Help - Speed Six Engine Issues
Discussion
Hi All,
Need some help diagnosing an issue with the old girl.....
Travelled all the way to South of France without an issue, and was here a while before she wouldn't start in the morning and noticed even when driving voltage was only 11.9/12.0 volts... Found an old-school English mechanic who suspected Alternator so replaced that and all seemed fine for a while.
However now I've got other type of engine issue. She starts fine, and under half-to-full throttle appears to go fine too, but anything less than half throttle and she stutters and spits and misfires... so much so that at every junction and roundabout engine stalls. To keep the engine running I have to hold it an 1500 rpm and its running very uneven and theres vibration like a misfire and a constant smell of unburnt fuel.
I've been through putting in new plugs, then a new coil pack, then new HT leads based on phone calls back to UK specialists but the problem is still there and I'm at a loss.
Finally managed to get EvoOlli's diagnostics running on a borrowed laptop... can't get the TVR diagnostiscs to run...heres some screen prints...
First use of Diagnostics after starting up...
Think some errors were when Alternator was playing up so reset them and warmed up before a run... having to hold at 1500rpm though otherwise will stall...
After a run... keep getting Crank Sensor error but no other errors logged after clearing... Turned off, Turned on again, went for another run, Crank Sensor error again..
And here's a quick snapshot of the logs.....
Today I tried to get to Lambda sensors to swap them over to see if anything changed.... but on axle stands with very few tools it is nigh on impossible.
Desperately in need of some help and advice - I need to get her back to England !!!
Thanks in advance
Mike
Need some help diagnosing an issue with the old girl.....
Travelled all the way to South of France without an issue, and was here a while before she wouldn't start in the morning and noticed even when driving voltage was only 11.9/12.0 volts... Found an old-school English mechanic who suspected Alternator so replaced that and all seemed fine for a while.
However now I've got other type of engine issue. She starts fine, and under half-to-full throttle appears to go fine too, but anything less than half throttle and she stutters and spits and misfires... so much so that at every junction and roundabout engine stalls. To keep the engine running I have to hold it an 1500 rpm and its running very uneven and theres vibration like a misfire and a constant smell of unburnt fuel.
I've been through putting in new plugs, then a new coil pack, then new HT leads based on phone calls back to UK specialists but the problem is still there and I'm at a loss.
Finally managed to get EvoOlli's diagnostics running on a borrowed laptop... can't get the TVR diagnostiscs to run...heres some screen prints...
First use of Diagnostics after starting up...
Think some errors were when Alternator was playing up so reset them and warmed up before a run... having to hold at 1500rpm though otherwise will stall...
After a run... keep getting Crank Sensor error but no other errors logged after clearing... Turned off, Turned on again, went for another run, Crank Sensor error again..
And here's a quick snapshot of the logs.....
Today I tried to get to Lambda sensors to swap them over to see if anything changed.... but on axle stands with very few tools it is nigh on impossible.
Desperately in need of some help and advice - I need to get her back to England !!!
Thanks in advance
Mike
I'm sure the experts will be along shortly. What draws my attention is the throttle positions are a long way off between cylinders 1, 2, 3 and 4, 5 and 6. They should be within 1% between each 'bank' ideally. Perhaps the throttles got disturbed with the alternator change or the adjustment screws weren't tight and they have gone out of balance. Could be a throttle position sensor gone bad, but more likely the throttles themselves have gone out of balance. There's probably a guide on here somewhere on how to adjust the throttles properly.
This video may help. If you don't have an airflow meter thing, you might be able to get it running better by adjusting the balance between the two 'banks' by ear - only one adjustment screw to turn and keep an eye on % values with the software. Once happy with the balance you'll need to reset the throttle positions using the software.
https://www.youtube.com/watch?v=Ks9M2-cj95M
https://www.youtube.com/watch?v=Ks9M2-cj95M
Ummhh,
Throttle position showing a long way out, the ECU is believing this as well hence inj duration. Doubt the throttle adjustment would just jump like that so maybe you have a pot (the blue n black and white n black sensors on the first and last throttle body) that is going wobbly but all this seems a bit odd.
My woes with rough running have nearly always been caused by poor earths. The fact you have a crank sensor fault as well and TPS so far out all of a sudden, assumes you, or another, haven't adjusted the throttle linkages, makes me suspect there is an earth problem, combine this with the recent work on the alternator i reckon that could be your problem.
