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940 no start, £2000 dealer diagnostic, still no start …

Jamesmoore

Jamesmoore

Active member
Joined
Jul 26, 2021
Location
united kingdom
My 940 died a few weeks back. No start condition, I tried everything I possibly could. ( I’m a mechanic by trade too )

Threw a bunch of spare parts at it. Basically everything that’ll make it run. Still no good

Finally gave in and towed it too a shop, got a free tow through insurance. It’s at a local Volvo specialist, these guys are ex dealer mechanics from the 90s and 2000s so they have lots of experience with these cars. They also have all the old dealer diagnostic tools, paperwork ect ect.

They charge £100 an hour, I’ve now racked up a £2000 bill, over 20 hours of diag time. (3 days) that’s with a discount for me. And it still won’t start. They can’t find anything. They’ve stoppped for now

Where do I go from here ? Do I let them continue to rack up a bill upwards of. 2000 or call it quits ?
 
mertz said:
I don't have Reddit and I'm not signing up to look at it as it says NSFW and wants me to confirm my age etc...

Can you post the details here?
Click to expand...
My bad don’t know why it’s nsfw lol it’s a photo of some writing on paper.

it says too large to post the photo on here
 
I don't have a Reddit account either but just clicked through the prompts, no problem. Is this the list you provided to the shop as a "This is what I've done" list or one that they gave to you?

OK, so a digital diagnosis from 3000 miles away at this point kinda goes like this:

1) Had you just gotten petrol? Was it from a known good source?

2) Were you driving steadily along, or accelerating from a stop, or decelerating, or hammering on it? I'm going to PRESUME you were driving steadily along at maybe 25mph in Burford or Glasgow, because that's how I'm picturing it, but you tell me.

3) Are you CERTAIN it just shut off like you hit the key, or is it possible that in the 1-2 seconds before it died you missed a couple stumbles. Maybe you had a real banger from BBC2 on and were distracted? Again, I'll assume that it was as you said and just shut off.

You SEEM to have all the elements: fuel, air, spark, time. HOWEVER, one (or more) of these is lying. Given the circumstances of the failure (all of a sudden) I would say you can rule out 2: fuel and air. If the fuel pump died, it would at least stumble a bit or something. 40 lbs fuel pressure cranking should be enough to at least make it sputter or do SOMETHING.

Here's what I would do if I were you. First, I would laugh at my Brit jokes to add a bit of levity to a stressful situation. Second, I would confirm that the ignition is firing IN TIME. You should be able to do it with a timing light, looking at the belt cover, cranking. I put a little bit of white touch-up paint in the groove in the balancer and on the timing cover to aid visibility. If it's in time, you need to reaffirm the quality of the spark with a proper spark tester. It simulates the resistance a plug encounters in the chamber, under pressure, to see if the spark is of sufficient quality to jump the gap. If it's NOT in time, congrats, you found the problem, but now you need to figure out why.

If it's not in time, I would do this, based on my jillion years as a GM parts consultant. I would confirm the way the immobilizer works. Not by asking someone, but by finding Volvo documentation. I've also read that it cuts fuel and spark, but not in any official capacity. Who knows if that's actually correct, or some layman's explanation of what's happening that's just been accepted as gospel? I don't KNOW, and right now it seems that knowing is pretty critical. What I'm saying is that is it possible that it throws spark, but 180 degrees off? I know this sounds dumb, but we're a bit on the fringes of what might be wrong. Has the ignition cylinder or switch or whatever component the car uses to read the key failed in some wonky way?

I'll monitor this space. I hope you get this figured out. Keep in mind that it was running and then stopped. Something failed and can be repaired, it's just eluding you.
 
Was the shop able to read the diag codes? Probably 1-1-1, but there might be a clue.

I'm still suspicious of the head mount distributor. I've never taken one apart, but could a PO have taken one apart and re-assembled it 180degrees off? They'd then need to swap the plug wires around to make up for the wrong rotor position. This would need to be compounded by some other failure causing it to die on you, and your inadvertently restoring the wires to factory locations while trying to diagnose the failure.

