Please help in Speed 6 engine data

[Griffithy]

Good afternoon,

would somebody of you, who knows about Speed 6, please have
a look at our enclosed data readings.
It is a Tuscan S 2002.
Our problem is, that one exhaust end (lefthand one) fails the
emission test by far, while the righthand exhaust seems to be fine.
We are already quite desperate, because having already fit
new cats and emission sensors and still no success.

We have no idea any more how to go on.

Do you have an idea what could be wrong on ours,
when looking at the data readings?
Is it normal or does it differs from healthy Speed 6es readings.

http://www.unet.univie.ac.at/~a9601613/tvrlog.pdf


Thank you very much for your help,

Best regards,

Griffithy

[330p4]

Martin what does it fail emmissions on co2,co etc also when you say you have changed the emission sensors do you mean the lambda sensors?
Ian

[Griffithy]

Hi Ian!

Yes, we renewed the Cats and lambda sensors and it is still failing in lambda and CO2/CO on lhd side exhaust.

Regards,

Griffithy

[dvs_dave]

I believe that the ECU runs the engine as 2 3 cylinder engines 1-2-3 and 4-5-6, hence the 2 throttle pots and 2 Lambda sensors. Sounds like the fueling on one of the 3 is out for some reason.

The things that could be wrong are the lambda (have you put the correct one in?), throttle pot, spark plugs/coilpack or the throttle balance for that group of three cylinders. Most likely the throttle balance, or a loose connection though.

Edited by dvs_dave on Saturday 23 January 23:03

[Robertjp]

dvs_dave said:

I believe that the ECU runs the engine as 2 3 cylinder engines 1-2-3 and 4-5-6, hence the 2 throttle pots and 2 Lambda sensors. Sounds like the fueling on one of the 3 is out for some reason.

The things that could be wrong are the lambda (have you put the correct one in?), throttle pot, spark plugs/coilpack or the throttle balance for that group of three cylinders. Most likely the throttle balance, or a loose connection though.

Edited by dvs_dave on Saturday 23 January 23:03

As above, with the HT leads added to the checklist

[Griffithy]

Thanks very much for your thoughts.

Spark Plugs are new as are the Heavy Duty HT Leads.
Connections should be fine as well.
Engine runs quite sweet and and pulls through the revs.
You can not fault the engine when driving.
Only the rolling road showed that it is also low on power: about 250hp.

Thanks,

Griffithy

[BGB autosport]

Could be the coil pack giving up, would cause the poor emmissions and drop power.

[kevin63]

Have all the throttle bodys been balanced up, they should all be taking in the same amount of air.

[330p4]

Martin if the CO2/CO are high presumably that half of the engine is running rich. Dont profess to be an expert at reading these graphs like other on here but several of your traces are showing lambda of 0.2 surely these should be 1. Water coolant sensor for the ecu could be faulty giving cold enrichment permanently although i would expect both banks of 3 to be out if this was the case. Could be the throttle pot on that bank giving a false reading & overfuelling or do you have a misfire letting raw fuel into the cats. Were the lambda sensors the correct TVR item? Hope this gives a few more ideas & you get the car sorted soon
Ian

[Griffithy]

Hi and big thanks again!

the throttle bodys had been balanced at last big inspection at
a well known specialist while MOTed in England in May.

What I do not know now, if they have also measured emissions on
both exhaust pipes then to check if really everything is fine,
or if possible throttle bodys went out of balance later on.

Sadly, over here I would not want anybody to touch the engine for
further adjustments as there is nobody experienced on Speed 6es.

The Lambda sensors were no original TVR parts, I got them by
Bosch-Service and they said this should be fine.

I had the Tuscan at Bosch several times yet, to find out
and solve it, but they are completely lost with it.

We have not touched the coil pack yet, it seems this would
be the next step to go.
If this does not work either, we should have a closer look at
the lambda sensor again and coolant sensor.


Thank you all for your kind help,

Griffithy

[330p4]

Martin i have not used this software but see if you can log both throttle pots on a graph & try different revs holding constant for a while & see if the two pots track one another it is unlikely to be any sensor in commom eg water temp/air inlet temp if they are common to both banks.
Ian

[Basil Brush]

Your throttles look to be out of sync on a couple of the charts but don't know if this is enough to cause an issue.

If your car has 3 wire lambdas, I had a pair of standard LR units put in my Tuscan in error last year and i had a real struggle getting it through the MOT. This was then spotted during a service as they couldn't set it up correctly so swapped them for the correct modified TVR units. If 4 wire then this doesn't apply.

[Robertjp]

Before forking out on a new coil, do a simple ignition check. I did this recently by pulling out a single HT lead at a time and listen to see if the engine note changes, if it DOESN’T you know you have an ignition problem. Obviously use insulated pliers…it makes you jump a little if you don’t….

Or, but yourself an ignition checker off eBay – about £7.

Also – see my other threads on throttle bodies and throttle pots, they can have quite a big affect on your running. You will be able to see the two throttle pots % (should be around 15% at throttle closed / idle) and also check them at about 2000 rpm to check they stay in sync.

Its feasible for throttle bodies to be out of sync within a few hundred miles in the throttle bodies are worn, so this would be another check.

If both lambdas follow each other reasonably well then its unlikely to be them both gone at the same time.


edited to say, your Lambda 1 does look very noisy at times, that could be the lambda itself or the AFR causing it to adapt, so you still should check all ignition and throttle bodies.

Edited by Robertjp on Monday 25th January 13:46

[fraxton]

Hi, I would suggest a compression check on all the cylinders, and measure all tappets, they could be to tight?How do all the spark plugs compare to eachother?

[BGB autosport]

I was thinking about this today while driving home. You say new cats? why did you replace them?

It has been known that when the cat material breaks up it can be pulled back up into the cylinder (due the the ammount of overlap on the cams). If your cats have broken up, this is a possibility and you may have a bent valve or damaged cyliner/piston. A simple compression check will let you know if this is the case.

If one or more cylinders is down drop an egg cup full of oil into that plug hole and repeat the test. If the pressure is up its the ring-bore seal, if no or little change its the valves not seating.

[dvs_dave]

Looking at the plots a bit more closely, the reading from Lambda 1 looks to be all over the place compared to Lambda 2. The throttle pots appear to be fairly consistent with each other (2 being slightly noisy). Assuming the lambdas and throttle balance is ok after its recent service, the readings you have and the low power output suggests it's either the ignition and/or a faulty injector(s).

Is the engine mechanically sound? If it's using lots of oil, that'll screw your emissions too.

[Basil Brush]

On page 6+7, off idle, the throttles seem a fair bit off (c.10%) and the trace for throttle 2 looks very rough. Is this OK?

[Robertjp]

Basil Brush said:

On page 6+7, off idle, the throttles seem a fair bit off (c.10%) and the trace for throttle 2 looks very rough. Is this OK?

I can see they are different by 2.1% on page 6?

Even this is enough to change things a little if you combine with worn throttle bodies.

[Robertjp]

though having said all of this Throttle bodies arent likely to mean down on power by circa 50 horsepower as you said earlier in the thread. More likely to be ignition, fuel, or mechanical. Do you know it to have dropped in power or simply that it was at this power when dyno'd?

[Griffithy]

Good morning,

thank you very much again for all your thoughts and ideas.
It seems the only way is going through all the tests and checks
you have been recomending and see what turns up.

It really is so good to know to have such nice people at hand
when hard hours turn up.

Best regards,

Griffithy