Throttle problem - maybe the throttle position sensor?
 

I would very much appreciate help with this problem my car has developed. I shall give the best description I can.


My car - 2006 ('55) Rover 75 Classic saloon, 2.0 diesel CDTI.


It has run perfectly fine until recently, the only thing I did between it running fine and the issues I now have was topping the tank from just over halfway to full. I was and always have been very careful to put diesel in so I know I didn't accidentally put petrol in the car, and I used a Texaco station rather than supermarket fuel.


I quickly noticed that the engine was running lumpy but that was minimised when revving up to the point that at two and a half to three thousand revs it seemed fine so I dismissed a blockage in the fuel filter, if less fuel is getting through then I would assume it wouldn't rev up.



The symptoms have now changed, it doesn't seem lumpy anymore but the engine light comes on when I first start it and sometimes I have absolutely no throttle response whatsoever, tickover is fine but put the pedal down and....nothing at all, then it sometimes picks up, or can pick up again after turning the engine off and on again, and is fine but stop at lights and some of the time it goes back to no throttle again. It appears to be more prevalent when the engine is cold, as far as I can tell, I haven't used the car much over the weekend so that is based on limited driving.


I have looked in the Haynes book and the only thing that makes sense to me is the throttle position sensor being dicky.


Please advise if anyone knows what the problem is.


I'll bob on and off the forum to see if anyone has asked any questions to clarify things, or ideally come up with a solution.


Thanks for reading this and I hope I have made sense:cool:

Normally if the tps fails you get nothing from the Pedal at all?

I have no idea, have you any clues on what could be causing the symptoms?


I admit to very limited engine knowledge so this is simply beyond me, which is why I'm asking for help.

Water in the fuel? Remove the fuel filter and pour the contents into a clear jug or jar. Sometimes you get rusty deposits at the bottom of a garage storage tank which can block the filter and/or pipework.;) I've seen it on bulk storage tanks. Most commercials used to have a clear glass filter and the water would collect at the bottom (oil floats on water). You would see it by bleeding off fuel into a clear jar or jug.
Examples on marine engines:-
https://www.kent-marine.com/en/1182/...l-filters.html

That would explain the lumpiness but would it cause the problem I have now of sometimes having no throttle response at all from idle?

I had driven it on a 220 miles round trip last weekend and done shorter journeys since then, the only way I believe it could be water in the fuel is if Texaco had water in their fuel as it was running perfectly fine before I topped up.

Even garage tanks get low sometimes and the water collects at the bottom. I've been out to recover trucks with water in the fuel and it was usually after filling with fuel. As the fuel circulates back to the tank in a 75/ZT, it would have a hit and miss effect but there will be evidence in the filter if it is water. When standing (ie overnight) the water will collect at the bottom. It only takes a few drops of water in fuel lines to affect the running.;)

Roverbarmy, that makes sense, we had a couple of unseasonably warm weather followed by cold, this could cause condensation in the fuel station tanks and if it were low then I could have sucked some of that water into my system.


I'll have a look and see what I find, before I start is there anything I need to buy, like a new sealing ring or will the one that is on it be okay if it is in good condition? I don't want to create a leak by not doing it right...I want fewer problems, not more:duh:

Don't get involved with YOUR tank. I meant the fuel station tank. Change the filter first and see if there is water there. You may get away with just draining the water from the filter. You may have to do it a couple of times. A cupful of water can have quite an effect, distributing drops of water around the system. Empty or change the filter and see if that improves things. It may take a couple of emptyings, unless thare is a lot of water in there. Water can spread and block the paper filters too.

LOL, no I wasn't talking about my tank, I actually meant I shall look in the fuel filter and see if I find any there!


Thanks for your advice, it's currently raining at the moment here so probably not the best time to be opening the fuel filter housing and risk either more water in the system or a misreading due to rain water. I haven't got a garage or even a drive, and no plastic sheeting large enough to keep rain water out.