P38 power loss

Rubberknees · Feb 2, 2021

wammers said:
MAF is for exhaust gas inflow measurement for EGR it has nothing to do with how the engine runs.

I remember when I was having power loss problems quite a while back and you helped me through it. When I explained that I had changed my engine for a pre EGR one and it did not have the wiring for IAT sensor I'm sure you explained it in great detail for me how the MAF could effect my car, I apologise now if it wasn't you wammers but thought it was plus by changing the MAF it did sort the problem. I'll try and find the post and make sure

Rubberknees · Feb 2, 2021

Right then, on EGR equipped cars IAT is a low preset in the ECU. ECU relies on MAF for running air temp readings. Normally if you have EGR fitted but disconnect the vac pipe to EGR valve car will run normally without issue. However EGR only runs at a steady fairly lightly loaded road speeds. It does not work at idle or on acceleration or when the engine is under load. If the MAF has gone duff and is feeding crap to the ECU the ECU may think EGR is operating and prevent high load fuelling. The ECU will only allow fuel to be injected that can be cleanly burned by what it thinks is the oxygenated air present in the cylinder. If the MAF is telling the ECU the airflow has dropped as it does when EGR is active, then that will cause your problems. If you run the car with MAF disconnected in your case the preset will be used for IAT. This may slightly change fuel usage as the fine metering adjustment extrapolated from IAT/ fuel temp and engine temp will not be as fine. Fitting good MAF is best option
Found the post don't know how to link it so have copied and pasted how you explained it all to me. Cheers wammers I was able to follow this.

Dopey · Feb 2, 2021

Rubberknees said:
I remember when I was having power loss problems quite a while back and you helped me through it. When I explained that I had changed my engine for a pre EGR one and it did not have the wiring for IAT sensor I'm sure you explained it in great detail for me how the MAF could effect my car, I apologise now if it wasn't you wammers but thought it was plus by changing the MAF it did sort the problem. I'll try and find the post and make sure

Me too, pulling off at junctions and roundabouts, and reversing was dead slow, and it didn't have enough snot to back up on to a kerb in reverse, changed the MAF it was a different car, and it was like that for 2 years before I sused it out

RovyCouple · Feb 8, 2021

Is the Mass Air Filter the MAF and is it the one attached to the fuel filter. 2.5dse 1997.? i.e. where is the MAF.

Henry_b · Feb 8, 2021

RovyCouple said:
Is the Mass Air Filter the MAF and is it the one attached to the fuel filter. 2.5dse 1997.? i.e. where is the MAF.

Mass air flow..

Rubberknees · Feb 8, 2021

MAP on fuel filter MAF on pipe from air filter

RovyCouple · Feb 8, 2021

Many thanks Henry-b and Rubberknees, very helpful,. I'm going to renew the little rubber pipe and the relay its attached to, as I'm not getting quite the oooomph it had before it came off. I'm still only getting11.4 per 100kms and glow plug lights coming on when hot, very elusive 'hot-trick' somewhere.

brianp38dse · Feb 8, 2021

No MAF fitted to a 97 unless its had a later engine and loom ecu fitted.

tomcat59alan · Feb 9, 2021

RovyCouple said:
Many thanks Henry-b and Rubberknees, very helpful,. I'm going to renew the little rubber pipe and the relay its attached to, as I'm not getting quite the oooomph it had before it came off. I'm still only getting11.4 per 100kms and glow plug lights coming on when hot, very elusive 'hot-trick' somewhere.

That "relay" is the MAP make sure the spigot on the inlet manifold is clear before you put the pipe on.

RovyCouple · Feb 9, 2021

Many thanks brianp38dse, it indeed has had an engine replaced before my ownership and what could be 'extra' wiring. I'll get a pic.
Many thanks also totomcat59alan I'll give it a go with a toothpick.

Grrrrrr · Feb 9, 2021

RovyCouple said:
Many thanks brianp38dse, it indeed has had an engine replaced before my ownership and what could be 'extra' wiring. I'll get a pic.
Many thanks also totomcat59alan I'll give it a go with a toothpick.

You might need Wammers if someone has dropped a later engine into an earlier car, although I am guessing they swapped the ECU and loom over. I don't know what differences there are but I am sure there are some.

RovyCouple · Mar 4, 2021

Pipe changed and running nicely again, incidentally have just changed the alternator for a new one and straight away the diesel consumption is noticeably reduced ! Could the old Alternator have made such a difference?. It'l pay for itself in no time.

Grrrrrr · Mar 4, 2021

RovyCouple said:
Pipe changed and running nicely again, incidentally have just changed the alternator for a new one and straight away the diesel consumption is noticeably reduced ! Could the old Alternator have made such a difference?. It'l pay for itself in no time.

I guess if the bearings are shot it would put a greater load on the engine. And with the FIP and injectors and ECU dependent on voltages I guess anything is possible.

P38 power loss

Rubberknees

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Rubberknees

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Dopey

Well-Known Member

RovyCouple

Active Member

Henry_b

Think outside, no box required.

Rubberknees

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RovyCouple

Active Member

brianp38dse

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tomcat59alan

Well-Known Member

RovyCouple

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Grrrrrr

Technician, Bodgit & Scarper Ltd

RovyCouple

Active Member

Grrrrrr

Technician, Bodgit & Scarper Ltd

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