Thread: TPS - Idle issue and rpm loss
09-09-2013, 04:38 PM #1
TPS - Idle issue and rpm loss
I reset both of my engine tps's on my boat bc one doesn't idle right, sometimes it drops below 2,000rps before picking back up when I give it a throttle rev, sometimes it just dies. This one engine is also 500rpms lower than the other when running WOT or even at 5,000. I first checked with the CanDoo and found 0 and 86 / 0- 81- on the troubled engine. After the reset I got 86.8 and 79. I tried to adjust the throttle cable on the one reading 79 thinking there was too much slack. I adjusted it until I saw the butterfly move and then backed it off a tad. I reset it again and got 80.7. Even if I move the butterfly by hand I can only get 81 so I know its not something with the throttle having too much slack. Any ideas? It has new plugs, new gas- the other engine rev's fine and tops out right at 8,000 vs 7,500 on the other.
09-10-2013, 06:49 AM #2
09-10-2013, 07:15 AM #3
Its expressed in degrees of blade angle so 81 ish is normal as at idle the blade is set aprox 7-9 deg. So 9+81=90 deg.
09-10-2013, 10:40 AM #4
So would the one reading 86 be too much? I cant seem to find out why one engine idles bad and is lower on rpms than the other. This is on a Speedster 200 btw.
09-10-2013, 11:12 AM #5
09-10-2013, 11:41 AM #6
If its not that then where should I be looking now? Idle valve issue.... How do I check that? It seems like it only does it when the engine is cold, if I gas it, it drops and picks back up if I feather the throttle, if not it will die. Once I can get it to rev it seems fine but seems a bit rough as the other engine is nice and smooth with moving the throttle. This same engine has a oil pressure switch fault- TOPS valve works, wiring is ok. I plan to change both sensors out this weekend. Could that cause a bad idle even if at the time it hasn't tripped a warning light?
09-10-2013, 11:44 AM #7
09-10-2013, 12:09 PM #8
- Join Date
- Sep 2009
Yeah, I would start with new plugs.
09-10-2013, 01:37 PM #9
It has new plugs, maybe 1 hr on them- that didn't fix the issue, I'll swap coils from the good running engine and see what they do.
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