[solved] LH-2.4 running issues

jamesinc

Okay I'm really stumped on this. Gather round as I spin a yarn of intrigue and misdirection.

Billie, the 244 turbo with LH-2.4 engine management, doesn't run properly. It ran fine, albeit a touch rich, for a few years, until one day @Philia_Bear pointed out it had an LH-2.2 AMM in it. I honestly have no idea how that happened, I think I was troubleshooting something when I first turbo'd it and must have swapped the AMMs without realising.

So I put in an LH-2.4 AMM I have on the shelf, and hey presto it fires right up. It then runs for a week or so before dying. It tries to start but won't idle, if you gas it it will rev up a bit, but generally it's just not running.

So at this point it's worth noting that Billie's bottom end was really worn, to the point where it almost didn't make enough compression to run at all. So given the car was busted anyway, I pulled the motor and rebuilt it. Along the way I replaced the O2 sensor and the ECT sensor, mostly because I could, and because I figured the old O2 sensor probably took a bit of a bollocking from all that sooty exhaust from the worn out bottom end. Before doing the rebuild I did hook up a fuel pressure gauge and verified 3 bar at the rail.

So I rebuilt it, fixed up a bunch of wiring while I was at it (see the build thread from my signature), and put it all back together, and it fired right up and ran beautifully.

The next day, however, when we started it, the idle was a bit inconsistent. Nina took it out but about 20 minutes later it was stalling out and not making much power, and so she parked it. I came up a few hours later with a new AMM, power stage, and coil, but none of them made any difference at all. Unplugging sensors etc hasn't yielded any definitive results either. I had the idle mixture lean/rich ECU code (2-3-2) and as I unplugged various sensors I saw codes for them too.

When I was doing my testing I was working on an engine that was only a touch above ambient air temps. It had been sitting for a good 3-4 hours at this point. Still no change. Disconnecting the battery to clear the ECU's memory had no effect.

I can get it to run by keeping my foot on the pedal a bit, but I can see it's running rich from the exhaust.

Basically, I'm out of ideas. What am I missing? Is this lame, is the ECU just a piece of shit? I have a spare ECU (I think) so I'll give that a go I suppose.

jared244

Hi James... some ideas for you:
1. Check for air leaks in the exhaust prior to the O2 sensor.
2. Check for air leaks on the inlet side? Injector O-rings? manifold gasket? All vaccuum lines accounted for?
3. Was the EFI coolant temp sensor new? Measure the reading (at the ECU end to validate the wiring as well) when the car is cold and see if it reads the right value for ambient temp).
4. As stupid as it sounds, maybe put the LH2.2 AMM back in and see what happens?

Slowbrick

When you were mucking around with the wiring did you accidentally disconnect the speed signal to the ECU? Also have you verified the TPS has been set correctly? Does it click when you just crack the throttle. Another thing to check is, is the throttle stop adjusted correctly? I had strange running issues with the 245 which was caused by a misadjusted throttle stop.

jamesinc

I didn't touch the ECU speed signal wire, and I did check, the TPS is adjusted correctly. The throttle body I haven't adjusted that I can recall, but I'll check it out today. I have a multimeter and a fuel pressure test with me. I'm going to start methodically backprobing everything until I see weird signals.

jamesinc

Okay so there's no leaks in the intake plumbing or vac hoses. I tried an NA ECU I had and nothing changed, in fact as I've done all this it's gone from reluctantly running to not running at all, which maybe suggests flooding. I'll pull the plugs and crank it and see.

jamesinc

Plugs are pretty fouled up given they've done about 20km since new

jamesinc

Man I am stumped. Everything I've looked at seems fine. Maybe it's mechanical in some way. Could it be a blocked cat?

Slowbrick

Check that throttle stop. Its a tiny 7 or 8mm bolt. I had all sorts of weird shit going on until I sorted it out.

Philia_Bear

This got @VolvoHordz before... can you try a different set of plugs?

jamesinc

Philia_Bear;133842 wroteThis got @VolvoHordz before... can you try a different set of plugs?

Uhhh, like different hotness?

jamesinc

@Slowbrick I'll re adjust per this guide https://www.brickboard.com/RWD/volvo/909624/220/240/260/280/throttle_body_cleaning_adjustment.html

Slowbrick

Yeah do that. I was chasing a weird idle and hard start for ages until I adjusted the plate. It looked perfectly fine in my hand and when off the car but it was a tiny bit off and caused all sorts of weird shit.

Philia_Bear

jamesinc;133843 wrote
Philia_Bear;133842 wroteThis got @VolvoHordz before... can you try a different set of plugs?
Uhhh, like different hotness?

Like just did not work properly
Swapped different plugs in an went back to working perfectly

jamesinc

Philia_Bear;133847 wrote
jamesinc;133843 wrote
Philia_Bear;133842 wroteThis got @VolvoHordz before... can you try a different set of plugs?
Uhhh, like different hotness?
Like just did not work properly
Swapped different plugs in an went back to working perfectly

They're new plugs, and the car ran perfectly the first couple of times I started it up, so I'm reluctant to blame the plugs. I don't think I have another set on hand at the moment. They're BPR6ES.

The fact that this problem was the same with the engine a couple weeks back and now, and that I changed plugs between those two events, suggests its not those.

I'm still really hung up on this whole AMM thing. I'll try running the 2.2 AMM again. Last time it didn't work though, after I put the 2.4 AMM in, when I swapped back to the 2.2 one everything was still borked.

The FPR read 50psi (3.5 bar) with pumps on and showed a stable 3.05 bar while not pumping (vac line disconnected). The 3.5 bar is a touch high, but from what I've read elsewhere it's not so high that it should be causing issues.

The injectors are red tops out of a V70, they are 315cc/minute, so should be fine in place of the stock 300cc green tops.

Also hard resets of everything don't work. It's possible maybe the internals are just now fouled up and stopping it from running properly.

Slowbrick

I haven't ever tried the red top injectors. Do you have some orange tops to test out of curiosity?

jamesinc

Oh I checked the ICV as well, not stuck or clogged.

I'm back home now, going to head back to the car this afternoon (it's 20 minutes away), and either figure it out or go and get a car carrier and bring it back to Eastwood, because I'm sick of side-of-the-road debugging.

jamesinc

Slowbrick;133849 wroteI haven't ever tried the red top injectors. Do you have some orange tops to test out of curiosity?

Not handy, or do you mean the 240 NA injectors? I have some of those.

Slowbrick

Nah I mean the 850 orange tops. I havent ever tried the red injectors so cant comment on their compatibility. That being said the car should still run on the yellow 240 injectors but just dont put it into boost because it wont have enough fuel.

jamesinc

Slowbrick;133852 wroteNah I mean the 850 orange tops. I havent ever tried the red injectors so cant comment on their compatibility. That being said the car should still run on the yellow 240 injectors but just dont put it into boost because it wont have enough fuel.

I'll bring them with me then, may as well see. I have an NA ECU though when I plugged that in before it did nothing.

All that said, this wouldn't be the first time I've been burned by multiple bad AMMs :)

I did test pin 2-3 resistance on the AMM and got I think 2.5Ω which is in-spec.

I tested the O2 sensor with ignition on reds and got 200mV, which is too low, it should be 500mV, and this might also lend weight to my "the exhaust is fucking full of soot" theory, because this car has been spewing soot for the last couple years.

I really wish I'd shone a light through the cat honeycomb when I had the engine out :|

jamesinc

Also found one of the fuel rail bolts is stripped in the manifold, so will need to helicoil it