Rough running!
Discussion
Can anyone help ? I've had my 4.3 Chim for 2 years now and its always been rough below 2000rpm. If you are accelerating its fine, but if you try and run at a constant speed, say 40 - 50 in 5th 1300 - 1500 rpm it shunts the transmission and annoys the hell out of me!
When ticking over you can watch the engine and see it rock every few seconds as though there is an intermitant misfire maybe ?
I've taken it to both TVR in sheffield and Wedge TVR independant who have both changed bits but ended up saying the - 'they all do that sir', do they really ?
In attempts to cure this its had :
Plug leads (x2)
Distributor Cap (TVR one)
Plugs
Ignition Module
Just had a look at the stepper motor last night which maybe be knackered. Should it move when the ignition is turned on and off ? It just buzz's with no sign of movement at the moment. If I need a replacement is it a standard land rover part ? or a TVR special?
Paul
When ticking over you can watch the engine and see it rock every few seconds as though there is an intermitant misfire maybe ?
I've taken it to both TVR in sheffield and Wedge TVR independant who have both changed bits but ended up saying the - 'they all do that sir', do they really ?
In attempts to cure this its had :
Plug leads (x2)
Distributor Cap (TVR one)
Plugs
Ignition Module
Just had a look at the stepper motor last night which maybe be knackered. Should it move when the ignition is turned on and off ? It just buzz's with no sign of movement at the moment. If I need a replacement is it a standard land rover part ? or a TVR special?
Paul
sounds like you might well have found the problem.youd be unlucky not to see it move at all when turning ignition on/off as the stepper recieves a signal from ecu telling it to move dependant on several factors that the ecu knows-air temp,water temp,throttle opening,engine revs etc.so the likelyhood of you turning the ignition on when it doesnt need to move is very slim.take stepper out and wait for a big change in engine temp-ie let engine go from hot to stone cold then see if it moves.the stepper controls bypass air which is used for idle speed control,and if the valve is in the wrong place then the fuel mixture will be affected and poor running will occur.hope this helps-mv
Hi
Mine did that - 450 99 Chim. One TVR dealer and one TVR Independent tried to get it right. Both failed.
Usual stepper motor dirty stories etc. All rubbish.
It was the Inlet manifold gasket that had gone. Water was getting into 3 cylinders.
Steve Howard of Precision Racing Hurst fixed it straight away and many other bits for the cost of a TVR dealer "Service". In 16000 miles it was never right.
It now goes like a missile.
Mine did that - 450 99 Chim. One TVR dealer and one TVR Independent tried to get it right. Both failed.
Usual stepper motor dirty stories etc. All rubbish.
It was the Inlet manifold gasket that had gone. Water was getting into 3 cylinders.
Steve Howard of Precision Racing Hurst fixed it straight away and many other bits for the cost of a TVR dealer "Service". In 16000 miles it was never right.
It now goes like a missile.
Hi all
I've also had the same with mine (94 4.0HC)
Took it to David Batty at The Garage who put a code reader on the ECU (no errors found) and also had a test drive in the car.
His verdict was that it was nothing to worry about and it is basically down to the ECU getting confused when using relatively low revs
The signals from the engine side are saying the engine revs indicate tickover but the diff sensor says "hang on a minute, we are moving"!
Whilst I understand what he says, I'm not convinced there isnt something else contributing to this. It is annoying around town and the sports exhaust does make the problem sound worse. No problems on the open road though
I've checked the stepper motor, seems clean. The exhaust manifolds were done just before I bought the car in Feb. Someone else suggested an 'idle potentiometer'??
Any ideas??
Mark.
I've also had the same with mine (94 4.0HC)
Took it to David Batty at The Garage who put a code reader on the ECU (no errors found) and also had a test drive in the car.
His verdict was that it was nothing to worry about and it is basically down to the ECU getting confused when using relatively low revs
The signals from the engine side are saying the engine revs indicate tickover but the diff sensor says "hang on a minute, we are moving"!
