240 93 Volvo with lean/rich codes and hesitation

240Dad · Post by **240Dad** » 24 Jul 2012, 16:04

Greetings all,
My 240 has 197000 miles on it. I have done extensive repair and replace over the last 3 or so years. It was running pretty well till a couple of months ago when it started hesitating at start up and the check engine light came on. I ran the codes and got the following:
232, 231, 221
After some research I determined that it was probably the O2 sensor. Other info suggested it might be as simple as a manifold leak. I did the cheaper thing first by changing the manifold gasket. That didn't solve the problem so i went with a Bosch O2 sensor. Unfortunately both the hesitation on start up and the same engine codes came back after a few miles of travel.

In the last couple of years I have replaced the fuel injectors and the MAF. I have changed the fuel filter as well. All plugs are relatively new and the plug wires are brand new.

What should I look at next?
Thanks, as always,
Bill

240Dad · Post by **240Dad** » 01 Aug 2012, 18:16

Repost

russellengineering · Post by **russellengineering** » 01 Aug 2012, 22:41

Hi Bill,

I am not the greatest at giving advice on repairs. But since it has been quiet here goes!

I have a 940 that I have kept running thanks to tips from this site http://www.volvoclub.org.uk/faq/EngineP ... iagnostics. I have a B230F engine like you, so a lot of this site applies to you. Sometimes, the 240 has differences that a 940 guy like myself does not realize.

I would first reconfirm that the oxygen sensor was the correct one for the car. Sometimes an online supplier will give you the wrong one. I would then test the oxygen sensor, I believe there is a procedure given in a past post.

I would then look at air leaks in your vacuum hoses, brake booster check valve, and the flexible intake air supply hose. Any tear in that intake hose will cause problems.

Fuel pressure regulator going bad will starve fuel and is a common and predictable failure. It will cause a lean or a rich condition. It happens when the engine is hot or cold whenever it feels like it.

Does it just act up just when cold? If it runs better once warm the cold start injector could be at fault. There is a test in a past post I believe for this.

Ignition amplifier, distributor, and hall sensor are all likely culprits that fail or at least need some cleaning. They seem to be a problem on hot or cold starts intermittently.

Anyways, that is a few thoughts to check out. Good luck and check back in!

Dave

240Dad · Post by **240Dad** » 02 Aug 2012, 10:09

Thanks, Dave,
Since my original posting the car has been running very well even when cold. The problem is that, after clearing the codes, the car will run for a few days and a few miles and the check engine light will come on again with the car running fine. When I check the codes they are the same as before.
I do wonder about the vacuum lines since my cruise control does not act right either. I think it works partially off vacuum too? I can set it and it will hold for a while then start slowing down.
I will check the vacuum and see if that helps.
I am afraid it might be the fuel pressure regulator since it is so stinkin' expensive. Maybe I can get someone to run a test on it.
Thanks again,
Bill

240Dad · Post by **240Dad** » 07 Aug 2012, 08:44

Follow-up;
I replaced the fuel pressure regulator last night. I am not sure it it solved the problem yet. I get a slight hesitation when I excellerate whether on the road or sitting still.
The only thing that I have left to change is the fuel pump(s).
Bill