Volvo 240 dl 232 and 212 codes
 

I'm new to Volvos and working on cars in general, so upfront let me ask that any advice be given in very simple terms.

I have a 1990 Volvo 240 DL 5 speed wagon. For a while now she has been giving me the 232 (running rich or lean at idle) and the 212 (o2 sensor) fault codes. I changed the o2 sensor and the 212 code went away for all of one short drive and then the next day it was back. No matter how many times I have cleared the codes, it is still there.

The engine shakes excessively, and sounds like it is coughing. Also she is stalling out much more easily at stop lights etc.

I have also just changed the oil and oil filter, along with the fuel filter. I've cleaned the spark plugs, but haven't changed them as they looked pretty good.

I read on other posts that disconnecting the battery can sometimes clear the 212 code, and I left it disconnected overnight but it is still the same. I have also heard that the 232 code can have something to do with vacuume hoses? But I don't know how I would check that out.

Any advice is welcome, I'm hoping to fix this myself as I can't really afored to take her to a mechanic right now.

Thanks in advance :)

Could be Fuel injection temp sensor.
Under the intake manifold.

Could need a valve adjustment.
Valves might be too tight causing it to run like that.

also could be air leaks in the intake path between the MAF and the throttle body.

if its running really dirty, it could have fouled your new O2 sensor in that day, bringing you right back to where you started.

You might also want to check the Fuel Pressure Regulator. I was having similar problems with my 92 240 and when I pulled the vacuum hose I found fuel going from the regulator to the intake manifold. Replaced the regulator and now it's running great.

when you pulled the spark plugs to clean them, what color were they? they should be a light to medium grey, and not greasy. were all 4 plugs about the same?

shaking engine is bad, sounds like its misfiring and/or not running on all 4.

I think I'd want to do a compression test on this engine before going too much farther. these engines usually last forever if they aren't overheated or run out of oil, but occasionally stuff happens. is there any oily sheen in your coolant overflow bottle, indicating oil got into the coolant, or any creamy goo on the inside of the oil filler cap or upper part of the dip stick indicating coolant got into the oil ?

The spark plugs were mid gray and all the same. There was no creamy in the oil, before or since I changed the oil, and as far as I can tell the coolant has no oily sheen.

Further info is that the car has no muffler, but the tail pipe looks good at least up to the o2 sensor.

Ok, to update: I have replaced a vacuum hose that had a crack in it, and I also had the throttle and IAC valve cleaned of carbon.

The car is running better, but she still coughs. It is worst at around 2000 rmp, but even at idle she will do it. If she is in gear and I take my foot off the gas and just let it roll on a level surface the whole car starts to shake and lurch forward.

Someone has suggested an ignition coil tune up, but I was hoping for a second opinion before I spend more money.

Again, thanks in advance for any possible suggestions.

I have rarely seen a coil go bad. My '55 VW beetle still has its original Bosch coil and it runs fine. If you haven't tuned up the car recently, then it wouldn't hurt to replace the plugs, distributer cap & rotor. I usually do them around 20k miles. Check the spark plug wires while you are there. They should last a good long time (100k miles if you use Volvo or Bugicord brand). If you don't know the history on yours or they are some cheap off brand, you may want to replace them.

Coils going bad may be rare but it happens. I have one going bad right now. My symptom is an intermittent no start that the previous owner threw a bunch of parts at trying to fix. The Bentley Manual provides a spec for the secondary circuit, something like 1.1-1.3 ohms. My coil varies, when cold it is 1.2-1.3 but as it warms it goes up. I have measured it up to 2.1 ohms and the car still starts but the spark at the plug is yellow. I have not had my DVM with me when the car won't start.

DC resistance of a coil is only a rough ballpark kinda thing, a coil is an AC device, what counts is its inductance, and this isn't easily read with a meter. a hot resistance of 2 ohms i no big deal.