740 Car died...now no start

740tankDriver said:

i imagine you do not have spare parts to swap out and confirm they are not the end-culprit.

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I've swapped most everything there is to swap. What spare parts are you referring to?

power stage and ignition switch

Power stage has been swapped. Ignition switch has not been. It was discussed but decided since there was spark and fuel present, the ignition switch was not the problem. I'm puzzled as to how the ignition switch could create a situation where there was fuel and spark but still no start.

At this point it would seem we've either got way too much fuel or not enough spark or spark at the completely wrong time. I would've thought the Accel super coil would have cured the not-enough-spark situation. I would have thought shutting the injectors off and pumping a little propane into the intake might've produced even a pop but it produced nothing. We did notice when we had the AMM stuck into the end of the turbo intake pipe, it would regularly "pop" back through the intake, making us suspect ignition timing. We do not hear this when the air cleaner lid is snapped down.

in the end it may come down to the rediculously easy solution or the rediculously involved solution that may cause you to loose your mind...as these Volvos sometimes decide to do

but seriously, the next spot would be to either change the wiring harness' out or go through the connections from terminal to terminal for the ECU and the ICU. that is easy for me to say, though, as i currently do not have a dashboard in my cabin.

740tankDriver said:

in the end it may come down to the rediculously easy solution or the rediculously involved solution that may cause you to loose your mind...as these Volvos sometimes decide to do

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I'm hoping for the ridiculously easy. I'm really hoping someone will drop in and say "my car did exactly the same thing and it was xxxx". I am, as are three mighty good mechanics, out of ideas.

Only reason I mentioned the cam thing is just a way out there guess. IF the cam pin snapped and the cam swung 180-ish degrees out, while the belt and aux shaft are still in time as they should be, before the cam bound to the gear enough to rotate, you'd still have compression, spark, fuel, but your spark events would be 180* out from where your compression is. Your marks would line up for checking spark events, belts would all line up, compression may be normal-ish sounding, but it'd be way off. It would also explain why you got nothing from the propane.

If you can consistently draw a 1" spark from the ignition system, coil and powerstage aren't likely to be an issue.

Have you tried firing it with every vacuum port (including IAC) capped on the manifold? Just to rule it out, one less thing to even have in the mix...

You mentioned no codes. Just to confirm, you did get the 1-1-1 from each system?

You happen to check the ignition rotor on your last round with it?

Given you're shooting for the really oddball stuff now, figured it can't hurt. I've done enough out there, oddball stuff on my wagon to be able to come up with these 'logical' hairbrained ideas sometimes....sadly.

No codes...1-1-1 on both ignition and fuel. Rotor was checked...it's fine. Pulled the cam cover off just confirm cam and gear are still attached and rotating as they should. Couldn't see any issues there...

Dale I wish I had something useful to add. But while I am going through something similar I think I still have a little ways to go. I replaced All the sensors in my 240 except for the CPS. The icu fiinally threw out a bad CPS code. So that is next on my list.

How about checking clearances on the CPS? To make sure they are tight enough.

I recall some time ago that someone picked up something like a small rock that bent the tone ring where the CPS reads. Someone else had a bent or loose plate, something like that, can't recall exactly if it came loose, but something related to the signal not getting read back there.
Aha; maybe take a look at this; not a rock but...
http://www.brickboard.com/RWD/volvo...terious_940_failure_bet_youve_never_seen.html
and further down is
<a href="http://www.brickboard.com/RWD/volvo/1415690/940/960/980/V90/S90/mysterious_940_failure_bet_youve_never_seen.html">Mysterious 940 failure, bet you've never seen this</a>

so, the engine speed sensor? that would, or should, store a fault code.

I've now read that you moved the AMM. There's nothing plugging/blocking the intake or piping? Ya know, starving it of air?
Tried starting it with the intake pipe disconnected at the TB? Also, the IAC isn't stuck, is it? Wouldn't seem likely if you've tried partial throttle when cranking though.

Several years ago we did cam seals on a friends 1999 240. Started it and every thing seemed fine. After driving it for a while it started shutting down and not restarting so we checked/replaced all the sensors you did. Still acted up.

After letting it sit for a day due to frustration, it magically started. We took that as an opportunity to limp it to the closest import repair shop. They found that the cam timing was one tooth off which apparently it can still run but anger the ecu?.