I would start with the one on the bell housing that links the engine bay harness to the ECU, worth a sniff around, you will have to take the airbox off to see it. The lamba earth that often gets referred to is at the end of the loom, I haven't had to mod this on any of the cars I have worked on and as you have numerous faults I don't think this is it.
Just as a guide tps should be 15% at idle. Don't adjust anything yet, follow your loom from sensors to earth to ECU
Good luck and keep us updated
J
Throttle position showing a long way out, the ECU is believing this as well hence inj duration. Doubt the throttle adjustment would just jump like that so maybe you have a pot (the blue n black and white n black sensors on the first and last throttle body) that is going wobbly but all this seems a bit odd.
My woes with rough running have nearly always been caused by poor earths. The fact you have a crank sensor fault as well and TPS so far out all of a sudden, assumes you, or another, haven't adjusted the throttle linkages, makes me suspect there is an earth problem, combine this with the recent work on the alternator i reckon that could be your problem.
I would start with the one on the bell housing that links the engine bay harness to the ECU, worth a sniff around, you will have to take the airbox off to see it. The lamba earth that often gets referred to is at the end of the loom, I haven't had to mod this on any of the cars I have worked on and as you have numerous faults I don't think this is it.
Just as a guide tps should be 15% at idle. Don't adjust anything yet, follow your loom from sensors to earth to ECU
Good luck and keep us updated
J
As above, look for trapped wiring or disturbed connections, check first close to anything that's been disturbed during changing the alternator
Do you know what was wrong with the alternator?
There's always the possibility that there was a charging fault due to bad wiring and that bad wiring has now deteriorated further
Do you know what was wrong with the alternator?
There's always the possibility that there was a charging fault due to bad wiring and that bad wiring has now deteriorated further
Thanks for advice will go and see what I can check and see !!! One Problem is very few tools here 😤 certainly not got a synchronometer .. maybe the mechanic has hopefully
I’m not aware the throttle linkages have been altered by anyone... last service mechanic said they were a pig to balance after I’ve had them ‘refurbished’
I presume it’s ok to rotate the throttles using the central linkage where throttle cable attaches as can’t reach accelerator pedal when stood by the engine!!
The drags say “Lambda Control Disabled” is that correct ??
Don’t know what problem was with alternator I think the mechanic said it looked like it was just a bit worn out ???
I’ve had the air box off a few times and have been looking for anything disconnected
What should I be looking for with respect to cables ?? Could I have done something to those very thin cables that plug into the loom on the bulkhead by the air box when I’m wiggling it back in place ??? They look ok.
Thanks
I’m not aware the throttle linkages have been altered by anyone... last service mechanic said they were a pig to balance after I’ve had them ‘refurbished’
I presume it’s ok to rotate the throttles using the central linkage where throttle cable attaches as can’t reach accelerator pedal when stood by the engine!!
The drags say “Lambda Control Disabled” is that correct ??
Don’t know what problem was with alternator I think the mechanic said it looked like it was just a bit worn out ???
I’ve had the air box off a few times and have been looking for anything disconnected
What should I be looking for with respect to cables ?? Could I have done something to those very thin cables that plug into the loom on the bulkhead by the air box when I’m wiggling it back in place ??? They look ok.
Thanks
Spike - Snap (cascade indigo)
Sounds very much like a wiring issue - something disturbed when the alternator was changed. When my crank position sensor went (Ford Escort part I think!) it just would not start, but again your issue may be an earth - engine to chassis. A synchronometer is not expensive and well worth getting; I have used it a couple of times when I have had an issue; the symptom being the engine not running smoothly at a constant speed in low revs, for example 50MPH through motorway roadworks. Your issue sounds different - check wiring/earths before you change or adjust anything else. Good luck.
Sounds very much like a wiring issue - something disturbed when the alternator was changed. When my crank position sensor went (Ford Escort part I think!) it just would not start, but again your issue may be an earth - engine to chassis. A synchronometer is not expensive and well worth getting; I have used it a couple of times when I have had an issue; the symptom being the engine not running smoothly at a constant speed in low revs, for example 50MPH through motorway roadworks. Your issue sounds different - check wiring/earths before you change or adjust anything else. Good luck.
Edited by s3dave on Thursday 1st July 11:04
EvoOlli said:
When the ECU says: Crank Sensor problem...why don't you replace it but instead you look somewhere else ?
Shouldn't be an expensive part...after that I would look after the throttle pots...
