[solved] B280F, LH2.2 - stalls when warm

Major Ledfoot

The V6 is giving grief.

Starts okay after sitting for a long while. After 10-15 minutes as it warms up, it will start to misfire a little bit, then progressively runs rougher and rougher, then it stalls, and doesn't want to restart. Until it's been left overnight.

When it refuses to start, it has spark.

Main fuel pump is new; main pump filter is new; both pumps run. Coolant temp sensor is new. Plugs and leads are new.

Is this a symptom of an LH2.2 ECU dying?

ramrod

Try another ignition coil, I had one that stopped working gradually the hotter it got

If that doesn't help try another ECU as a test

Major Ledfoot

It still has spark though when it doesn't run.

Do failing LH 2.2 ECUs slow down fuel delivery when they warm up and they're faulty?

volvodriverman

Has it got spark on all 6 when it starts missing?

Major Ledfoot

volvodriverman
Has it got spark on all 6 when it starts missing?

Not sure about all 6 pots, but it has good spark on at least 1 cylinder when it refuses to run. The coil isn't getting hot.

What seems odd is how this object makes a buzzing noise. Is it supposed to do that?

carnut222

Is the main fuel filter new as well? Also sometimes if there's crud in the fuel tank, it can block the fuel pick-up screen in the tank as it gets sucked up by the in-tank pump. Then after the car sits for a while, the fuel can backwash a bit and partly unblock the fuel pick-up screen. Then next time you drive it same thing happens again. I had a similar issue with my 1800ES years ago...car just felt like it was running out of fuel...turned it off for a while, then it would run again for another 10 km then do same thing. That was the problem on my car. Just a thought if it is fuel-related.

Major Ledfoot

@carnut222 the main fuel filter is brand new (under 100 kays), as is the pump, as it the coolant sensor. This is why it's so perplexing. It has over half a tank of fresh fuel, so if there was a problem with the little hose on the pre-pump, that shouldn't cause this issue.

I ran it again this morning from a dead cold start and it fired up at the first turn of the key. I didn't move the car. I kept the revs at about 1500 RPM or so, pipping the throttle, for about 8 minutes. Then it stalled.

carnut222

Major Ledfoot
@carnut222 the main fuel filter is brand new (under 100 kays), as is the pump, as it the coolant sensor. This is why it's so perplexing. It has over half a tank of fresh fuel, so if there was a problem with the little hose on the pre-pump, that shouldn't cause this issue.
I ran it again this morning from a dead cold start and it fired up at the first turn of the key. I didn't move the car. I kept the revs at about 1500 RPM or so, pipping the throttle, for about 8 minutes. Then it stalled.

I'm not thinking hose on pre-pump, I'm thinking filter sock on pre-pump pick-up. One way to test would be to remove the hose from the inlet to the main pump, and put that in a container/bucket. Then apply 12V to the pre-pump only, and watch to confirm fuel flow is consistent for 8-10 minutes.

Oh, and you said fuel pumps run...I assume they continue to run OK after the car dies? As fuel pump relays sometimes heat up due to the current flowing thru them and then they go haywire...so might be worth swapping in another fuel pump relay if you have it just to confirm.

volvodriverman

Sounds like sparks OK. Checked it's got fuel pressure when it won't restart?

That's the IAC valve, they do buzz. No harm in cleaning it if you think it's suspect.

There's a rudimentary test light procedure I found when I was chasing issues with my 760, I'll see if I can find it

timbo

Is this the version of the v6 with an inductive pickup on no1 spark plug lead?

Major Ledfoot

timbo
Is this the version of the v6 with an inductive pickup on no1 spark plug lead?

I don't know - it's a B280F with LH 2.2, US spec, with Eagle Premier heads and the distributor mounted on the front left of the left-side head. Matt (the PO) took this pic of it before he installed it.

volvodriverman

Cap and rotor? I had a rotor which was half burned out causing similar issues on a 760, albeit a kjet car.

Dunno, but could it be a dud O2 sensor? As it heats up it goes way out of range? Only a stab in the dark.

https://www.volvoclub.org.uk/faq/EngineV6.html#DesignforanLEDSensortoDiagnosetheV6

This is useful.

thetrough

Check the distributor cap and rotor - rotor more importantly. Mine and others I know used to start and run fine til they were fully warmed up (20 mins or so) then start to miss, run on only a few cylinders and put you into a real panic. It ended up being the distributor rotor on both occasions - worn out. When cold they ran fine, but of course it wasn't until you were far from home that the gremlin would awake and the terror begin :(

volvodriverman

There should be the pickup timbo mentioned. It's around lead #1 and has a plug on the other end. It's how the ecu differentiates which bank is knocking it there's a knock incident if I remember correctly.

timbo

I think we established previously that I have the correct cap and rotor on the shelf here?

Major Ledfoot

@volvodriverman where is the distributor cap located on a K-Jet V6? Are they in the same place as the engine pic above?

@timbo - Yes, it does has the inductive connection to #1, funny how these things number the #1 pot on the RH rear of the engine....

@thetrough - any tips for young players for removing the dizzy cap without disconnecting the hose from the radiator? These caps are not in the most accessable position, to say the least.

volvodriverman

Major Ledfoot
@volvodriverman where is the distributor cap located on a K-Jet V6? Are they in the same place as the engine pic above?
@timbo - Yes, it does has the inductive connection to #1, funny how these things number the #1 pot on the RH rear of the engine....
@thetrough - any tips for young players for removing the dizzy cap without disconnecting the hose from the radiator? These caps are not in the most accessable position, to say the least.

nope kjet dizzy is up the back

volvodriverman

The cap on yours should come off without removing the rad hose unless there's something different to my old b280'd 760. It's a bit fiddly...

ramrod

How's the fuel pump relay?

Major Ledfoot

@timbo please let me know payment details for that dizzy cap and rotor you have? I'm about to use up my spares.

As you can see, the old rotor's looking a wee bit crusty....

JFTR, it's a 3mm Allen key for these screws on the rotor, and then there's three 10mm screws on the dizzy cap.

About to replace the rotor, do some fancy dexterity to install a new dizzy cap, and then we'll see.