So my '89 240 is surging at idle. Not all the time, but most of the time. Some times it surges and bucks enough that it dies.

I've not been able to find any vacuum leaks, including the injector o-rings. Also, when driving it runs fine.

I've got new injector o-rings ordered, and will install them when they get here. The spark plugs & wires all look fine.


Got any ideas? Thanks!

 

Have you examined the idle air control valve? The IAC is often the culprit. Disconnect it and see if idle changes. If not, then pinch one of the hoses leading from it carefully as to not damage the hose. Flat jawed hose pliers are best, but I've used Channel Locks with a rag. If idle drops as you close the hose, the IAC is not working...but that doesn't mean it has failed always. Other factors can cause the IAC to malfunction. A poorly adjusted throttle position switch will cause non-activation. Too, if a speedometer signal is either not reaching the speedo or is not making from the speedo to the ecu, no signal will be sent to idle the car. Just some food for thought as you explore...

 

Thank you for your help!

I disconnected the IAC valve, and the car continued to run the same. I will look into that further when I have a few more minutes.

I will check into the TPS then as well.


I have to be honest about this car. I've grown to loathe and hate it. It has been nothing but a pain in the butt since I bought it last year. Transmission failure, abysmal economy, constant electrical problems, incurable idle surge, etc. I've done mechanical work my whole life, but everything about this car is completely bass-ackwards. The only car I've ever owned, that was worse than this one, was a 79 Oldsmobile Diesel. When I get it running, to the point where I can sell it and recoup some of my money, I'll never have another Volvo in my driveway again!

 

...as an addendum...

I have tried to test the TPS. There is no "click" with the ignition is on, but the engine is not running. With the engine running I've unplugged the TPS and the engine runs exactly the same.

Does this mean the TPS is shot?

 

The click of the TPS is internal and mechanical...will occur whether power is present or not. If it isn't clicking, either it is mis adjusted or failed. It should click just as the throttle blade opens.

 

Well, the TPS appeared to be non-functional, and disconnecting it did nothing to the idle surge. So I replaced it.

Nothing has changed, other than that I wasted even more money on this POS.

I guess I will continue to try to find a way to get this thing running better, as it's worth no more than scrap price right now.

 

For starters do you have any codes?

 

So much hate. Remember, love keep her in the air! Take it from the number one space cowboy: First Rule of Flying, by Mal Reynolds - YouTube

+1 for codes.

Also, what do you mean by surging? Does it rev really high? My car hunts, which means it just oscillates between like 1100 to 700 rpm. I like it's a small vacuum leak in my car's case. I plan on having it smoke tested. The local school is looking at buying one, so I might get it done for free. I'd replace vacuum hoses and do some standard checks for vacuum leaks.
Volvo in their green book suggests:
Inlet system, air leakage
Air control valve hoses clogged / loose
Air control valve seized
Coolant temp sensor not connected properly
Throttle valve loose / incorrectly adjusted
Throttle switch incorrectly adjusted
Ignition timing incorrect
Line pressure incorrect
CO-setting incorrect

Until you've done all that, you haven't shown her enough love. The part about the coolant sensor not being connected properly just means to make sure the the knock sensor and coolant sensors are not plugged into the wrong connectors. I would suspect the air leak to be the most likely. It's probably a really small one in a hose somewhere.

 

When I say it's surging, what I mean is that it's bucking - swinging from near death to probably 1500 rpms. When I'm accelerating, or at any kind of road speed, it runs smoothly.

I had a code (I forget which one it was) that indicated a bad O2 sensor. I replaced the sensor, and no more code, but no better performance.

I have gone over all vacuum lines with repeatedly. I've even done the propane bottle method, and have never detected a leak. All my interior baffles work well.


I will remove and inspect the IAC valve tomorrow - even though it appears to be almost new. I'll also re-inspect all the hoses & connections.

I'm willing to keep hunting down freebies, but I'm done throwing money at this worthless pig.

 

When you changed the TPS, did you go through the adjustment procedure? Also, have you checked the throttle body to see if it needs cleaning.

Basically the operation here is that when the gas pedal is released, the throttle body should be completely closed. This position is detected by the TPS (this is the click you should hear) and it engages the IAC circuit to control the airflow to keep the idle around 700 RPM.

Many times the throttle body gets so gunked up that it doesn't close properly and the TPS never turns on the IAC.

Hope this helps.

 

^ Thank you. I'll double check that, again. And yes, I do believe I have properly installed the new TPS.


I will add that the beast seems to surge and buck less in the morning, before the engine has warmed up.

I will also clear, then scan for codes again.


Gotta be honest though. For the ride, for the mileage, for the constant headache involved, I'm probably just going to get rid of this pig and drive my old Grand Cherokee. I've done mechanic work for over 30 years, and have never run into a nightmare like this car.

 

You mentioned that after you replaced the TPS that if functions the same. I assumed that you didn't hear the click in this case. This is why I thought it may be mis-adjusted or that the throttle body was dirty.

In order to hear the click, the key should be on (position II) but the engine need not be running. It should be easily audible with the engine off.

 

The new TPS seems to be functioning as intended - click and all.

I scanned the codes last night. 111 on both sides. I'm going to scan them again this morning & see if anything new has arrived.

 

So I rechecked codes this morning. I got the codes 113, 123, 224. It appears that both 224 & 123 point toward the Coolant Temp Sensor. 113 is injectors, which I assume might be a symptom of the other 2 codes.

Is this the same as the Fuel Injection Temp Sensor?


Looks like I'll be dumping even more money into this pile of crap.

Is there any brand of CTS I ought to look for? Any one to stay away from? Is there a supplier you'd suggest? I've been happy with the stuff I've gotten from IDP. Or would I be okay getting one from OReilys?

 

These code stack meaning the first code to set usually is the problem one and the other codes are caused by the first code. So just remember when you are reading the codes the last one you see is the primary one. So with that said was 113 set first or was it 224?

 

I bought mine from car quest. It takes a 3/4" deep socket to remove/install. It's the same as a 19mm. I think an O2 sensor socket is the same size. I found a 12pt socket easier to use than a 6pt. I don't think that the one I bought cost too much.

 

123, then 113, appeared on the #2 slot.
224 appeared on the #6 slot.

Is it safe to assume that the Injection Temp Sensor is the most likely culprit? And again, is this the Injection Temp Sensor, with the 2-prong connection?


Thanks!

 

That's the one. It sounds like a likely suspect to me, given the codes. I've had one fail that would have a dead spot in the range of detection, so it would act very oddly.