Thread: TD5 Nanocom readings help - low power at low revs - any clues?

Originally Posted by simonmelb

Hi All,

My TD5 has consistently low power at low revs. Very very poor throttle response. When the turbo finally kicks in its OK.

Please see the attached (partial) Nanocom graph. Test drive was today at Beechworth, about 32C ambient.

TD5 low power.jpg

ABC.CSV

Any clues as to what may be wrong?

Happy to upload more graphs. See the CSV file also.

Usually the engine is very strong - at the moment I can floor the accelerator and it takes a fair while to get the revs up to where the turbo kicks in, then all is OK. (but may be still slightly down on power).

No difference if I drive with the MAF plugged in or unplugged.

Thanks !
Simon

Your MAP/IAT sensor looks to have died at a quick glance.

And the MAF also on a second look... This would suggest a significant leak or dodgy wiring.

Probably wiring as the MAP should never read that low.


Edit:

I just loaded it up on the data cruncher program... I've never come across that before, the AAP is also reading low, although if you are at 500 MSL it could be about right..

Definitely check wiring, oil at the ECU, and blockage in the airbox.

Cheers
James

Sorry just saw Beechworth, AAP is probably right.

Thanks James - this is a big help !

I'll check for blockages and leaks, then when I get back home, finally replace the engine harness for a the new one I purchased a few years ago but never had the need to fit until now! Then when I know the wiring is all new / sound I'll re test and report back.

Cheers
Simon

Hi, +1 for the MAP sensor low reading, it should be very close to the ambient pressure at idle... check it first if it's not full of gunk eventually clean it with spray, the pressure sensing element is in the hole's bottom near the probe which is for temperature, pointed with red in the pic, if the sensor is clean and keeps reading so low replace it

Thanks Sierrafery and James,

I replaced the complete engine wiring loom as I had a new old stock original LR 841 loom in the shed anyway. This is the same as the original 831 loom, but without the EGR wiring - which is very handy as my EGRs fell off many years ago! See pic of the old 831 loom and the new 841 loom.

After test driving with the new loom the car definitely runs a bit better, bit still way down on power below 2500RPM and as you can see the Nanocom readings are pretty much the same.

I did clean the MAP previously and the small hole is clear. I'll give it one more good clean then if no change, buy a new one!

As you can see I taped the new loom in places it usually chafes with good quality Tessa loom tape. So should last at least 10 years I recon.

Thanks again -will report back when I have fixed the MAP problem!

INP.CSV

IMG_3204.jpgIMG_3203.jpgIMG_3202.jpgIMG_3205.jpgIMG_3187.jpg

IMG_3188.jpgIMG_3189.jpgIMG_3194.jpg

Cheers
Simon

Originally Posted by sierrafery

Hi, +1 for the MAP sensor low reading, it should be very close to the ambient pressure at idle... check it first if it's not full of gunk eventually clean it with spray, the pressure sensing element is in the hole's bottom near the probe which is for temperature, pointed with red in the pic, if the sensor is clean and keeps reading so low replace it

The MAF reading is very low as well, i missed that in the first log as it wasnt so obvious from the beginning , did you try to drive it with MAF unplugged, if it runs better that way you need a new sensor. If the EGR is still on this can be also the root of the problem

Yes, the idle Maf reading is quite low I noticed.

I think the MAF and MAP sensors are original so maybe they both need replacing!

Yes I drove with the MAF unplugged and no change. There is no EGR.

Originally Posted by sierrafery

The MAF reading is very low as well, i missed that in the first log as it wasnt so obvious from the beginning , did you try to drive it with MAF unplugged, if it runs better that way you need a new sensor. If the EGR is still on this can be also the root of the problem

Fixed! Cleaned the MAP sensor again with carb cleaner - no change, still reading 0.5 Bar too low.

Popped down to Rovacraft to buy a new Bosch MAP and problem solved, now reading correctly and drives well.

The MAF is still reading slightly low so may replace that before the next big trip.

Thanks all for the help with this.

Cheers
Simon

Originally Posted by sierrafery

The MAF reading is very low as well, i missed that in the first log as it wasnt so obvious from the beginning , did you try to drive it with MAF unplugged, if it runs better that way you need a new sensor. If the EGR is still on this can be also the root of the problem

Yeah from the log it was pretty obvious, either wiring or sensors.

I'm having to get a lot of MAP sensors replaced the last few years on them.

With how low that MAF is reading, you might be better with it unhooked until you get a new one.

Cheers
James