Short answer. You haven't verified compression and cam timing by having people listen to it and say " Yup sounds right". I'm not saying this is your problem, but it was in this case.

245gti said:

It's got compression...let's rule that out. Both Matt and Ian agree compression is not a concern.

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Yes, the fact you got it started again rules out the washdown theory after flooding that I proposed earlier. Compression measured by seat of the pants is probably fair enough.

245gti said:

I don't know how much ignition timing the computer can correct but the aux belt skipping a tooth or two would explain why timing could be miles out; if it even is. Last night when Matt checked it, it was bang on...

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How much can it correct? EZK can make a running car out of one whose flex plate was installed one bolt off. Running. Not running well. 45 crank degrees.

If neither you or the other two mechanics have access to a scope, a timing light will do pretty well to ferret out missing or wrongly timed ignition caused by a bent tone ring. You move it around to all four plugs and watch for consistency, when you manage to have it running. No, EZK's OBD can't know the signal isn't in the right spot, and no, I don't understand why the aux belt could affect ignition timing in the least.

I'm going to throw in one of my patented ridiculously long posts here.

The bottom line, whether it's running or not, cranking or not, is this:

It's spraying fuel during cranking. Reliably. This has been visually confirmed by pulling the rail, which also showed an aggressive and tidy cone of fuel coming from the injectors. There's plenty of fuel coming out the return line as the injectors are firing as well, and you can feel a strong pulse in the hose from return line to jerry can, indicating injectors firing and presumably good fuel pressure too.

It's sparking during cranking. Reliably. We have checked rotor position (remember, it's LH 2.4, so the distributor does nothing but path the spark) relative to the crank (pulley), we have checked the crank (pulley) relative to the cam (pulley), we have shone a timing light at both crank and cam pulleys and they were in the appropriate places. When Ian checked timing he couldn't see the mark on the crank, but I had trouble seeing it too 'till I got the light/shadow right (we didn't have a paint stick or chalk or a sharpie or anything). We have pulled plugs and bead blasted, visually inspected, and spark tested them. You can even see the spark happen a little after you hear the compression whoosh out of that plug hole.

It's got compression. The engine cranks exactly like it did before, and it is quite relieved when the plugs are pulled. As Dale said, the cam and cam pulley have been checked relative to one another, so that's fine, and I've checked the crank and cam relative to one another and they're fine. It's a B23 so the crank pulley can be trusted. The block mount dizzy has been checked and it's pointing to #1 when the cam timing mark is showing TDC compression #1, and the firing order has been verified as correct.

The electrical system appears to be working fine. Ignition switch is powering ignition and fuel computers during cranking, evidenced by the injectors firing and the spark sparking and the fuel pump pumping. Whether or not they're still working during running is hardly material right now, since it barely ever gets running.

If it were having troubles just cranking and it ran okay, the tests above would have shown something wrong, and we would have fixed it by now. If it were having troubles staying running, it should at least fire (which it barely does).

What baffles me is the sequence of events. The RSR wasn't working when I got there, so after swapping it out and now hearing the click of the injectors through a screwdriver-stethoscope, I know THAT was a problem. Swapped old and new RSR in, verifying the old one no longer working. The RSR is a car killer, in the sense that when it fails, the car stops, but what could have happened to the rest of the car that now prevents it from running now that the RSR has been replaced? Looking at it a different way, what could have failed in such a way that killed the RSR in the hour between it dying and me showing up?

Yes, the engine could have fired backwards, it could have kicked a cam out of position, it could have spat turbo oil at the AMM. All of these have been checked or corrected. Yes, it could have been a power spike, but both ECU and ICU have been replaced with spares, and both are communicating with the communication plug dealiebob. Ignition module, CPS, and AMM have also been replaced with spares, as have the cap & coil.

I have little experience with LH 2.4 or EZ116K. I assume it ignores the knock sensor, O2 sensor, and the AMM during cranking. I assume it relies upon the IAT sensor (in the AMM?) and obviously the coolant temp sensor for starting. We know from experience what a failed or insufficient crank sensor signal does - erratic spark & injection. What's that thingie in the crankcase vent return hose?

