1991 TBI- Slow return to idle speed
Thread Starter
Junior Member
Joined: Sep 2021
Posts: 10
Likes: 4
From: S.E. Wisconsin
Car: 1991 RS Convert
Engine: 305 TBI
Transmission: 5 speed
1991 TBI- Slow return to idle speed
I'm getting to know my new to me RS. In driving it I've noticed it is slow to return to idle. With the car fully warmed it idles at 700-750 rpm in neutral. Car is a 5spd manual.
When driving as I decel and push in the clutch, the idle will hang at 1200rpm. It will take 2-4 seconds to drop down to 750rpm. So if I'm cruising town slow, and shift slow, the engine stays at 1200rom between shifts.
I've checked all the easy stuff. No floor mat by gas pedal. Under hood throttle and linkage work smooth and open/close fine. Other than this slow idle return, the car runs and performs as it should.
Is there a DIY cure for the issue?
When driving as I decel and push in the clutch, the idle will hang at 1200rpm. It will take 2-4 seconds to drop down to 750rpm. So if I'm cruising town slow, and shift slow, the engine stays at 1200rom between shifts.
I've checked all the easy stuff. No floor mat by gas pedal. Under hood throttle and linkage work smooth and open/close fine. Other than this slow idle return, the car runs and performs as it should.
Is there a DIY cure for the issue?
Joined: Nov 2008
Posts: 2,093
Likes: 175
From: Milwaukee
Car: 92 Firebird, 77 Trans Am SE, 86 Z28
Engine: 5.7 HSR, T/A 6.6, empty
Transmission: T-5, TH350, T-5
Axle/Gears: 3.08 posi, 3.23 posi, 3.23
Re: 1991 TBI- Slow return to idle speed
I assume this is still a stock 305 tbi? 750 is a bit high an idle as I recall. 600 rpm is what's un my memory. (Been a long time since I had tbi) Being it's high could be an indication of a problem that your symptoms is a byproduct of.
does the throttle blades close fully when running?
Check for manifold leaks? Triple check vacuum lines?
Is the minimum idle set correctcorrectly in the first place?
Initial timing correct?
does the throttle blades close fully when running?
Check for manifold leaks? Triple check vacuum lines?
Is the minimum idle set correctcorrectly in the first place?
Initial timing correct?
Thread
Thread Starter
Forum
Replies
Last Post