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        General >> Problems >> Diesel auto wont rev past 2200 rpm
        
(Message started by: discodave on Jun 1^st, 2006, 10:40am)

Title: Diesel auto wont rev past 2200 rpm
Post by discodave on Jun 1^st, 2006, 10:40am

Just bought a diesel auto unfortuantly it wont rev past 2200 in drive. Is suspect turbo not coming in. any ideas.? Is there any real reason why u are not supposed to tow with a diesel auto? The car has done only 64000 miles and is otherwise immaculate.

Title: Re: Diesel auto wont rev past 2200 rpm
Post by mazzy_j on Jun 1^st, 2006, 10:54am

Firstly, hello and welcome to the site :)

It could be several things that my cause your problem. With the car in P or N will the engine rev freely and above 2200? If not, the cable may have unadjusted itself and so the throttle never gets to 'wide open'. That is if the engine actually has a cable throttle, i heard somewhere that it my be fly by wire :-/ You may find that the turbo is fine, but when it gets on boost it could be causing one of the inlet pipes to 'fold in' on itself and so restricting the air flow. Kind of like a kink in a hose pipe. I believe the diesel auto has the 125bhp version of the td which has a computer controlled turbo, maybe something could be up with this and it is opening the wastegate early which will mean no power and not revving flat out.

As for towing with the diesel auto, i think its because of the huge amount torque the engine produces the gearbox internals may not be able to withstrain the extra strain of towing a heavy trailer.

Hope this is of some help,

Matt

Title: Re: Diesel auto wont rev past 2200 rpm
Post by discodave on Jun 1^st, 2006, 12:28pm

My car is one of the last 98 spec models and it is the drive by wire system, when the car is in park the engine will rev freely to 4000 rpm, i have also drove up the road with the auto locked in first, it pulled strongly to 2200 rpm then just about made it to 3000 rpm. any futher advice would be appreciated. I should have test drove the car myself before buying it.

Title: Re: Diesel auto wont rev past 2200 rpm
Post by mazzy_j on Jun 1^st, 2006, 1:06pm

I was going to suggest that the fuel filter could be sucking in air if it had been replaced incorrectly, but having said that it wouldn't pull strongly even up to 2200, wouldn't idle well, wouldn't start well, and would be as lumpy as badly made gravy through the rev range. Maybe it could just do with a new fuel filter as it could be all clogged up if it hasn't been done in a while.

Matt

Title: Re: Diesel auto wont rev past 2200 rpm
Post by discodave on Jun 1^st, 2006, 1:14pm

Thats a good idea, in actual fact when the fuel filter on my old disco blocked , that was hopeless too, unfortuantly ive just checked the airfilter and there isnt one there....... Im about to check the maf sensor with a bit of dread.

Title: Re: Diesel auto wont rev past 2200 rpm
Post by mazzy_j on Jun 1^st, 2006, 1:27pm

No airfilter :o That would explain why it won't rev out fully, the fuel computer system is probably in a confused state because of the excess air. Lets hope there MAF is actually there...

Title: Re: Diesel auto wont rev past 2200 rpm
Post by discodave on Jun 1^st, 2006, 1:46pm

just got the maf box out and it does not even look like the one shown in the website photos on how to clean maf, the housing is only held on by 2 bolts to the cleaner box and is made of black plastic not ally, in the centre there is a rectangular card looking thind about 3/4 an ich long any idea? i can not see any little wires.

Title: Re: Diesel auto wont rev past 2200 rpm
Post by Simmo on Jun 1^st, 2006, 2:54pm

Unless I'm mistaken surely there have been posts before which say the Diesels don't have a MAF?.

Title: Re: Diesel auto wont rev past 2200 rpm
Post by mazzy_j on Jun 1^st, 2006, 3:01pm

The earlier diesels (like mine) don't, but i'm pretty sure the later computer controlled 125bhp ones do.

Matt

Title: Re: Diesel auto wont rev past 2200 rpm
Post by sector-9 on Jun 1^st, 2006, 10:01pm

Quite correct - if it has an auto box then it will indeed have a MAF sensor. However there is write-up on the main site about a very similar problem - that boiled down to being a boost pressure sensor I think...

Darren

Title: Re: Diesel auto wont rev past 2200 rpm
Post by SaveTheNight on Jun 1^st, 2006, 10:06pm

two problems I reckon .. MAF < clean first > AND MAP sensor on the drivers bulkhead ... second hand if poss as a new MAP might be over a hundred squid !! ...regards ...STN

oops ..ps ..you CAN tow with a diesel turbo ..best fit additional auto cooler though and run the fluid level a 500ml can higher .. you need to have faith in your auto box though ... cheers

Title: Re: Diesel auto wont rev past 2200 rpm
Post by sector-9 on Jun 1^st, 2006, 10:17pm

The diesel engine has a lower capacity cooling system than any of the petrol engines. I also think it has a smaller radiator as the intercooler has to fit alongside it. That, combined with the raised cylinder pressure when the turbo is running fast, make it very easy to overheat if the cooling system isn't spot on and these engines don't like being cooked! Ford's solution seems to have been having a massive finned sump and an air-liquid oil cooler beneath the main radiator - the total oil capacity isn't much less than the cooling system!!!

On a petrol auto, the gearbox runs it's fluid through the end of the water radiator, and through a separate cooler. The cooler used is actually very similar to the diesel's oil cooler and fits in the same place, so obviously that can't be used on the diesel. Also bearing in mind the small size of the cooling system I wouldn't be suprised if the gear oil didn't go to the radiator either in case it overloads it.

I guess the reason the diesel auto isn't recommended for towing is simply down to the possibility of overheating the transmission or engine, rather than any torque limitations - after all, the Cosworth engine gives out more...

Darren

Title: Re: Diesel auto wont rev past 2200 rpm
Post by discodave on Jun 2^nd, 2006, 4:28pm

The maf is definatly caput, need new one, unlike the petrol this one is a boshe. Does any ony one know if this particular one is fitted to any other cars. Can the ford petrol one be made to fit complete with filter box? Has any one got a spare map i can buy off them?

Title: Re: Diesel auto wont rev past 2200 rpm
Post by sector-9 on Jun 3^rd, 2006, 3:29pm

The Bosch EDC system was also fitted to Rovers with the 2.0 L-series diesel (i.e. 620 and newer 220/420 models) - try scouring a scrapyard for one of those.

Darren