B

BladeRob

Member
Hi, I am looking for suggestions - I have just brought a 1999 P38 diesel auto which has done about 100k miles.

There are a couple of issues with windows & door locks, but more concerning for me is the trip computer is saying that the average consumption is around 18! (which I believe as you can almost watch the needle going down!). This is when driving like a granny.

It has road tyres which are inflated correctly.

It has apparently had a replacement turbo recently fitted.

I don't know if this is normal, but the first 3/4 of throttle travel has very little effect, whilst the last 1/4 of pedal travel seems to give reasonable power / speed. There doesn't seem to be excessive smoke.

Hot starting is a problem, for which I have just ordered a fix off ebay to hopefully sort it out.

Does anyone have any ideas of what could be the cause of the poor economy?

Thanks, Rob
 
Your fuel computer may be correct! I have a 1998 DSE and around town & climbing hills I have had mine showing approx 19MPG. Try running down the motorway at a steady 50mph and reset the computer via the button on the stalk, it should come up on the message display "Computing" This takes about 1 minute. Keep the spped at a steady 50 / 60 and see what the reading shows. Mine averages 30MPG on the motorway at 50MPH. The onboard fuel computer is very delicate as soon as you hit a hill it drops rather rapidly. Also check the range after you have reset, you will find this will also increase. It seems to adjust it's self in conjuction with the MPG.
With regards to the hot start, I had the same problem, so I bought the more expensive one from eBay @ £31.00 inc p&p and i have never looked back. Engine fires up within 2 seconds of me turning the key, no more black soot out the back and easy to fit.
I hope this helps.
 
your mpg seems ok i have a p38 diesel manual and to drive it in town and short journeys 18-22mpg is norm on long journey it will do up to 30 mpg i would imagine an auto would be heavier on fuel as regards your power issue you have to hoof them pretty hard to get a power response as regards your hot start and your static timing may be retarded (happens with wear) a member on here who i know had a lousy hot start advanced his static timing a bit (with faultmate) and now has fantartic hot start. I advanced my timing without faultmate and gave myself fantastic start hot or cold and serious lift in power but my timing is advanced too far as i have a good puff of smoke each time i hit the throttle spudH plugged in mine and im advanced 1.5 degrees too much but im going to leave it as it is great to drive. So your power and hot start could be static timing issue. hope this helps.
 
Fill the tank, reset the computer and see what you get. Mine does around 24mpg as a long term average, traffic not so bad here though. Check the leak off pipes as they are a common cause of poor fuel consumption.
Never got the consumption down that low even towing the caravan around the UK.
 
same story with me .......
19/20 around town etc - 26 on the motorway at 70 mph

I did throw in 2 cans of some gunky stuff that kwik fit sells thats supposed to clean the injectors - mpg is defo a little better now.
 
I have owned a few lancruisers in my time with the mighty 4.2 turbo diesel they struggled to do 18-20 mpg but at least they had some grunt
the td range rover engine IMO is two small for the size and wieght of a RR bmw should have left it in the car it came from
 
At 100k your injectors will be tired. Get them serviced. Get static timing reset. Make sure MAP sensor is connected properly (no splits in pressure hose) and working. Check all electrical contacts to FIP, MAP sensor and ECU temp sender are clean. Make sure you have good fuel flow from lift pump. Remove and clean out intercooler, make sure all hoses are free from collapse with no internal delamination. Fit a new air cleaner. After all that it may improve a little. A 100k motor will never be as good as a new one. 18 mpg around town is not a bad figure if you live in an hilly area. But maybe could be improved slightly with a little work.
 
Thanks for the replies, please keep suggestions coming.

It will take me a few weekends to get through the suggestions but I'll get there eventually!

Being a tight arse, I'm going to go through the suggestions that cost the least first (timing, clean intercooler, check connections etc).

On the drive to work this morning on a decent stretch of the A5 (no hills etc) at 50 mph the consumption was 28. By the time I got to work, all on the A5 but quite busy so some of it was at 40ish mph, the average had dropped to 20.
I would imagine the 50mph consumption is as good as it will get, and any averages will be worse than this. Reading that other people get averages of high 20's / early 30 on a run, I am convinced that there is a problem with mine.
 
BladeRob said:
Thanks for the replies, please keep suggestions coming.

It will take me a few weekends to get through the suggestions but I'll get there eventually!

Being a tight arse, I'm going to go through the suggestions that cost the least first (timing, clean intercooler, check connections etc).

On the drive to work this morning on a decent stretch of the A5 (no hills etc) at 50 mph the consumption was 28. By the time I got to work, all on the A5 but quite busy so some of it was at 40ish mph, the average had dropped to 20.
I would imagine the 50mph consumption is as good as it will get, and any averages will be worse than this. Reading that other people get averages of high 20's / early 30 on a run, I am convinced that there is a problem with mine.
Click to expand...

It depends where you live, hills or not, traffic stop start or not. Mine drinks fuel in stop start traffic and at 30 mph. So much for the governments slow down and use less fuel crap. If i could do 50-60mph everywhere it would be good on fuel.
 
wammers said:
It depends where you live, hills or not, traffic stop start or not. Mine drinks fuel in stop start traffic and at 30 mph. So much for the governments slow down and use less fuel crap. If i could do 50-60mph everywhere it would be good on fuel.
Click to expand...

It is not very hilly, traffic is fairly free flowing. If I go the lanes way to work, they are 50 to 60ish mph lanes with the odd junction.

I cleaned the intercooler when I got home, as I thought it might be clogged up due to the old turbo expiring but it wasn't that bad. Checked the air flow sensor connection which looked OK.

