Hunting idle RPM

[PeteBDN]

Hi everyone, I am new here and new to Volvo's, I bought a S80 2.4 manual MY2004, with an aftermarket LPG conversion, new to LPG too! I have had the car a week.

A few issues have come to light since I bought it, as there always are with second hand cars, but I would like some advice on a specific problem with mine:

The idle occasionally hunts between 1000 rpm and 500 rpm when put into neutral when I pull up at lights or junctions etc, it does this both cold, warm, on petrol and LPG. It does also occasionally cut out. 4 times today in 60 miles.

My thoughts having read Oscar the Dachshund's post in S80 articles desribing this exact problem is that firstly I need to clean out the ETM butterfly valve. I will do this at the weekend and see what happens.

If this doesn't solve the problem I will change the spark plugs, as it has been suggested in a few places around the forum that they could be the issue. It has misfired on a cylinder occasionally when under heavy acceleration up 10% gradient hills, twice or three times in 400 odd miles.

I have assumed that my problem is nothing to do with the LPG system as the problem is common to both fuels. And the fuels put into the car since I have owned it have been from different places so I have discounted bad fuel.

If none of the above two sugggestions work I would like to know what to look at next???

[The Hooded Claw]

Pete,

SLOW DOWN Mate .. yer getting WAAAAYYY ahead of yerself here ... Too much Info "Clouds yer mind" & you'll be Zippin all over the engine doin this & That...

Take it ONE STEP AT A TIME ....

A. clean out the ETM ... & then TRY IT OUT on a Run (if no better) move on to

B. Change the Plugs (& remember to get PROPER VOLVO ones ANY other type just "won't cut the Mustard" ....& Then TRY IT OUT on a run (if No Better) move on to

C. Post back here & we'll help out with more Good Ideas to try...


Pete ... TRUST ME you WILL MASH YER HEAD IN if you go about with "several Solutions" in your head ...

Softly Softly .. One Step at a time WILL Solve the Problem ...


Keith

[PeteBDN]

You are probably right, too much too soon!

I will go for the ETM at the weekend and run it for a few days, and see what happens.

[capt jack]

Good advice there, but would have to disagree with the Col on just one point - LPG and Volvo plugs don't go so well together in my experience.

I'd recommend single point copper-cored plugs - Denso work best in my LPG V70.

When I tried the Volvo (multi-electrode) plugs the car ran like a three-legged donkey.

Cheers

Jack

[classicswede]

I would also normaly be saying plugs but two important issue's suggest something else IDLE and does the same on PETROL.

The ETM is the most likely cause and would me first step. Then after that I'd be looking at air leaks.

Just do one thing at a time as suggested.

[PeteBDN]

Thanks for the replies, I will clean up the ETM tomorrow after work and let you know how it goes.

[richard willetts]

good old ETM

[PeteBDN]

Well, I have cleared the ETM valve and driven 35 miles with no hunting, and I spent some extra time down hills in neutral just to be sure!

I even took some pics to show how clean it now is! Forgot to take any before shots, sorry! It was quite dirty. I used lint free cloth, an artists brush and small amounts white spirit to clean.

While I had the ETM pipe off from the airbox I noticed the EGR pipe had partially come off the engine airbox end, doesn't look like the right pipe to me, seems to short and I guess is a replacement pipe. I should have left the pipe off after the clean up and driven to see if I had cured the hunting but hey ho. I doubt the pipe would cause idle hunting when the engine is hot. Probably won't have helped when cold though.

Once this pipe was reattached and I started the car the initial cold idle soared up to 1800rpm for 20 seconds before returning down to 750 as it should. Is 1800 rpm normal after start from cold? Until today it was normally 1600.

Thanks for your help!

[PeteBDN]

Well, all was well until yesterday afternoon when my engine starting hunting at idle again. Did it on the way to work this morning too.

When it has hunted this time it hasn't cut out, it has sorted it's self out within 1-2 seconds so there has been a definite improvement.

It hasn't done it on petrol since cleaning the ETM so I am thinking time for the spark plugs to be changed.

[ajpaynter]

I have had this trouble for a long time. It has been partly cured by disconnecting the new Mass Air flow sensor which had been fitted by Volvo in Malton. The engine management light stays on all the time though. It doesn't cure it completely but it is more comfortable than the terrible hunting & hesitation I had before. I don't know where to start looking for leaks in the air flow system.
A clean out of the ETM helped a bit at first but not for long.