How i improved my MPG and general running.

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Pgups

Active Member
Posts
155
Location
SE London
Afternoon peeps.

Spent the last few days working on the P38 DSE as i have had poor fuel consumption recently and a flat spot with loss of power between 1st and second.

The first thing I did was to remove the inlet manifold and replace the EGR with a blanking system i got from ebay for £40. Next i spent ages cleaning out the inlet manifold getting out as much of the thick black goo as i could. I used lots of carb cleaner and a long driver with a rag. Was surprised how caked up it was in there.

Next I removed the rocker cover. Inside the cover is a filter system so removed about 20 little bolts and removed the wire mesh and gave it all a good clean and degunk.

Next i got rid of the air filter and replaced it with a performance filter. not a cone filter but a panel filter inside the standard air box.

While i was there I gave the MAF a good clean out with some carb cleaner and the vac pipe that runs from the MAP (next to fuel filter) to the inlet manifold. This was full of oil.

From reading all the notes on here i also thought it was a good idea to change the colant temp sensors. These were 30 quid for the pair. One for the ecu and one for the gauge.

With all this done I put the car back together and took it for a spin. The transformation was amazing!

The Average MPG figure on the dash (i know this isnt accurate but as a guide i used it) has increased considerably. I was getting a reading of 16mpg around town on my reg drives and im now getting 24-26MPG. As well as that it pulls away easier, theres hardly any smoke, hills are a breeze, and its costing me less.

As well as the performance issues i was also having a problem with the EAS keep going into high mode by itself. On the off chance i swapped the yellow relay in the fuse box for one of the others and it seemed to work! as a result i popped out and bought a couple of new relays at £4.50 each and changed that one as well as the 2 for my heated front screen and that now works too!!!! would appear that basically all my yellow relays were dead so if your having heated screen issues give it a try.

So thats about it for now. The P38 is running well.

Hope this is helpful to anyone with similar issues.

Few pics below of rocker cover and EGR.
 

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Looks like a good comprehensive spruce up - 'cept for the "performance" air filter which is unnecessary. The OE one will be just as good - unless the new one doesn't actually filter stuff it should filter!
 
yeah i don't really know much about filters. At least with this one it can just be cleaned and doesn't need to be replaced saving a few quid. wasn't much more than a standard one either.
 
Afternoon peeps.

Spent the last few days working on the P38 DSE as i have had poor fuel consumption recently and a flat spot with loss of power between 1st and second.

The first thing I did was to remove the inlet manifold and replace the EGR with a blanking system i got from ebay for £40. Next i spent ages cleaning out the inlet manifold getting out as much of the thick black goo as i could. I used lots of carb cleaner and a long driver with a rag. Was surprised how caked up it was in there.

Next I removed the rocker cover. Inside the cover is a filter system so removed about 20 little bolts and removed the wire mesh and gave it all a good clean and degunk.

Next i got rid of the air filter and replaced it with a performance filter. not a cone filter but a panel filter inside the standard air box.

While i was there I gave the MAF a good clean out with some carb cleaner and the vac pipe that runs from the MAP (next to fuel filter) to the inlet manifold. This was full of oil.

From reading all the notes on here i also thought it was a good idea to change the colant temp sensors. These were 30 quid for the pair. One for the ecu and one for the gauge.

With all this done I put the car back together and took it for a spin. The transformation was amazing!

The Average MPG figure on the dash (i know this isnt accurate but as a guide i used it) has increased considerably. I was getting a reading of 16mpg around town on my reg drives and im now getting 24-26MPG. As well as that it pulls away easier, theres hardly any smoke, hills are a breeze, and its costing me less.

As well as the performance issues i was also having a problem with the EAS keep going into high mode by itself. On the off chance i swapped the yellow relay in the fuse box for one of the others and it seemed to work! as a result i popped out and bought a couple of new relays at £4.50 each and changed that one as well as the 2 for my heated front screen and that now works too!!!! would appear that basically all my yellow relays were dead so if your having heated screen issues give it a try.

So thats about it for now. The P38 is running well.

Hope this is helpful to anyone with similar issues.

Few pics below of rocker cover and EGR.

Cleaning the manifold was good and the cam cover vent. Cleaning the MAP sensor and feed pipe did most good. Blocking the EGR with a penny would have been cheaper. Cleaning MAF if you have blocked the EGR was a waste of time. When are you planning cleaning the intercooler? Performance air filters on a turbo are as useful as tits on a Mars bar, standard filter just as good if not better.
 
yeah i don't really know much about filters. At least with this one it can just be cleaned and doesn't need to be replaced saving a few quid. wasn't much more than a standard one either.

