Discussion
Recently I have been suffering some difficulties with second cam.
The symptoms.
The car would only go onto cam in the following circumstances. Just after the engine has got to temp for about 1 min and if the engine is hot after a long run, if I stop for fuel, when I pull out of the forecourt, it would come on cam for a couple of mins.
There were a number of solutions tried.
The usual check of fuses / oil etc, no luck.
The oil diverter valve was dismantled and serviced. Did not cure the problem.
New ECU (Gulp) at least it was a motorsport ECU but still no luck with the ECU. This also made the the cam NOT come on at a lower RPM making the car more frustrating to drive.
Temperature. First of all the early 111R had a "plumbing change" due to uneven engine heating. This had been corrected at the factory. The next suggestion was Thermostat. An open / faulty thermostat would cause uneven warming of the engine and the temp sensor would read incorrect. This was also a blind alley because the benefit of hindsight, there is only one temp sensor and that was telling the dash the correct info for going on cam.
Connections (looms and connectors) It seems that the ECU connectors have a very limited lifespan and according to lotus this can be as low as 5-6 time of disconnection / reconnection from ECU. It was also suggested that the loom had been damaged - this eas discounted as there was no error messages that would indicate this type of fault.
Cam sensor. There is a cam sensor that tels engine speed and cam position for timing and cam switchover reasons. This was replaced with no effect.
At this point lotus gave up, they know about the ECU and ancillaries that surround the engine but they consider the engine to be a sealed unit that arrives assembled and is simply slotted in the back of a car. Effectively a black box.
On to toyota, and trawling Pistonheads. A brief note from a Toyota tech / pistonheader called Graeme pointed the way.
Ameyc had watched my car go on a few test runs every day for nearly 3 weeks and the technicians had scratched their heads over the car so much most of them have bald patches. Every time they car would drive past the showroom Ameyc would look out for the "thumbs up". When he finally got the thumbs up, I think they cracked open the bottle of champale reserved for the selling of Ferrari's!
So the final problem was due to timing chain stretch. Something that shouldn't happen until well over 100k miles. Due to the compound of stretch and the error in the yota manual the problem was compounded. The engine timing marks look like they are within tolerance but in effect the timing is out enough to dis allow the second cam.
Thank yous.
Ameyc - I have bugged the s
t out of this man and hes has suffered this with style and grace. He even politely caught the toys as they departed my pram at high velocity.
Ben - you do make me smile.
John + Dave - fir fixing and telling me in real speak not sales speak what was happening.
Graeme - for a number of very helpful e-mails.
The symptoms.
The car would only go onto cam in the following circumstances. Just after the engine has got to temp for about 1 min and if the engine is hot after a long run, if I stop for fuel, when I pull out of the forecourt, it would come on cam for a couple of mins.
There were a number of solutions tried.
The usual check of fuses / oil etc, no luck.
The oil diverter valve was dismantled and serviced. Did not cure the problem.
New ECU (Gulp) at least it was a motorsport ECU but still no luck with the ECU. This also made the the cam NOT come on at a lower RPM making the car more frustrating to drive.
Temperature. First of all the early 111R had a "plumbing change" due to uneven engine heating. This had been corrected at the factory. The next suggestion was Thermostat. An open / faulty thermostat would cause uneven warming of the engine and the temp sensor would read incorrect. This was also a blind alley because the benefit of hindsight, there is only one temp sensor and that was telling the dash the correct info for going on cam.
Connections (looms and connectors) It seems that the ECU connectors have a very limited lifespan and according to lotus this can be as low as 5-6 time of disconnection / reconnection from ECU. It was also suggested that the loom had been damaged - this eas discounted as there was no error messages that would indicate this type of fault.
Cam sensor. There is a cam sensor that tels engine speed and cam position for timing and cam switchover reasons. This was replaced with no effect.
At this point lotus gave up, they know about the ECU and ancillaries that surround the engine but they consider the engine to be a sealed unit that arrives assembled and is simply slotted in the back of a car. Effectively a black box.
On to toyota, and trawling Pistonheads. A brief note from a Toyota tech / pistonheader called Graeme pointed the way.
Graeme said:
'Could possibly be the timing chain being put on a tooth or 2 out as if memory serves me correct the book actually tells you to time it up a certain way. If this is followed, the timing according to the marks on the engine are out slightly. Could be this causing the trouble. I would take it back to a Toyota dealer and get them to slap their tester on it. After all they did the work and are liable for it.
>
> If the ECU detects the slightest hint of trouble with the timing, it will not allow the high lift cam to kick in due to the really tight tolerances.
>
> By the way, in case you are wondering, I am a Toyota techie myself, but am down in London, so can't really help any more than give you pointers and advice I'm afraid. '
Apparently the engine can not be set up as the toyota manual suggests. So we know that the timing is 10 degrees out but not which way. The timing had to be changed by 10 degrees positive, cranked over 30 times by hand to check for interference and the tried to see if it comes on cam. No joy. Reversed by 20 degrees, hand cranked by 30 times to check for interference then started.>
> If the ECU detects the slightest hint of trouble with the timing, it will not allow the high lift cam to kick in due to the really tight tolerances.
>
> By the way, in case you are wondering, I am a Toyota techie myself, but am down in London, so can't really help any more than give you pointers and advice I'm afraid. '
Ameyc had watched my car go on a few test runs every day for nearly 3 weeks and the technicians had scratched their heads over the car so much most of them have bald patches. Every time they car would drive past the showroom Ameyc would look out for the "thumbs up". When he finally got the thumbs up, I think they cracked open the bottle of champale reserved for the selling of Ferrari's!
So the final problem was due to timing chain stretch. Something that shouldn't happen until well over 100k miles. Due to the compound of stretch and the error in the yota manual the problem was compounded. The engine timing marks look like they are within tolerance but in effect the timing is out enough to dis allow the second cam.
Thank yous.
Ameyc - I have bugged the s
t out of this man and hes has suffered this with style and grace. He even politely caught the toys as they departed my pram at high velocity.Ben - you do make me smile.
John + Dave - fir fixing and telling me in real speak not sales speak what was happening.
Graeme - for a number of very helpful e-mails.
LivinLaVidaLotus said:
The worrying part of all that is, "Lotus gave up" - Surely this is something they should know, and if all the obvious avenues have been taken, then they should explore the timing, to make sure it is 100% spot on.
It wasnt the lotus dealer who "gave up". It was the hethel engineers. Thay basically said we have reached the limit of our knowledge and experience.Gooby said:
LivinLaVidaLotus said:
The worrying part of all that is, "Lotus gave up" - Surely this is something they should know, and if all the obvious avenues have been taken, then they should explore the timing, to make sure it is 100% spot on.
It wasnt the lotus dealer who "gave up". It was the hethel engineers. Thay basically said we have reached the limit of our knowledge and experience.
wantalotus said:
glad it's sorted, but how many miles caused the chain to stretch? And was the timing wrong from the factory, or had others played with it?
Is it something we should all watch for, or was yours an 'isolated case'?
Just before xmas I had some major engine work - when putting the engine back in the timing was set up correctly (wrong). This was at 60k miles.Is it something we should all watch for, or was yours an 'isolated case'?
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