Throttle Body Set Screw- '98 V70

Post by **bmdubya1198** » 01 Nov 2017, 17:30

I was messing around with my throttle body today, trying to diagnose an increasingly frequent pulsing idle, and I noticed that it takes a little bit of movement of the throttle pulley to move the butterfly off of the set screw on the back (or side).
When I turn the pulley by hand, the rod that connects to the arm from the pulley has a little play and the butterfly does not move off the set screw until I move it a little further. I apologize, because I know I'm probably not explaining this great.
Anyway, should the butterfly open instantly when I turn the throttle pulley? Should I tighten up the screw a little bit to get rid of the play, or is it supposed to be like that?

I also tightened up my throttle cable a little bit after watching Robert's video showing the slack in the cable (while searching for information on this screw!). I always figured if when I pulled the cable and it turned the pulley, that was good enough. A couple turns tightened up the slack and definitely improved throttle response!

Post by **E Showell** » 01 Nov 2017, 17:59

Don't know about that set screw, but if it cures your pulsing idle, let me know. I've had a pulsing idle for years.

Post by **bmdubya1198** » 01 Nov 2017, 18:55

I'm leaning towards the MAF as far as the pulsing idle. I'll go ahead and adjust it tomorrow and see what happens. Anyone else?
Anyone know if the EVAP hoses can cause an idle issue? I have P0442 and occasionally P0455 pop up.

Post by **E Showell** » 01 Nov 2017, 19:21

No evaporation issues for me.

I suspect air idle control valve. Mine's original at 340k miles. I cleaned it once, but it didn't seem to matter.

MAF not the cause of my wavering idle. I suspect it won't be the cause of yours.

Post by **bmdubya1198** » 02 Nov 2017, 07:57

Hmm, that's weird. I cleaned the heck out of my IACV back in February, and I've had it out once or twice replacing hoses and it still looks good. Later that day though, my car was idling in park at around 1,400 RPM, so I had to pull it and clean it again the next day, which cured the high idle.
Of course, there's always a chance the valve failed mechanically.

Post by **E Showell** » 02 Nov 2017, 09:06

Or there's an internal short in the wiring.

Post by **abscate** » 02 Nov 2017, 11:03

You should be able to monitor the MAF output with a decent scanner and confirm the numbers are stable

Post by **bmdubya1198** » 02 Nov 2017, 16:01

So... adjusting that screw didn't decrease play in the pulley, just increased idle speed... which I kind of expected.