TXws6

iTrader: (10)

Just wondering what the problem could be with my car (cammed & stalled-specs in sig). I had it tuned back in August by MTI and it ran great for a couple weeks, then i started having problems with the car starting if its hot.. It also will die in reverse after it starts like this...The car will start, but i have to give it gas and keep it at 1k till it finds idle. When i have to start it like this the car will often surge like a mother and die on me if i have to stop.

It has NEVER failed me on a cold start, and always fires right up finds the idle immediately. Couple weeks ago i replaced my battery, i got an optima. After i put that it the whole problem dissapeared for a whole week! And now its back to where i started.

Any ideas on what could be going on? I tried to describe what is going on as clear as i could...so let me know if i need to clarify anything. If its a problem with the tune, i know MTI will fix me up so hopefully thats whats goin on. Thank you for the help guys!

-Ryne

radkon

iTrader: (2)

When the car is cold it is running in open loop (not using O2 sensors)

When its warm it is running in closed loop (using the O2 sensors). In other words your tune needs to be adjusted or since the problem is new one (or more) of your O2 sensors may be dead or dying.

TXws6

iTrader: (10)

thank you radkon!

edcmat-l1

iTrader: (10)

When you start the car, whether its warm or not, it starts in open loop. And it stays in open loop for a period of time before switching over.
Now, as far as the problem.
First, you said you had it tuned and it was fine for a while, then a couple weeks later started acting up. Is this correct? If so, two things.
1: the fueling isnt correct. Most likely a "maf" tune, which consists of scaling the maf to get the fueling correct. Quick and dirty, **** *** way to tune.
2: the long term fuel trims are still enabled, and it took a while for them to be skewed by the fact that the tune is off. Thats why it was fine for a while, and then started acting up a couple weeks later.
Take it back to them, tell them to tune it in SD to get the VE table right, then tune tour maf. Also helps greatly to just disable the long term fuel trims.
Once the VE table is correct, you may need to tweak the open loop table just slightly, but it should be damn close.

Frost

iTrader: (45)

Ed, the 2/3-bar cars I have tuned I left the LTFTs disabled because as they learn in their "block of VE" fashion it creates noticeable spots when driving at part throttle. If it runs well in OL and then the STFTs stay close when re-enabled, I couldn't think of a good reason to re-enable LT trimming... though on all of the 1-bar cars or more radical cars that needed to have the VE fully gone over I usually just re-enable LT trims and don't think twice about it. Makes me wonder if the LT trims should have just been left off on those cars as well. I can't really think of a reason to have them though if the VE and MAF are very close. Thoughts?

-Sorry for the thread jack as well.

Billiumss

iTrader: (11)

Most big tuner "shops" don't fully tune the VE & MAF tables. I'm going to guess that you got a blanket tune and then tweaked it here and there.

Auto cars are harder and more time consuming to get the idle and driveabilty right.

Take it back to them and maybe even leave the car with them for a day or 2, that way they will have plenty of time to get it right for you.

TXws6

iTrader: (10)

I called MTI and they said they would take a look at it this weekend for me. They have some A+ customer service! Hopefully we will get it figured all out this weekend, thanks for everyones feedback! I will let yall know how it goes