I only found the crank sensor error after finally getting your diags to work EvoOlli... so I will order one of those just in case I can’t find a wiring problem. I’m not looking somewhere else but having changed some things TVR specialists advised me to do in absence of diags I did t want to just keep buying part after part. Thanks fir your advice..great diags by the way once I got a serial-usb cable that worked !! Shouldn't be an expensive part...after that I would look after the throttle pots...
The flow through the throttle pots need to be balanced / sync'd.
https://www.youtube.com/watch?v=2qmJTYr47yY showing it being done on another brand.
They are terrible on the factory set up S6 for not staying in balance / sync.
Being out of balance / sync can lead to terrible rough running.
https://www.youtube.com/watch?v=2qmJTYr47yY showing it being done on another brand.
They are terrible on the factory set up S6 for not staying in balance / sync.
Being out of balance / sync can lead to terrible rough running.
RedSpike66 said:
What do you mean ‘look after’ the throttle pots ?? Can I remove them and clean them or something ???
Thanks
They show complety different values...Normally they should be the same +/- some %. At idle they should show around 15%. You should do a throttle reset. If your car is not stable at idle then you could do the throttle reset without the engine running. This isn't perfect, but should bring them in sync.Thanks
Then you could look at both values increasing the throttle. They should go from 15% to around 90%, but both must be in sync. If the difference from one to another is too big, one is shot...
The sync of the throtlle bodies is another thing. This must be done with an underpressure meter like in the photo above.
Another problem maybe: The throttle cable is in the middle of the throttle bodies.1-2-3 are to the right with one throttle pot and 4-5-6 are on the left with one throttle pot. If you push the throttle, are all 6 disc in the throttle bodies moving the same amount ? If not, the linkage between them is not correct...
Throttle 1 is the front (blue) one and appears to be the one that's giving an erroneous value (unless you really were at 60% throttle for the table above). If you unplug it, the ECU will assume the rear one speaks for both and will hopefully run a lot better and should be good enough to get you home. Reset your adaptives as well. Speak to Joolz about a replacement as he has had some made, they're hens' teeth otherwise.
Not sure how changing the alternator could have damaged anything, it's nowhere near the loom which runs along the top of the throttles.
Not sure how changing the alternator could have damaged anything, it's nowhere near the loom which runs along the top of the throttles.
OP,
Can you please list your symptoms time line, I mean alternator / charging fault and how long time / miles after the rough running started, trying to understand if linked or coincidence. Any thing else that has happened recently?
For others to say the alternator change would not / is unlikely to interfere with the engine / ECU harness is partly correct but to swap an alternator the air box has to come off and the removal is a bit of a twist and pull. may be worth a play with the ECU plug at the bulkhead as these are pretty poor and do fur up so the slightest knock can upset them, like most bits of a TVR. I had one that was letting water in that in turn ran down the cables and into the ECU, I pulled the ECU out to see what was wrong and water ran out.... an hour later after a dry out it was fine....While the airbox is off you can get a visual on the throttle plates / butterflies and they should all look closed, I am aware you are in France without all the tools so balancing may be a mission but you would see if the linkage has been caught or knocked accidentally and one bank of three isn't returning / closing properly. Without kit I would leave well alone as once you start you need to finish and personally from what I understand from what you have written I think unlikely to be out of adjustment.
The reset TPs is a good idea, then you can get ignition on, engine not running, open the throttles by the cable linkage and watch the TP % shift, both should track. When running if you reset adaptives you should hear and feel a change, thinking if you don't you may have a NovRam that is dead. I had one that failed and the car wouldn't behave at all, a reset made no difference, I guess it wasn't storing any data so the learnt adaptive wasn't being stored? Anyway good luck.
j
Still suspect earth.
Can you please list your symptoms time line, I mean alternator / charging fault and how long time / miles after the rough running started, trying to understand if linked or coincidence. Any thing else that has happened recently?
For others to say the alternator change would not / is unlikely to interfere with the engine / ECU harness is partly correct but to swap an alternator the air box has to come off and the removal is a bit of a twist and pull. may be worth a play with the ECU plug at the bulkhead as these are pretty poor and do fur up so the slightest knock can upset them, like most bits of a TVR. I had one that was letting water in that in turn ran down the cables and into the ECU, I pulled the ECU out to see what was wrong and water ran out.... an hour later after a dry out it was fine....While the airbox is off you can get a visual on the throttle plates / butterflies and they should all look closed, I am aware you are in France without all the tools so balancing may be a mission but you would see if the linkage has been caught or knocked accidentally and one bank of three isn't returning / closing properly. Without kit I would leave well alone as once you start you need to finish and personally from what I understand from what you have written I think unlikely to be out of adjustment.
