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Dead cylinder for the first mile

I'd check that the ignition system has good +12v and good ground. The best check (furthest from the battery) would be probing the outer 2 pins at the distributor with a multimeter while idling. If that's not convenient, probing across +12v at the coil and the ground ring terminal by the headlight relay might be good enough.
 
Hi,

Bought a second hand Bosch coil and I don't trust it one bit. Doesn't really look like my old original one, and it also doesn't measure right (and it didn't fix my problem, but that could of course be because the coil wasn't the problem).

The Bosch coil and the old un-branded coil, both measure 1.1ohms primary resistance, which according to Haynes is the coil for computerised ignition systems. Sadly, my system does not match anything in Haynes.

However, that coil according to Haynes, should measure 9-11K Ohms. My old, un-branded one measures 8K Ohms but the Bosch one I bought only measures 5.5K Ohms which is far, far lower than any type listed in Haynes.

I just don't trust it.

I might buy a new one instead.

Next steps are to smoke leak test the inlet and leak-down test the cylinders.

But I am genuinely about to give up. Scrap the car? Buy a new engine?

Replacing the head-gasket helped massively, but it's back to being quite bad. So is it still something to do with the gasket or maybe the block surface? I suppose a leak-down test would tell.

Regards,
Henrik Morsing
 
Hey Henrik,
I know it's frustrasting, but don't give up, been there many a time, you'll get it. Question: Is the misfire, now, still random, or has it gone back to #2 only, or always #2 and another cylinder, or always #2 and random other cylinder? Did you do another exhaust video?
 
apollokid said:
But I remember wrong or the missfire was in the cylinder #2 before head gasket renewal and now has moved to #1?
Click to expand...

It was a misfire on #2 which would clear up after a bit of driving.

Just over a month ago, it suddenly turned much worse. It was permanently driving on three cylinders and when I checked, it was now cylinder #1.

Changing the head-gasket made it better, but it has been getting worse again. I am also concerned about the amount of smoke from the exhaust, I really don't think it used to do that.

I don't trust my replacement second hand coil, so I have ordered a new one, but it's NGK as you can't get Bosch anymore. But do I actually still have two problems? Is there a block problem? I'm not losing coolant.

Just curious, but why does an ignition coil have to specifically fit a model car? They should all take 12V and output around 30kV, can I not just get any Bosch coil? Or make my own?

Regards,
Henrik Morsing
 
Hi Henrik,
I've just been reviewing your history, been a little complicated to keep track of. So #2 was original misfire (when cold / for 1 mile), then #1 (for a 140 mile trip). Then head gasket replacement. Then #4 (at idle, and in traffic, better on the freeway). Then #1 (your video). I couldn't really see if #2 was also not firing. Is it possible that both #1, and #2 are misfiring with #1 being worse? Can you have some one start up the car, and idle / rev engine while you're back by the exhaust, so you can really smell the fumes? Fumes still look white to me, and it dissepates without hanging in the air, so I don't think it's oil. But without smelling it, can't tell if it's coolant (Thick, kind of a sweet smell, that you can feel like you're also tasting it), or unburned/not ignited fuel (Sharp, acrid smell, with a burning sensation to eyes, and lungs).
 
morsing said:
Just curious, but why does an ignition coil have to specifically fit a model car? They should all take 12V and output around 30kV, can I not just get any Bosch coil? Or make my own?
Click to expand...
It was a topic discussed a few weeks ago, if you are curious take a look at this thread: https://turbobricks.com/index.php?threads/no-codes-no-start.371125/ (especially the last part)
In a brief summary, output voltage is a function of the input to output number of turns ratio like any voltage transformer while speed of charge depends on input impedance.
 
tbrcktch said:
Hi Henrik,
I've just been reviewing your history, been a little complicated to keep track of. So #2 was original misfire (when cold / for 1 mile), then #1 (for a 140 mile trip). Then head gasket replacement. Then #4 (at idle, and in traffic, better on the freeway). Then #1 (your video). I couldn't really see if #2 was also not firing. Is it possible that both #1, and #2 are misfiring with #1 being worse? Can you have some one start up the car, and idle / rev engine while you're back by the exhaust, so you can really smell the fumes? Fumes still look white to me, and it dissepates without hanging in the air, so I don't think it's oil. But without smelling it, can't tell if it's coolant (Thick, kind of a sweet smell, that you can feel like you're also tasting it), or unburned/not ignited fuel (Sharp, acrid smell, with a burning sensation to eyes, and lungs).
Click to expand...
+1

I just add this meditation: how we trust the test of inverting the 2 injectors made ad the beginning? I think that it could be useful to see how really is the spray pattern of those injectors :unsure:
 
Hi,

Another thing, I realised yesterday that I had been running with the primary coil on reverse polarity. Changed it and made no difference though.

