please help - misfire
Discussion
Going to le mans with the TVRCC in two weeks and the chim has started acting up...
Its a misfire but it is puzzling and would appreciate any ideas.
It started off with a single one off 'jolt' once in a while and now the car sounds different a idle but idles OK but wont rev past 3500 / 4000 rpm, especially under load. Have driven it but have to stick to about 2500 / 3000 rpm and short shift - driving on torque if you like.
Was hoping it was a dodgy plug or lead and would clear up when i did the full service at the weekend (new plugs (went for the bosch super 4 ones...? and leads (magnecor), oul, filters, etc plus an all round clean up) but it hasn't - if anything its a little worse...
Thoughts are...
Ignition coil - swapped over with an old one last night and still the same plus the one on the car is relatively new (a year or so) - flamethrower type..?
Timing - since the car ticks over and only has a problem revving dont think its this plus why / how would it change..?
distributor - seems OK but if anyone has had problems it may be worth checking..?
ignition module - the symptons seem the same as described in the bible - is this a landrover part or a specific TVR unit? If its cheap enough may just order one and eliminate it...
Sorry for the long post but am in a bit of a plight trying to get the car sorted out for the Le mans trip - The local dealer (HHC) is very busy at the moment so am trying to get this sorted myself plus driving there is difficult!
Thanks in advance for any replies.
Its a misfire but it is puzzling and would appreciate any ideas.
It started off with a single one off 'jolt' once in a while and now the car sounds different a idle but idles OK but wont rev past 3500 / 4000 rpm, especially under load. Have driven it but have to stick to about 2500 / 3000 rpm and short shift - driving on torque if you like.
Was hoping it was a dodgy plug or lead and would clear up when i did the full service at the weekend (new plugs (went for the bosch super 4 ones...? and leads (magnecor), oul, filters, etc plus an all round clean up) but it hasn't - if anything its a little worse...
Thoughts are...
Ignition coil - swapped over with an old one last night and still the same plus the one on the car is relatively new (a year or so) - flamethrower type..?
Timing - since the car ticks over and only has a problem revving dont think its this plus why / how would it change..?
distributor - seems OK but if anyone has had problems it may be worth checking..?
ignition module - the symptons seem the same as described in the bible - is this a landrover part or a specific TVR unit? If its cheap enough may just order one and eliminate it...
Sorry for the long post but am in a bit of a plight trying to get the car sorted out for the Le mans trip - The local dealer (HHC) is very busy at the moment so am trying to get this sorted myself plus driving there is difficult!
Thanks in advance for any replies.
Hi Peter, I have read of people with similar problems, who ended up changing lots of parts trying to trace the fault, may be worth it to book it into a tuning place like A19 tune if your located in the south of Durham or look in the yellow pages for someone similar if not.
may end up saving you money.
But as a start I would unplug and replug the ecu (just like resetting your computer)
check the connections on the AFM,
remove the hose from the airflow meter (to checking that the air filter is not choked)
be careful nothing gets sucked into the engine !!!
On the distributor there is a unit that advances the ignition timing at higher revs
this is driven of vacuum from the induction side but I am unsure if this would give the faults you are describing.
Spark plugs,Bosch super 4, I was thinking of trying them, but decided against it as there was some posts on here that said not to use them.
could be low fuel line pressure (not getting enough fuel into the engine at higher revs) not sure how you would test for that without special equipment.
Phil
may end up saving you money.
But as a start I would unplug and replug the ecu (just like resetting your computer)
check the connections on the AFM,
remove the hose from the airflow meter (to checking that the air filter is not choked)
be careful nothing gets sucked into the engine !!!
On the distributor there is a unit that advances the ignition timing at higher revs
this is driven of vacuum from the induction side but I am unsure if this would give the faults you are describing.
Spark plugs,Bosch super 4, I was thinking of trying them, but decided against it as there was some posts on here that said not to use them.
could be low fuel line pressure (not getting enough fuel into the engine at higher revs) not sure how you would test for that without special equipment.
Phil
Edited by PRTVR on Wednesday 30th May 12:56
Edited by PRTVR on Wednesday 30th May 12:57
sorry but they have a lousy failure rate,if your going to fit plugs Denso or NGK.[quote=PRTVR]Hi Peter, I have read of people with similar problems, who ended up changing lots of parts trying to trace the fault, may be worth it to book it into a tuning place like A19 tune if your located in the south of Durham or look in the yellow pages for someone similar if not.
may end up saving you money.
But as a start I would unplug and replug the ecu (just like resetting your computer)
check the connections on the AFM,
remove the hose from the airflow meter (to checking that the air filter is not choked)
be careful nothing gets sucked into the engine !!!
On the distributor there is a unit that advances the ignition timing at higher revs
this is driven of vacuum from the induction side but I am unsure if this would give the faults you are describing.
Spark plugs,Bosch super 4, I was thinking of trying them, but decided against it as there was some posts on here that said not to use them.
could be low fuel line pressure (not getting enough fuel into the engine at higher revs) not sure how you would test for that without special equipment.
Phil
A19 Tune - they are good yeh..?
Thanks for your thoughts - I would love to book it into a garage and them to find and fix the problem the two local places I either know about ot have been told about (HHC or R&P Woods in newcastle) cannot fit me in!!!
Tried un plugging the ECU - no difference
Tried swapping the ECU with a spare unit - no difference
Will double check the AFM - have a spare one of them so might swap instead...
Filter is a K&N and has just been cleaned and re-oiled
Will double check the advance retard mechanism but it doesnt feel like that...?
Not had any problems with BOSCH plugs in the past, just thought i would give them a go...
