Low Hp: Bad Gas or...
 

Hi all,
I had my 2015 FR-S tuned yesterday and it revealed a problem. I trust my tuner implicitly as he is an expert on this type of vehicle. My power train is stock except for the TRD hi flow air filter. The problem was the car started out on the Dyno at only 105hp which is probably about 25hp below what an automatic should be. It has been suggested that the 91 octane gas I've been putting in it may be bad. I hope so, but has anyone ever heard of this particular problem? My tuner got it up to 132hp but I am afraid there may be a bigger problem. The car seems to run without issue, even when I romp on it, but as this is my first car like this, I have no experience to base whether it has been performing properly. Any ideas or suggestions would be greatly appreciated.
Thanks,
FRed-S

hmmmm..... 200 HP at the crank and 105 HP at the wheels ..... ??

I reckon something IS wrong with your car.

132 HP is better, but it seems it should be higher, with a good tune.

I'll shush ...... cause others know more about this than I.

However, I would also wonder about the calibration of the dyno .... ??


humfrz

All dynos read different i believe maha,s read particularly low and it depends on how all the calibrations and adjustments on the dyno are set up.

pretty warm day as well

The main thing you looking at is the gain over stock which is about 25 hp or so this seems very good good for just a tune on a stock car.
normally you would only see 10-15 or so.

What may have happened is the base run was compromised maybe wheel slip or you had been lugging the car round at low rpm in high gears prior to the run. I have seen iam down to 0.4 when people drive that way on 91 fuel and it can result in quite a few lost hp over entire rpm range. A bit of light throttle driving through the rpm range will see the IAM return to closer to 1 and the hp return.

On 91 fuel with stock tune the engine knocks quite a bit especially in low rpm high load, this causes the ecu to take action to reduce the knock and it will reduce a parameter called the Ignition Advance Multiplier or IAM to pull timing reducing knock and also reducing power over the entire rpm range

The tuner does his work and reduces knock in the problem areas and lots of other stuff the IAM now runs at 1 as you tune is optimized for 91 fuel not 93 as the stock tune is. The car will run better smoother and less knock and more power as you have seen.

Just taking a shot in the dark, but ambient temps were 105F so that could be a factor. I also live in AZ and when the temps are high the car runs like garbage.

I would Try a different dyno before i worry too much. Dynos really vary from one to another.

Who is your tuner?

That is a possibility as it is my daily drive and most days it's only driven around 14 miles round trip to work at mostly up to 45-50 mph. That will change in a few months as I'm moving an the drive will be longer and faster. Do you think the ECU will correct itself as it "learns" the new driving? The car only has around 5,000 miles on the odometer.

The ECU constantly "learns" fuel trims and knock correction.

you can "force it to learn quicker by doing some light steady throttle runs from about 2000 to 6000

see here
http://www.ft86club.com/forums/showthread.php?t=68328



on the stock tune on poor fuels like 91you can get varied results on a dyno depending on how the car was driven just before it went on the dyno.

The stock tune needs about 93 octane to run at max performance. If lesser fuel are used the ecu aggressively retards timing to reduce knock and hence reduces power.

once your tuned for lower quality fuel like 91 things will be much more stable. and the tuner can optimise the tune for 91 so the ecu does not have to intervene constantly to reduce knock.


below is a log of a south African BRZ on 95 ron fuel probably about your 91 or a bit worse. his IAM is 0.2 (should be 1 for full timing advance and max power) the FLKC fine learning knock control is intervening constantly to surpress knock

http://datazap.me/u/steve99/south-af...0&data=2-20-28



below is a log from a tuned car on a much better fuel notice the IAM=1 and no FLKC intervention

http://datazap.me/u/steve99/jamie?lo...zoom=2837-4009

Thank you Steve99. That sounds very credible. I'd give you one of those official thanks if I knew how lol. New to this forum stuff.

you'll get a thanks button after ten posts. I wondered that too.

Quarter mile traps never lie/mislead about power to weight. Do you know yours?

My 2015 made 155 whp on 91 on dynojet which is pretty low for that dyno. I even did a ecu reset after a few pulls which would put the IAM at .7 and it didn't make any difference.

After putting on a proper header and front pipe and switching to flex fuel and dyno tuned it is now 50-60 whp stronger.

I'd love to go E85 but it's so scarce around here and especially where I'm moving to in a few months. I would burn a quarter tank justify for the fuel run.

Sent from my XT1254 using Tapatalk

On the stock tune IAM initial parameter is set to 0.7, so when you reset the ecu on a stock tune iam will go to 0.7 not 1. After the reset on a stock tune you would need to drive for a period with the ecu seeing little or no knock for the iam to move up to one, light throttle runs 2000-6000 will generally achive this quickly if no\minimal knock detected.

If you on crap fuel the iam may actually go down to 0.5 or less,especially driving in lower rpm range and applying quick throttle applications.

The difference between runs at iam 0.5- 0.7 to 1 could be arround 8hp

Most tuners will set iam initial to 1 in thier tunes so after a reset ecu runs full timing. ie reset the ecu on a tuned car and iam will start at 1 not 0.7 like stock tune

Its a trick\trap that can make tunes look better\worse than they are

I'd just set the ecutek up to log and do some 0-60 runs

if the performance of the car is on spec then your power level is fine