I just bought an '89 Volvo 245 that is idling WAY ROUGH. Runs fine when it's cold....once it gets warmed up the idle becomes rough. Push down on the accelerator and everything seems fine. Pull up to a traffic light, put my foot on the brake pedal and the car starts sputtering and pulsating, I guess. If I take my foot of the brake it will drive on its own in short power bursts. if I put my foot under the accelerator and pull up, the idle smooths out until the next time i come to a stop.
so.... first thing i did was put in a new thermostat b/c the car never seemed to heat up all the way -- the heat blew relatively hot, i guess, but the needle of the temp gauge never went above the 1/4 mark.. so that was replaced. didn't make any difference. all the plugs have been checked, ditto the wires and cap, etc. two mechanics both diagnosed a faulty air mass meter b/c it was running lean and sucking air... one also suggested that I get a new vacuum and breather hose for the flame trap, which had cracked and been mickey mouse siliconed. so i replaced the trap but not the hoses b/c they looked fine. next. i got a new air mass meter which didn 't make any difference . so today, the new diagnosis by my 'mechanic' is that i need a new throttle body. which seems to have been recently replaced -- b/c the gasket looks brand new. which means to me that the previous owner was probably having the same problem and was equally stupefied.
my volvo parts guy told me that it was unlikely that i needed a throttle body... i'...I've been told by various folks that it's one thing and then another by someone else...here's the list

1] temp sending unit that sends the signal to the computer
2] frozen kick down cable
3] tear/hole in the bellows from the air mass to the throttle body
4] throttle body

hope someon can help shed light. i'm nearly broke and want to avoid spending more money unessarily on uneeded parts. any advice would help.

well, didja fix it, or go broke trying. inquiring minds want to know. thanks, chuck.

See porkface's reply to my post of Friday, 23 January, "Cutting Off." I'm having the exact same problem. Runs fine at start up, then idles all the way into the ground. Porkface says either the idle motor is going away, the throttle body is sludged up, or the throttle sw is not working. I don't know what a throttle sw is, but I'll for dang sure check it now.
This is what I'm going to try: disconnect the air intake from the throttle body and get my dad or somebody to spray throttle body cleaner into it while I work the pedal. This probably won't work for me, because everything that goes wrong in my life must be expensive. I hope you have better luck!

Karin,

The 240 intake bellows often rub on the inside of the fender. The high point of the "accordian" like corrigations wear and often the opening can not be seen until the intake bellows is removed. Also I had a Scan Tech (after market brand) intake bellows split where one of the small hoses attaches to it near the throttle body. To remove the bellows for inspection .... loosen the large clamp at the AMM and clamp where it attaches to the throttle body. Then loosen clamps and remove the two smaller hoses near the TB. The bellows can now be pulled off and you can take a close look at it for any breaks or tears. Bend the corrigated area to see if any of those high points have worn through. Also check the reinforced areas where the small hoses connect. If the bellows needs replacing buy a Volvo part and stay away from Scan Tech. The SC bellows I bought failed in 1500 miles and three weeks of driving.
The brake booster is located on the firewall just in front of the driver's position. A large round metal canister about the size and shape of a fruit cake can. There is a hose running into it and the brake master cylinder and brake fluid reservior are mounted on the front.
If you want to know a lot more about how your Brick works and what to do to fix it ... I'd recommend buying a Bentley 240 Manual. IPD and others sell them.
Hope this helps and good luck with your Brick.

Like darmstrong says, check the booster. Pinch the hose with some vice grips while the engine is idling, and that will tell you quick enough.
On the other hand, have any of the mechanics you have talked to watched the O2 sensor readings? That is a sure fire way of determining whether the engine is in good fuel control, and it is probably fuel control that is causing the rough idle. These engines will pull a bit of the intake manifold gasket in and cause an air leak on one cylinder. Any good mechanic will spray some propane or (I like this stuff) acetylene gas around the manifold runners at the head and figure it out quickly enough, or eliminate this as a possiblity.
BTW don't let any of these mechanics sell you a mass meter, or whatever. Have them exchange those parts with known good ones to prove where the fault is, and if they are wrong, re-install the original without charge. Don't pay for their education.

thanks for your insights. unfortunately I've already paid for quite a mechanics eduction.

wondering if you could help me locate the brake booster ....
....thanks in advance.

oh.... if it is the brake booster, then what would i need to do?
and is it okay to drive the car as is until this nagging idle issue is resolved?