Confession time: We cannot vouch for the condition of most of these spares. ICU/ignition module and AMM all came from a junked '91 turbo, and haven't been tested prior to now. None of these (aside from the AMM) are really failure prone, and the car that's in the JY is a MESS - valve shims have been busted and have gone everywhere, CPS was mangled... mechanically the engine is wrecked, so I believe it was running fine when it ran out of oil. We're only relying upon 110 years of combined experience to verify compression, so we probably should check it at some point, and I don't like the fact that Ian (the most experienced one) couldn't see the timing mark... but he's pretty old and his eyes might be going. Lord knows his mind is. Regardless, all our "questionable" spares (aside from the AMM) have proven to do what they need to do. ICU and module are both providing the car with good spark at the right time, and the engine SHOULD run on limp mode without the AMM plugged in... right?

Injector pack next to the power stage. Its usually one or the other. especially for intermittent starting and no run conditions.

Long posts are good. The man of few words gets little help from a grunt and a nod.

Only surprise I read is she is a B23 with LH2.4, but I should have expected that on TB. There must be about 20 of us right now wishing we could spend an hour alone with her this Saturday morning. I don't know what else to say, so I'll just wish you the best and hope you'll spill all the details when you've hit on it.

I spoke with Dale a bit last night on the phone (SOOO much easier than typing). Seeing Matt's post as well, many of the culprits are covered pretty solidly. The cam/crank timing were verified visually based on cam lobe position vs. crank position.

One thing I might suggest, which I forgot to ask about last night...have you hard-wired to bypass the RSR yet? I did have an instance on mine that had fuel, spark, compression, correct timing, injectors firing based upon feel, yet the car wouldn't start. Even though the injectors were clicking, and some fuel was spraying, the engine still wouldn't start. Randomly unhooked one injector and it fired up. The RSR in the car was one I'd resoldered in the past, but the contacts were a little corroded/burnt from the age. Probably not the issue given you guys have pulled the rail, but a hairbrained idea.

I gave Dale a couple other things to just double-check, but between the three of you guys, there ain't much untouched yet.

The RSR has been jumpered, yes. Thinking about it more, I'm leaning very heavily towards an electronic failure of some description; not mechanical. More accurately, a failure that could significantly mess up ignition timing and possibly a fuel quantity issue. I'm off to grab a new CPS this morning as I've had hints that a bad CPS can show spark and fuel events but no-start. If it's not the CPS, we'll start with the finer diagnostics...measuring resistance of sensor etc...


The CSI was unplugged but was never checked to see if it was locked open mechanically. Will do that if the new CPS does nothing. This is a little puzzling too as with the RSR unplugged, the car should fire on the CSI fuel alone...

Hi Guys,
I had a very similar experience on my 945, all the symptoms of starting, fuel, spark etc were there but just would not fire.
Now I might be off a bit here, because I do not know if the same thing is employed on the 740, but here goes: -
There is a sensor on the top of the flywheel casing at the back of the engine, bolted in with a 10mm bolt, the cable connected to the wiring loom by a plug at the top of the back wall.
If this component is damaged in any way, or just worn the mentioned symptoms appear.
On my 945 this looked in good condition, however it had failed - I replaced this sensor and wire (all one bit) and all worked again.
This may not be the solution but it is worth consideration.
Hope this is helpful.
Cheers.

dustyv said:

Hi Guys,
I had a very similar experience on my 945, all the symptoms of starting, fuel, spark etc were there but just would not fire.
Now I might be off a bit here, because I do not know if the same thing is employed on the 740, but here goes: -
There is a sensor on the top of the flywheel casing at the back of the engine, bolted in with a 10mm bolt, the cable connected to the wiring loom by a plug at the top of the back wall.
If this component is damaged in any way, or just worn the mentioned symptoms appear.
On my 945 this looked in good condition, however it had failed - I replaced this sensor and wire (all one bit) and all worked again.
This may not be the solution but it is worth consideration.
Hope this is helpful.
Cheers.

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Thanks for the comment. That's the crankshaft position sensor, otherwise known as the CPS. I have replaced that twice now. The first time with a spare I had. The second time with a new one...

Further to this...CPS was replaced with a new one this morning. No change. Went through all the greenbook EZ116K diagnostics and everything checks out and is within spec. Looking for the LH2.4 step by step diagnostics. Anyone have a copy?