Whilst I understand what he says, I'm not convinced there isnt something else contributing to this. It is annoying around town and the sports exhaust does make the problem sound worse. No problems on the open road though
I've checked the stepper motor, seems clean. The exhaust manifolds were done just before I bought the car in Feb. Someone else suggested an 'idle potentiometer'??
Any ideas??
Mark.
Mine did the same. I cleaned the stepper which was filthy but was also told that "5th gear is for motorways". So - doing 40-50 mph in 5th wasn't for my Chim. Since then, I've been conscious of gear/revs etc and she's running beautifully. Fifth only seems to run smoothly at over 2000 revs. Does yours run ok at the speed/revs you detail but in 4th gear ?
Nope, any gear and any speed, as long as the revs are below 2000rpm it will shunt the transmission.
A further point is the rev counter hunts up and down all the time, I've had two sets of plug leads which seemed to improve this, but its back with avengance.
Is it possible the leads have deteriated over the winter ? Its been in the garage for 6 months? The leads are good quality and have only covered about 1500 miles since new.
A further point is the rev counter hunts up and down all the time, I've had two sets of plug leads which seemed to improve this, but its back with avengance.
Is it possible the leads have deteriated over the winter ? Its been in the garage for 6 months? The leads are good quality and have only covered about 1500 miles since new.
We have noticed similer with ours (94 4.0L HC) around town but quickly came to the conclusion to run in a lower gear at around 30mph and keep the revs up a bit (sounds more impressive as well). It is a sports car after all, not a "normal" car. Runs smoothly on tickover and fine on open road.
This could be normal as many of the 500s were reknowned low bad low speed running. My first was not good at this but my current 500 is smooth but it was setup with a Tornado Chip by Mark Adams who also mapped it for unleaded fuel. Does save a few pennies to recoup the cost of the rechip.
Steve
www.tvrbooks.co.uk
Steve
www.tvrbooks.co.uk
paul,the hunting you describe is another symptom of a stepper motor fault.i currently have this problem on my everyday rover and know for sure its the stepper as i swapped mine with my fathers(same car) and its fine.if the stepper valve is open more than it should be then it will hunt,cause a lean mixture, which also encourages snappy behaviour coming off throttle and thus shunting(easily done on these cars anyway).try swapping it with someone elses if you can .id certainly let you swap with mine to try it out if its same type(griff 500),dont know if you live nearby though?
>> Edited by mongoose on Thursday 10th April 18:47
>> Edited by mongoose on Thursday 10th April 18:47
I've had a similar problem which got worse after I replaced the distributor cap.
At just over 2000 RPM the engine started running very lumpy and the rev counter jumped to about 2900 RPM, even though the engine seemed to be running at the same speed.
After passing about 3100 RPM the car was fine again.
It turned out to be caused by the HT leads being routed next to other signal wires (from the ignition amplifier and the distributor sensor), after routing the HT leads away from the other wires the car has been fine and the slightly lumpy running at low throttle openings (which I have always had) has now gone. I presume that the HT leads induced noise onto the other wires which was then fed into the ECU and upset it.
Hope this helps, costs nothing to try anyway.
Andy G
At just over 2000 RPM the engine started running very lumpy and the rev counter jumped to about 2900 RPM, even though the engine seemed to be running at the same speed.
After passing about 3100 RPM the car was fine again.
It turned out to be caused by the HT leads being routed next to other signal wires (from the ignition amplifier and the distributor sensor), after routing the HT leads away from the other wires the car has been fine and the slightly lumpy running at low throttle openings (which I have always had) has now gone. I presume that the HT leads induced noise onto the other wires which was then fed into the ECU and upset it.
Hope this helps, costs nothing to try anyway.
Andy G
paulj said: Nope, any gear and any speed, as long as the revs are below 2000rpm it will shunt the transmission.
A further point is the rev counter hunts up and down all the time, I've had two sets of plug leads which seemed to improve this, but its back with avengance.
Is it possible the leads have deteriated over the winter ? Its been in the garage for 6 months? The leads are good quality and have only covered about 1500 miles since new.