Based on your description of braking causing the rough idle, maybe there's a problem with the brake booster, such that when you apply the brakes, it's impacting on the intake vacuum.

How about trying an experiment, where you disconnect the brake booster vacuum hose from the intake, plug the intake, and see if the idle problem persists. Be careful of course, as you will have no vacuum assist on your brakes, and will need significant extra pressure on the pedal to stop.

If the engine seems to run smoother for this test, then the problem is likely a leak in the brake booster.

Really sounds like a vacuum leak, masked by the rich running when cold right after startup. My strong suspicion is the big snorkel between the AMM and throttle body. Remove it (carefully), and check it (esp. the underside) for holes. Use duct tape for a temporary fix if you have holes.

hey there and thanks for your insights...
yes, i've been told to check the 'bellows' which i did yesterday by eye... i actually thought that i saw a pinch on the top -- and pointed it out to my mechanic, but he dismissed it without really looking. the reason i was checking it in the first place is b/c my guy at the salvage yard felt bad for me when i called to order the throttle body one day after the air mass meter... so he looking into it and some volvo friends suggested the bellows. i guess i need to disconnect and remove it to do a proper inspection? is a hole in the bellows hard to find?
thanks again ...

Holes in the snorkel are easy to find, once it's off the car. Typically they occur on the underside, where the snorkel may rub against other parts.

Never heard of having to replace a throttle body. They do however need cleaning out after many miles. In an extreme case there can be so much crud build up in the bore that the butterfly does not fully close, this can affect closure of the Throttle Position Switch and of course idle. The fact that lifting the pedal smooths out the idle would indicate this.
What is your idle RPM?

There are instructions in 700/900 FAQ section on throttle body cleaning and adjustment, applies to your 245 as well.

Other poster's instructions about setting base idle are not applicable as your 89 has the LH2.4 fuel system which has no base idle adjustment or any idle adjustment for that matter. His other comments are applicaple.
--
David Hunter

hey david and thanks so much for your insight.
you just saved me an entirely new hassle of figuring out how to set the base idle.
my 'mechanic' has already cleaned out the throttle body -
and said that's not the problem...
there IS a new gasket and what looks to be a replacement tb on there already...

it is possible that the prior owner - who had this vacuum leak -- was also given the misdiagnosis of a faulty throttle body...and so had it relaced... - but installed incorrectly, or missaligned as another poster on this thread has written?

my mechanic said the problem was that the butterfly was stuck open -- that it was the plate on the throttle body...

is there any chance, as its been suggested by the guy at the salvage yard -- that it might be that the kickdown cable is frozen or that i needed to change the temp sending unit that sends the signal to the computer?

i've heard so many different diagnoses that my head is spinningggggggggggggggggggggg

thanks again.

It really sounds like you have a vacuum leak somewhere, this will also explain the lean running as well as the rough idle.

to disregard the kickdown cable, just unhook it from the linkage. the car will drive fine, just won't kick down the trans. NEVER seen a kickdown cable cause a running problem, never. shifting problem-yeah, lotsa times. make sure there are no vacuum leaks anywhere. the intake hose, intake manifold gasket, those hoses that "looked " ok, etc.. good luck, chuck.

Check the Bellows carefully by Eye...
this is free if you have a screwdriver.

check the Throttle Position Switch...
it should click as you open the throttle,
I expect it's working because you have surging idle
which should mean the Idle Air Control is working

Setting the Base Idle:
This is also free
1. Warm up the engine

2.ground the idle test point
this should be located on a pigtail connector near the ignition coil...
some one else will have to give you the color code I don't know it
this will cause the computer to stop regulating the idle

Alternately clamp the hose into the Idle Air Control

3. adjust the idle using the Base Idle Adjuster...
this the black knob under the Throttle Body...NOT the little screw
that adjusts the throttle plate
The Base Idle is roughly 730 RPM...but is probably written on the
sticker on the fender or fan shroud

4. disconnect the ground wire.

The following should be noted:

If some one has missadjusted the Throttle Plate Stop Screw this won't work
the throttle screw should just stop the throttle plate from
slamming shut (1/4-1/2 turn from touch)

There is a link that goes from the spool looking thing with the
throttle cable to the TB it could also be missadjusted.

The Throttle Plate can be held open by a missadjusted Throttle Position Switch.

Given the above you may be ahead to pull the TB and do all of the
adjustments before you go on to setting the idle

One last thing...
If the Idle Air Control is flakey you will still have problems

Luck
Miguel
--
My First Volvo - stock (for now) '84 244, 230+kmi. Owned it since 9/03