lumpy engine - any ideas?
Discussion
folks, on my last two journeys, on a few occasions when under acceleration the car has been very lumpy. It's alomst as if it's running a cylinder or two short, with the feeling that once it's cleared its throat it kicks in and goes - a bit 'kangarooey' if you know what I mean. The thing is it doesnt happen all the time. I've also come to notice the lumpiness when cruising along so that when I press the throttle down it exacerabates the lumpiness. Like I say, it doesn't happen all the time and when idling it seems very smooth.
I'm thinking of running it into the garage but would be interested in what folks on here think it might be (electrical (coil/leads)?; mechanical throttle bodies/shim)?; fuelling?) in case I have to prepare myself for a large bill!
Thanks.
I'm thinking of running it into the garage but would be interested in what folks on here think it might be (electrical (coil/leads)?; mechanical throttle bodies/shim)?; fuelling?) in case I have to prepare myself for a large bill!
Thanks.
Have you got a diagnostics lead? Mine was a little hesitant around 2,200 rpm and generally a little lumpy at low speeds.
I sorted mine out by adjusting the idle speed (was a little low), reset the throttle and adaptive maps, and it's been running sweet ever since.
Well, that was until I neatly ran out of petrol and the lumpiness returned. Again, sorted it by deleting adaptive maps. Couple months down the line and still good.
I sorted mine out by adjusting the idle speed (was a little low), reset the throttle and adaptive maps, and it's been running sweet ever since.
Well, that was until I neatly ran out of petrol and the lumpiness returned. Again, sorted it by deleting adaptive maps. Couple months down the line and still good.
It sounds like a fuel / air issue to me - particularly if it 'clears its throat' at times.
When was it last serviced, how many miles has the car done total? my experience with throttle bodies shows they leak...all over...go out of balance quickly and can make a big difference to how the car feels. I have changed to roller bearing throttle bodies and invested in some throttle body gaskets - made a huge difference.
Can you access software and a syncrometer? A quick run up to check the throttle body balance would tell you a lot.
Some other basic checks if you feel up to it...unplug each of the injectors briefly to check they all change the running 'tone' of the engine - if one doesnt, check it out. Use a spark plug tester if you have one to check them out - of touch each of the manifolds with a tie wrap - if it doesnt melt, check out that spark / injector.
When was it last serviced, how many miles has the car done total? my experience with throttle bodies shows they leak...all over...go out of balance quickly and can make a big difference to how the car feels. I have changed to roller bearing throttle bodies and invested in some throttle body gaskets - made a huge difference.
Can you access software and a syncrometer? A quick run up to check the throttle body balance would tell you a lot.
Some other basic checks if you feel up to it...unplug each of the injectors briefly to check they all change the running 'tone' of the engine - if one doesnt, check it out. Use a spark plug tester if you have one to check them out - of touch each of the manifolds with a tie wrap - if it doesnt melt, check out that spark / injector.
thanks for your help/suggestions - much appreciated. I've only just managed to get back on-line after my posting so with apologies for pause in reply....
I nurse the car when it's cold, keeping the revs down so only noticed the problem when it's properly warmed up (i.e. 70+).
Car was last serviced in June and it's done less than 1000 miles since then. The tappets were examined at the same time and only minor adjustment was needed. I have the tappets examined and if necessary adjusted at every annual service.
Car has done about 38,000 miles. It hasn't had any engine work done to it (it's a very early 2003 car). At what sort of mileage does a worn throttle body issue generally arise?
At idle, the car seems fine and I havent noticed the problem when warming the car up. It's only after it's been warmed and I've given it the beans that the problem occurs. It's only then that I notice the occasional lumpiness when crusing along. Like I say, it doesn't do it all the time, but it's a little more frequent than "now and then", if you known what I mean!
I did wonder about the coil pack as it's never been changed whereas the leads have been (about 2 years ago). Is there any way to check if the coil pack is working properly?
I nurse the car when it's cold, keeping the revs down so only noticed the problem when it's properly warmed up (i.e. 70+).
Car was last serviced in June and it's done less than 1000 miles since then. The tappets were examined at the same time and only minor adjustment was needed. I have the tappets examined and if necessary adjusted at every annual service.
Car has done about 38,000 miles. It hasn't had any engine work done to it (it's a very early 2003 car). At what sort of mileage does a worn throttle body issue generally arise?
