Causes of sustained pre-det in one cylinder only.. (check out this plug pic)

[mark1905]

Re: Causes of sustained pre-det in one cylinder only.. (check out this plug pic)

Ayuh,... Disconnecting those wires is Not the same as joining 'em together...

Lol.. agreed. I did disconnect them. The second sentence in the same instruction says to "Temporarily join the engine harness wires together."

Which engine harness wires? Could they be any more ambiguous? If they are talking about connecting the two wires together than I just unplugged from the shift interrupt switch (thereby bypassing it), the engine dies out.

 

[Don S]

Re: Causes of sustained pre-det in one cylinder only.. (check out this plug pic)

Lol.. agreed. I did disconnect them. The second sentence in the same instruction says to "Temporarily join the engine harness wires together."

Which engine harness wires? Could they be any more ambiguous?

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Geezzz, pay attention you disconnect the wires from the shift interrupt switch and hook them together. Not the switch wires, that would do nothing, you hook the engine wiring harness wires together.

 

[mark1905]

Re: Causes of sustained pre-det in one cylinder only.. (check out this plug pic)

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Geezzz, pay attention you disconnect the wires from the shift interrupt switch and hook them together. Not the switch wires, that would do nothing, you hook the engine wiring harness wires together.

GOT IT!

The problem was that the jumper wire was not making good enough contact with the leads. If the jumper wire is contacting good enough, then the engine will run with the switch bypassed. If not, the motor will just die when the two interrupt wires are connected.

So, timing results are now fine. It's reading 1deg with the jumper wire on, 12 deg with it removed and shift wires re-hooked up.

I then checked all around using carb cleaner looking for leaks. Didn't find any. Pulled the new NGKs that I put in yesterday, and #2 looks fine and just like the others.

I'm wondering at this point if it was a POS Champion plug that did it? Wrong heat range but stamped the same as the rest?

 

[Don S]

Re: Causes of sustained pre-det in one cylinder only.. (check out this plug pic)

What rpm are you idling at before you try to hook the wires together? If it's too low, adjust the idle up so it will be around 700 when plugged in. You CANNOT set timing if you don't put it in base timing mode.

 

[mark1905]

Re: Causes of sustained pre-det in one cylinder only.. (check out this plug pic)

See above edited post, Don.

Thanks again for the patience and help as always..!

 

[John_S]

Re: Causes of sustained pre-det in one cylinder only.. (check out this plug pic)

I am not that familiar with the 4cyl Merc. Anything I have learned, it was just from reading posts here on iBoats. I thought that motor had a combined intake/exhaust manifold. If true, the spray test would bot be able to tell a leak between exhaust and intake port. You may want to hook-up a vacuum gauge and get some readings.

In your earlier posts, you indicated a louder "tic" sound. Is this still present?

You will want to keep pulling that plug after every outing, just to check. I wouldn't get too comfortable that it was just a bad or mis-labeled plug.

If I remember correctly, I thought that the Merc 4cyl was borderline lean just to pass emmissions. I also thought that there was something about how to run them a bit richer. Sorry, if it was info on a 350 I could give better details.

 

[Don S]

Re: Causes of sustained pre-det in one cylinder only.. (check out this plug pic)

The 3.0L engines did have problems with idle mixture being too lean for to pass EPA specs, but that didn't happen till around 2002 or 03 I think. Then, all you had to do is pull the tamper proof cover of the idle mixture screw and back it off about a 1/4 turn and the idle smoothed out and the dieseling settled down, and starting was much easier. But nothing was changed for high speed. There was some problems with head gaskets blowing, I'll have to look up that service bulletin again.

 

[Don S]

Re: Causes of sustained pre-det in one cylinder only.. (check out this plug pic)

Might want to read this service bulletin.

http://www.boatfix.com/merc/Bullet/98/98_14.pdf

 

[John_S]

Re: Causes of sustained pre-det in one cylinder only.. (check out this plug pic)

Don,

That was probably it, and you were probably the one I saw who posted it.

 

[mark1905]

Re: Causes of sustained pre-det in one cylinder only.. (check out this plug pic)

Might want to read this service bulletin.

http://www.boatfix.com/merc/Bullet/98/98_14.pdf

Wow.. so wait. It's better maybe to retard the timing to 1deg ATDC rather than 1deg BTDC?

 

[mark1905]

Re: Causes of sustained pre-det in one cylinder only.. (check out this plug pic)

In your earlier posts, you indicated a louder "tic" sound. Is this still present?

The ticking sound has gone away for now on the hose, but I'll know more when I take it out and get it under load. It has to be better than when I had a melted plug in there.

To be totally honest, I don't know how I ran it all this last weekend.. towing skiers and all.. with that plug. It ran on all 4 cyl with almost no power loss. I did feel like when I was being towed that it didn't have quite the same power out of the hole, but I attributed that to people being on the boat.

 

[John_S]

Re: Causes of sustained pre-det in one cylinder only.. (check out this plug pic)

Given the service bulletin, I'd do a compression and possibly a leak-down test, before heading back to the water.

 

[fat fanny]

Re: Causes of sustained pre-det in one cylinder only.. (check out this plug pic)

Don so if I read this correctly if you have had a blown head gasket ( mine in between the #3 & #4 cylinders) the timming should be set at 1degree atdc? not @ 1 degree btdc? if so this would explain some of my issues with starting and slightly rough idle over the last 2 yrs