If your plug wires are long enough, it's easy enough to move them by 2 positions on the dizzy and see if it behaves any differently. Firing order is 1-3-4-2 so you'd swap the 1 and 4 wires at the dizzy, likewise for the 2-3 wires.
 
shoestring said:
I don't have a Reddit account either but just clicked through the prompts, no problem. Is this the list you provided to the shop as a "This is what I've done" list or one that they gave to you?

OK, so a digital diagnosis from 3000 miles away at this point kinda goes like this:

1) Had you just gotten petrol? Was it from a known good source?

2) Were you driving steadily along, or accelerating from a stop, or decelerating, or hammering on it? I'm going to PRESUME you were driving steadily along at maybe 25mph in Burford or Glasgow, because that's how I'm picturing it, but you tell me.

3) Are you CERTAIN it just shut off like you hit the key, or is it possible that in the 1-2 seconds before it died you missed a couple stumbles. Maybe you had a real banger from BBC2 on and were distracted? Again, I'll assume that it was as you said and just shut off.

You SEEM to have all the elements: fuel, air, spark, time. HOWEVER, one (or more) of these is lying. Given the circumstances of the failure (all of a sudden) I would say you can rule out 2: fuel and air. If the fuel pump died, it would at least stumble a bit or something. 40 lbs fuel pressure cranking should be enough to at least make it sputter or do SOMETHING.

Here's what I would do if I were you. First, I would laugh at my Brit jokes to add a bit of levity to a stressful situation. Second, I would confirm that the ignition is firing IN TIME. You should be able to do it with a timing light, looking at the belt cover, cranking. I put a little bit of white touch-up paint in the groove in the balancer and on the timing cover to aid visibility. If it's in time, you need to reaffirm the quality of the spark with a proper spark tester. It simulates the resistance a plug encounters in the chamber, under pressure, to see if the spark is of sufficient quality to jump the gap. If it's NOT in time, congrats, you found the problem, but now you need to figure out why.

If it's not in time, I would do this, based on my jillion years as a GM parts consultant. I would confirm the way the immobilizer works. Not by asking someone, but by finding Volvo documentation. I've also read that it cuts fuel and spark, but not in any official capacity. Who knows if that's actually correct, or some layman's explanation of what's happening that's just been accepted as gospel? I don't KNOW, and right now it seems that knowing is pretty critical. What I'm saying is that is it possible that it throws spark, but 180 degrees off? I know this sounds dumb, but we're a bit on the fringes of what might be wrong. Has the ignition cylinder or switch or whatever component the car uses to read the key failed in some wonky way?

I'll monitor this space. I hope you get this figured out. Keep in mind that it was running and then stopped. Something failed and can be repaired, it's just eluding you.
Click to expand...
Legend brother !

1) petrol was about 4 days old, I’d driven (flawlessly) 200 miles over the weekend, fully loaded for a camping trip. Then on the way back from work on the Monday it died. So probably 1/4 of a tank of 99 shell 4 days old. I actually drained this and refilled as part of my troubleshooting.

2) i was driving steadily, unfortunately the radio doesn’t currently work haha I used a Bluetooth speaker over the weekend but work is only a 15 min drive so just went with no music this day. Not that I’d rock out to radio 2, that station is your nationwide “British broadcast” that seems to solely talk about the war in the Middle East, or the immagrant crisis we’re currently having. Opinions aside on that, it did literally just turn off. I was probably doing 40mph and next thing I know engine braking is sending me through the window. No signs before hand whatsoever, also leading me to checking the spark side first

3) my next step will be getting the car back from the shop and sucking up the bill for the labour and the tow back.
Then I’ll look into lending or buying a timing light. I’ll do some further digging on how the imobiliser works. Like you say the fact it was running and driving and then died, rather than something “wearing out” shows it must more than likely be a component failure.

I did a complete engine rebuild about 6 months (3/4000) miles prior to this. Ran really well for the most part.
 
bobxyz said:
Was the shop able to read the diag codes? Probably 1-1-1, but there might be a clue.

I'm still suspicious of the head mount distributor. I've never taken one apart, but could a PO have taken one apart and re-assembled it 180degrees off? They'd then need to swap the plug wires around to make up for the wrong rotor position. This would need to be compounded by some other failure causing it to die on you, and your inadvertently restoring the wires to factory locations while trying to diagnose the failure.

