Help...car can't rev over 4K rpm after tune
 

My car is NA and has a few bolt on mods: CAI, full HKS exhaust, lightweight pulley, bigger throttle body and etc.
I had my car tuned at a local tuning shop last Dec and brought my car to the track few days after. At the first session, I instantly noticed that the car can't rev over 4K rpm, It acted like as if it was hitting the speed limiter. The RPM hovered around 4K. It kept acting like this and then all of sudden, i was able to rev up. However, I can still feel that th car is reluctant to accelerate between 2.5 to 4K range(above 4K is normal). I then took my car back to my tuner. He put it back on dyno machine and car rev up well. He couldn't find anything wrong with it.
I then drove my car for another few days and noticed that car now could not rev over 2.5k when going up a gentle long slope. It only acts like this when going up slopes as it runs okay at flat surface.
I have never had this issue before the tune. Was wondering does anyone here have similar experience? Does this issue related to the tune itself or it is something else?
Btw, CEL and T/C were not turned on.
Thanks:bow:

Hmmm the ecu has a failsafe mode were rpm is limited to 4000, but this usually only kicks in if ecu detects a problem with engine or sensor. generally you would expect to get a CEL or traction light with this.


Assume the tuner read the error codes from ecu and found none ?


Put the stock tune back on car and see if you still have same problem.

Thanks, strange though the 2.5k rom issue only happen to 3rd and 4th gear. It was okay when running at 1st and 2nd(both gear can go over 2.5k anytime).
Was thinking about the same to ask my tuner put the stock tune back on and see how it goes.

When you say it wont rev over 2500 in 3 or 4 is that if your at low rpm in 3rd or 4th and try to accelerate quickly with large throttle input ?


Will it rev over 2500 in 3 or 4th or higher gear if you ghange down a gear or two and be more gently on accelerator ?


If it bogging at low rpm with large throttle input then its likely a tune problem with load limits or the fueling/maf scaling that's causing engine to bog.

Hmmmm, 1st and 2nd gear are okay as I was able to rev up to 2600 or 2700 before change gear up. RPM drops down to around 1900 at 3rd gear. Car can still accelerate like normal from 1800. It then stalls at 2400 and not willing to go any higher. RPM was then hovering between 2200 to 2400 like I hit the speed limiter. I was trying to give more throttle to break that but it didn't work at all.
It I change to higher gear at this point, the car will acclerate okay(again rpm dropped to around 1900). Strange though as this only happens when I drive up slope(long gentle long instead of a steep one:) )

You rearly need some form of method of logging whats going on like android torque app or similar.


but your tuner should be able to sort it.


It possible you have a hardware problem with car like exhaust or intake leak bad sensor or similar. but usually they will throw a cel code if the symptoms are as bad as you describe.

If your MAF and injectors arent scaled correctly then your tune is up shit creek. Flash your old tune back and give it ago. Not all tuners are equal.

What are you tuning with ECUTEK?

Is your car auto or manual?

Have your tuner ride with you on the street amd get a data log if it isnt repeating on the dyno

Thanks guys, I will bring my car back to them tomorrow and have it scanned at the same time. Might as well request to put the OEM tune back and see how it goes.
I didn't use Ecutek. It is a ECU reflash that developed by them(btw, the shop hads been in tuning business for more than 20 years, not someone dodgy��).
Car is manual. I am not 100% sure how to reproduce the said symptom as it might not happen at all while he with me��

Even people that have been in the biz 20 years can over look things. Being it only happens on the road and not the dyno deff think some logging with the tuner while on the street is the way you need to go.

My tuner has begun tuning a full dyno session, then uses the dyno to simulate a few hills, (up and down,) and then rides in the car with me while datalogging to confirm there aren't any unexpected events where the tune or the hardware isn't playing nice outside of idle/WOT.

Why is your tuner insisting on replicating on the dyno when you can easily replicate it on a normal drive? Get him to come for a drive and be logging while it happens.

Thanks for the inputs guys. To share some updates:

The CEL and T/C light came on this morning on my way to the workshop. The tuner hook it up with the scanner and it says the car is running too rich.

We then went off for a ride and found out that it has something to do with the throttle position. What happened is that the throttle stays 69% open between 2400 to around 4000 rpm even we flat the accelerater.

Have booked a time to bring my car back next Wednesday and have it re-tuned. Fingers crossed this can be resolved by then.