But, both the coils I know have measure 1.1 Ohms on the primary side, and I'm not convinced that is correct.

Regards,
Henrik Morsing
 
apollokid said:
+1

I just add this meditation: how we trust the test of inverting the 2 injectors made ad the beginning? I think that it could be useful to see how really is the spray pattern of those injectors :unsure:
Click to expand...

Ok, maybe. But I still think the spark tester showed a weak spark. I can try swapping the injectors again though. Or maybe get them out and do a spray test.

I'm currently spending a lot of time getting the Saab ready for the MOT. If it passes I will have the time for the Volvo but more importantly I will not be relying on the Volvo to get to work.

Regards,
Henrik Morsing
 
morsing said:
Ok, maybe. But I still think the spark tester showed a weak spark. I can try swapping the injectors again though. Or maybe get them out and do a spray test.
Click to expand...
I'm sorry but I've no exprerience on how to use/interpret the measures of the spark gap tool since I use other instruments, for the spray test I hope it could help in finding what's wrong with your 240.
I wish you the best

P.S. may be I'm wrong but when you sayd that the missfire was fixed on a cylinder and that you had spark outside the cylinder but not using the timing gun I was more inclined to think it was really an ignition problem, now that the missfires seems to be able to affect also other cylinders I'm not so confident as before.
 
bobxyz said:
I'd check that the ignition system has good +12v and good ground. The best check (furthest from the battery) would be probing the outer 2 pins at the distributor with a multimeter while idling. If that's not convenient, probing across +12v at the coil and the ground ring terminal by the headlight relay might be good enough.
Click to expand...

Thanks, will need to check the grounds thoroughly.

ZVOLV said:
I also had luck with manually making a coil spark by tapping the ground side with a jumper wire to a good ground with the correct rythmn.
Click to expand...
I actually tried this a few days ago and could not get any spark out of it.
 
Greetings,

I have a really bad cold which means two things: 1) I cannot smell the exhaust and 2) I have to stay indoors today and possibly tomorrow for any chance of recovering. But once the engine warms up, there is no visible smoke and my hand doesn't get wet from the exhaust.

But, I did a leak-down test yesterday and I also changed the coil out for an NGK coil measuring 1.1 / 8 kOhms. I also cleaned up the ground connections, but it made no difference.

Before I started the leak-down test, I noticed this, though, which it has not done before:


I just don't get what is going on with this engine.

Here are the leak-down test results:

ld1.jpgld2.jpgld3.jpgld4.jpg

So, it's all very odd, as always. The dead cylinder #1, has the least leakage. But they're all ok, I think, also bearing in mind by the time I did the test, the engine was no longer hot.

I did notice though, that on cylinders #1 and #3, when I initially put my ear to the expansion tank, I heard a gurgle. But only right at the start, it never did it again, and I may have been too slow to put my ear to it with the other cylinders.

So, in-conclusive, again? Or is there a block deck/head-gasket problem?

Once my cold is gone, I will test the injectors and do an inlet smoke-leak test. I will also remove the fan belt and run the engine to be able to pin-point the smoke from it.

Regards,
Henrik Morsing
 
It sure seems like there's still a completely dead cylinder. Ignoring the testing that you've done already, I'd suspect a bad part in the high voltage path - plug wires, coil wire, cap, rotor. Have you tried misting it with a water spray bottle in the dark to see if you can see any arcing?

In your video, the cable from the distributor sensor is clipped to the high-voltage cable from the coil. There's a chance that this is causing electrical noise in the disti sensor. As a test, remove the cable clip and separate those cables by a couple inches.

For an example of a Ford 1.6 Turbo engine that runs fine but has a brief misfire on startup, see:
 
I've been reading this thread over and over and am still wondering what happens after the first mile is driven?
 
Last edited:
philski o'flood said:
I've been reading this thread over and over and am still wondering what happens after the first mile is driven?
Click to expand...
Hi Phil (?),

Originally, cylinder #2 had a mis-fire that would clear up. Then, out of the blue, cylinder #1, which had been fine up until that point, died completely, and had been dead for the last 500 miles. I have no idea if the two things are related.

Regards,
Henrik Morsing
 
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