Bucking/ Kangarooing

[kyle'87]

Disclaimer: I know there are other recent threads on the forum and also spread out across the internet but in the interest of finding a solution, I am starting my own individual thread to collect my thoughts and document.

Problem: When the car is cold or warm I get a bucking/ kangaroo effect from the car. The best way to describe this (without a video) is that imagine you were driving along at about 2000/3000 rpm and all of a sudden you decided to take your foot off of the gas pedal and then slam it back on, then take it off again and slam it back on. That is what is happening. I am seeing all of this via the Hondata Kpro app on my iPhone.

(Video)

What I am initially noticing is that I can driving along at part throttle for a few seconds and then the car bogs down by about 500 rpm, this then causes a rocking of the car and what I imagine is my foot pressing on the gas pedal (unintentionally) to pick the car back up again, and the process repeats giving the kangaroo effect. I am not 100% yet on this but I think as long as I drive over 3000 rpm then the rev drop doesn't occur. Prior to all of this, I started to notice my rpm dropping when on full lock so my first instinct was the IACV.

There are no EML lights on, however I have yet to check in Kpro if any have been logged in the ECU.

• I have swapped my TPS between the two that I have, both scale smoothly and calibrate correctly. I'm sure it is not the TPS.
• I cleaned the IACV. It spins freely when the magnet that controls it is disconnected and running the car with no intake pipe on I could listen and hear the function of it altering the idle. However I will be testing the wiring for the IACV this evening and likely replacing the IACV, because the internet consensus is that it is the root of all evil. Also bleed coolant system after removing IACV
• 02 sensor is new by about 1 month. I plan to swap back to the old one tonight and test in case of a faulty primary 02 sensor - will be done this evening
• I have yet to follow the idle re-learn process - Will be done this evening.
• Plan to check spark plugs
• I have ordered a new fuel pump because in the past I have seen that just after 3000rpm the fuel mix goes lean, this also happens at other areas in the rev range randomly. Maybe a drop in fuel pressure - will update when fitted.
• Engine mounts have the energy inserts fitted to them. Engine feels rock solid so ruling them out causing a rocking and pulling the throttle cable.

Car was mapped recently to resolve an issue with bogging down during clutch engagement, I will get in touch with them however I don't think this is map related as the car has bee fine for the most part and made good power.

Any one have any ideas, please feel free to chip in.

Also, does anyone else have the Hondata Kpro app that can verify something for me. I notice that the Kpro app detects a gear change, even though I haven't changed gear. It can go all the way through to sixth gear when I haven't actually changed gear. Does this happen for anyone else?

 

[jrscho]

I ain't no expert but have you tried giving the car a good B road blast? As sometimes that helps clearing it up a little

 

[kyle'87]

I know what you are saying. If I could get it to a B road I would give it some beans but it is literally undrivable at the moment I will get a video up this evening to hopefully give a better perspective.

Luckily when it started to play up on Saturday I was on my road so I could back up the traffic, floor it and then coast to my house. It was rather wet on Saturday so I do wonder if water has gotten in somewhere.

 

[Hobs]

I had a very similar issue with my a DC5 lately.

I had no EML, and it looked like my TPS was calibrated and scaling correctly. But when I watched the trottle presentage reading on the torque app, The trottle % readung was very jumpy and would sometimes drope to 0.

So I ended up replace the TPS with an acuity one and the difference was night and day, all of the jerkyness was gone from the car.

 

[kyle'87]

I had a very similar issue with my a DC5 lately.

I had no EML, and it looked like my TPS was calibrated and scaling correctly. But when I watched the trottle presentage reading on the torque app, The trottle % readung was very jumpy and would sometimes drope to 0.

So I ended up replace the TPS with an acuity one and the difference was night and day, all of the jerkyness was gone from the car.

I checked the throttle % via the Hondata App to check the TPS response. I am going to do some data logging to try and see any variables that I cannot see due to the limited nature of the app. While I think both my TPS are working, I am not ruling out a wiring issue somewhere between the sensor and the ECU.

I have seen the Acuity ones with the hall effect insides on the CPL website, it is something I am willing to entertain if swapping the 02 sensor and fitting a new IACV do not work. Thank you for the input.

 

[kyle'87]

UPDATE:

Last night I switched out the primary 02 sensor followed by the documented idle relearn process. Since I have done this the kangarooing has stopped and the car drives nice and smooth again at part thottle. I am not suggesting either fixed the issue as it has only been one day since. I will update this thread in a few days as it is too early to tell if I did fix the issue or the issue has hidden itself for now.

I am going to speculate and say that the short term trim was pulling fuel and maybe with the 02 sensor becoming dodgy, it was making the car run lean, lose power and therefore revs and then adding fuel and then pulling it etc etc.

I will still be fitting my new fuel pump but might hold off on the IACV install for now.

As a side note, my idle is much better since stripping and cleaning the IACV and idle relearn, no more dropping below 1000 rpm when on full lock.