effect POV

Naf

iTrader: (1)

Pm me your tune, i have the same setup on my v and i can compare a few parameters for you.

In lb what are your injectors?

Naf

iTrader: (1)

And post an idle log for me to see where your map is during all the issues

Nintastio

Thanks for all the quick responses guys. To answer the questions:

I do not know the weight of the flywheel but I will find out shortly, waiting for a response from the builder

The injectors are 84lb Injector Dynamics. The tuner said the injectors could also be a problem but I know the spray pattern is great on these and I had no issue tuning my little 1.7L honda on 1000cc ID's so I can't imagine these are too big for a 500hp v-8. May require some work as my Honda did, but certainly possible.

The P0103 existed since I bought the car but I'm fairly certain that is because the tuner had disabled the MAF. I think he had issues tuning it with the MAF, but I'm not sure if that's because he doesn't know how or if there is an actual issue with the car. Probably should have pointed that out in the first post.

Naf, I will send over both tunes shortly once I get them from the tuner. Original tune the only issue was the P0103 code and stumbling issue.

They way it stumbles though is the idle will drop to usually 300RPM or so, then shoot up to 1500-1800ish and go through that cycle 2-3 times before it settles in at normal idle speeds. The first minute or so after the car is started it will not do this however and runs great. It seems throttle response is much worse also when this happens. This happens both when the car is cold and after being warmed up.

Naf

iTrader: (1)

Yup its a small tune issue...

I suffered from this before but there is a cure and more timin isnt it

Naf

iTrader: (1)

I have 52lb injectors btw, you could go to a smaller size of you wanted to...

Nintastio

Do I have a way of doing this without the HP Tuner equipment? Only thing I currently have is one of those cheap amazon obd2 bluetooth scanners. I'm sure I can get the tuner to do a log for me with hp tuner though.

Naf

iTrader: (1)

I will work with your obd2 scanner. Tell me a play by play on the tps and map vs rpm.

I want to know what the map and tos are doin as the rpm drops then screams up.

Stft and ltft are useful as well. Thats fuel trim

Naf

iTrader: (1)

Bosch has a great spray pattern as well. They have a narrow and wide option. Find one around 60lb in wide pattern and you are set...

Naf

iTrader: (1)

I had the 1516 code when my mech drilled a hole in my tb. The ecu is tryin to lower the rpm and cannot so it tosses the 1516.

He may have too much fuel, too little maf, too much maf or a wrong settin for the tb...

Nintastio

I will have to do this once I get off work later today. I think I can log data with the software but if not I can at least take screen caps and send those to you.

I do know the stft was going wild during normal driving and the tuner pointed that out. He would smooth out the middle of the fuel chart and the car was still asking for 20%+ more fuel and put a rather large hump in the middle of the chart.

Right now I believe he has the rolling idle set to be active at any speed over 1mph which probably has something to do with the codes. I am going to have him revert those settings later this afternoon and hopefully go back to just the p0103 and stumbling issues under load.

Nintastio

Id prefer to stick with my current injectors unless they prove to not work with my setup. I don't think they are the issue cause the car runs great the first minute or two after it's started.

He told me when he input settings for the TB the car would run much worse so he put them back to stock values. This may very well be our issue and he is inputting the wrong values for the NW 102.

Naf

iTrader: (1)

Ask for the tune, lets put that to sleep and get you on the right track.

Btw your stft is goin crazy for the cam is large, what cam you running? Good news is its controllable, like i said i got mine fixed, you just need to find the proper balance

Nintastio

I asked the tuner to send it over and he asked if I wanted the original tune or the new "band-aid" tune. I asked for both so hopefully will have those for you soon.

The spec sheet for the motor says:

.625 .625 236 250 115+4

Naf

iTrader: (1)

We will get it working properly. Dont you worry.

Fyi you should think about swappin to a larger maf, lpe's 100mm is a great maf to have in your car.