Big flat spot on throttle pick up
Discussion
I've just bought a '94 4.0 litre (fab car!)
It has a problem that occurs when starting a journey from hot (i.e. car already warmed up).
When ever I take my foot off the throttle (coasting in gear) and then put my foot down again to accelerate, the car lurches (like there's no fuel)for a second then shoots off again. This also happens when changing gear upwards to accelerate. It makes the car practically undriveable.
It also manifests when sat still idling - If I aggressively blip the throttle the Chim does a massive hiccup (with an air sucking type noise) before the revs rise.
Does anyone have any ideas? This is spoiling the fun with my new car!
It has a problem that occurs when starting a journey from hot (i.e. car already warmed up).
When ever I take my foot off the throttle (coasting in gear) and then put my foot down again to accelerate, the car lurches (like there's no fuel)for a second then shoots off again. This also happens when changing gear upwards to accelerate. It makes the car practically undriveable.
It also manifests when sat still idling - If I aggressively blip the throttle the Chim does a massive hiccup (with an air sucking type noise) before the revs rise.
Does anyone have any ideas? This is spoiling the fun with my new car!
Clearly there's a fault, but you already knew that.
This sort of problem can be caused by a wide range of faults and can be hard to track down unless you're experienced at this sort of thing. If you're a gambling man you can try guessing where the fault is and substitute components until it goes away but this can be expensive and time consuming, and there's a risk that you do more damage along the way.
I suggest you take the car in to your local TVR specialist and ask them to have a look at it, it does not sound like an expensive problem to me.
This sort of problem can be caused by a wide range of faults and can be hard to track down unless you're experienced at this sort of thing. If you're a gambling man you can try guessing where the fault is and substitute components until it goes away but this can be expensive and time consuming, and there's a risk that you do more damage along the way.
I suggest you take the car in to your local TVR specialist and ask them to have a look at it, it does not sound like an expensive problem to me.
OK I'm gonnabe first to say...
Stepper Motor
http://tvrsseries.com/steppermotor/steppermotor.htm
Worth a go I reckon.
Cheers
Matt
>> Edited by M@H on Thursday 20th May 12:51
Stepper Motor
http://tvrsseries.com/steppermotor/steppermotor.htm
Worth a go I reckon.
Cheers
Matt
>> Edited by M@H on Thursday 20th May 12:51
shnozz said:
mine is doing this a little at the mo too. Cleaned the stepper motor and no joy. Going to try a new set of HT leads and new Bosch coil after some great input from Phers on my thread "bit lumpy"
When you put the stepper motor back, did it have a washer ??
I've just had similar symptoms, erratic tickover/flat spot after cleaning, and it didn't really need cleaning before I removed it !!!
It appears I had too much "washer" on the threads (PTFE tape) stopping the motor being screwed in far enough for its valve to seat and bleed the correct amount of air!!
How many others may have done the same ?? Do suggest you check that the shoulder is "nearly" up against the Plenum Chamber, PTFE tape should be used to "seal", but not too much.
Trev McM
K4TRV said:
mine is doing this a little at the mo too. Cleaned the stepper motor and no joy. Going to try a new set of HT leads and new Bosch coil after some great input from Phers on my thread "bit lumpy"
When you put the stepper motor back, did it have a washer ??
I've just had similar symptoms, erratic tickover/flat spot after cleaning, and it didn't really need cleaning before I removed it !!!
It appears I had too much "washer" on the threads (PTFE tape) stopping the motor being screwed in far enough for its valve to seat and bleed the correct amount of air!!
How many others may have done the same ?? Do suggest you check that the shoulder is "nearly" up against the Plenum Chamber, PTFE tape should be used to "seal", but not too much.
Trev McM
never had any probs before I must say. just suddenly developed in the last week or so. Felt as though the fuel was cutting out. At the time, I was running a little low and going around a slight bend in the motorway so just thought I was almost out of gas and eased off to a petrol station. My SM doesnt have any tape on it. just screwed in the most annoyingly difficult place to get a spanner on
cant see much in there to know if its screwed in ok.
Cleaned the stepper motor (came off with a 32mm socket no problem). But this has not cured the intermittent flat spot.
Also took advice and have been along to local dealer. It misbehaved nicely for us throwing us both down the road in a jerky manner, but they have no idea what the problem is either!
have re-set the ECU, and also tested the fuel cut out trembler switch under the dash. No joy so far. It is not temperature related since it has now misbehaved from cold as well as when warmed up.
Any more ideas chaps?
Also took advice and have been along to local dealer. It misbehaved nicely for us throwing us both down the road in a jerky manner, but they have no idea what the problem is either!
have re-set the ECU, and also tested the fuel cut out trembler switch under the dash. No joy so far. It is not temperature related since it has now misbehaved from cold as well as when warmed up.
Any more ideas chaps?
What you don’t want is the mixture running too lean, as this will kill the piston crown, and lead into a hole. It sounds like starvation of big proportions, and the horridness of it all sound likely.
Good pressure at fuel pump (remember that sound)
Coil these tend to spring a leak (its hot enit)
Distributor, is it clean?
Basic stuff I know but worth ten mins. with a spanner, and a flat head screwdriver.
Hope it helps. Fingers crossed.
Good pressure at fuel pump (remember that sound)
Coil these tend to spring a leak (its hot enit)
Distributor, is it clean?
Basic stuff I know but worth ten mins. with a spanner, and a flat head screwdriver.
Hope it helps. Fingers crossed.
might want to have a look at this recent thread of mine. minded to replace the coil
www.pistonheads.com/gassing/topic.asp?t=100306&f=8&h=0
www.pistonheads.com/gassing/topic.asp?t=100306&f=8&h=0
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