Where to go next?

[BCRedHaze]

2012 Roadster 15K kms with RamAir and TORs.

I have been battling this for a while now. On quick acceleration, the engine seems to run OK, but if I hold the RPMs above about 3300, it will run really rough with popping, backfiring, etc. To try and resolve, I have done the following:

- 3 different tunes. The original 20355, the Powertripp R3R, and a tune @HansO was great to forward. All had similar results with the rough running maybe moving up and down the RPM range a bit.
- I have re-crimped the coil leads more than once and ensured they are on securely. I metered the coil itself and it they seem to meet spec.
- I reset the ISCV from 0.59 and 0.69 to 0.60 and 0.72. I do the reset ISCV function after each tune download as well as reset adaptations. I cannot get a green TPS light in TUNEECU though.
- Balanced the throttle bodies.

I think I have done all the preliminary troubleshooting and am looking for advice on the next direction of troubleshooting.

 

[rocketjohn]

I hope it's not your case, but every engine has a limit where it cannot be modded or adjusted any further without internal mods, like valve porting or cam changes or so forth....but just maybe Carpenter Racing can give some ideas.

Also, a telling thing...if the TPS won't green light....are you quite sure it's giving appropriate readings to the ecu? They do fail, and connections get crummy....especially given where it's located on Rocket 3's!

 

[HansO]

I am thinking you may have a faulty TPS I had something similar, try this with engine running in the "Diagnostics" screen slowly bring up revs to problem area and watch the TPS reading (top left gauge) on screen what happened to me was as I got to the problem area the voltage start jumping all over the place, what this means is the Tps has a weak spot and needs to be replaced I have had 2 TPS failures to date I now have 64,000 km on clock the first went after 40,000km and the second only lasted 15,000km, so there is obviously no set life span

 

[rocketjohn]

In my experience with cars...tps's should have a good life, but depending on service they won't. We can consider motorcycle service to be severe service though I reckon.

 

[kipper]

+ 1 with Hanso . Around 3k engine started feelin bad, missing like a bad plug or loose coil connection ,then shortly after started gettin the high/low idle. New tps an she's as good as new. Milage was at 43k miles when it went bad.

 

[BCRedHaze]

I connected and in the areas that the engine was missing/popping/backfiring, the voltage stayed pretty much constant when it started and it didn't seem to jump around. I noted the voltage, shut the engine off and tested the throttle from fully closed to fully opened and especially around the voltage that the trouble starts and there did not seem to be an issue.

Undecided on whether to buy a new TPS and based on something I had read somewhere on this forum, I took the TPS off and tested it with an ohmmeter. When slowly rotating the pot, I thought I found a couple areas where the TPS seemed to lose continuity very briefly and then quickly back to continuity. This happened consistently so off to the dealer to get a new TPS.

I Installed it tonight, reset the ISCV, reset the adaptive and still could not get a green TPS light. I took it for a ride and I still have the same issue. In first gear, It starts slightly about 3500 and is more pronounced between 4000-5000.

I think I have done all the basic troubleshooting here and am still coming up short. What am I missing?

 

[HansO]

a long shot but try spraying a starter spray (either based spray help start engines, sold under many names) around the base (in between throttles) of throttle bodies with air cleaner in place, where they join engine head via rubber boot, there has been a couple of guys with cracks in rubber causing similar issues, if spraying while engine is running there is a change in revs then you may have a rubber manifold with a crack, I am puzzled as why you dont get a green TPS light you may need to do a 12 min tune which actually takes a lot longer as the 12 min's start when fan cuts and you can not touch throttle at all from starting onwards to end of 12 min after rad fan cuts in

 

[UberR3]

I connected and in the areas that the engine was missing/popping/backfiring, the voltage stayed pretty much constant when it started and it didn't seem to jump around. I noted the voltage, shut the engine off and tested the throttle from fully closed to fully opened and especially around the voltage that the trouble starts and there did not seem to be an issue.

Undecided on whether to buy a new TPS and based on something I had read somewhere on this forum, I took the TPS off and tested it with an ohmmeter. When slowly rotating the pot, I thought I found a couple areas where the TPS seemed to lose continuity very briefly and then quickly back to continuity. This happened consistently so off to the dealer to get a new TPS.

I Installed it tonight, reset the ISCV, reset the adaptive and still could not get a green TPS light. I took it for a ride and I still have the same issue. In first gear, It starts slightly about 3500 and is more pronounced between 4000-5000.

I think I have done all the basic troubleshooting here and am still coming up short. What am I missing?

Check health/condition of the battery. Make sure you have adequate voltage.

Remove all the modifications and start with a stock setup. This will rule out the mod variables. Add one mod back at a time until you find the problem. You can't easily troubleshoot a problem like this without stepping back and looking at the big picture. Rule out the basic, simple issues like faulty battery or bad gas.

 

[BCRedHaze]

The bike isn't highly modified, just a RamAir and TORs. I have gone through a couple tanks of fuel, and ran some seafoam through it so I don't believe it is bad fuel. Battery doesn't seem to be a problem. It has been on a tender since new and the bike starts immediately with no issues.

The other day, I took the throttle bodies off to see if the rubber interface to the block were cracked or split similar to what happened to @Wrecka. I was also able to have a good look at the vacuum lines/plugs and everything looked perfect. Re-assembled everything and torqued to spec and still have the same issues.

I am wondering now if the MAP sensor has gone bad. Is there a way to test it or bypass it to rule that out?

 

[BCRedHaze]

I also noticed when I pulled the throttle bodies, that the intake valves seemed to have quite a bit of carbon on them. I guess I would expect some, but the amount seems excessive.