The reset TPs is a good idea, then you can get ignition on, engine not running, open the throttles by the cable linkage and watch the TP % shift, both should track. When running if you reset adaptives you should hear and feel a change, thinking if you don't you may have a NovRam that is dead. I had one that failed and the car wouldn't behave at all, a reset made no difference, I guess it wasn't storing any data so the learnt adaptive wasn't being stored? Anyway good luck.
j
Still suspect earth.
Can't see any obvious cable issues at the moment... but need proper lighting in the garage (pretty dark even during the day with doors open) so will go get a strip light...
Hooked up diags again...
Engine not started... we have no faulty sensors and...
Throttle ... 72% / 13%
Lambda ... 0.04v / 0.03v
Adaptive .. 0.4% / 0.4%
Reset Throttles as that 72% looks seriously wrong..
Didn't change anything...
Started Engine.. and gradually increased revs a bit.... two screen grabs shown below....
No crank sensor error this time but it's a cheap part so will order one..
But... looks like Throttle Pot - Front - Blue is not happy.... Would have to be the one that's made of unobtainium wouldn;t it ? Will call Jools...
Other interesting thing... one TVR specialist told me to get a heat gun to check the temparature of all six exhausts.... to narrow down to whether it was just one cyclinder perhaps not firing for a faulty HT lead or Plug...
Cyls 123 -> 110 degrees
Cyls 456 -> 450-500 degrees
so looks like Cyls 123 are hardly firing at all ??
If I disconnect Blue throttle pot and run just on the White one would that be ok to get me back home? It's a long way and I don't want to cause any more damage that might already have been done !!
Thanks for all your help guys !
Hooked up diags again...
Engine not started... we have no faulty sensors and...
Throttle ... 72% / 13%
Lambda ... 0.04v / 0.03v
Adaptive .. 0.4% / 0.4%
Reset Throttles as that 72% looks seriously wrong..
Didn't change anything...
Started Engine.. and gradually increased revs a bit.... two screen grabs shown below....
No crank sensor error this time but it's a cheap part so will order one..
But... looks like Throttle Pot - Front - Blue is not happy.... Would have to be the one that's made of unobtainium wouldn;t it ? Will call Jools...
Other interesting thing... one TVR specialist told me to get a heat gun to check the temparature of all six exhausts.... to narrow down to whether it was just one cyclinder perhaps not firing for a faulty HT lead or Plug...
Cyls 123 -> 110 degrees
Cyls 456 -> 450-500 degrees
so looks like Cyls 123 are hardly firing at all ??
If I disconnect Blue throttle pot and run just on the White one would that be ok to get me back home? It's a long way and I don't want to cause any more damage that might already have been done !!
Thanks for all your help guys !
Don't throw parts at it that aren't needed. Don't buy a crank sensor. You probably don't actually need throttle sensors as not both of them would give erroneous readings at once ..
this is looking far more of a global issue .. earth points, or possibly even ecu issue. .. if you are on 4 wire lambdas you can try disconnecting them (near the exhausts on the nearside there 2 plugs, one for each lambda) and see if that helps - the heater earth path is known to cause issues
All you can really do also is check the earth on the top of the bellhousing, and check any connectors and ecu for water.
80 percent throttle is virtually full open, you would instantly see if that was the case with airbox off, but also the engine would be revving its bits off at standstill !!!
this is looking far more of a global issue .. earth points, or possibly even ecu issue. .. if you are on 4 wire lambdas you can try disconnecting them (near the exhausts on the nearside there 2 plugs, one for each lambda) and see if that helps - the heater earth path is known to cause issues
All you can really do also is check the earth on the top of the bellhousing, and check any connectors and ecu for water.
80 percent throttle is virtually full open, you would instantly see if that was the case with airbox off, but also the engine would be revving its bits off at standstill !!!
I don't know anything about TVR's but it does look like the cylider 123 bank is running very lean, with very low injection duration. 2.75 ms looks OK, but 2.02 ms looks as low as it will go. Coupled with the low exhaust temperature, I would think this bank is not injecting correctly.
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