Car Jerks when decelerating

illiminator · Post by **illiminator** » Wed Oct 11, 2006 11:02 am

Hi

I recently created a graph to analyze and find knock since knock was audible at lower RPM, when I tried to run a datalog I received a message that the calibration was loaded with an older version and that I would need to re-load the calibration with the new version I have loaded on my PC (1.2.1.9) in order to be able to run datalogs. So I did.

I run a datalog and it indicated knock in the 5500-6250 RPM range and allot of knock between 2500-3500.
The car was originally tuned with 91 Octane so I waited for the gas tank to be empty and I tried the 94 Octane before reducing the ignition advance and this solved the knock at the lower end but on the higher end of the RPM I had to reduce it by 2 degrees and is now perfect.

The problem I noticed after loading the calibration with the new version of KManager (1.2.1.9) and even prior to these changes for the knock that the car jerks at lower RPM from 3500 downwards when decelerating. Note: I did not make any changes to the Calibration at this point of the RPM scale. Just wondering if uploading with the latest version might have caused this jerking and should I try reloading the calibration with an older version of KManager?

K-Pro
2003 RSX type S
Injen cold air
Vibrant Cat-Back
DC-Sport shorty Headers

Thanks

Razathorn · Post by **Razathorn** » Wed Oct 11, 2006 12:36 pm

Did you re-upload your calibration from disk or download it and re-upload it. If you downloaded it from the ecu, it may have been corrupted.

Wayne

illiminator · Post by **illiminator** » Wed Oct 11, 2006 1:29 pm

Uploaded from disk

Razathorn · Post by **Razathorn** » Wed Oct 11, 2006 1:44 pm

Datalog of said jerking?

tryfe · Post by **tryfe** » Wed Oct 11, 2006 9:30 pm

Is it the same as when you're barely going 1mph with just the clutch engaged and no throttle?

illiminator · Post by **illiminator** » Thu Oct 12, 2006 7:02 am

Tryfe,

Yes similar effect It's like being on first.

Wayne,

Find attached 2 datalogs as you requested.

Thanks for the help.

Frank

tryfe · Post by **tryfe** » Thu Oct 12, 2006 8:09 am

illiminator wrote:Tryfe,

Yes similar effect It's like being on first.

Wayne,

Find attached 2 datalogs as you requested.

Thanks for the help.

Frank

Looks to me like you're foot is on the gas pedal when you decelerate. I'm sure whenever you're feeling the jumpiness, it's when your TPS goes up, which mean's you got a heavy foot. That's just my assumption..

Post by **Hondata** » Thu Oct 12, 2006 9:55 am

You need to adjust your TPS so that it reads 0% with the throttle closed. Also check that the cable is not too tight.

bossman032 · Post by **bossman032** » Sat Oct 14, 2006 11:45 am

same problem here.

when I lift of gas it jerks.

maybe because most of the time I am in vtec.

to stop the jerks I keep my foot on the gas and slowly lift off.

fvang · Post by **fvang** » Sat Oct 28, 2006 7:02 pm

I have also noticed this, but it occurred on previous versions also. I datalogged and it seems that when you decelerate, there is a jump in the cam angle to ~30-50 deg then back to 0. This quick change in the cam angle seem jerk the car maybe due to the quick air intake change.

Any help on this would be appreciated.

kornsined · Post by **kornsined** » Sun Oct 29, 2006 12:03 pm

I can say i've had this issue too but I thought it was related to some IAC valve issues as well being turbo too. It's most noticable when the engine is cold.

2000Accord5sp · Post by **2000Accord5sp** » Wed Nov 01, 2006 8:29 am

I have been having similar issues. Initially I thought it was just tuning since the TSX stock calibration provided by Hondata states that it needs work on partial throttle. I really noticed the problem when the car is cold but also while driving if I have to play around with the throttle around 1-10%.

Note, I realize that it's always been mentioned to make sure TPS is at 0% when throttle body is closed. I have a brand new throttle body from Honda so I assumed at 1% (when closed) should not be causing issues...or am I being naive?

While street tuning, my tuner noticed first off that the hesitation only occurs when TPS is under ~7%. What seems to be causing (at least in my case) the hesitation is that the injectors seem to turn off. You can see this in a few occurances on the datalog I have attached.

Any info on this would be greatly appreciated.

Note cursor positions such as 0:00:02.292, 0:00:06.017, and 0:00:53.512

Post by **Hondata** » Thu Nov 02, 2006 2:49 pm

You have a different issue. The K24 draws more vacuum on overrun than the k20a and you're seeing a fuel cut based on vacuum, not tps.

Go into 'Parameters', 'Advanced' and set the low cam overrun cutoff to 15 KPa all the way acrosss.

colinkao · Post by **colinkao** » Thu Feb 01, 2007 1:07 am

I'm a newbie here and have had a similar problem. I've taken the car to the dealership multiple times and they can't figure it out. It has an abrupt jerk when initially stepping on the accelerator or letting off it. You can make it somewhat smoother by really feathering it, but you shouldn't have to concentrate that hard. I've driven manuals since I was 16, and I'm 34 now, so it's not my mediocre driving :) Does the K24 reflash affect this problem? If so, it would make driving the car so much more pleasant, especially for the queasy passengers! Thanks.

illiminator · Post by **illiminator** » Mon Jul 07, 2008 7:25 am

Sorry,

I wasn't able to get back earlier to give feedback on this as I didn't have time to adjust the TPS to read 0% I finally did and the results are the same. The only way I can get it to stop is by loading the stock calibration regardless of TPS 0% or 1% as it was from factory.
As soon as I load any of the calibrations that have been tuned for my setup the car jerks again.

So the issue is definately with the tuning of the maps somewhere.