At idle, the car seems fine and I havent noticed the problem when warming the car up. It's only after it's been warmed and I've given it the beans that the problem occurs. It's only then that I notice the occasional lumpiness when crusing along. Like I say, it doesn't do it all the time, but it's a little more frequent than "now and then", if you known what I mean!
I did wonder about the coil pack as it's never been changed whereas the leads have been (about 2 years ago). Is there any way to check if the coil pack is working properly?
Your description of what yours is doing is almost identical to mine (2001 Tuscan 52K miles no rebuild).
Most of the time, it is as strong as an Ox but occasionally, when you put your foot down, it almost hesitates as if only 3 cylinders are firing until it clears its throat at which point it pulls fine to the top of the rev band.
To me, it feels as though something is occasionally putting it into the wrong part of the Map. It only does this under load.
I am told that the intermittent nature suggests that it probably isn't plugs and leads, but you can check this by removing them one by one. It also does not seem to be temperature or dampness related.
The advice I have had is that it sounds electrical, probably sensor related - either Throttle Position sensor on one bank or perhaps the block temperature sensor. I believe it is one of th TPSs.
The way to check this is to get the software connected and go for a drive monitoring the values. when it goes wrong. see what has changed. I planned to do this this week but haven't as yet. I might do tomorrow and will let you know what happens.
Bob
Most of the time, it is as strong as an Ox but occasionally, when you put your foot down, it almost hesitates as if only 3 cylinders are firing until it clears its throat at which point it pulls fine to the top of the rev band.
To me, it feels as though something is occasionally putting it into the wrong part of the Map. It only does this under load.
I am told that the intermittent nature suggests that it probably isn't plugs and leads, but you can check this by removing them one by one. It also does not seem to be temperature or dampness related.
The advice I have had is that it sounds electrical, probably sensor related - either Throttle Position sensor on one bank or perhaps the block temperature sensor. I believe it is one of th TPSs.
The way to check this is to get the software connected and go for a drive monitoring the values. when it goes wrong. see what has changed. I planned to do this this week but haven't as yet. I might do tomorrow and will let you know what happens.
Bob
when i looked into the throttle body wear it typically occurs at 30k miles + one sign is, when in a higher gear and light throttle it feels like a hesitation or misfire. Its not noticable all the time.
However i would expect it to go off tune slightly and be lumpy at idle too.
It could also be throttle pots. Which could in
turn affect fueling
Let us know how u get on!
However i would expect it to go off tune slightly and be lumpy at idle too.
It could also be throttle pots. Which could in
turn affect fueling
Let us know how u get on!
Edited by Robertjp on Thursday 18th October 22:51
Mine has been running quite bad recently.
Its been missfiring under moderate to hard acceleration.
Ended up driving down to Coventry to get a new chip fitted at Doms only 3 days before heading off to Spain.
Had a fuel leak on the way down but seemed much better but before the end of the first week was noticing the same symptoms.
Got steadily worse but still driveable up to Moderate acceleration.
Had to leave it at home unfixed to leave for a 5 week business trip but heading home at the weekend and so back to finding out what it is.
I'll post my results.
Good luck.
Its been missfiring under moderate to hard acceleration.
Ended up driving down to Coventry to get a new chip fitted at Doms only 3 days before heading off to Spain.
Had a fuel leak on the way down but seemed much better but before the end of the first week was noticing the same symptoms.
Got steadily worse but still driveable up to Moderate acceleration.
Had to leave it at home unfixed to leave for a 5 week business trip but heading home at the weekend and so back to finding out what it is.
I'll post my results.
Good luck.
so called said:
Mine has been running quite bad recently.
Its been missfiring under moderate to hard acceleration.
Ended up driving down to Coventry to get a new chip fitted at Doms only 3 days before heading off to Spain.
Had a fuel leak on the way down but seemed much better but before the end of the first week was noticing the same symptoms.
Got steadily worse but still driveable up to Moderate acceleration.
Had to leave it at home unfixed to leave for a 5 week business trip but heading home at the weekend and so back to finding out what it is.
I'll post my results.
Good luck.
Best of luck with getting her fixed. Sounds like a blocked injector or ignition problem maybe? Its been missfiring under moderate to hard acceleration.
