ok guys - for starters i have a 93 r1 with a comp single turbo, non ported stock engine that was rebuilt ~8000mi ago tuned with a powerFC. it idled perfectly, no bounce at all prior to the drive i last went on.

i've only had the single turbo setup for a couple of months and ~500mi. it has been driving beautifully for most of those miles until i was returning home from a spirited drive a couple of weeks ago. i noticed that it had the bumpy idle (what you see below in the youtube link) after we all stopped for a look at the scenery. the car shakes minimally, but more than normal. the idle doesn't appear to bounce too much on the tach, but it certainly sounds it. it seems to drive fine on the freeway and the only noticeable issue is this funky idle. however, i didn't push it very hard after the idle started doing this, but everything else seemed normal.

so i move on to prelim troubleshooting by unplugging the TPS and that just makes it worse and when i plugged it back in, the car died. i haven't gotten the multimeter out (dark now), but i plan to check that tomorrow for sure. i also am going to try to rustle up a compression tester...

anything else you guys might think would cause this?

 

Mine did this try the set screw under the throttle body you'll need a flat blade get the car warmed up then adjust it until that stops mine also drop rpms when I'd suddenly let off the gas coming to a stop or stopped also not sure if yours is doing this yet

 

it's not really a low idle, but i'll give that a shot. the idle seems constant at ~800rpms.

 

Your video is set to private.

But with what hair ball said might be right. Mine was also having idle issues, but I thought it was around at the right RPM. What happens is if the screw isn't set right the ecu will be working hard to get it to the right idle hence the bouncing.

 

crap - not private anymore. wasn't able to get on it today - tomorrow...

also, i have a datalogit from the powerFC...anything i should look at there that would be indicative of something wrong?

 

if your afrs are good then no idle has to do with vaccum useally

 

Has the idle rpms changed at all (higher/lower)?

 

no, that's the odd thing. the # appeasr the same, maybe ~200 lower...MAYBE. but the sound is way off and vibration is not normal.

 

Show the commander showing all the temps, rpm, and "boost" values.

thewird

 

will do - i'll have that and compression #s friday (day i actually get time to do it).

 

Ok so I forgot I needed the thin wall spark plug socket so I need to get that for the comp test. Here are some diagnostic pics of the commander and the gauges during idle.

 

also, which set screw are you referring to? there are a few there...

 

Make sure the vacuum line to the FPR is hooked up without leaks. Do the same for the line going to the map sensor. Otherwise compression test is your next thing. That commander screen doesn't look good but it sounds like its idling rich personally so inspect those 2 lines and anything connected to them carefully.

thewird

 

What specifically doesn't look good?

 

Extremely low vacuum which can come from a blown motor, a motor running extremely rich for some reason, or a break in the vacuum line to the map sensor (causing it to run rich also).

thewird

 

Have you checked to make sure all the plugs are firing?