P38A MAF etc opinions

oakey · May 16, 2019

Hiya
V8 95 auto 186k
Has got newish plugs and a SS exhaust last MOT and new exhaust is twin pipe whilst original was single pipe.
Adaptive values are something like 127% and 3 or 4% on other bank. I dont really understand what an adaptive value is but presume it is a number that relates to injector opening time and is determined by O2 sensor.
She just passed her MOT and was thinking of rewarding her by cleaning MAF.
Good idea?
Ta much

ukadamwest · May 16, 2019

if it ain't broke, don't fix it !

kermit_rr · May 16, 2019

If you can plug into obd then have a look at the output see if it's in the expected range

oakey · May 16, 2019

Yes i can understand that view but I have no idea if it is broke or not. MPG isnt as good as it used to be but engine goes fine

The readings were from Nanocom

Grrrrrr · May 16, 2019

ukadamwest said:
if it ain't broke, don't fix it !

+1.

Don't think it is supposed to be cleaned although people try with carb cleaner and the like. Think that's last resort territory though.

oakey · May 16, 2019

Ok I accept that ta
Should I reset adaptive values?

RangeRoller dt · May 16, 2019

There is ‘special’ MAF cleaner you can buy. Not sure what it is though or how good, could be watered down snake oil for all I know, I have no MAF on purpose - horrid things and pricey

Henry_b · May 16, 2019

You have to use MAF sensor cleaner on them..

Use carb cleaner and you'll ruin it..

If you're getting bad economy, check the Lambda sensors if they're faulting she'll go into a open loop and dump fuel in..

Edit.

Rubberknees · May 17, 2019

Dodgy territory cleaning MAFs leave it alone

wammers · May 17, 2019

RangeRoller dt said:
There is ‘special’ MAF cleaner you can buy. Not sure what it is though or how good, could be watered down snake oil for all I know, I have no MAF on purpose - horrid things and pricey

MAF on a diesel is there for a total different reason than a MAF on a petrol engine.

RangeRoller dt · May 17, 2019

wammers said:
MAF on a diesel is there for a total different reason than a MAF on a petrol engine.

Makes sense now - air is constant in doozles cylinder.

Are there different cleaners? I’m sure redex used to be different types carb/diesel, turbo/non just fuel type now.

wammers · May 17, 2019

RangeRoller dt said:
Makes sense now - air is constant in doozles cylinder.

Are there different cleaners? I’m sure redex used to be different types carb/diesel, turbo/non just fuel type now.

Just so, MAF is for exhaust gas measurement when EGR is active. The reduction in airflow indicates exhaust gas ingestion. Redex would never go near the MAF sensor. So not an issue, may have been different formula for diesel/petrol. When i took over the garage business i used to own, i inherited a half full 45 gallon drum of Redex.

RangeRoller dt · May 17, 2019

Carb type knowing your luck. You probably still have half in the shed

wammers · May 17, 2019

RangeRoller dt said:
Carb type knowing your luck. You probably still have half in the shed

Got used, given away Etc.

RangeRoller dt · May 17, 2019

I only thought about it as I found half a bottle of old carb type in shed other day. cement mixer all it’s good for now

wammers · May 17, 2019

RangeRoller dt said:
I only thought about it as I found half a bottle of old carb type in shed other day. cement mixer all it’s good for now

Marketing is what it's all about nowadays. Usually much the same stuff in different cans. But the one that is used most costs the most.

Datatek · May 17, 2019

wammers said:
MAF on a diesel is there for a total different reason than a MAF on a petrol engine.

The sensing element is also different to a petrol MAF.

oakey · May 17, 2019

The can of stuff I have says petrol MAF cleaner.
Nanocom doesnt say that Lambda sensors are knackered but adaptive values are totally different between banks and I have no idea what a "good" adaptive value is

Henry_b · May 17, 2019

The adaptive values are a number of things that the ECU learns while the car is being driven, so things like correction factors on the MAF sensor, long term fuel trims etc etc.
The adaptives are things like a MAF correction factor, a correction to the fuel mapping to account for worn injectors, a iffy/old fuel pressure regulator etc etc , on a brand new engine with brand new sensors and everything working as it should, then there will be no corrections needed so the factory settings in the engine ECU will be spot on. But, you don't have brand new components so things will have aged and that is where the adaptive values come into play, best reset them and take her for a run, varying throttle and load situations..

Kick down a few times etc etc.

On a Gems P38 the adaptive values are lost when a bettery is disconnected, so they'll have to be "reprogrammed" in with a good drive..

oakey · May 17, 2019

Thats great Henryb very useful thank you
I have just changed all the filters apart from fuel which is tomorrow but I wont change values unti just before I am going on a long run.
Thank you

P38A MAF etc opinions

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Think outside, no box required.

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