Doubt it, but anything's possible. I'd check the plug extender thingys, only a few quid each from ACT (advertise on this site). They deteriorate with age too.
rude girl said:
joospeed said: if you're near sheffield why not bring it down to me .. I'll take a look over a couple of days, if I don't fix it you owe me nothing .. can't say fairer than that?
Now thats what i call a service.
rude girl said:
Quote:
This is why we all love Joolz
Well, some of us love him for other reasons too
Blimey !!
Chaps and chapesses
My understanding of all this rough running/shunting at low revs is due to the bias on the Lambda sensors. ie at low revs (below 3100rpm i think) the Lambda sensors adjust the mixture ratio depending on what they think is best. My sensors were giving max richness at idle and varying the mixture up to 3100rpm. However I think that the low speed shunting is due to the lambda sensors not being quick enough to keep up with the small throttle demands we make in traffic queues etc. ie they were swinging from "no extra fuel=0%" to "max extra fuel=20%" and causing the shunting.
The same will be true with a dodgy stepper motor not sealing properly due to crap on it or indeed a leaky manifold gasket for example. Nothing wrong with the sensors they are just doing their best under difficult circumstances hance the shunting as they change the mixture to try and compensate for the extra air.
The problem on my car was due to 3 almost non-funtioning injectors. Therefore the Lambda sensors saw a weak mixture due to a lack of fuel in 3 of the cylinders and tried to compensate. Now with a new set of injectors and a mapping session concentrating on the low speed handling (thanks Mark its much better...) the lambda sensors now only compensate by 6% instead of the 20% they were compenstating by, so they swing from 0% to 6% therefore less shunting. And less to come as we had to cut short our mapping session.
I could be wrong of course but this is how I see it.
The rev counter hunting problem was cured on my car by fitting a Bosch coil. Basically the pattern coil (as fitted by TVR???) had broken down inside and there was a short circuit.
(BTW the rev counter runs off the electrical pulses from the coil)
Hope it all makes sense.
Cheers
Ed
My understanding of all this rough running/shunting at low revs is due to the bias on the Lambda sensors. ie at low revs (below 3100rpm i think) the Lambda sensors adjust the mixture ratio depending on what they think is best. My sensors were giving max richness at idle and varying the mixture up to 3100rpm. However I think that the low speed shunting is due to the lambda sensors not being quick enough to keep up with the small throttle demands we make in traffic queues etc. ie they were swinging from "no extra fuel=0%" to "max extra fuel=20%" and causing the shunting.
The same will be true with a dodgy stepper motor not sealing properly due to crap on it or indeed a leaky manifold gasket for example. Nothing wrong with the sensors they are just doing their best under difficult circumstances hance the shunting as they change the mixture to try and compensate for the extra air.
The problem on my car was due to 3 almost non-funtioning injectors. Therefore the Lambda sensors saw a weak mixture due to a lack of fuel in 3 of the cylinders and tried to compensate. Now with a new set of injectors and a mapping session concentrating on the low speed handling (thanks Mark its much better...
) the lambda sensors now only compensate by 6% instead of the 20% they were compenstating by, so they swing from 0% to 6% therefore less shunting. And less to come as we had to cut short our mapping session. I could be wrong of course but this is how I see it.
The rev counter hunting problem was cured on my car by fitting a Bosch coil. Basically the pattern coil (as fitted by TVR???) had broken down inside and there was a short circuit.
(BTW the rev counter runs off the electrical pulses from the coil)
Hope it all makes sense.
Cheers
Ed
Sorry guys
I meant to say....
cue A-Team music
The bottom line is, if you have a problem and you can find him.......maybe you can hire......Mark Adams.
As shpub has often said a rolling road session is sometimes the quickest way of solving a fuel injection or electrical problem rather than just replacing part after part.
Cheers
Ed
I meant to say....
cue A-Team music
The bottom line is, if you have a problem and you can find him.......maybe you can hire......Mark Adams.
As shpub has often said a rolling road session is sometimes the quickest way of solving a fuel injection or electrical problem rather than just replacing part after part.
Cheers
Ed
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