Ended up driving down to Coventry to get a new chip fitted at Doms only 3 days before heading off to Spain.
Had a fuel leak on the way down but seemed much better but before the end of the first week was noticing the same symptoms.
Got steadily worse but still driveable up to Moderate acceleration.
Had to leave it at home unfixed to leave for a 5 week business trip but heading home at the weekend and so back to finding out what it is.
I'll post my results.
Good luck.
Would have thought Dom would have picked that up straight away though.
If it missing throughout the rev range or just at one point?
Robertjp said:
Best of luck with getting her fixed. Sounds like a blocked injector or ignition problem maybe?
Would have thought Dom would have picked that up straight away though.
If it missing throughout the rev range or just at one point?
Not really sure. It's basically and hard acceleration between 1500 and 3000.Would have thought Dom would have picked that up straight away though.
If it missing throughout the rev range or just at one point?
Also if I load the engine when really I should have dropped down a gear.
This problem existed before I left for Spain. One of the last things done was to change the rubber fuel pipe to the injector 'thingy'.
Then 2 days later I had to change the pipe again as it was a real mess. I thought at the time that some particles of rubber must have passed through.
But like I say this was after the problem existed.
Back home Saturday so will head to Torque RVT in the week.
Ian, help !!!
so called said:
Not really sure. It's basically and hard acceleration between 1500 and 3000.
Also if I load the engine when really I should have dropped down a gear.
This problem existed before I left for Spain. One of the last things done was to change the rubber fuel pipe to the injector 'thingy'.
Then 2 days later I had to change the pipe again as it was a real mess. I thought at the time that some particles of rubber must have passed through.
But like I say this was after the problem existed.
Back home Saturday so will head to Torque RVT in the week.
Ian, help !!!
What's the fuel consumption like? IIRC 3k revs is around the point the engine goes into open loop so maybe be a dodgy lambda causing over fueling in the closed loop zone. Have you checked your adaptive maps? Also if I load the engine when really I should have dropped down a gear.
This problem existed before I left for Spain. One of the last things done was to change the rubber fuel pipe to the injector 'thingy'.
Then 2 days later I had to change the pipe again as it was a real mess. I thought at the time that some particles of rubber must have passed through.
But like I say this was after the problem existed.
Back home Saturday so will head to Torque RVT in the week.
Ian, help !!!
First of all I would link up the diagnostic and reset all adaptives, checking for faults too, then I would check all the throttle bodies are taking in the same amount of air with an flow meter, then I would start on such things like plug leads and coil pack. After that I'm stuffed as what to do.
Basil Brush said:
What's the fuel consumption like? IIRC 3k revs is around the point the engine goes into open loop so maybe be a dodgy lambda causing over fueling in the closed loop zone. Have you checked your adaptive maps?
I feel like I'm steeling this thread but hopefully the advise is helpful for the OP.Regarding fuel. I have been smelling fuel for many weeks now and fuel consumption is up.
One strange thing was when driving back from Spain. North of Madrid, we got tangled up in the Tour of Spain bike race. Had to wait for the road through the mountains to our hotel to open. Once we were underway slowly climbing the mountain in a stream of traffic, the smell of fuel was vegy bad. It continued until we were on the downward run. After a lot of slow second gear driving on steep roads, still stinking of fuel, I changed up to third and the engine cut out. I tried to bump start several times but no. After free wheeling for about 10 minutes down the switchback road, with next to no, it got so hairy I tried to bump start again she fired up fine. Smell of petrol dissappeared and she rant much better then for the rest of the drive home ?
I love my TVR
Can't really say on the revs but I think below 3k.
She gets regular services at TorqueRVT and Ian always balances the throttles etc.
He had to do it early this last time because she was running so bad and he said that she was way out with one side running rich.
Apoligies to Fimbo for being your thread parasite but just wanted to update on the outcome for my problem.
It turned out to be an overheated coil pack.
The 3 and 6 coils were showing very clear signs of overheating with melted core plastic and bulging etc.
Car is now running fine again.
Thanks Fimbo and all.
It turned out to be an overheated coil pack.
The 3 and 6 coils were showing very clear signs of overheating with melted core plastic and bulging etc.
Car is now running fine again.
Thanks Fimbo and all.
Edited by so called on Friday 26th October 10:01
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