Eeeee, I hope the RR doesn't use hot wire MAF (I wish I knew, but honestly I've never looked into it). Otherwise you're in trouble.
The oils in these cleanable filters build up and lead the engine to run lean. This in a turbo means you're gonna have a bad time.
 
the intercooler will be out next week hopefully. A friend has a cleaning bath and he will be taking it off me for a day to clean it for me.

Is the MAF redundant now then that the EGR has been blanked off?
 
The MAF is used to adjust fuelling. Without a MAF the engine will go into default mode and not alter fueling at all. Very inefficient as it will generally over fuel in this instance. If you cake the hot wire in oil you insulate it, making the vehicle under fuel. Leaning out an engine makes it run hot. Not good with a turbo as you generally want to run slightly rich to keep the temps lower.

A better option is to spend the £10 or so quid on a standard filter.
 
the intercooler will be out next week hopefully. A friend has a cleaning bath and he will be taking it off me for a day to clean it for me.

Is the MAF redundant now then that the EGR has been blanked off?

Mostly, that is what it's there to control. Does not mean you can take it off though. ECU would not like that.
 
Oh i see.

Cheers chaps this is all very useful.

For a short period the flat spot when changing gear completely went but now its back. Any ideas what that might be? Overfueling?
 
The MAF is used to adjust fuelling. Without a MAF the engine will go into default mode and not alter fueling at all. Very inefficient as it will generally over fuel in this instance. If you cake the hot wire in oil you insulate it, making the vehicle under fuel. Leaning out an engine makes it run hot. Not good with a turbo as you generally want to run slightly rich to keep the temps lower.

A better option is to spend the £10 or so quid on a standard filter.

MAF its there to fine control EGR.
 
Do you have to have a spare gasket handy if taking the rocker cover off? Where the 20 small screws to remove the rocker and do they have to go back on cross-ways like a head would or does it not matter? Might take mine off to clean it...

Nik
 
I dont live too far from the spares place so didnt bother having a gasket handy. Mine went back on fine i just made sure it was nice and clean and no gunk around the head.

The filter bit inside i did put the bolts back as you suggest as its habbit when i have something that long and flat. Never hurts to be careful.

I imagine you can buy a replacement mesh for the inside too but i left mune to soak and it came up pretty clean.
 
Do you have to have a spare gasket handy if taking the rocker cover off? Where the 20 small screws to remove the rocker and do they have to go back on cross-ways like a head would or does it not matter? Might take mine off to clean it...

Nik

Always replace a gasket, it never seals properly if you try to reuse one. You could cheap out and use a smudge of blue gasket stuff, but it has a tendency to get mixed in with the oil if you mistakenly use too much (easily done) which can bung up the works.
A new gasket is usually less than a large coffee at a well known multinational.

Replacing screws in a cross pattern is good practise for anything.
 
Always replace a gasket, it never seals properly if you try to reuse one. You could cheap out and use a smudge of blue gasket stuff, but it has a tendency to get mixed in with the oil if you mistakenly use too much (easily done) which can bung up the works.
A new gasket is usually less than a large coffee at a well known multinational.

Replacing screws in a cross pattern is good practise for anything.

In that case, I best get a gasket before I start playing! :)

tnx

Nik
 
Oh i see.

Cheers chaps this is all very useful.

For a short period the flat spot when changing gear completely went but now its back. Any ideas what that might be? Overfueling?
Check the tube to the MAP sensor is not perished or blocked.
I would not use any air filter that uses oil on the filter element, it makes it's way to the MAF and knackers it.
The flat spot really needs diagnostics live data, could be a lot of things.
 
What controls fuelling on the none EGR engine?
MAP and the manifold air temperature sensor, both systems of course have basic fueling maps which are modified according to pressure and mass of incoming air, the pre EGR used air temperature as a rough guide to mass, MAF is simply more accurate to meet the newer emissions regs and as you say it goes hand in hand with the EGR system.
 
MAP and the manifold air temperature sensor, both systems of course have basic fueling maps which are modified according to pressure and mass of incoming air, the pre EGR used air temperature as a rough guide to mass, MAF is simply more accurate to meet the newer emissions regs and as you say it goes hand in hand with the EGR system.

It is there to control the EGR Keith. That is why it is fitted, the ECU takes readings from it to control and measure the amount of exhaust gas allowed into the engine. The more exhaust gas enters the engine the less flow will be shown by the MAF the ECU reads this and modulates the EGR valve within mapped parameters depending on air flow measured at the MAF and engine temp. As exhaust gas is entering the cylinders the combustion will be less efficient so engine rpm will fall measured by the CPS, fuel will be increased to maintain RPM. Using a MAF the EGR can be more finely controlled than it could with none MAF controlled EGR systems. Engines with EGR control meeting EC level 1. No MAF. Engines with EGR (feedback control MAF fitted) meeting EC level 2.
 
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