Thread: DonDownUnder's D3 dropping into Limp Mode

Originally Posted by Grentarc

To me, that reads that the LPFP is a good place to start investigating from

But Don said he replaced both the LPFP and the HPFP as well as the belt. The problem still persisted.

Originally Posted by Graeme

Does it throw the fault on WOT in 1st gear for a couple of seconds? This might identify if it's associated with WOT only or with high fuel demand. WOT in 1st gear wont require the fuel that's needed in a higher gear.

Worth getting the ecm s/w updated to the latest level if it's not already.

Sorry mate, what is "WOT" short for? The limp mode drama is most evident when overtaking. Typically when you're behind someone, sitting on 80 and you plant the foot to get around them. It's almost as if you're in top gear, then plant the foot but the gearbox doesn't shift down. Instead you get a pause, then a "ding" sound and you have to pull over.
Interestingly, so long as I limit the amount of throttle, it's fine and has a gut load of power to get around. I can quite comfortably sit on a 100 up a steep incline (such as Cherry Tree Hill between Rylstone and Lithgow) So long as I don't plant my foot to the floor, it won't go into limp mode.
I see quite a few accelerator pedals on the market... Worth a shot maybe? Will check earths first though.

WOT - wide open throttle.

You might want to remove the fuel filter housing to check for blockages, as well as blockages in the fuel lines themselves.

I have the same issue when towing - in my vehicle the ECU is not getting the right MAP that it is expecting - I believe it is relatively common as a number of people have reported similar particularly if cruise control is engaged when towing - WOT in high load situations - for me only when towing over 1 tonne and speeds above 100kph - usually going up hill.

If I potter along at 100-110kph when towing and don't use WOT then I don't have an issue. Also never have an issue when not towing. However if I use WOT when towing I will get the fault alert straight away so I usually try to use high throttle if needed but not WOT - if the fault comes up a switch off and on clears it immediately and if the road is straight and safe I do it when still driving - into neutral, switch the engine off for 2 seconds and back on, then back into drive - limp mode/fault cleared.

So I would be looking at MAP first before spending money on pumps and filters. My own thought it is a fault in the way the software has been written and the ECU cannot accept the MAP it is getting when the throttle is wide open in high load conditions - that is my thought anyway.

Garry

Just a thought but have you tried changing down gear manually to see what happens. I'm thinking that this will raise the revs without you putting the pedal to the metal so to speak. Might help to see if it is high revs versus throttle position.

Martin

Originally Posted by garrycol

However if I use WOT when towing I will get the fault alert straight away so I usually try to use high throttle if needed but not WOT

This needs to be fixed! Does it happen with WOT at slow speeds when insufficient fuel pressure cannot be the cause?

Originally Posted by garrycol

I have the same issue when towing - in my vehicle the ECU is not getting the right MAP that it is expecting - I believe it is relatively common as a number of people have reported similar particularly if cruise control is engaged when towing - WOT in high load situations - for me only when towing over 1 tonne and speeds above 100kph - usually going up hill.

If I potter along at 100-110kph when towing and don't use WOT then I don't have an issue. Also never have an issue when not towing. However if I use WOT when towing I will get the fault alert straight away so I usually try to use high throttle if needed but not WOT - if the fault comes up a switch off and on clears it immediately and if the road is straight and safe I do it when still driving - into neutral, switch the engine off for 2 seconds and back on, then back into drive - limp mode/fault cleared.

So I would be looking at MAP first before spending money on pumps and filters. My own thought it is a fault in the way the software has been written and the ECU cannot accept the MAP it is getting when the throttle is wide open in high load conditions - that is my thought anyway.

Garry

Definitely worth investigating. I've found I can trigger limp mode if I plant the foot from a complete stop. So the fault is evident in the low gears as well. I'll blow the fuel lines out when I service the car this week but it really does sound like it's a communications issue, as you say. That's what has me thinking about the accelerator pedal. I've seen electronic ones go bad before and give incorrect resistance / reading to the ECU.

Originally Posted by letherm

Just a thought but have you tried changing down gear manually to see what happens. I'm thinking that this will raise the revs without you putting the pedal to the metal so to speak. Might help to see if it is high revs versus throttle position.

Martin

Yep, I use engine braking all the time and no issues with limp mode. The thing is, the car doesn't actually have to be at high revs to trigger limp mode, the throttle just needs to be open.