Hi mmchenry,

You are in Kansas so your 740 may have encountered winters with road salts, I'll guess.

Yeah, the L-jet 240 flame trap hoses are a tough bunny to secure to the flame trap box and the other odd's n' ends.

In some cases I pre-assemble and orient the hoses to the flame trap breather box and connectors, then assemble it. I then use those funky plastic zipping ties to ensure a secure fit and and air tight one.

Your flame trap was missing? A prior individual may have removed it when it was clogged. I think I'd read that some normally aspirated four cylinder did not include the plastic sieve flame trap on your L-jet enabled B230 engine.

Weather you have a flame trap or no, doubtful that'd cause your L-jet ECU to set a 2-2-1 code. Your running B230 engine creates positive pressure in the crankcase. Combustion chamber blow by into the engine sump and the engine oil boiling off water and other hot temp gasses. The crankcase is (more or less) a sealed air space where the oil sump and chambers are. I sort of have to presume your oil cap and engine seals would be secure enough as to prevent atmosphere exchange that could cause code 2-2-1 since the AMM (or MAF) would not measure such a atmosphere. Code 2-2-1 is another of the codes that indicates a mis-measure between what the AMM (or MAF) sensor senses air intake volume and the balance of oxygen in the exhaust gasses for optimum emissions and economical operation (fuel economy). The factory docs say 2-2-1 is only a lean fuel trim condition fault.

The other cause of funky petrol like gassy smells in the passenger compartment are a faulty gas tank vapor recover system (it uses positive gas tank pressure and engine vacuum to draw fuel vapors from the gas tank to the engine intake with a charcoal canister in between to hold the gas fuel vapor when the engine is not running). A faulty vapor recovery system can be caused by damage to the vacuum lines. These lines in from the fuel sending unit at the top of the gas tank all the way to the charcoal canister. From the charcoal canister to the air intake around the throttle body. The charcoal canister can fail from corrosion and form an air intake leak.



I think that is it. So, if not, we ...... -->

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Okay, now we go into speculation other than the obvious fixes for Volvo Bosch L-jet code 2-2-1. At this point I'm presuming you have thoroughly inspected and diagnosed exhaustively (ha-ha yes to puns!) the air intake system on your 740 as well as tuning (spark plug gap) issues that can negatively impact operation as to set such a fault code. That also includes injector seals - when I mean the complete air intake system. (Read the 700-900 FAQ and search for articles for code 2-2-1 solutions here on the beloved b-board! Also, all gaskets on the air intake port. The whole air intake shamballa.


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Have you inspected electrical connections around the engine compartment? An unplug or wiggle can dislodge corrosion at the connector.

Your 740 uses a preheater method by drawing hot air from the exhaust manifold shroud through that silver hose that connects to the air filter box. I'm unsure the air filter design you have, but on 240s, the flap valve that moves back and forth to create optimal air intake temps can fail to the hot side. So, in Summer, all of the air intake is wholly heated and that can damage the AMM (or MAF) sensor. The Bosch L-jet system will operate on a less than ideal AMM (or MAF) sensor, yet as it fails from exposure to the overly hot gasses, that may cause. Though I'm not sure when an AMM (or MAF) sensor fails for this reason, does it it lean out or enriches the fuel trim? I forget.


I don't have my 700 manuals at the ready here, so if any other 700/900/90 series owns can provide illumination on these matters, please do so.


I've encountered it when the fuel mixture was rich when I had to replace the hardware the connects the head pipe output to the catalytic converter input. Your 1991 740 has the same metal doughnut spin gasket as does my 1991 240. The factory hardware on the factory converter is on size to small and if the head pipe or converter has been replaced, as exhaust mechanics are always so correct in their work, I sarcastically say, that union may be leaking and faulty. Any leak at that exhaust union can futz up emissions and fuel economy. Yet the leak may be so small you don't hear it. If that exhaust union leaks, it will usually leak out under engine load yet will suck atmosphere in on over run like when you coast downhill at speed with your foot off the gas pedal and as you stop and go in city traffic. The same holds true if the exhaust manifold to head pipe flange union leaks.

With Bosch L-jet, proper emissions controls also means you extract maximum performance from your Volvo. Even truer on newer autos such as OBD II and newer.

Have you inspected the control pressure regulator vacuum line to verify proper operation of the control pressure regulator?

A failed RWD Volvo L-jet injection control pressure regulator leaks fuel via the vacuum hose. Yet you don't smell gas, you say you smell crankcase fumes in the passenger cabin when the check engine light illuminates.

How is the exhaust? A rich exhaust may smell similar to crankcase gasses in spite of code 2-2-1 suggesting an excessively lean fuel trim.

Have you checked for optimum resistance of the two fuel inject ground leads? A Volvo TSB recommends replacing the two connector rings and soldering the new connector rings to the ground wires. These ground wires number in four as two pairs and are two ten mm bolts on top of your. A weak fuel injector ground lessens fuel delivered.

And finally, we have fuel delivery issues. The L-jet system ain't delivering enough fuel to the engine. Why I suggest the fuel injector ground before this. Yet, reduced fuel delivery problems can cause a an excessively lean fuel trim, causing your L-jet ECU to set code 2-2-1. Fuel filters (main and unlikely the prepump intake sock filter) can become clogged. The 740 in tank fuel pump, like in the 240, is an immersion pump at the fuel tank bottom. There is a piece of fuel line between the prepump out to the fuel delivery outlet pipe that passes through the horizontal metal surface comprising the top of the fuel sending unit assembly that is secure to the top of the fuel pump. The hose can deteriorate causing the in gas tank fuel prepump output to leak back into the tank. If the in tank prepump is wholly failed or if that piece of fuel line (I think it is a 3/8" ID rubber fuel line piece) has deteriorated, well, the main pump has some difficulty drawing the fuel into it as a functioning prepump assembly with that piece of fuel line in tact keeps the main pump primed. Else, even with a sound prepump and fuel line, your main pump may be starting to fail and may not be spinning fast enough to deliver the correct fuel pressure. The main fuel pump will make noises like a bee in a jar if it operates without the prepump priming action. Else, the main pump may be failing.

If you choose to inspect anything in the fuel system, you MUST observe safety, you must use proper tools. For example, don't use brass and not steel tools when removing the fuel sending unit assembly as that can cause a spark - you can rent or get the bung tool to remove and re-secure the fuel sending unit.

I may be missing something from my longish extemporaneous diatribe here.

Please review. Let me know if you have questions.

I'll review this in a day or so and see if I missed something.

Sorry to be so long winded. Blame it on the subject. Yet thank you as I need to do something to keep my tech writing going even though this text is in an informal narrative form of conversation.

Thank you,

Unemployed Technical Writer
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Can't afford no .sig nor good grammar. Ain't no way!