Supercharged and lots of knock and low IAM
 

Hi

I got a HKS v2 supercharger installed in October last year. The installation was done by a professional tuner in Germany, who has done a lot of tuning on GT86, BRZ and a lot of other Subarus.
They had perfected their own EcuTek tune over several thousands of kilometers, which was then flashed and checked on a dyno, to see if it needed adjusting. The tuner showed me the values and it all looked perfect with fuel trims very close to 0 all over the rpm range and without any knock.

Just a few months later back in Denmark, where I live, I decided to connect my OFT from before my supercharger days. My butt dyno told me that the car didn’t feel as powerful as when I drove it back from Germany.
There was quite a lot of knock correction and the IAM would often fall below 1.
At first I thought that the reason was/is worse fuel quality here. The highest graded fuel you can get here is V-Power rated at 99 RON.
I noticed however that the knock almost exclusively occurred at tip-in and partial throttle.
When accelerating more aggressively but still in closed loop, it would stop pulling ignition and often actually add ignition.

I’ve corresponded a lot with the tuner to try different things. He explained different things I could do to reset/recalibrate the tune with different driving patterns. Didn’t work though.
The last thing I tried was to replace my HKS Hybrid air filter with the stock Toyota air filter and I also replaced my MAF sensor, which he thought could give false readouts.
Just after switching to the new MAF the fuel trims seemed to get closer to 0 than they were before, but the knock wasn’t totally gone. Also after having done more than 100 kilometers now the fuel trims are actually a bit worse than before :/
Why would they first get better and then worse?

What else could influence the knock, IAM and fuel trims?

Could the O2 sensors be faulty? I had a catless header before, which I then had to replace with the OEM one when going FI for the car to be legal.
So I have had the O2 sensors out twice but have of course been very careful with them.

Hope some of you guys have any suggestions. I am a bit desperate as I am worried that all this knock could damage the engine. Just yesterday the IAM was at 0.77 and still at light to medium acceleration it would pull up to 2 degrees.

/Casper

So you are using a universal tune and not a custom tune?

different fuel quality between the two countries???

did you clamp all the hoses on intake manifold including ones under intake manifold. ??


If you ltft are big at idle and low rpm and get much smaller at mid/higher rpm, its likely you may have developed an intake or exhaust leak causing incorrect sensor readings.


Is the DI computer that sits under bonnet securely earthed via its mounting bolts




"He explained different things I could do to reset/recalibrate the tune with different driving patterns. Didn’t work though."

Im not surprised this did not work, unless you reflashed a tune with changed parameters, any resetting of ecu or changed driving techniques will not change anything, ecu continuously learns fueling and timing corrections

They flashed a template they had developed over many kilometer, which was then adjusted on my car using a dyno. I've attached some of the readings from the dynorun.

Yes, in Germany V-Power is rated 100 RON and in Denmark "only" 99 RON. Seems there is quite the difference between those two liquids as they smell very different.

I have looked several times to see, if I could find any hoses that weren't attached correctly but couldn't find any. Also the tuner was very careful that everything was tightened and went over it twice.
Can you explain or show me in a picture, what hoses you mean?
I'm not that mechanical gifted, which is why I had professionals do the install.

How much is a large LTFT number in your terms? At idle it usually sits between +5 and +7. After having driven it hard it sometimes sits between 0 and +3 at idle. Also after replacing the MAF sensor it sat between 0 and +3 for a day or so.
Going at around 80-90 KPH in 6th gear LTFT would be close to 0.
At highway speeds of 120 KPH or higher LTFT would be at -5 or an even higher negative trim.
But it also was like this before I got the supercharger, so my believe was that this could maybe have something to do with the fuel and the ethanol in it.
Here in Denmark all petrols have to contain at least 5% ethanol.

Sorry, what is the DI computer and where exactly is it?

Car-related forums in Germany are full of b/s like this. Now workshops are spreading this as well..?
My conclusion is they either don't know what they're doing or they don't take the problems of their customers seriously. Either way, it doesn't appear very professional.

does not look like they would touch DI computer in your install. Its the black/silver box bolted to left side of engine in front of battery in your photo.




Hoses are shown here
http://www.ft86club.com/forums/showthread.php?t=109444


easy way to get at them
http://www.ft86club.com/forums/showthread.php?t=46456


looking at your fuel trims it does not look like their is a big vacuum leak.




Their does not appear to be much knock in those logs, does this knock occur if you accelerate mildly in high gear like 4,5,6 ??


If you can capture a log of when knock occurs and what gear its in would be helpful.


maybe log with oft and set up knock alerts so oft will beep when knock occurs, I put setup in the OFT TIPS thread.

How do you detect knock while driving? I know how to listen for it when a car is idling, but never heard of it on the move. Also what is IAM? Sorry, would like to supercharge mine in the future and would like to know these things. Thanks!

try a octane booster, just because the fuel is rated 99ron doesn't mean it is.
We have E85 here in the states and where I am it is E85 all the way to E95 coming out of the E85 pump. On the East coast the fuel drops all the way to E60 out of the E85 pump I am told by my friends. which is just crazy but happens

When I went to the car to go for a drive just after having written the initial post, the OFT showed knock correction of -1.39 immediately when the car turned on without me touching the throttle and even with the IAM at 0.77. Very weird and unusual! After a few seconds the rpm dropped below 1400 and the knock stopped.

I just drove over 100 km today mostly highway but also some city driving, and the fuel trim actually seems even better now with more than 200 km done after the new MAF sensor and OEM air filter. Idling between -1.5 and +3 and sometimes even sitting at 0% both at STFT and LTFT. So doesn't really look like a vacuum leak.

I have previously tried to log with the OFT, but after having switched to Ecutek I can see the data live on the OFT and save a file, but I can't get it onto the computer. When I try to connect it, it says "Unconfigured device. Can't be used." - or something like that.

I have however had the alerts set up for a long time, so I tried to figure out the circumstances at which the knock occurs.
It happens in every gear from 1st to 6th, but the interesting thing is, it happens only with throttle between 11%-15%. If I accelerate very slowly with a throttle position of max. 10% theres no knock. If I accelerate harder with throttle position of 16% or above it doesn't knock, and it even adds ignition back, if the IAM had fallen below 1.
Would that indicate a way to aggressive tune at these throttle positions?

Have a look here at steve99's Tuning basics. I used my OpenFlashTablet, which I had used to tune before supercharging and changing to Ecutek.

I have already tried different octane boosters. The last one was Torco Race fuel, which also didn't stop the knock, so it probably isn't all about the petrol.

Did you address the knock issue?

You are complaining about knock at low throttle applications and then post a log from a full throttle pull.

Do a log with accelerator angle, MAP, AFR target and actual, STFT and LTFT along with knock correction coarse and fine and ignition correction coarse and fine. Do this under the conditions that you get knock (light throttle application).

it's a thread of more than 2 years ago.

Ha! I'm a moron, I never look at dates.