Thread: td5 bad throttle response

3 things did this for mine.

1. Boost modulator failure and also when by passed - check your hoses at least.
2. Leaking diesel hose - this chaffed through where it dog legs over the cross member next to the fuel tank, there was a minor diesel leak at the back. This was mainly after the first start.
3. Just before the fuel pump dies. I get about 120,000km from OE/VDO ones, it gives really bad lag when taking off - it happens not long before the pump dies.

Originally Posted by Henryque

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Checked fuse F2 and it is ok, also checked wiring conductivy and its also ok, MAP numbers seems to be 90 kpa.
My TD5 is 2001/2002, so i guess that its an 10P, without EGR

For now i want to fix this performance issue, that crossed B i will try to fix later, one step at a time

All Td5s had EGR unless owner had removed it

Originally Posted by mrs

All Td5s had EGR unless owner had removed it

Yeah, i mean that mine doesnt have, for sure the previous owner removed it.

Originally Posted by Slunnie

3 things did this for mine.

1. Boost modulator failure and also when by passed - check your hoses at least.
2. Leaking diesel hose - this chaffed through where it dog legs over the cross member next to the fuel tank, there was a minor diesel leak at the back. This was mainly after the first start.
3. Just before the fuel pump dies. I get about 120,000km from OE/VDO ones, it gives really bad lag when taking off - it happens not long before the pump dies.

Sorry for my lacking of knowledge , but how i can test my boost modulator ? i saw some videos explaining how to bypass it

Ps: My fuel pump is almost brand new, i bought an bearmach WFX000280

As mentioned, all TD5s that I know of came with an EGR.

On ANY TD5 the MAF can simply be unhooked if suspected of being faulty, EU2 motors use speed density for fuelling, EU3 uses Mass air but will very effectively default back to speed density if the MAF is unhooked... It will run fine.... IF the MAP/IAT is functioning properly.

If you are getting a reading of 90kpa AAP with the engine idling or off but with ignition on, unless you are @ 1000 metres above Sea level, you have a failed MAP/IAT sensor.

If both MAP and MAF have failed you will get very very poor performance.

If they have failed bad enough to go outside of a couple of checks and balances the ECU runs, I think the ECU will default to 100kpa map pressure.

100kpa pressure will equate (very roughly) to 500mg air in the cylinder.

500mg of air on a stock TD5 tune will inject a maximum of about half of the stuck fuelling

That will equal about half the torque a stock TD5 produces.

It will be very slow.

Originally Posted by shack

As mentioned, all TD5s that I know of came with an EGR.

On ANY TD5 the MAF can simply be unhooked if suspected of being faulty, EU2 motors use speed density for fuelling, EU3 uses Mass air but will very effectively default back to speed density if the MAF is unhooked... It will run fine.... IF the MAP/IAT is functioning properly.

If you are getting a reading of 90kpa AAP with the engine idling or off but with ignition on, unless you are @ 1000 metres above Sea level, you have a failed MAP/IAT sensor.

If both MAP and MAF have failed you will get very very poor performance.

If they have failed bad enough to go outside of a couple of checks and balances the ECU runs, I think the ECU will default to 100kpa map pressure.

100kpa pressure will equate (very roughly) to 500mg air in the cylinder.

500mg of air on a stock TD5 tune will inject a maximum of about half of the stuck fuelling

That will equal about half the torque a stock TD5 produces.

It will be very slow.

Actually my city is 852m above the sea level.

I got that 90kpa with engine on, (idle). What do you recommend me to do?

While driving the car it has a very weak pull, as example in this video

Discovery TD5 Auto acceleration problem - YouTube

I found that the MAF had a lot less effect than the MAP.

Originally Posted by Henryque

Actually my city is 852m above the sea level.

I got that 90kpa with engine on, (idle). What do you recommend me to do?

If you can drive the car whilst watching the map pressure, do so and report back.

It's really hard without dedicated Diag gear.

AAP should be roughly the same as MAP @ idle.

Check that as well.