Thread: td5 bad throttle response

Originally Posted by sierrafery

In the first readings there was a Ambient pressure reading of 82 so the MAP at idle of 90 seems ok if we dont presume that both sensors are faulty, in my previus reply i said: "... read the MAP sensor's inputs too (manifold and inlet air pressures)" my bad i wasnt 100% cear with that

the IAT(inlet air temp) reading was completely neglected untill now, this is the second function of the generically called MAP(actually MAP/IAT) sensor it can cause such driveability issues.

also see the injector balances too

another thing is that you can't 100% rely on that chinese auto-com tool, i've had one myself and it wasnt very accurate with the Td5 ECU compared to hawkeye which is the closest to the original testbook's protocol.

IAT readings are 27ºC

I'm starting to suspect the ecu, due to that fault on MAF circuit as scan showed. Is it worth opening to check it out?

Originally Posted by Henryque

IAT readings are 27ºC

I'm starting to suspect the ecu, due to that fault on MAF circuit as scan showed. Is it worth opening to check it out?

Before opening ECU i did this test on maf sensor as video bellow explain

Td5 - Mass Airflow Sensor - How to Check with a Voltmeter - YouTube

And surprisely i got those results with engine on (idle)

pin 1: Earth ( When placing the red probe on the battery positive and the black probe on pin 1 it gives 13.7v. which seems that earth is ok)
pin 2: 0.30v (this value doesnt increase while throttling)
Pin 3: 14.23v

I got those values on the two maf sensors that i have, the one that came in the car when i bought (an chinese), and another one that i bought from second hand, an siemens.

You better try with a new sensor before you mess with the ECU or unpin the wire from pin 2 and measure so the sensor's output and if then it's OK means there is a resistive short on that line or the ECU is suspect... if you get the same result with pin 2 disconnected both sensors are fubar...though if the MAF sensor was a problem the engine would run well with it disconnected

Originally Posted by sierrafery

You better try with a new sensor before you mess with the ECU or unpin the wire from pin 2 and measure so the sensor's output and if then it's OK means there is a resistive short on that line or the ECU is suspect... if you get the same result with pin 2 disconnected both sensors are fubar...though if the MAF sensor was a problem the engine would run well with it disconnected

With the MAF sensor disconneted i got the same engines behavior

Disconnected pin 2 and got the same numbers

WhatsApp Image 2023-12-24 at 15.32.30.jpgWhatsApp Image 2023-12-24 at 15.32.30 (1).jpgWhatsApp Image 2023-12-24 at 15.32.30 (2).jpg

I'm starting to get confused, 3 pipes isnt 15p engine ?

my 8 last vin numbers are 2A737649

Yes it's 15P, it was a batch of pre-facelift modells with 15P engines with MSB ECUs, a kind of "hybrid" and the MSB101330/manual and MSB101340/auto ECUs in this modells are a quite common failure but in your case seems that both MAFs are fubar just that with it disconnected it should run well... what's the p/n on your ECU?

Originally Posted by Henryque

With the MAF sensor disconneted i got the same engines behavior

Disconnected pin 2 and got the same numbers

So it seems you need a new MAF like SF mentioned, but this isn't the issue you're having. With a dead MAF, if disconnected the engine will run a bit better. So you still have an issue to find.

Originally Posted by Henryque

....

I got those values on the two maf sensors that i have, the one that came in the car when i bought (an chinese), and another one that i bought from second hand, an siemens.

Highly recommended(if you want to get the engine running good again) ... don't waste too much money on just buying parts(or incompatible scan tools).
I've been through this too.
If you want to keep the disco going, it is very highly recommended that you get a nanocom(or Hawkeye). The money you spend on this will save you money in the long run(on parts you probably don't need to replace)
And like everyone has already mentioned, with the nanocom it will do datalogging so that you upload the saved log, and it will **almost likely** show the problem.

There are some situations where it won't show a problem, but not many.
eg. I haven't yet seen anyone mention that the fuel pressure regulator could be bad. There are a couple of options for changing it, one cheap, one more expensively(full kit). Fuel pressure is not monitored(fuel temp is) so diagnositic equipment will not reveal this info.
You have to measure fuel pressure manually.
That td5 MAF test video you watched, TrailerFitterToolbox ... he also has a video on how to check fuel pressure.

Check your ECU part number, does it start with MSB or NNN?
My understanding of the fuel pressure regulator(FPR) is that 10P also have the "3 pipe" in later years.
Again, my knowledge on 10P vs 15P engines are that (as std) MSB is for 10P and NNN is for 15P. NNN is more easily programmable, MSB needs chip replacement. Switching from MSB to NNN is a desirable modification for some folks, so no guarantee of indication that your engine is 10P or 15P.

Why I say this is, on my D2 TD5 I had a lot of problem trying to upload a ECU program a while ago. What happened was that the ECU didn't match the VIN number. Also turned out that the BCU didn't match too. A previous owner had issues(got the D2 stuck in deep water) and obviously swapped out dead electronics ... so again, no guarantee that ECUs are original.

What is more important here tho: Don't do same mistakes as other have .. waste money on swapping parts, instead of spending on tools that will identify issues. I'm guilty of this. Not 100% guarantee that the diagnostic tool will locate your issue, but it certainly helps.
diagnostic(in mine and many others here) nanocom is used for a few other reasons. One issue with Hawkeye now is availability and longevity. It is a Bearmach product, and Bearmach is now no longer in business. May be hard to find to buy, and or any future updates for it may no longer be possible.

Wastegate modulator(bypass). WGM can cause boost pressure issues. the solenoid costs about $60-100. You can easily check it by bypassing it. There are three hoses check them carefully, take a photo for reference .. it is easy to put them back incorrectly again.
You can bypass it by running a pipe directly from the lower intercooler pipe to the wastegate actuator, this will bypass the valve. I can't remember is any of the hoses are long enough to do this. but it's OK to have the hoses on the WGM solenoid disconnected for a short test. What will happen tho is that if this is the problem, as you build up (turbo)power in the engine it will most likely overboost, and then the ECU will cause new lack of power issues which is easy to fix again by turning engine off and start again.
So WGM bypass is not a proper fix for WGM problems. Just a easy zero cost method to work out if its no good.

Have you checked to see if the wastegate is stuck wide open?