Throttle stop screw adjustment!

turbomrk

.020 Over
Joined
Sep 10, 2020
Messages
23
Ride
Rocket 3 Roadster
Ok all of you talented troubleshooters here's one for you. Friend of mine's R3Roadster would not idle. So not knowing any better, he adjusted the throttle stop screw, located where the cables attach at the throttle body! He got it to idle but is was a bouncing idle, this is after he got a MR12 Race Gas tune from Bob Carpenter. Put regular fuel in it after the MR12 ran out, and that's when the idle issue started. I checked it with TuneECU and the TPS and ISCV were off, so I adjusted them to spec. Idled smooth and steady, but now just off idle at 1100 rpm it's bouncing. His idle is set at around 950 rpm, runs like crap at 1100 then is fine past that range. We checked my adjustment on my Roadster and reset his throttle adjustment to match mine. Reset ISCV and TPS to spec Synchronized throttle bodies and no change. Is it possible that his TPS is bad even though there are no trouble codes? He has no 02 Sensor and it's switched off. That's all the information I have to give. I'm thinking the manual idle adjustment threw off the MAP setting, and the MAP sensor may not like the pressure reading. HELP!
 
Might be a vacuum leak making it run rich, bog and die at idle. And the throttle stop screw job is compensating for it. What were the MAP numbers when doing the balancing?
 
Bob tunes them all that way for dyno chart, but I doubt he left it that way
 
You started by saying it wouldnt idle, then added, after getting an mr12 tune, then it wouldnt idle, probably would have had to compensate fuel (add or subtract) at idle in tune ecu id expect it needed more fuel than was getting at idle, then things went south, go back to beginning id suggest, try to get idle screw back in position from factory unless theres no stepper) and add fuel (i think) in tune ecu but really this needs to be done if its understood how to. This is my guess on this issue. After 1100 its ready right? Crack that thottle it probably goes?
 
R-III-R Turbo said:
Might be a vacuum leak making it run rich, bog and die at idle. And the throttle stop screw job is compensating for it. What were the MAP numbers when doing the balancing?
Click to expand...
Cylinders 3 and 1 were 630 and cylinder 2 was 640. Couldn't really get them to synch any better than that either. If you just hold the throttle at 1100 it will just bounce for as long as you hold it. Get past 2000 grand and it runs like a bat out of hell! I will check lines going to the T and the MAP sensor, and the vacuum plugs. It has individual K&N filters and no trouble codes are showing, which is why I don't suspect a sensor. Thank you for your input R III R
 
Ya you shouldn't muck with the spring loaded throttle stop. That is the area the idle is controlled in next thing you know if you move that screw you just might disturb all the ISCV adaptations. I know you are aware of how much the actual throttle position signals produced by the throttle position sensor is used by the ecu , the timing tables, fueling and lambda tables, F & L switch over.
The easiest way to understand that is if you. Take the stepper motor off or just unplug it and then try to perform a full ISCV RESET synchronization with out it. Anyway if that makes sense I don't recommend trying to adjust a idle, thats why your bike has a computer, multiple sensors and yes the stepper motor (a servo motor controlled by the ecu.)
 
idk said:
Why did he get it tuned with racing fuel when he was not going to be using it? I would bet that if he put racing fuel back in, and reset everything to where it was, then it will work again.
Click to expand...
Well I can't explain that one. But as it turned out the issue was the EVAP system/ junk! I removed it and set TPS and ISCV and synched the throttle bodies, and Bam it runs better than it ever has since he got the bike.
 
But as it turned out the issue was the EVAP system/ junk! I removed it and set TPS and ISCV and synched the throttle bodies, and Bam it runs better than it ever has since he got the bike. I put the throttle stop screw back to where it should be by using my bike's setting. No more bouncing idle or off idle stumble.
 
R-III-R Turbo said:
Might be a vacuum leak making it run rich, bog and die at idle. And the throttle stop screw job is compensating for it. What were the MAP numbers when doing the balancing?
Click to expand...
But as it turned out the issue was the EVAP system/ junk! I removed it and set TPS and ISCV and synched the throttle bodies, and Bam it runs better than it ever has since he got the bike. No more stumble or bouncing idle, bike runs better than it ever has!
 
You must log in or register to reply here.

Similar threads

Bad Throttle Acuator
Replies
1
Views
106
TURBO200R4
What throttle body’s fit a 2005 rocket
Replies
3
Views
894
Cushman
06 would not stop cranking
2
Replies
19
Views
2K
Mongler07
Tacho stopped working
Replies
8
Views
465
chevy400
Hesitation and backfire through throttle body at 2000 to 3000 rpm
Replies
6
Views
2K
Pete
Menu
Log in
Register