LH2.4 B230f Idle Issue - fixed again!!

PS I figured out what to say - drop it off at my place and I’ll dismember it and sell the bits LOL!

I have a fuel pressure gauge set-up to use on these...may be worth looking at that. Is the fuel level low, medium or high? Maybe feel the fuel pump fuses and see if they’re getting hot? Just thinking out loud.

morch_66479

https://ozvolvo.org/discussion/comment/191127#Comment_191127

Like a gauge that goes up on the rail?

It's 2/3 full and has the new fuel pump relay installed as i encountered that not starting issue a while back. I'll have a check of the fuses later on.

Yep, I have cut up a spare fuel rail and made it into an adapter with a fuel pressure gauge so it can bolt between the rail and the input hose. The reason I was asking about fuel pump fuses (and maybe also check the relay) is it almost seems to be running out of fuel...I was wondering whether there’s something going on with the pumps and/or electrical supply to the pumps. Advise again, can you drive the car fine if you’re able to keep the revs up? Battery is OK and battery voltage check (not something odd going on with alternator causing voltage spike/drop?)

Definitely worth a shot, If there's enough of an oil/carbon film on the throttle body it can cause low idle,and throw the fuel trims off. It's pretty common issue on redblocks and high km whiteblocks.i

It will be pretty obvious if that's your issue if you pop the hose off and have a look. If it's particularly dirty it's easier to remove it and give it a good clean but be careful not to split the gasket if you don't have a spare.

I wouldn't worry about that self diagnostic test result at the moment.

Does it have any fault codes stored in fuel or ignition ecu?

3-3-2 doesn't look like it's a legit LH2.4 code. See list of codes at URL below.

https://www.volvoclub.org.uk/faq/EngineOBDCodes.html

@Major Ledfoot it's a seperate self test that's detailed in the video that @morch_66479 posted earlier, not the regular one press fault code readout

You need to clean the throttle body

If it is half blocked which it will be if you haven't recently cleaned it, it won't want to run at idle. You need to remove it, buy a can of carb cleaner and a toothbrush, get it clean enough to eat from (surgically clean), spray the carb cleaner nozzle through the two vacuum line ports and verify the fluid sprays out of the tiny holes in the body near the butterfly valve

I have new throttle body gaskets

ramrod

You need to clean the throttle body

If it is half blocked which it will be if you haven't recently cleaned it, it won't want to run at idle. You need to remove it, buy a can of carb cleaner and a toothbrush, get it clean enough to eat from (surgically clean), spray the carb cleaner nozzle through the two vacuum line ports and verify the fluid sprays out of the tiny holes in the body near the butterfly valve

I have new throttle body gaskets

Yes, but if you watch his video, it seems to run fine for about a minute, then it starts surging then it dies...methinks something else is going on...almost as if the fuel is cutting out, or maybe a component (power stage? Fuel pump relay?) is overheating and causing a failure. I’m just speculating...if it runs fine when he applies throttle, then we need to consider other things. Could even be something like crud in the fuel tank...runs fine for a while then as the crud gets sucked towards the pick-up screen, it blocks fuel flow and dies? Really depends on whether he can get the car to run with application of throttle as it starts to die, as if that’s the case then it’s prob not something fuel related??

(this is me clutching at straws)

Are there any holes in the convoluted tube between the AMM and the throttle body? A crack or wear hole caused by that hose rubbing on another hose due to engine movement over many miles is a known issue. (It looks like it's rubbing on one of the aircon hoses in the video). If there's a hole in that tube, it throws off the actual air flow reading from the AMM, since the engine's sucking extra air through the hole which hasn't passed through the AMM.

I may be wrong, but it looks to me like the car is stalling as the ECU transitions away from relying on the IAC for cold start and and warmup and switching over to running temperature mode.