slight hesitation

anlo

Registered User
Not really strong enough to call bucking but ever so slight miss at light throttle slow speeds 1/4 throttle. 1/2 throttle doesn't affect rpms. Strong at wot. Good boost. So far. Resealed tubes -top cleaned throttle body changed. I a c. sealed. Vacuum lines only 10 VAcuum. At idle in drive. About. 12 / 13 in park. New plugs oil change transmission. fluid change. Cranks runs good just at part throttle 30. 40 MPH missing. Idle isn't. Perfect. But acceptable. Hoping wires are the culprit. Changing them today. Car to be driven to Texas this weekend. Any other suggestions? ???
1994. Auto
 
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Replacing plug wires sounds like a good idea.

Sometimes you can see arcing in the dark if they are starting to get worn areas in them.
 
cool

That's the. Last. Trick left in. My bag. Besides fuel filter. Then its trying to find a competent mechanic in the Houston area.. some one asked how its shifting. Could any component w tmission cause a symptom. Like this? Seems to shift good
 
Not really strong enough to call bucking but ever so slight miss at light throttle slow speeds 1/4 throttle. 1/2 throttle doesn't affect rpms. Strong at wot. Good boost. So far. Resealed tubes -top cleaned throttle body changed. I a c. sealed. Vacuum lines only 10 VAcuum. At idle in drive. About. 12 / 13 in park. New plugs oil change transmission. fluid change. Cranks runs good just at part throttle 30. 40 MPH missing. Idle isn't. Perfect. But acceptable. Hoping wires are the culprit. Changing them today. Car to be driven to Texas this weekend. Any other suggestions? ???
1994. Auto

Sounds like a small vacuum leak, possibly from a cracked hose going to the boost vacuum gauge. This would also account for the unusally low amount of vacuum showing on the gauge. If you have a stock cam you should be showing 19-21 inches of vacuum at idle. If the actual vacuum leak was that big, you wouldn't be able to keep the motor running without constant throttle input, and that's why I think it might be the line to the gauge that is leaking.

David

PS: If it were wires or other ignition parts, it would get much worse under a load and WOT.
 
Another vote for wires. My '94 daily driver SC started to show very similar symptoms about 6 weeks ago. Interestingly enough I first took notice of the problem a couple of days after I drove home in a torrential downpour. 2 weeks ago I finally changed the wires, and the issue has been resolved. Found some pretty rotten vacuum hoses while I was in there. Picked up some new hose and replaced a bunch of the vacuum hoses after that the idle improved.

There are a few of SC's in the Houston area, there is a mechanic up in the north suburbs that used to frequent the forum.
 
thanks

thanks guys about to do the wires and fuel filter in a little bit.. do yo have any details on the houston s/c guru ? my sons driving it back saturday to houston and would like to know theres someone in the area who knows the car for future reference.. thanks again todd

anyone heard from vernon lately ? have an email ?
 
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Sounds like a small vacuum leak, possibly from a cracked hose going to the boost vacuum gauge. This would also account for the unusally low amount of vacuum showing on the gauge. If you have a stock cam you should be showing 19-21 inches of vacuum at idle. If the actual vacuum leak was that big, you wouldn't be able to keep the motor running without constant throttle input, and that's why I think it might be the line to the gauge that is leaking.

David

PS: If it were wires or other ignition parts, it would get much worse under a load and WOT.


Agreed. Vacuum is light at 10 inches.
 
boost hose

boost hose seems sound sucked on it and held vacuum blew into it guage acted accordingly now i did the brake cleaner spray trick and the only place i can hear a raise in rpms seems to point to what is known as the evaporative emmision hose that runs from the rh fender well under the intake hose.. when sprayed directly behind throttle body rpms rise so wherever that evaporative hose connects could be leaking .. it runs underneath the throttle body to somewhere i cant see or really feel .. could this be a source of an extreme vac leak to cause these symtoms ???. after wires and fuel filter seems tiny bit better but i can re create my main issue by very light acceleration under light load.. does not occur while coasting or heavier acceleration. it sort of feels like bucking within the drive train and not the motor. as you add more throttle and t mission downshifts issue is not present.. if anyone knows exactly eher the evap. emmissions hose connects behind throttle body.?? i think i need to replace it. can it be replaced without removing a bunch of crap???

guage still reads 9-10 at idle in gear and about 12-13 in park at idle

the plugs i picked were autolite a5144 gapped at 52 is this bad ? no misfiring under wot boost is almost pegged and idles pretty darn good its just the in between where the problem is

ive done all i think i can my sons just gonna have to drive it back to houston and find VERNON to figure it out...
 
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boost hose seems sound sucked on it and held vacuum blew into it guage acted accordingly now i did the brake cleaner spray trick and the only place i can hear a raise in rpms seems to point to what is known as the evaporative emmision hose that runs from the rh fender well under the intake hose.. when sprayed directly behind throttle body rpms rise so wherever that evaporative hose connects could be leaking .. it runs underneath the throttle body to somewhere i cant see or really feel .. could this be a source of an extreme vac leak to cause these symtoms ???. after wires and fuel filter seems tiny bit better but i can re create my main issue by very light acceleration under light load.. does not occur while coasting or heavier acceleration. it sort of feels like bucking within the drive train and not the motor. as you add more throttle and t mission downshifts issue is not present.. if anyone knows exactly eher the evap. emmissions hose connects behind throttle body.?? i think i need to replace it. can it be replaced without removing a bunch of crap???

guage still reads 9-10 at idle in gear and about 12-13 in park at idle

the plugs i picked were autolite a5144 gapped at 52 is this bad ? no misfiring under wot boost is almost pegged and idles pretty darn good its just the in between where the problem is

ive done all i think i can my sons just gonna have to drive it back to houston and find VERNON to figure it out...


Smoke test
 
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