1986 Volvo 240 fuel injectors need cleaning?

[Sam_Julier]

Before deeming the MAM at fault and spending some serious money I’d want to know the condition of all the components that send the ECM a signal. That the air, vacuum, fuel and ignition systems are working perfectly.

The 1991 240 maintenance update I’m doing has been educational. This is the car I purchased in San Antonio and drove home in early November (pictured in the oil change thread).

Lots of original parts. Ignition parts that have been in too long: ie spark plugs with half the electrode remaining. Non OE parts. Hoses that snap like potato chips. Loose junctions. Ignition wires rubbing the valve cover. Fuses that crumble when removed. A power steering return line reservoir nipple that broke off in my hand. A half clogged flame trap. Lots of little things.

Nothing that interrupted a fun 2,080 mile trip home.

A systematic approach based on a check list is the only way to go. Just my opinion.

 

[atikovi]

Lots of original parts. Ignition parts that have been in too long: ie spark plugs with half the electrode remaining. Non OE parts. Hoses that snap like potato chips. Loose junctions. Ignition wires rubbing the valve cover. Fuses that crumble when removed. A power steering return line reservoir nipple that broke off in my hand. A half clogged flame trap. Lots of little things.

Nothing that interrupted a fun 2,080 mile trip home.

A systematic approach based on a check list is the only way to go. Just my opinion.

As mentioned before, new spark plugs and wires, distributor cap and rotor plus ignition pick up, timing belt, throttle body and MAF sensor cleaning, fuel and air filters, checked fuel pressure which is normal. New air intake hose on order to eliminate vacuum leaks as well as a reman MAF.

 

[Sam_Julier]

As mentioned before, new spark plugs and wires, distributor cap and rotor plus ignition pick up, timing belt, throttle body and MAF sensor cleaning, fuel and air filters, checked fuel pressure which is normal. New air intake hose on order to eliminate vacuum leaks as well as a reman MAF.

How about the ECT, Oxygen sensor, TPS, and air box T-stat?

Is there unmetered air via the oil separation/PCV system; the climate control vacuum check valve; the charcoal canister vapor lines?

Is the intake manifold tight to the gasket?

I‘m not trying to be a jerk. Just trying to help.

Sam

 

[atikovi]

ECT read 6000 ohms at 40°F which is fine. O2 sensor looks new but haven't checked it yet. TPS is just an on/off switch on this year. I don't see any thermostat on the air box. I smoked the system and saw just leaks at both ends of the air hose which is why I ordered a new one.

 

[jsean]

Started it up cold this morning. Idle smooth, no missing, all good. Drive 3 miles to the post office, running great. Come out of the p.o. and it's hard to start. Have to engage flood clearing mode and crank for 10 seconds. Then it runs rough and misses for another 10 seconds before smoothing out. Next the idle speed creeps up to maybe 2500. Disconnect the MAF and idle drops to about 1200. Drive around the lot like that but of course no power. Plug MAF connector back in and now idle is normal and I drive home just fine.

Replace the MAF sensor? I did check the resistance of the platinum wire per the repair manual spec of 3.5-4.0 ohms and it was 3.1. Would that little off cause this? What brand to buy? Not spending $800 for Bosch.

Sounds like the issue I had, my readings were off just a hair but it was enough for the random bogging/mis idling.

Mine is a ‘91 and uses the later style 016 AMM.

I wouldn’t spend the $800, that’s insane. I purchased a known good used one off TB. It’s been 3 years now and works just fine.

I see that you already have an accordion hose on order - those age and cause unmetered air to get in which causes issues. At this point, the paper intake gasket is likely toast too. I did mine a while back when I cleaned the flame trap and the breather box.

There would be an inlet into the air filter box to the bottom left (if you’re looking at it leaning over the radiator). That inlet would have an accordion looking hose going to the bottom of the exhaust manifold. On the inside of the air filter box, on the other side of this inlet is the little thermostat that can get stuck open and cause issues. I used a stainless steel welding rod to keep mine closed permanently.

 

[andyd]

nevermind

ECT read 6000 ohms at 40°F which is fine. O2 sensor looks new but haven't checked it yet. TPS is just an on/off switch on this year. I don't see any thermostat on the air box. I smoked the system and saw just leaks at both ends of the air hose which is why I ordered a new

 

[atikovi]

Bought and installed this rebuilt MAF sensor a few days ago. https://www.ebay.com/itm/3034933591...PbLDmIDDgtAFs1IzY06k2G7Q==|tkp:Bk9SR-CJg8qlYQ Only driven it a few times here and there but so far, none of the symptoms I had before.

 

[JHZR2]

If it’s a decent car I’d agree to send the injectors to @Trav as a preventive maintenance regardless. Change whatever rubber items are in the way, it’s likely time for most.