Trying to hunt down the problem

[4everun22]

I've actually owned two vehicles over the years that had valve timing issues (an old Mazda 323 with a stripped keyway on the crank, and a 2nd Gen 4Runner) and both of those got harder to start when the problem started happening. There were other symptoms as well, such as reduced power and horrible fuel economy.

Since the timing belt on 3rd Gens lasts so long I'd say it's a long shot that that's what the problem is here, but I'd definitely pull the timing belt cover, bring the crank around to the TDC mark, and see where the pulleys are at. It's too easy to rule this out and then move on to something else.

The compression check will fail if the valve timing is off enough, so I'd want to make sure it's right before pulling plugs.

True. I tried pulling off the top cover this morning but idk how to remove the cam sensor connector from the cover. Not sure how it is clipped on. But I'm also not getting bad mileage or power loss. It's the first 10 seconds then it runs fantastic.

 

[jeremyc74]

True. I tried pulling off the top cover this morning but idk how to remove the cam sensor connector from the cover. Not sure how it is clipped on. But I'm also not getting bad mileage or power loss. It's the first 10 seconds then it runs fantastic.

I think it just slides on, but I can't remember from which direction. There's probably a little clip you have to release to get it to move.

You're talking about the one on the far left in this photo right?

But the symptoms don't really sound right for having jumped time. Even if the ECU were able to compensate for valve timing issues after it went closed loop it wouldn't get there that quickly.

 

[4everun22]

I think it just slides on, but I can't remember from which direction. There's probably a little clip you have to release to get it to move.

You're talking about the one on the far left in this photo right?

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But the symptoms don't really sound right for having jumped time. Even if the ECU were able to compensate for valve timing issues after it went closed loop it wouldn't get there that quickly.

Yeah that's the one. It sure looks like it slides but it wouldn't budge and it was close to snapping. I'm sure I'll figure it out after playing with it. I'm at the point where I have no clue what the problem could be. I've been up and down this thing for so long im going crazy. I'll check the timing and compression but It runs so beautifully after the first 10 seconds I just can't believe it would be anything serious like rings or valves causing the problem.

 

[jeremyc74]

Yeah that's the one. It sure looks like it slides but it wouldn't budge and it was close to snapping. I'm sure I'll figure it out after playing with it. I'm at the point where I have no clue what the problem could be. I've been up and down this thing for so long im going crazy. I'll check the timing and compression but It runs so beautifully after the first 10 seconds I just can't believe it would be anything serious like rings or valves causing the problem.

I'm going to throw something out that you probably don't want to hear, but it could be a head gasket. If it's leaking into one cylinder and fowling the plug, it's possible it's also causing a misfire on the cylinder that shares the coil with the bad one. After running for a few seconds it burns off and clears up.

Is it using any anti-freeze at all? I'd want to get the plugs out and see if anything obvious shows up.

 

[4everun22]

I'm going to throw something out that you probably don't want to hear, but it could be a head gasket. If it's leaking into one cylinder and fowling the plug, it's possible it's also causing a misfire on the cylinder that shares the coil with the bad one. After running for a few seconds it burns off and clears up.

Is it using any anti-freeze at all? I'd want to get the plugs out and see if anything obvious shows up.[/QUOTE

That's been my main concern. It doesn't seem to use any and no smoke or smells. Any test to check for this? ]

 

[4everun22]

Well. .. I have an update. I did a compression check. Took the spark plugs out and cyl 3 was oily. They all looked like they were running lean. Including 3 even though it was oily. Took my inspection camera and all cyl were great ( very little build up which is crazy after 200000) exempt cyl 3 had build up and oily. But the crazy thing is cyl 3 had compression matching cyl 1,5,and 2 at 145psi (Maybe from the oil). But... cyl 4 had 130. And sadly.. cyl 6 had 110.... sigh.. I'm guessing it's the dreaded head gasket. Maybe the valves? Im a diy kind of guy no matter what, but a head gasket or engine replacement might be too much for me. I guess I'll have to check the valves