My 2001 very nice 90K mile RR drives beautifully. Smooth and quiet but floor the peddle and you get hesitation, some more revs and not a lot else!

Now is the time to rectify this! Help please.

I took the car to an indy a couple of weeks ago and he cleared all faults.
On my Nanocom now, this is what it shows on faults.

https://i.imgur.com/A6zB8Vu.jpg

https://i.imgur.com/ZFWxzgF.jpg

https://i.imgur.com/OllCcq3.jpg

https://i.imgur.com/UKeQAzr.jpg

And from the Indys code reader

https://i.imgur.com/k1JwRE8.jpg

I would be most grateful for some pointers to restore its power. Thanks.

P0172 / P0175 point to system too rich cylinder banks 1 / 2

I'd expect the fault to be due to incorrect spec or failed lambda sensors, or a failed MAF.

P1000 Doesn't normally indicate a fault, ir only means drive cycle(s) haven't been completed so the OBD system hasn't had opportunity to detect certain types of faults. Some vehicles have P1000 every time you start them up, the code goes away if drive cycles are completed without other fault codes occuring.

Is this a P38?

Yes, a P38.

Interesting. Would you say that it would be a positive thing to replace the lambda sensors?

Possibly also the MAF? Happy to do so, if they are faulty.

It would be wasteful (time and money) to replace components that are working OK, so first I would want to run some diagnostics to determine which if any components were broken.... But as said, it is likely changing lambda sensors or MAF would fix the problem.

Have you had any components changed on it recently?
How old are the lambda sensors?
Are they definitely the correct type lamba sensors (connected using he original vehicle lambda sensor connecting plugs) or has someone spliced in generic sensors or sensors from an older P38?

As far as I’m aware, everything is original on the car. It is in great condition apart from the fact it is so slow!

Would a more professional code reader give any more answers?

I will pop underneath the car tomorrow and check out the lambda sensors as far as I can.

You say when you floor it, you get "more revs and not a lot else!"
How may more revs? What's the starting point, and how much higher does it go?
Just wondering if the transmission is slipping and you are chasing other pre existing issues?

Was this sudden onset, or has it been creeping up on you over time?
When was the trans last serviced?

Good point, but definitely not the transmission. I serviced it changing oil and filters when I first got the car about 15 K ago. What I meant was, you floor it, there is generally hesitation, and then it tries to rev out but sort of struggles to gain revs. It will go through the whole rev range if you accelerate slowly and if you do, you will eventually get to 100 mph absolutely flat out with a following wind

Normal scenario, dawdling car in front at about 40 mph, apply foot to accelerator to activate kickdown and surge forwards . Hold your breath to see if you can pass car within a far too long period!

Use the Nanocom to look at the live data, particularly the output from the lambda sensors. The Thor has standard 0-1V sensors with 0V meaning lean and 1V meaning rich, Both at idle and when being driven you should see these flip flopping between the two extremes. I suspect they have failed (and if original I suspect they have well outlived their lifetimes) so are giving 0V output, that makes the ECU think the engine is running lean so it will try to bucket more petrol in to get it right. Obviously this has doesn't happen so the fuel trim adaptive values reach the limit of what is expected and gives the codes. If you reset the adaptive values it will be OK for a short period until it corrects what it sees as an error in fuelling.

Same thoughts as Bolt did occur to me but I forgot to mention the potential for a gearbox problem being the underlying problem.

I do think though, like Gilbert, that the problem is probably due to duff lambda sensors. I have seen a lot of P38s with duff lambda sensors usually with the owner and general garages the owner used the services of unaware.

Normally if a 0>1v lambda sensor fails it will output close to 0v, which for a 0>1v sensor implies lean mixture, but the error codes point to rich mixture while the symptoms point to lean mixture. If lambda sensors incorrectly read rich mixture it may have the effect of leaning the mixture off. Given the aforementioned (question to everyone) - What are the chances that someone spliced in 5>0v sensors instead of the 0>1v sensors? I know that in this company I have no need to mention that with the 5>0v sensors a 5v signal; points to lean and a 0v signal points to rich...So if a fitter had mixed up their P38 models and spliced in 5>0v sensors on a model that should use 0>1v sensors there would be constant rich running error codes and the fuel trims might be leaned off leading to reduced engine torque, the engine would still rev but the car would lack power and go up through the gears slowly.

I currently have @Jacckk 's P38 in the yard, the last time I saw this P38 was 10 years ago but he fitted a 4.6 to replace his 4.0 and the LPG fuelling was off after the engine change. Today I got it running much nicer on LPG than on petrol, probably due to some petrol injector issues (only petrol injectiors on 7 and 8 seem to be working great, others probably not working very well).

Lpgc wrote:

What are the chances that someone spliced in 5>0v sensors instead of the 0>1v sensors? I know that in this company I have no need to mention that with the 5>0v sensors a 5v signal; points to lean and a 0v signal points to rich...So if a fitter had mixed up their P38 models and spliced in 5>0v sensors on a model that should use 0>1v sensors there would be constant rich running error codes and the fuel trims might be leaned off leading to reduced engine torque, the engine would still rev but the car would lack power and go up through the gears slowly.

Pretty remote. Not only are the electrical plugs different so you can't mix them, but I understand the threaded boss in the downpipes are a different size for precisely this reason, so you can't fit the wrong ones.

Going to put it on my sons diagnostic reader in the next few days.

Can you tell me what the readings should be from the sensors and the MAF please?

Lambda sensors should flip flop between 0V and 1V, MAF should show 20kg/hr at idle rising to 61kg/hr at 2,500 rpm. Both figures plus or minus 3kg/hr.

Nanocom can do it as you've been using that for the faults so you don't need another diagnostic reader.

Thanks for that. Not used that facility yet!

Nanocom isn't great for the Lambda sensor voltages, simple because it's a bit slow, but you should still see the voltages changing. The other values can be read ok though.

I use a generic bluetooth diagnostic dongle when I need to check the O2 sensors, simply because I can view the flip-flop on my iPhone !!

Pete12345 wrote:

simply because I can view the flip-flop on my iPhone !!

Poser....

Agreed, the Nano is a bit slow so only refreshes about once a second but will still show the changes. If it isn't changing then the reading will stay the same but even with the slow refresh rate you'll still see changes.

Just going to connect and test.

I take it I am looking for these values with a warm engine ? Do I check them on idle or do I run the car through it’s rev range?

Warm engine yes, as when cold they will read permanently rich. Check both at idle and with some revs on.

I am just winging this so be patient. :)

These readings taken stationary with a warm engine.
The MAF sensor on idle reads 29.
The MAF sensor when running at 2500 rpm is reading 66.

The O2, sensor on idle, bank, A 0.73 – bank B, 0.78

The O2 sensor at 2500 rpm, bank, A 0.59 – bank B, 0.66

Hopefully that is the right information.

If the O2 sensors are staying at those values and not varying between 0 and 1V, they are dead.

MAF readings are a bit high at both idle and 2,500 rpm but that shouldn't be a problem.