Lots of knock right off idle

[clubsfit]

Quick question, got my PTU serviced and they pulled the DP to get to filler hole. Might be coincidence, but I also filled up right after. But now car runs great, however, RIGHT off idle if I got WOT it shows 5-7.5 of KR until I let off. Then fine again. Does not happen any other time. Perfect example is 1-4 gear data log, shows it, if I'm rolling already nada? Bad fuel?, leak at DP?

 

[ZSHO]

I also had mine performed a while back at roughly 30k and had to have it flushed out twice and also found an air leak by the rear turbo which screwed up my AFR readings and installed new gaskets+some RTV for a nice secure leak free system and making sure the bolts are nice and tight and hopefully no pinched 02 sensor wires......IMO would just try to rule out it being bad gas and try to take it easy until the next fillup...any changes to the mix?  Z 

 

[clubsfit]

Well today I had enough burned up, and stopped and added 1/3 tank of pure race gas in case it was too much ethanol. Expensive, but it was driving me crazy!! Did a 0-100 pull 10 miles later, and all fixed!! I can't believe how one bad tank of fuel can jag up the whole system so easy!

 

[ZSHO]

Well today I had enough burned up, and stopped and added 1/3 tank of pure race gas in case it was too much ethanol. Expensive, but it was driving me crazy!! Did a 0-100 pull 10 miles later, and all fixed!! I can't believe how one bad tank of fuel can jag up the whole system so easy!

What station did you fill up prior? found using a busy high traffic top tier gas stations like BP,Chevron to be the best and great to hear all is well especially after all that ordeal.  Z

 

[clubsfit]

Well today I had enough burned up, and stopped and added 1/3 tank of pure race gas in case it was too much ethanol. Expensive, but it was driving me crazy!! Did a 0-100 pull 10 miles later, and all fixed!! I can't believe how one bad tank of fuel can jag up the whole system so easy!

What station did you fill up prior? found using a busy high traffic top tier gas stations like BP,Chevron to be the best and great to hear all is well.  Z

It was a Kwik Trip, I have always used Shell, but this is a VERY busy station, and I am VERY careful of where I gas up etc. So thanks for the help!

 

[SHOdded]

Does the tune you use require the race gas additive?

 

[sholxgt]

Race Trac, Quick Trip, or any of the others outside of BP, Shell, Chevron, Texaco, etc is just rolling the dice.  They do not have their own refineries and purchase fuel from the lowest bidder.

You can get good gas in the morning from them and then bad gas later the same day.

 

[sholxgt]

Does the tune you use require the race gas additive?

Curious of the same thing.  I recall that your race tune requires both ethanol and higher than 93 octane.  Was this problem on your race or street tune?

Maybe both are right there on the edge which leaves zero room for anything but the best fuel?

 

[ajpturbo]

What kind od race tas did you add and how much was it? Where did you get it?

 

[clubsfit]

I'll try to get everything answered.

1- No I don't need additive for my street tune. Yes this was my street tune.
2- I am friends with a fuel distributor and it was Sunoco 100.
3- Yes I normally only do Shell or maybe BP, I learned my lesson even being a busy station.

 

[clubsfit]

Does the tune you use require the race gas additive?

Curious of the same thing.  I recall that your race tune requires both ethanol and higher than 93 octane.  Was this problem on your race or street tune?

Maybe both are right there on the edge which leaves zero room for anything but the best fuel?

My race tune doesn't require E20 and additive. Only 100 octane no matter how I get it. I decided to go to track on zero notice, so I had E20 in the tank already. Also, my street tune is what I was running. I used race fuel because it doesn't have ethanol, and I have a feeling I got bad E85, so I wanted to make sure I didn't have too much ethanol as well.

 

[FoMoCoSHO]

I doubt it was bad e, you are changing fuels and tunes which is temporarily throwing your fueling off until the trims do their job.

What is you stoich point set at in your tune?

 

[clubsfit]

I doubt it was bad e, you are changing fuels and tunes which is temporarily throwing your fueling off until the trims do their job.

What is you stoich point set at in your tune?

makes sense! And I don't tune my own, so I would have to ask. I'm sure it was the combo of additive, E85, changing tunes etc.

 

[FoMoCoSHO]

Lets say for example my tune is stoiched for E30....

Now I go and put in E38 and decide to punch it right off the bat...

I'm going to be lean and the car is going to have to add fuel to hit my target but the car is always behind trying to play catch up because it uses the wide band reading of fuel that has already burned to make the adjustments. The bigger that gap from the stoich point the worse this issue will be.

Depending on how off you are you can actually feel it because your throttle response will suffer a bit.