Here's a new one... not seen this issue anywhere on forum yet, but I'm sure I'm not the only one that has experienced this...

When taking off and driving at around 1500 - 2000 RPM the engine rides (as if the accelerator pedal is stuck down for a couple of seconds) when I poke the accelerator pedal and doesn't come back down to normal revs for about one/two seconds, this is quite a pain actually.

This can be a c t when I reverse into my driveway as the engine hunts itself until I tap the brake pedal.

I have only just recently blanked my EGR's and had the patch put on to get rid of EML

Any ideas chaps ?  RRS 2.7 HSE Stornoway Grey
P38 4.6 HSE V8

Hi Derek,

Did you find a solution for this problem? mine does the same.

Thanx.
Jim

When you say "..the engine rides.." do you mean that the rev's increase, but the speed doesn't?
(If this is the case it sounds like the torque converter isn't locking up quickly enough.)

got the same issue lol RRS TDV6 2010

No it is not that the revs are climbing and the speed isn't. It is that the revs stick at 1500-2000rpm when releasing the throttle. Car just keeps pulling, sometimes really tricky, cause you have to brake against the engine (or put it in neutral)

Ah, OK. They have an electronic throttle control, so it's not a sticking cable like it would have been 20 years ago. (Yes I am getting on a bit!).
The ECU adds fuel based on what it reads from the throttle position sensor, and the MAP sensor. There are a number of things I would check.
Firstly have a look at the inlet air hoses for splits. ie the big rubber hoses leading from the air box to the throttle body. Check them all round, if you can.
Secondly remove the MAP sensor, and check that it is clean. ie unscrew it and pull it out. You might find it has quite a layer of gunk on it.

Good advice Rob,
I have also had a build up of crud around the actual motor driven throttle butterfly valve which can prevent the valve from fully closing at times.
It's easy to get at and easy to clean with some throttle body spray.
Worth a look.

The butterfly is there for EGR use.
It doesn’t control the engine.

Hi Andy,
I'm talking about the "Electronic Throttle Body" in the intake pipework at the front of the engine.
It is controlled by the ECM which in turn receives it's input from the accelerator pedal position sensor (APP), ie, a fly by wire system.
The throttle body then controls the air flow to the engine by operating a large butterfly valve
It is driven by a small DC motor and has a spring return to the closed direction.
If gummed up, the spring return may not fully close it.

You may actually see some of the crud i'm talking about in the photo, between the valve and the body near the shaft.

Cheers

Just a follow up on my comments above.
Andy, the EGR system does vent into the throttle body on downstream / low pressure side, hence the confusion.
The amount of exhaust gas recirculation is controlled by other modulated solenoid valves nearby.

The diesel 2.7 only have one throttle butterfly.
And this closes off clean air to allow more EG to be used by the engine.

On diesels they use pedal position and air flow to determine fueling. Diesels don't have a throttle butterfly like petrol engines do

Hi Andy,
You are right about the pedal position signal being used for fueling.
But how do you think the actual air flow is controlled ?
Answer. By the Electronic Throttle.

If you have a manual check out the "TDV6 2.7 Diesel - Acceleration Control" section and see a complete description.
Here is an extract.

Acceleration Control - TDV6 2.7L Diesel - Acceleration Control
Description and Operation
Acceleration control for the TdV6 diesel engine is achieved via an electronic throttle drive by wire system.
The throttle is electronically connected to the engine control module (ECM) and the ECM then controls the fueling for the relevant throttle demand signal from the accelerator pedal position (APP).
For additional information, refer to: Electronic Engine Controls (303-14C Electronic Engine Controls - TDV6 2.7L Diesel, Description and Operation).

ELECTRONIC THROTTLE

The electric throttle controls the air flow into the engine. In addition to the normal engine power control function, the electric throttle allows the cruise control, idle speed control and engine speed limiting functions to be performed without the need for additional hardware.
The electric throttle consists of a throttle body which incorporates a throttle plate driven by a direct current (DC) motor via reduction gears.
A return spring biases the throttle plate in the closed direction. That's what you should check Derrek.

The basic principle is;
Power and RPM demand is initiated by the driver from the Accelerator Pedal Position- APP (plus other trims)
Actioned by control of airflow via a throttle. In this case an electronic throttle.
Inlet airflow, Manifold air pressure and temperature (plus a few other parameters) are measured to determine the optimum combustion mixture.
Actioned by the ECM via the fuel injection system.

Cheers

I’ve removed the butterfly from mine which is what you are asked to do when the EGRs are blanked.
It drives normally

There was nothing said about removing the butterfly when I read up and blanked my EGR’s?

Steve Steve

2005 2.7 TDV6 HSE, ongoing project.
1998 Volvo V70 R auto FWD, mothballed future project.
1999 BMW Z3 (owned from new) garage queen.

Some sellers tell you, some don’t.

It can cause a very minor hesitation if left in which can be very difficult to track down
However if yours is fine, leave it.