Got an 01 s60 / 2.4t ... It's still surging under acceleration (randomly) ... Thus far I've tried:

* cleaning the etm (took it off the car and cleaned it good)
* 2 ignition coil packs (new to swap around in an attempt to find a bad pack)
* new fuel filter
* both NGK & Bosch OE spark plugs


..... Any ideas? It does a weird surge thing only under a load and only randomly (not every time). Seems hard to hold the car steady at any rpms

 

Need my car back guys, this is going on 2 months now. Any suggestions would be great. I'm thinking of cleaning the air mass fuel meter next.

 

Does the car have a CEL?

 

Nope, it's not throwing any codes :-(

 

Cleaned the air flow meter, and checked & tightened all my air / turbo connections ... Still no dice, the engine still has a slight miss or surge when under a load. Seems to occur around the 2000 rpm range more, or if held in the lower 1000-1500 range when driving. Surge occurs less so under acceleration, and more so at lower RPMs and when de accelerating. Idle is ok, however. It seems to stumble a but upon startup then evens out and runs fine at idle .

 

i am just wondering if you have one of the magnetti marelli etm's. they gave a lot of trouble and basically needed to be replaced although there are organisations that repair/rebuild them. here is an example of one organisation that provides refurbushed etm's.
Electronic Throttle Module for Volvo | Xemodex Inc.

 

Yes, I have the Marelli ETM. I took it off of the car, completely cleaned it - no difference (at all) in the symptoms I've described however. Not to say that it (isn't) the problem, but I thought an ETM problem would cause a rough idle / hunting idle issue with is not occurring

Any suggestions / or a test procedure for the ETM would be great so I can put that one to rest. Also, if there is a way to test the coil packs (I did a resistance test with them off the car, and they all fall within a certain range when on the 1st pin, and 3rd or 4th can't remember... I thought perhaps one of those was running weak, and replaced another one with no difference swapping them around and such. Fuel pump is another suspect.... or clogged cat.

 

from what i understand, cleaning the etm will not help if the carbon tracks are worn. from what i undertsand, the magnetti design used a variable mechanical mechanism for varying the resistance. This has a tendency to break down (i am a layman in this regard so my description may not make sense). do a search on faulty volvo etm etc to get a better explanation

 

Maybe a fuel pressure sensor issue??
Could clean throttle body also.

 

Yeah I did some research on the Etm previously and from what I can tell it causes an irratic idle. My car idles fine, and does weird stuff upon acceleration. Not saying it couldn't be that though. What are symptoms of a bad fuel pressure sensor?

 

I don't think the 01 has a fuel pressure sensor, but maybe I'm missing something? Tried cleaning the throttle body already and it made no difference

 

My 2003 S60 had an idle surge during deceleration, coasting through parking lots. I chased this problem for more then a year. I changed the mass airflow sensor then cleaned the throttle body, then replaced the throttle body all with no results. I replaced the oiltrap/spark arrestor and cleaned the oilports leading to it(they were clogged with carbon deposits), it fixed the problem. I have driven over 10000 miles and it has not reoccurred.

 

Where is the spark arrestor part located? Under the manifold??

 

It is under the manifold. It will need to be removed to change it. The whole project took me about 3 1/2 hours in my driveway with minimal tools. You will need a new intake manifold gasket.

 

Sweet, thanks man -- i'm going to try replacing that part. If it takes a while to do it (2-3 hours) then I'm just going to buy a new one and replace it. Are the bolts on the manifold Allen ? anything I should be aware of besides the gasket?

BTW, the car is no longer surging under acceleration -- just does this weird engine stumble at idle when first turned on / cold ; then goes away quickly with a foot on the gas pedal.

thanks again!