S40 t4 rough idle and stalling.
 

Hey people, just took delivery of a 2000 s40 t4 today and she's running a bit rough!

Looks like its got a bit hot under the bonnet at one point ( coil cover is a bit melted!)
I have receipts for a head rebuild and new coils, there's no check engine light coming on but when the revs drop to around 400 rpm the little up arrow lights up.

Do I need to get it hooked up to a scan tool to have the idle raised or is there a trick to bumping the idle speed up?

I also found a sensor (map?) on the cold side of the intercooler piping the has nothing plugged in, could that be the problem?

Thanks in advance
Paul

400rpm's is far too low an idle speed anyway isnt it?
My V40 T3 idles normally and smoothly at 750.

Yes, 400 rpm is too low, hence me asking how I can raise the idle speed...

The computer controls the idle, no adjustment for you to make. I would start with a compression test.

Right, just to tidy this up abit.

On cold start there is what seems like a heavy miss fire for around 7-8 seconds. Accelerator pedal needs to be used to hold any form of idle while cold.

Once the engine is at operating temperature, the idle is erratic and between 300rpm-700rpm while in park or neutral. Although If you give the car a bit of right foot a few times the engine will idle at a steady 950rpm in neutral and 750 in Gear, but only for a few minutes, then it goes back to idling like **** and randomly stalling when ever it feels like it.


I also realised today that the check engine light has either blown or been removed by the seller of the vehicle! I am waiting on my new OBD-II scantool to arrive so I can't pull any codes yet, but I am expecting a fair few codes to be present!


I'm going to pull up the codes as soon as my scan tool arrives, and my weekend looks like it is going to be filled full of chasing sensors mixed in with a little iac and tb cleaning

Any change if you disconnect the MAF briefly?

Not as yet, I did remove it yesterday and gave it a thorough spray with some maf cleaner as it was filthy due to previous owner fitting a k/n panel filter.

My scan tool arrived this morning and only 1 dtc was present, p0103 maf/vaf circuit high input.

So it's either air leak, wiring problem or dud sensor. I am leaning towards dud sensor, but obviously I will check for air leaks and wiring problems to rule them out before ordering a new maf.

Cheers

Anyone know what resistance values I should be reading from the maf sensor?
Got quoted $650 aud for a new genuine volvo Siemens unit at the local Volvo stealership!

Also found that I am getting around .36v on all three wires going to the maf with the ignition on. Obviously I have a wiring issue that needs tracing, just want to make sure the maf hasn't burnt out in the process.

idles rough and stalls
 

I have been through this and maybe I can help out on the cheap.
-First I tackled the coil cover problem. Make sure no oil has accumulated there as filling the oil and missing the opening just a bit the oil collects where the wires are and down into the spark plug holes! I cleaned mine up real good and replaced the spark plugs while I was there. ONLY USE VOLVO PLUGS. Changing to other plugs is a crap shoot. S40 either like s them a little or does not like them a lot. But with VOLVO plugs it really loves them!
-Next I took the idle control valve out and cleaned it. I should have replaced it but at $150 to $200 there was no option for me. Replace the gasket before putting back. You can get the original gasket for about $2.
-So far I spent $30 on the spark plugs. With me?
-Then I replaced the thermostat, BE CAREFUL that gasket is brittle. Have a new one ready $6. Thermostat is less than $20.
-Buy new coolant sensor and replace it while you are there at the thermostat. $25.
-Next the big buy! the MAF was the answer the whole time IMO. $35.
----in total I spent less than $150.----car runs brand new. Now the damn drivers window fell off the track. AT 175,000 miles and that is it for major work done than I cannot complain!
BTW Do not do what I did and discover these problems one at a time. I could have done it all in one weekend. Instead I took about a week. Made me look bad as my neighbors were not so nicely telling me I needed a Japanese car. No Thanks! Been there done that! Volvo for life!

Would love to know where you got a maf for $30...
Because that ain't going to happen in Australia.


Well I pulled the plugs today to check their condition, and looks like the head will be coming off! Obviously whoever did the head reco either didn't replace the head bolts put the wrong headgasket in or ****ed the mating surfaces.
Moisture in the bores of cyl 2 and 3. I was expecting it, but hoping it wasn't the case.

At least I know all the work will be done properly this time.