Where is the ECU temp sensor located - looked through the manual for about 45 mins but can't find it!

Planning on checking the timing at the weekend. Do you need the adaptor for the dial gauge or will a mag mount do the job? Does anyone know the diameter of the crank locating pin?
 
Hi i had a p38 2.5 1996 with all the same problems . I replaced all the injector rubber hose returns. replaced in tank fuel pump this put bad starting right .I also fitted a psi power box it will do 29-32 at 70 motorway 24-27 round country roads I did all this about 3 years ago still running great Pete
 
I took the engine cover and pipe from the filter housing off and discovered that the egr has been removed and blanked off. Will this be ok?

Also whilst looking for the ecu temp sender, I found a jumper lead between the sender and the original wiring which went to a small box (quite old looking and obviously not original) with "power link" on the sticker. This was getting a signal from the manifold pressure sender.

Am I correct in thinking this is an after market hot start device? What ever it is I have now removed it and will find out of any notable differences in the morning.

Whilst doing this, I could see that the injectors and leak off pipes look ok from the outside with no leaks.

I have a ultrasonic bath - Would it be worth taking the injectors apart to give them a clean or leave it to the experts?

Thanks, Rob
 
BladeRob said:
I took the engine cover and pipe from the filter housing off and discovered that the egr has been removed and blanked off. Will this be ok?

Also whilst looking for the ecu temp sender, I found a jumper lead between the sender and the original wiring which went to a small box (quite old looking and obviously not original) with "power link" on the sticker. This was getting a signal from the manifold pressure sender.

Am I correct in thinking this is an after market hot start device? What ever it is I have now removed it and will find out of any notable differences in the morning.

Whilst doing this, I could see that the injectors and leak off pipes look ok from the outside with no leaks.

I have a ultrasonic bath - Would it be worth taking the injectors apart to give them a clean or leave it to the experts?

Thanks, Rob
Click to expand...

Don't even think about doing that. Take them to a specialist.
 
BladeRob said:
I took the engine cover and pipe from the filter housing off and discovered that the egr has been removed and blanked off. Will this be ok?

Also whilst looking for the ecu temp sender, I found a jumper lead between the sender and the original wiring which went to a small box (quite old looking and obviously not original) with "power link" on the sticker. This was getting a signal from the manifold pressure sender.

Am I correct in thinking this is an after market hot start device? What ever it is I have now removed it and will find out of any notable differences in the morning.

Whilst doing this, I could see that the injectors and leak off pipes look ok from the outside with no leaks.

I have a ultrasonic bath - Would it be worth taking the injectors apart to give them a clean or leave it to the experts?

Thanks, Rob
Click to expand...
Sounds like your little box may have been fooling the ECU into thinking that the engine was cold all the time which would account for poor fuel consumption.
 
redrrover said:
Hi i had a p38 2.5 1996 with all the same problems . I replaced all the injector rubber hose returns. replaced in tank fuel pump this put bad starting right .I also fitted a psi power box it will do 29-32 at 70 motorway 24-27 round country roads I did all this about 3 years ago still running great Pete
Click to expand...

Pete, I missed this post yesterday.

Did the pump just improve the starting problem or did it help with fuel consumption as well? (I cant see how it would but thought I'd ask!).
 
Hi the intank pump made the starting ok .did nothing to fuel mpg .there was a cold start unit fitted this only tells ecu engine is cold so less mpg 18-20. I removed all of this. but the psi power box does the job it runs fine now Pete
 
Still no improvements with the fuel consumption.

Checked a few things out already - running gear etc, MAF, MAP, & temp sensor wires, pump timing which was 1.1mm. I set it to 0.9 as in Rave but starting was notably worse so I'm going to set it to 1mm tomorrow.

Going to try some injector cleaner next.

Put some new radius arm bushes in today. I have access to a decent press and made up a taper but still managed to cheese a bush! Because of the damaged bush I was only able to do one side but it has made a big improvement to the straight line precision. If I can get a new bush I'll do the other side tomorrow.

I'll get there eventually! (but have the feeling it will be like the forth bridge..)

Rob
 
BladeRob said:
Still no improvements with the fuel consumption.

Checked a few things out already - running gear etc, MAF, MAP, & temp sensor wires, pump timing which was 1.1mm. I set it to 0.9 as in Rave but starting was notably worse so I'm going to set it to 1mm tomorrow.

Going to try some injector cleaner next.

Put some new radius arm bushes in today. I have access to a decent press and made up a taper but still managed to cheese a bush! Because of the damaged bush I was only able to do one side but it has made a big improvement to the straight line precision. If I can get a new bush I'll do the other side tomorrow.

I'll get there eventually! (but have the feeling it will be like the forth bridge..)

Rob
Click to expand...

yes it will be like that rob,but keep going as it will be well worth it in the end.no matter what you do to it though the fuel consumption will never be great,just live with it mate.also consider fitting a psi power box to it,i fitted one to mine and it made a big improvement to the power and a little better to the MPG.:D;)
 
You must log in or register to reply here.

Similar threads

D
P38 in need of some love
Replies
7
Views
788
stuu
stuu
feyniriel
P38 key not locking the car
Replies
13
Views
1K
Grrrrrr
Grrrrrr
F
2001 P38 2.5 Diesel EKA Via NANOCOM
2
Replies
35
Views
1K
Datatek
Datatek
jimmacD
P38 Diesel intank sender...... pump only?
Replies
7
Views
681
Alexander V
Alexander V
feyniriel
P38 windshield wiper liquid not spraying?
Replies
9
Views
431
pwood999
pwood999