If your plug wires are long enough, it's easy enough to move them by 2 positions on the dizzy and see if it behaves any differently. Firing order is 1-3-4-2 so you'd swap the 1 and 4 wires at the dizzy, likewise for the 2-3 wires.
Click to expand...
I did a complete engine rebuild about 6 months 4K miles prior to this. I rebuilt the distributor ect.

The wires were on the correct way, meaning the distributor must also have been installed correctly.

I actually tried changing the wires around like you say out of interest and it made no difference.
 
your first problem is posting anything other than cut springs on Reddit

i can’t believe a shop would charge 20 hours worth of work and not have anything to show for it

you’re not new here, this is what this forum is about.

I’ll read all that later and hopefully be of some use
 
For immobilizer details, see ipdown's post here:
https://turbobricks.com/index.php?t...-no-injector-pulse.346112/page-2#post-5889517

At a high level, the '984 ECU talks to the immobilizer and won't fire the injectors if it doesn't get the correct response from the immobilizer. Using a non-immobilizer ECU, or swapping to non-immobilizer chips, ignores the immobilizer. The immobilizer itself doesn't interrupt spark/injectors/starter/shifter interlock, etc., it just talks to the ECU.
 
Last edited:
Radio Suppression Relay? Didn't see that in your list? I always carry a spare in the car.
 
ZVOLV said:
Does it run on brake cleaner?
Click to expand...
From earlier thread:
https://www.turbobricks.com/index.php?threads/progress-keep-going-…-no-start-car-has-fuel-and-spark-and-timing-is-correct-wtf.375943/
Jamesmoore said: "I tried starting fluid with the injectors unplugged, and got both a backfire out the exhaust and out of the intake …"


I thought more about this no-start and, grasping at straws, have a few more ideas:

1) Maybe the spark isn't occurring at the correct time?
This could be a bad rotor to camshaft alignment, or a bad cam gear to camshaft alignment. If the cam gear alignment pin had sheared off, it must have spun exactly 180 degrees since the compression test is good. If the spark isn't timed correctly, it would explain the not running on starting fluid.

You could check this with a timing light on #1 plug wire - verify that it flashes ~10deg BTDC on the crank pulley and, through the oil filler cap, that the #1 lobes are both up. You could also crank it around to #1 TDC and verify that the tip of the rotor is roughly aligned with the #1 plug wire post in the dizzy cap.


2) Maybe the spark is too weak?
You could test this with an adjustable "spark gap tester", or follow cleanflametrap's example shown in the last couple pictures here:

If you have a labscope, you could measure the coil tabs and confirm that, while charging, the coil the + tab stays at ~12volts and the - tab drops to ~1volt.


3) Maybe the injector voltage is weak?
Are you running low-Z injectors with the resistor pack, or high-Z injectors with the resistor pack bypassed?

You might be able to test this by running the 4 injectors into small jars and verifying that they're equal and have a reasonable volume of fuel.

If you have a labscope, you'd look at the voltages on both injector pins when energized, and the +12v on the resistor pack (if still present). If the fueling was poor, it should still run on starting fluid, which doesn't match your testing.
 
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I can't imagine spending 20 hours on what they wrote down. I don't know, if I were them I'd either charge you nothing out of shame or keep living comfortably off of my incompetence. Don't know, "chance is what makes the thief" kind of situation.


Anyway. "Timing verified through starter hole" means nothing. "Missing holes on the flywheel are somewhere vaguely around the starter hole, while mark on harmonic balancer, that is attached to belt gear by a piece of rubber which is know to slip and wander off are somewhere there." Doesn't mention what does dial indicator say about actual piston TDC. For £2000, id definitely check...

Also, having fuel pressure, noid lamp (what current?) blinking and "changing injectors" doesn't equal fuel in proper quantity exiting the injectors. Measuring cups say that.


When you're sure that timing is correct, by way of comparing mark on balancer with actual indicated TDC and no1 valves closed, you can check spark with a strobe light. You're a mechanic, you need a strobe light in your life. And they can be had for around £20, orders of magnitude less than £2000...


Also, any LH2.4 ECU, turbo or non turbo, from 89-94 200/700/900 cars without immo is going to work in a pinch.


Report back when able.
 
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