1986 Volvo 240 fuel injectors need cleaning?

[atikovi]

136,000 miles and I've done all the usual maintenance items you do on a used car you just picked up. 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. Car has two issues.

1) On mostly cold starts, the engine runs rough and misses for about 5-10 seconds during which the exhaust smells quite rich. After that it smooths out fine. Thinking the injectors may be leaking when the engine is off or dumping too much fuel when first started.

2) Sometimes when idling, the rpms will rise way too high. Seems like something around 2-3,000 rpm. Also seems to happen mostly before it's fully warmed up but doesn't happen every time I drive it either. Could that be MAF sensor related? I see junkyard markings on the one it's got.

Car is pre even OBD1 so no plug in scan tool or codes to retrieve and give any direction. Car runs fine otherwise with good power and smooth running. Whoever said the older cars are easier to work on probably never worked on a fuel injected model.

 

[TomYoung]

I would start with a bottle of Techron. Is your fuel economy okay, and do the problems disappear when warm? It could be mass airflow, clogged injectors, vacuum leak, really anything. I would also empty a can of carb cleaner into intake.These engines are so easy to work on, you could certainly just throw new parts at it. The engines are so durable, that there is probably nothing seriously wrong. Actually wondering if you have priced out a MAF sensor....

 

[Passport1]

At 136K that Volvo is a baby. It should have a primative diagnostic port inside on the left front fender. Could be an out of value coolant temp sensor. Check the Brickboard for help. I sent my 940 turbo injectors to a shop near Charlotte and they cleaned and rebuilt them. Car runs like brand new. Parts are cheap. If you have the Bosch system maybe replace the radio supression relay, power stage, and crank sensor.

If you have a Regina system can't help.

 

[atikovi]

This is the early LF fuel injection before diagnostics. Sending the injectors out to be tested and cleaned would be the first step. A new MAF sensor is all over the place on price. $800 for Bosch, $100 Delphi, $50 SKP whatever that is.

 

[atikovi]

Another thought. Would unplugging the MAF sensor during an episode of high idle, indicate something? If the idle drops to a default speed for example.

 

[twouvakind]

Contact @Trav for injector service.

 

[RooflessVW]

Your high idle is likely a vacuum leak, an issue with the IAC, a sticky throttle body, a poorly adjusted TPS, or a combination of multiple.

 

[demarpaint]

Contact @Trav for injector service.

That's what I would do.

 

[Sam_Julier]

I’d send the injectors to @Trav as others suggested. I’ve sent two sets to him from my 240s. You will notice the difference.

I’d replace all the vacuum lines, IAC lines, check intake for leaks, replace oil separator, PCV hoses, etc.

Recently I didn’t set the throttle body linkage correctly after cleaning. The engine would not come off a high idle. I had to take it to my shop with the engine revving like a stallion. Lesson was a little bit of un-metered air goes a long way.

How old is the ECT, CPS, TBS, O2 sensor?

Is the air box T-stat working properly?

 

[Egg_Head]

Were/are B23 engines prone to PCV issues?

 

[Sam_Julier]

Were/are B23 engines prone to PCV issues?

Not prone.

Overtime, especially for a car with short trips, the flame trap and oil separator will fill up.

In my experience trip length and oil change intervals do make a difference.

 

[jsean]

Sound like MAF sensor issues I had on my 240. You can try unplugging the MAF and starting the car/idling to see if it helps before cleaning out the injectors.

 

[Greasymechtech]

Clean the MAF

Run it almost empty and fill up with Shell Nitro

Shell V-Power® NiTRO+ has seven times the cleaning agents required to meet federal standards and removes an average of 70% of baked-in deposits left by lower-quality premium gasoline, starting with the very first tank.​

 

[atikovi]

Sound like MAF sensor issues I had on my 240. You can try unplugging the MAF and starting the car/idling to see if it helps before cleaning out the injectors.

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.

 

[AlpacaBowl]

Almost sounds like an air leak.

 

[atikovi]

Almost sounds like an air leak.

Wouldn't that cause a lean condition and make it idle lower?

 

[RooflessVW]

Wouldn't that cause a lean condition and make it idle lower?

No. An air leak is how engines idle.

Increase the air, idle goes up. The mixture only leans out if the air is umetered. Idle speed increases either way.

 

[Sam_Julier]

If I were in your situation I would take it to Swedish Motors in Marietta PA.

Central PA's Choice for Import Car Service & Repair | Swedish Motors, Inc.

Family-owned and operated European and Import car repair shop. Your trusted dealership alternative in the Central PA region for vehicle service.

www.swedishmotors.com

 

[Egg_Head]

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.

Volvo Mass Air Flow Sensor - Genuine Volvo 8251497

Volvo Mass Air Flow Sensor - Genuine Volvo 8251497

www.fcpeuro.com

 

[atikovi]

Nope that's for newer models. Mine takes,

Volvo Mass Air Flow Sensor - Bosch 8602791

Volvo Mass Air Flow Sensor - Bosch 8602791

www.fcpeuro.com