slant911

Just a thought here, but is it possible the car was flashed prior to you owning it so 1.1 bar would then be normal. Then the boost hoses were cracked/broken so it would only boost to .7 (which would be normal boost for a stock car). Finally the ECU throws a code or two for the cracked hoses so you replace them and bingo you are back to the flashed boost of ~1.0 bar which you hadn't seen before because the hoses were cracked.

luke byron

Possible... but I find it hard to believe since the car is 100% stock even the DV's.

At least I got a taste of what a flased car feel like WOW!

I hope I can get this resolved so I can enjoy the car without blowing something up.

In the meantime I am actually scared to drive it.

Flyby

When I bought my car it had a flash and a bad one at that. It would read .9 -1.0 bar while I was into the throttle. When I let off the throttle it would spike to 1.2 or so for a moment. That's what I meant by transitory. My thought was that it may have been flashed.

luke byron

Can someone please tell me if .9 - 1.1bar boost is safe on 91 octane (highest available here)?



Thanks.

Chuck Jones

You have same octane rating as all of us guys/gals here in California...and we've been running our TT's on 91 for years. Although it doesn't give the best performance, all of the tuners have files that tune to the 91 and there has been no problem with that octane even on boost of 1.1-1.2. Your car will run much nicer on 93 or 94....but we're not blessed with that octane level in this state...unless you want to go buy racing gas at $7.25 a gallon...

slant911

Chuck is right the car will be fine. You will not be getting maximum performance though on 91 octane. I have been mixing 100 octane race fuel with the 91 (about 5 gallons per tankful) and that raises the octane to about 94 in the tank. So that is an option if you have any stations around that sell race fuel.

luke byron

What about Octane Boost? or is that just snake oil in a can?

Thanks for your replies!

slant911

Well I can not remember the details but in a word NO don't do octane boost from a can. The article I read some years ago was very long a detailed what all was in those bottles and the final verdict was that they really didn't raise the octane and if used to much could do damage. Plus if you price it out just putting some 100 octane race fuel in is only slightly more than doing a tankful of 91 and a can of octane boost.

luke byron

Thanks for your response Slant.

I took the car out today and I am so amazed! how much faster it feels and still seeing .9 -1.1 with 1.2bar spikes.

No lights or faults as of yet but I do believe I heard what sounded like a faint engine knock at peak boost. It scared me so I backed off and tried not to let it go past .9bar.

I will be taking it to my Indy so he can check the actuators/wg's in case they are sticking. If they are fine I guess it was flashed although the DV's are stock.

I would like to check to see if the car is running lean @ peak boost.

Can this be checked?

slant911

Just because the DV's haven't been replaced doesn't necessarily mean it hasn't been flashed.

Your indy should have some logging software to see where the AFR's are.

Chuck Jones

Those 8 or 12 ounce cans of "octane booster" are the biggest ripoff on the shelves. I recall someone once figured that a can of that "booster" in a 12 gallon tank of gas would ad about .1 worth of octane boosting.....that would effectively give you about 91.1 or less.....not exactly a major improvement for the $10 you'll be spending on that can of do-nothing.

I buy Toluene and like Slant....I use a couple gallons of Toluene (rated at approx. 110 octane) per tank if I'm going to be running hard. I buy the Toluene at Sherwin Williams for around $40 for a five gallon can., but some of the stores won't sell unless you have an account with them....toluene is an abuse substance used by the kids to sniff....and it's VERY volatile...so store it away from any source of flames.

ZX9RCAM

I never heard of doing this.....I presume it has been researched & proven to be safe???

adam_

The wastegates are actuated (opened) using a pressure 'signal'. The purpose is to 'protect' the engine as boost increases.

If one or both of the rubber pressure lines TO the wastegate are cracked and leaking, then the wastegate will not open. If the wastegate is corroded or broken or the internal bladder is ruptured then the pressure will not open the wastegate...finally, if the flap door inside the wastegate is stuck, then the pressure to the wastegate itself may not be opening the door.

I vote cracked hose to the wastegate.

I am a bit disturbed with the discussions of octane and boost- if your car is stock, something is wrong. Fix that, don't try to change the octane to accommodate the fault.

IMHO

A

porsche52

Luke... I pulled up the fault printouts for the faults you provided. P1250 (Boost Pressure Control Deviation - Above Limit) possibe fault causes as per workshop manule, bypass flaps incorrectly adjusted, or Turbocharger faulty. I would look into the incorrectly adjusted bypass flaps (waste gates) and discard the faulty turbo idea. The other fault, P1109 input variables, charge measurement, above limit. Possible fault causes as per wm, heavily soiled throttle, throttle body itself, or Mass Air flow sensor. I would suspect this fault is caused by the fault (p1250). Like many others have suggested, take a good look at both wastgates, control lines, air diagphram, linkage etc. if the faults return. Correct me if I am wrong, that the faults were present with the split inter-cooler hose and have not returned to this date?? The lack of boost .7bar is a direct result of the split hose, and the faults you provided could also be caused by this (split hose).

Chuck Jones

Whereas I agree with Adam that you shouldn't indiscriminately use octane boosters to remedy non specifc problems....here's the article and facts on the use of Toluene that started me using it.

Rather than try to convince or dissuade you on the pros/cons....you make up your own minds. I've been using it judiciously for over a year with no problems....again, the operative word is judicious use.

http://www.elektro.com/~audi/audi/toluene.html