LH2.4 B230f Idle Issue - fixed again!!

morch_66479 · 2021-05-16T00:14:28+00:00

For LH2.4, the throttle position switch adjustment is critical. If the switch is misadjusted, the ECU doesn’t know it’s meant to control the idle speed, so i...

carnut222

OK, one more thing. You start the car, it idles fine for about a minute then starts shaking and dies. Can you then re-start the car immediately and it will run fine for a minute then repeat the shaking and stall, or do you have to wait some time period before you can get it started and running again? If it’s the latter, you could try something...just after it dies, pull off one of the vac hoses on the inlet manifold and spray in some start-ya-bastard and see if it then starts up and runs fine for a short time...that would probably indicate a fuel supply issue. Might help narrow things down a bit. Of course doing a fuel pressure check/monitor would also be extremely helpful at this stage. Happy to loan you my fuel pressure gauge set-up but a bit of a hike to come up and get it.

morch_66479

I can start the car immediately after it stalls, it runs ok for 20s or so and then starts to splutter again and the time to stall is much quicker so it's harder to keep it running. If i repeat the start ups immediately the time between idle - hesitation and the time to cut out decreases

Yeah, good thinking. I'm going to get some Aerostart today and just tick off a bunch of items tonight. Aerostart being the first on the list. I should have thought of this before!! Thanks Greg :)

If i have no success i may pay you a visit on the weekend!! haha

VolvoHordz

To me this all sounds like the idle air valve isnt working properly, or something associated with it i.e. wiring, ecu, etc.

If it hasnt been tried already, I'd be unplugging the idle air valve and starting the car to see what happens. It should default open enough for the car to idle slightly high. If it idles fine and doesnt stumble, the idle system is where your focus should be.

The idle valve is part of a closed loop system i.e. the ecu detects the rpms dropping to low and sends a signal to open the idle air valve more, and vice versa, in a constant cycle to maintain the rpm within the desired range.

The fact that the idle air valve has voltage doesnt tell you much, in reality it is pulsing on and off way quickly that a multimeter can detect. The speed of pulses determines how far the valve is open. From memory it is the earth signal that is pulsed.

carnut222

VolvoHordz
To me this all sounds like the idle air valve isnt working properly, or something associated with it i.e. wiring, ecu, etc.
If it hasnt been tried already, I'd be unplugging the idle air valve and starting the car to see what happens. It should default open enough for the car to idle slightly high. If it idles fine and doesnt stumble, the idle system is where your focus should be.
The idle valve is part of a closed loop system i.e. the ecu detects the rpms dropping to low and sends a signal to open the idle air valve more, and vice versa, in a constant cycle to maintain the rpm within the desired range.
The fact that the idle air valve has voltage doesnt tell you much, in reality it is pulsing on and off way quickly that a multimeter can detect. The speed of pulses determines how far the valve is open. From memory it is the earth signal that is pulsed.

Yes, BUT, I think he said when he opens the throttle it struggles to get over 2000 rpm...once throttle is opened the IAC is more or less out of the loop, so this tells me something else is amiss...in part of the setting of the idle speed, one check is the RPM should drop to about 500 rpm if you pinch off the hose to the IAC...which tells me the car should idle very low (or possibly stall) but should run fine at higher RPM even if the IAC is totally dead.

carnut222

carnut222
https://ozvolvo.org/discussion/comment/191273#Comment_191273
Yes, BUT, I think he said when he opens the throttle it struggles to get over 2000 rpm...once throttle is opened the IAC is more or less out of the loop, so this tells me something else is amiss...in part of the setting of the idle speed, one check is the RPM should drop to about 500 rpm if you pinch off the hose to the IAC...which tells me the car should idle very low (or possibly stall) but should run fine at higher RPM even if the IAC is totally dead.

Sorry I may have mis-read an earlier post...in fact he said he had to rev it to about 2000 RPM to keep it running...

carnut222

To me it sounds like symptoms of blocked fuel filter or fuel pick-up screen in tank, but I could be wrong...sometimes in this case, particularly with in-tank pick-up screen blockage, when you shut off the car, it can back-wash a bit and then the car can be re-started but it sucks up the crud again and dies out. Just a theory...using the Aerostart or doing a fuel pressure test could help determine that.

morch_66479

UPDATE: I'll try summarise it nicely

I've carried out the following tasks tonight to no avail:

Car runs/idles fine when spraying Start Ya Bastard in the Air intakeFitted new spark plug leads (new distributor cap installed yesterday)Swapped out the Idle Air Control Valve with a known good one (@VolvoHordz when i disconnect it whilst running the car enters a higher idle but its not stable and is lumpy, hiccupping etc)Checked earths on fuel railRemoved and cleaned the throttle body and checked that the galleries were clean, i did notice that the TPS connector had oil in it which is strange?Swapped out the ECU with a known good one

carnut222
https://ozvolvo.org/discussion/comment/191279#Comment_191279
Sorry I may have mis-read an earlier post...in fact he said he had to rev it to about 2000 RPM to keep it running...

I think it could could be a fueling issue as @carnut222 has pointed out and the car will not rev over 2,000rpm as of tonight. So the problem is worsening. This is the next item on my list to check! Keep in mind it runs fine on Start Ya Bastard.

I fitted a new fuel filter last year but is there other strainer/ gauze filters i should look out for?

