D5 (D5244T to 2005) Injector readings (MPG lower than normal)

[RPhoboS]

I'm just going through some tests to figure out why I've suddenly gotten worse fuel economy on my D5 (one particular journey is usually 57mpg - now is 37mpg).

I cleaned the throttle body, was really gunked up, just a lot of brake cleaner sprayed in, and gently cleaned with a mf cloth (no pushing the flap).
I'd assume the EGR and the rest of the intake is probably in the same state (140k miles).

Vida is reporting that glow plugs 2 & 3 aren't happy, so new ones will be installed tomorrow.

The MAF sensor was clean but I used a a little contact cleaner on it, without touching anything just let it dry out.

The MAP sensor was just replaced, the old one was a bit wet, oily - and the paint on the little thing dangling had come off (tbh I don't think there was anything wrong with it).
I'm wondering if the intercooler might need cleaning out or if it's leaking slightly, to replace it but no loss of power.

I just quickly did this test for the injectors, seems like 1 & 4 are the most out currently but not sure if that's a large percentage out ?

Appreciate any pointers

[5cilinder]

vida mentions the tolerance i think it is 2 mg pro cylinder , but check it yourself in vida.
Next is a leakback test to check the leakback pro cylinder its max 40 ml at idle pro minute.
In the mean time try a good injector cleaner, i had good results with millers oil eco max
If thats all good, and still large correction values try a compression measurement.

Spraying on the MAF is a bad idea , any residue will compromise the cooling and resistance. and will give distorted air masses or the sensor will die

[RPhoboS]

Appreciate your post, not sure what I can do with the MAF at this point though, as I did that 48 hours ago

I'll have a look at a leak back kit, is there any you'd recommend ?

[5cilinder]

There are dedicated maf cleaners as a spray (without residue), maybe its wise to buy one and soak it again(with a disconnected connector)

Leakback kits are all the same, i just bought some tubing and siringes which i taped upside down in a cardbox.
But maybe a second hand cheap one will do as well without the hassle , or one from temu

[RPhoboS]

I added some injector cleaner during the week, and I replaced the glow plugs after a 30 min run on the motorway today, afterwards changed the oil\filter.

I've not had a chance to run the car again, will do tomorrow.
I tried to check the intercooler for leaks, couldn't see\hear anything (sprayed some soapy water around the main areas), I wouldn't say it was a really conclusive test as I didn't take it off.

When I sprayed the MAF last week I used WD40 Specialist Contact Cleaner, it says it leaves no residue and doesn't look like it contains some sort of varnish in the ingredients sheet.
(I can try some Liqui Moly MAF cleaner during the week)

I noticed when I unplug the MAF whilst the car is idling, nothing really changes but I guess that might be normal for these cars ?

I'll order a leak back test kit and give it a go too, the injectors all look dry and no nasty stuff around them.

I did took a snap of these bits of info, not sure if it's saying anything odd or not:

[Clan]

Originally Posted by 5cilinder

vida mentions the tolerance i think it is 2 mg pro cylinder , but check it yourself in vida.
Next is a leakback test to check the leakback pro cylinder its max 40 ml at idle pro minute.
In the mean time try a good injector cleaner, i had good results with millers oil eco max
If thats all good, and still large correction values try a compression measurement.

Spraying on the MAF is a bad idea , any residue will compromise the cooling and resistance. and will give distorted air masses or the sensor will die

Indeed I have seen too many good £350 volvo air mass meters ruined by "Cleaning" It has to be asked how can they get dirty being fed by very clean filtered air and they have an electric heater to burn off any deposits if a speck of dirt lands on them.

[RPhoboS]

I appreciate the comment but it's not particularly helpful at this point, unless you're saying it's now broken from those readings?

I'm looking for ideas to test out until the leak back kit arrives during the week.

One thing I didn't verify is if the new fuel filter housing (direct from Volvo) included a filter, I'll check it tomorrow now that I have the right tool to undo it.

[5cilinder]

If it has no residue its safe for the MAF but always diconnect the connector and let it dry, soaking in pure alcohol will do as well (and drying)

At idle the MAF is at huge lamda (even with egr working) so it will function normal, it will get problematic under load and throw a code and go in limp mode.
Also the Maf is used to control the egr flow and to a lesser degree for power.

Checking the intercooler for leaks wont work with soap and no overpressure (assuming you did that)
I isolate the intercooler with adapters and overpressure and watch the pressure gauge and listen for noise

[RPhoboS]

I just performed the leak back test, all looks ok, colour is a little off on 2 & 3 due to a little rust from the connectors.
This was just an idle test for 4 mins, first photo is at 1 min, 2nd at 4 mins.

The thing is I can see the MPG info going down when I'm just sitting there idling

So it's possibly not the MAF if the car drives fine, no codes at all, all of the power ?

Just to ensure I understand you correctly, you mean remove the intercooler and pressure test it off of the car ? (if so, I'll need to get someone else to do it as I don't have a kit for it, I have a compressor just not the fittings for something like that)
I have noticed dry oil residue on the front left o the intercooler, as well as oil residue inside the pipe that goes to the throttle body, I've just no idea how long it's been there as I inherited the car from my late step father.

Thanks again

[GrahamBrown1]

You can pressure test it on the car no need for removal just remove the hoses from each end. You are correct tho it requires blanking plugs for the hoses including one for your air line to connect to. You could make something up if you have time or buy a generic kit as these are a bit cheaper and try and make it fit best you can. You ideally want to pressure test as much of the pipe work as possible. I did this on an XC90 euro 3 and from memeroy I removed the pipe straight off the turbo and the plugged it right at the inlet essentially trying to capture as much of the charge system as possible. In an ideal world you would actually use a smoke machine for this test rather than compressed air as it makes it so much easier.