Topic: Hesitation on shifting/accelerating
in Forum: C3 Driveline Components
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I'm not sure what the problem is, but I thought this might be an appropriate place to post. I got my SAE back from a week of paint work and right away I noticed it seems to hesitate when accelerating and when it shifts gears (automatic trans) - at least tat's my best nterpretation of when the hesitating is occuring. As a result, obviously, it doesn;t have the "pick-up" tha it used to. Also had some thick exhaust smoke (more white than black - really looked like dust or sand) on the drive home. I haven't driven it since. Any ideas what I might be dealing with?
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white smoke.... sounds like water/coolant... checked your radiator level?
art-corvette
art-corvette
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20219
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Check the vacuum modulator on the pass. side of the trans. Pull the rubber hose off of it, and see if any trans fluid runs out of it. If so, the modulator is bad. This sucks fluid up into the intake manifold, and burns it as white smoke from the tailpipe. It would also cause a shift problem, as well as suck fluid out of the trans, making it low on fluid.
Wouldn't have anything to do with paint work...just something that happens on it's own, at any time.
Wouldn't have anything to do with paint work...just something that happens on it's own, at any time.
Joel Adams
C3VR Lifetime Member #56 
My Link 
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
OK - so here's where it stands. I replaced the air filter, and cleaned the carb with carb cleaner. There was a fairly thin layer of deposits (carbon I presume) everywhere. Cleaned that and took it for a spin - definitely better but seems to idle a little rougher and at 100-200 rpm lower than before.
So, 3 questions arise.
1. could a dirty air filter and a thin layer of carbon residue in the carb cause that?
2. If not, could the carb need adjusting (i.e. air/fuel mix)? My mechanic says he likes to re-adjust a carb when the weather goes from cold to warm or vice versa.
3. Joel, I'm a newbie when it comes to car repairs (learned a lot through c3vr), so is this vacuum mod on the underside of the car or topside. If the mod is bad, is that a simple repair or a professional job?
Thansk for all the input.
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20219
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
1: It could create a slight hesitation if the filter was dirty enough to "choke" the air supply for the engine.
2: The carb may well need an O/H, since spraying it helped, but now there are other issues. You may have moved some "trash" from one spot to another while spraying it down, and gotten something in one of the sir bleeds, on the top of the carb. Happens all the time.
3: The mod is on the pass. side, rear of the trans. Unfortunately, it is only accessible from underneath. It is a simple thing to replace, tho. Just remove the 1/2" bolt that holds the mod. "clip" on, remove the mod, and replace in reverse. I have a pic posted here somewhere...lemmie see can I find it....
CLICK for linkAdams' Apple 2007-05-06 18:00:55
2: The carb may well need an O/H, since spraying it helped, but now there are other issues. You may have moved some "trash" from one spot to another while spraying it down, and gotten something in one of the sir bleeds, on the top of the carb. Happens all the time.
3: The mod is on the pass. side, rear of the trans. Unfortunately, it is only accessible from underneath. It is a simple thing to replace, tho. Just remove the 1/2" bolt that holds the mod. "clip" on, remove the mod, and replace in reverse. I have a pic posted here somewhere...lemmie see can I find it....
CLICK for linkJoel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Well, it seemed to improve after replacing air filter and cleaning carb - but only temporarily 
. So - I took it in and my mechanic adjusted my carb and all is well now 
. Don't know if that helps or not.
in Forum: C3 Driveline Components
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