Thanks everyone for your help, this has been a journey but hopefully will help someone else later on.

carnut222

morch_66479
UPDATE: I'll try summarise it nicely
I've carried out the following tasks tonight to no avail:
Car runs/idles fine when spraying Start Ya Bastard in the Air intakeFitted new spark plug leads (new distributor cap installed yesterday)Swapped out the Idle Air Control Valve with a known good one (@VolvoHordz when i disconnect it whilst running the car enters a higher idle but its not stable and is lumpy, hiccupping etc)Checked earths on fuel railRemoved and cleaned the throttle body and checked that the galleries were clean, i did notice that the TPS connector had oil in it which is strange?Swapped out the ECU with a known good one
https://ozvolvo.org/discussion/comment/191282#Comment_191282
I think it could could be a fueling issue as @carnut222 has pointed out and the car will not rev over 2,000rpm as of tonight. So the problem is worsening. This is the next item on my list to check! Keep in mind it runs fine on Start Ya Bastard.
I fitted a new fuel filter last year but is there other strainer/ gauze filters i should look out for?
Thanks everyone for your help, this has been a journey but hopefully will help someone else later on.

Definitely sounds like it’s not getting enough fuel if starting spray keeps it running. Yes, there is a strainer in the fuel tank on the bottom end of the fuel pick-up tube. There’s also the possible split/degraded hose in the tank between the tank pump and top of fuel sender unit where it exits to the external pump. I guess there’s also the possibility that somehow the fuel pressure regulator has failed in the full open position (broken internal spring?) resulting in very low fuel pressure, but it seems odd the car would start and run for a bit then start gagging...that leads me back to fuel tank pick-up strainer/sock or main fuel filter? Hmm...

carnut222

This may be of interest, however I’d recommend doing a fuel pressure test prior to digging into the tank as it’s a lot easier!

http://cleanflametrap.com/transferPump.htm

morch_66479

UPDATE: Possibly found the fault!

carnut222
This may be of interest, however I’d recommend doing a fuel pressure test prior to digging into the tank as it’s a lot easier!
http://cleanflametrap.com/transferPump.htm

I tried the first steps where it talks about tapping into the fuse panel to send power to the lift pump, tried this and it's dead. I then went and unplugged it and put power to it and still no movement. So then i removed it and tried putting power to it one final time but still no go.

So now i believe my in tank lift pump has failed unless I'm testing it incorrectly?

ramrod

So after the recent work carried out, the car is running worse?

Something isn't right

You mentioned the idle was the problem before, now it won't run without starting fluid, something seems to have been missed or disturbed

morch_66479

Yeah, I'm going down a hole here and i need to go back to checking the basics again. I'm trying to decide on the next steps. . .

We know it runs perfectly fine spraying Starting fluid in the air filter box so that tells me everything downstream is fine right? (i.e: maf, iac, tps and injectors)

So if i focus my attention on upstream it leads me back to the tank where i should check the filters for blockages etc and then who knows where to go from there. Maybe start looking at the fuel rail and pressure regulator system.

How else should I approach this? Again, thanks for all the advice :-) We'll get there in baby steps!! haha

ramrod

How does the engine run under load?

morch_66479

ramrod
How does the engine run under load?

Slightly better but need to keep rpm up or else it would bog down and stall. Since last night it's got worse and can't rev in Neutral so it probably won't run under load at all now.

Essbos

Have you checked engine air filter?

morch_66479

Essbos
Have you checked engine air filter?

Yeah, sure have! It's good and wouldn't run with the pipe off the filter box anyway as i had it removed when spraying in the starter fluid.

Essbos

Good one to rule out @morch_66479 !

Would be worth checking the under car fuel lines for crushing or links. Especially around the under car fuel pump/filter area. The pump to filter hose is easily damaged.

Low power/poor running is sometimes caused by catalytic converter failure, but I think your aerostart test has ruled that out.

volvodriverman

Had a fuel tank full of rust in the gt & it'd start and run acceptably when cold but once it got warm it did what you're describing.

morch_66479

volvodriverman
Had a fuel tank full of rust in the gt & it'd start and run acceptably when cold but once it got warm it did what you're describing.

I had a simlar scenario on my motorbike a few years ago, wouldn not run when i gave it some throttle. Tank was totally rusted out and needed new filters etc.

carnut222

morch_66479
UPDATE: Possibly found the fault!
https://ozvolvo.org/discussion/comment/191295#Comment_191295
I tried the first steps where it talks about tapping into the fuse panel to send power to the lift pump, tried this and it's dead. I then went and unplugged it and put power to it and still no movement. So then i removed it and tried putting power to it one final time but still no go.
So now i believe my in tank lift pump has failed unless I'm testing it incorrectly?

Could be...I guess the best way to be sure is to disconnect the feed hose from the input to the main pump and put it in a jar or something then re-run your test of the in-tank pump and see if fuel comes out...carefully! Double-check the connections and the earth for the in-tank pump (IIRC it’s just a screw thru a ring terminal on the wire near the fuel tank access panel). I have one of the fuel tank ring removal tools if you need to borrow it...you’re welcome to borrow the fuel pressure gauge as well. In fact I MAY have a complete fuel sender/pump from a 93 240 that was in good condition when I pulled it.

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