Fuelling is a thought - will check that next.
Have ordered an Ignition module from HHC - should arrive tomorrow - hopefully fitting that will solve all my problems - if not its another spare I have and its back to the drawing board...oh well...
may end up saving you money.
But as a start I would unplug and replug the ecu (just like resetting your computer)
check the connections on the AFM,
remove the hose from the airflow meter (to checking that the air filter is not choked)
be careful nothing gets sucked into the engine !!!
On the distributor there is a unit that advances the ignition timing at higher revs
this is driven of vacuum from the induction side but I am unsure if this would give the faults you are describing.
Spark plugs,Bosch super 4, I was thinking of trying them, but decided against it as there was some posts on here that said not to use them.
could be low fuel line pressure (not getting enough fuel into the engine at higher revs) not sure how you would test for that without special equipment.
Phil
A19 Tune - they are good yeh..?
Thanks for your thoughts - I would love to book it into a garage and them to find and fix the problem the two local places I either know about ot have been told about (HHC or R&P Woods in newcastle) cannot fit me in!!!
Tried un plugging the ECU - no difference
Tried swapping the ECU with a spare unit - no difference
Will double check the AFM - have a spare one of them so might swap instead...
Filter is a K&N and has just been cleaned and re-oiled
Will double check the advance retard mechanism but it doesnt feel like that...?
Not had any problems with BOSCH plugs in the past, just thought i would give them a go...
Fuelling is a thought - will check that next.
Have ordered an Ignition module from HHC - should arrive tomorrow - hopefully fitting that will solve all my problems - if not its another spare I have and its back to the drawing board...oh well...
pja said:
Im sure if thats the only reason they are there TVR would have fitted longer leads
I'm not arguing with their function, merely double checking you mean the same thing. If you search the last 5-6 years of posts regarding those parts I think you'll find they've usually been referred to as plug extenders. 
A19 tuning ...heard mixed reports about them but no worse than other garages, but I would think any auto electrician - tuning garage, Land Rover garage, would be able to do the tests,
you have a fault that can be repeated and that should be easy to trace,
How does it run with the fuel filler cap off ? just thinking that the vent system may not be working properly.
Phil
you have a fault that can be repeated and that should be easy to trace,
How does it run with the fuel filler cap off ? just thinking that the vent system may not be working properly.
Phil
A19 tuning ...heard mixed reports about them but no worse than other garages, but I would think any auto electrician - tuning garage, Land Rover garage, would be able to do the tests,
you have a fault that can be repeated and that should be easy to trace,
Agreed - not rocket science, just need to find someone I trust.
How does it run with the fuel filler cap off ? just thinking that the vent system may not be working properly.
Easy enough to try i guess...
Plug extenders are only a year old from Tim @ ACT...but, again, should be easy enough to remove to temporarily test for a miss...
Dizzy cap and rotor arm are also relatively new and proper lucas items...less than 4000 miles...
Sorry to keep seemingly rubbishing thoughts on possible reasons but now you might be getting an understanding of how confusing it is when most of the parts are new and of good quality!!! Keep them coming though...
you have a fault that can be repeated and that should be easy to trace,
Agreed - not rocket science, just need to find someone I trust.
How does it run with the fuel filler cap off ? just thinking that the vent system may not be working properly.
Easy enough to try i guess...
Plug extenders are only a year old from Tim @ ACT...but, again, should be easy enough to remove to temporarily test for a miss...
Dizzy cap and rotor arm are also relatively new and proper lucas items...less than 4000 miles...
Sorry to keep seemingly rubbishing thoughts on possible reasons but now you might be getting an understanding of how confusing it is when most of the parts are new and of good quality!!! Keep them coming though...
Around this area there are a couple of mobile guys that have Krypton type tuners in ther back of their vans. One is called "Mobile-Tune" Original I know! Perhaps others will have similarly inventive names. Don't know how good they are but perhaps their diagnostic skills would at least help pinpoint your problem. Yellow pages?Edited by s5tuart on Wednesday 30th May 18:34
peteA said:
A19 tuning ...heard mixed reports about them but no worse than other garages, but I would think any auto electrician - tuning garage, Land Rover garage, would be able to do the tests,
you have a fault that can be repeated and that should be easy to trace,
Agreed - not rocket science, just need to find someone I trust.
How does it run with the fuel filler cap off ? just thinking that the vent system may not be working properly.
Easy enough to try i guess...
Plug extenders are only a year old from Tim @ ACT...but, again, should be easy enough to remove to temporarily test for a miss...
Dizzy cap and rotor arm are also relatively new and proper lucas items...less than 4000 miles...
Sorry to keep seemingly rubbishing thoughts on possible reasons but now you might be getting an understanding of how confusing it is when most of the parts are new and of good quality!!! Keep them coming though...
Do you need to trust them ? you know your car pretty well it appears, and could guide them in what you want, and were things are, its not as if they are going to dismantle anythings just check things out with equipment you don't have.you have a fault that can be repeated and that should be easy to trace,
Agreed - not rocket science, just need to find someone I trust.
How does it run with the fuel filler cap off ? just thinking that the vent system may not be working properly.
Easy enough to try i guess...
Plug extenders are only a year old from Tim @ ACT...but, again, should be easy enough to remove to temporarily test for a miss...
Dizzy cap and rotor arm are also relatively new and proper lucas items...less than 4000 miles...
Sorry to keep seemingly rubbishing thoughts on possible reasons but now you might be getting an understanding of how confusing it is when most of the parts are new and of good quality!!! Keep them coming though...
as for the petrol cap idea, read straw grasp
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