First off -
Bone Stock 86 Grand Prix. 305, 4bbl. 58k miles (yeah, I've been driving it Juuust a bit - Bought it 6 months ago with 50k Original Miles).
All I've done is a "normal" tune up - Plugs, Wires, Cap, Button. Left the coil alone.. Fluid Changes.
Runs great, but had this Slight miss on a very light touch of the gas pedal with a steady hold.. Sometimes.. not all the time.
Stomping on it, and opening the 4bbl with a quick, hard push gave me some hesitation, but after it "caught up", it ran quite well. I don't want to over dramatize it, it wasn't BAD.. Your 4bbl typically goes "Whom..Whooooom" - Mine went "Whom.. da da da da.. Whooooom"
So, since its getting warmer out, I have started doing "those little things" that come with owning a 30+ year old car. Little this, little that... but I never really did much to the engine since it really ran quite well. 27mpg cruising on the highway with the symptoms above, I'm not complaining. (200R4 4 Speed-stock open rear)
However, I did start perusing the forums about this hesitation and watched some youtubes just for hints/tips.. (I come here for REAL information, I take youtubes with a grain of salt) and ran across something that struck me as "ya know what... that isn't a bad idea to check"
I DID have a 44 code (Lean) and I attributed that to my HVAC Control Valve leaking constantly. The hiss was audible, and I tracked it down to that.. mainly because the only thing that worked was Defrost. I pushed on it, it made a difference, so... thats the culrpit. I changed it out, and now I have defrost, floor, vent, etc... But I did what follows at the same time, so I really can't say which thing helped. (probably both, but...)
The 9 or so top bolts (the hex bolts in my case) holding the air horn to the actual Body of the carb Can Work Themselves Loose, apparently... So, while I was piddling around, I just popped off the air cleaner and checked them.
7 out of 9 were loose.. Not a little loose... like 1/4 free turn, just move with your fingers, loose.
Tightened them up a bit, and with replacing the HVAC Control Valve (Get it from NAPA by the way - $29 instead of $50+ from other places, even RockAuto - which surprised the hell out of me) things are Much Better.
While the combination of snugging them down and the HVAC Control Valve replacement did NOT solve the issue completely, it sure helped a LOT.
The very light touch of the gas pedal with a steady hold is almost imperceptible now, and the hesitation with a quick wide open went down about 50%. (Whom.. da da.. Whooooom" for those that liked that description)
Did it SOLVE the issue? Absolutely not. Did it HELP the issue? Absolutely.
My opinion is the carb needs attention... specifically the accellerator pump, I think... But does it need it RIGHT NOW? Absolutely not.. it runs fantastic, no starting issues, and great gas mileage.
But it does need a rebuilt to be Perfect. And I will, I just thought mentioning the fact that the Air Horn Bolts do work themselves loose might help someone down the road.
-Gonz
Bone Stock 86 Grand Prix. 305, 4bbl. 58k miles (yeah, I've been driving it Juuust a bit - Bought it 6 months ago with 50k Original Miles).
All I've done is a "normal" tune up - Plugs, Wires, Cap, Button. Left the coil alone.. Fluid Changes.
Runs great, but had this Slight miss on a very light touch of the gas pedal with a steady hold.. Sometimes.. not all the time.
Stomping on it, and opening the 4bbl with a quick, hard push gave me some hesitation, but after it "caught up", it ran quite well. I don't want to over dramatize it, it wasn't BAD.. Your 4bbl typically goes "Whom..Whooooom" - Mine went "Whom.. da da da da.. Whooooom"
So, since its getting warmer out, I have started doing "those little things" that come with owning a 30+ year old car. Little this, little that... but I never really did much to the engine since it really ran quite well. 27mpg cruising on the highway with the symptoms above, I'm not complaining. (200R4 4 Speed-stock open rear)
However, I did start perusing the forums about this hesitation and watched some youtubes just for hints/tips.. (I come here for REAL information, I take youtubes with a grain of salt) and ran across something that struck me as "ya know what... that isn't a bad idea to check"
I DID have a 44 code (Lean) and I attributed that to my HVAC Control Valve leaking constantly. The hiss was audible, and I tracked it down to that.. mainly because the only thing that worked was Defrost. I pushed on it, it made a difference, so... thats the culrpit. I changed it out, and now I have defrost, floor, vent, etc... But I did what follows at the same time, so I really can't say which thing helped. (probably both, but...)
The 9 or so top bolts (the hex bolts in my case) holding the air horn to the actual Body of the carb Can Work Themselves Loose, apparently... So, while I was piddling around, I just popped off the air cleaner and checked them.
7 out of 9 were loose.. Not a little loose... like 1/4 free turn, just move with your fingers, loose.
Tightened them up a bit, and with replacing the HVAC Control Valve (Get it from NAPA by the way - $29 instead of $50+ from other places, even RockAuto - which surprised the hell out of me) things are Much Better.
While the combination of snugging them down and the HVAC Control Valve replacement did NOT solve the issue completely, it sure helped a LOT.
The very light touch of the gas pedal with a steady hold is almost imperceptible now, and the hesitation with a quick wide open went down about 50%. (Whom.. da da.. Whooooom" for those that liked that description)
Did it SOLVE the issue? Absolutely not. Did it HELP the issue? Absolutely.
My opinion is the carb needs attention... specifically the accellerator pump, I think... But does it need it RIGHT NOW? Absolutely not.. it runs fantastic, no starting issues, and great gas mileage.
But it does need a rebuilt to be Perfect. And I will, I just thought mentioning the fact that the Air Horn Bolts do work themselves loose might help someone down the road.
-Gonz
