Solving mysterious miss in 92' MTX (testing injector connectors)

[93rev2sev]

Update guys.

I'm beginning to think way back to when 93rev said the car spit a shim he was right and I believe that may of been a side effect, I'm going to email the PO to ask about it..


From the Outside:
http://s757.photobucket.com/albums/xx220/vortex2450/?action=view&current=100_2863.mp4

That sounds absolutely the same as my 93 that spit out a shim.

I first noticed something wrong when I would start the car and it sounded JUST LIKE THAT...but I would let it warm up and it would clear up and smooth out. What I was noticing is that's how it sounded when a valve was stuck open but this shim was still there in it's bucket. After several seconds, the valve would loosen up and all would be well.

My real problems started when the valve decided to pop closed while there was no cam lobe there to keep it in place.




It's definitely mechanical. Don't bother trying to troubleshoot anything electrical. You need to get that valve cover off and inspect every cam lobe, every bucket, every shim.

 

[vortex2450]

Good advice, I'm good at finesse , hopefully I strip any. But what you did is a good alternative. the only thing i could find is a 5mm in a seven piece set. It has a rounded headed for angling the bit a little, Hopefully it'll still seat solid and hopefully the hex is 5mm and not 5.5mm because Lowes and Home Depot doesn't have a 5.5mm head on a 3/8" ratchet...

Worst comes to worse and I'll break out the heavy duty dremel blades and do what you did.

That sounds absolutely the same as my 93 that spit out a shim.

I first noticed something wrong when I would start the car and it sounded JUST LIKE THAT...but I would let it warm up and it would clear up and smooth out. What I was noticing is that's how it sounded when a valve was stuck open but this shim was still there in it's bucket. After several seconds, the valve would loosen up and all would be well.

My real problems started when the valve decided to pop closed while there was no cam lobe there to keep it in place.




It's definitely mechanical. Don't bother trying to troubleshoot anything electrical. You need to get that valve cover off and inspect every cam lobe, every bucket, every shim.

Really now? And how involved was it correcting the issue?

Thanks for the picture as well, now I'll have an idea of what's I'm looking for...


And I know it's without a doubt a the problem exists with one of cylinder #2's valves but I'll still look over the others.

Also, it's a little late to tell me not to bother with the electrical stuff I've already ran through both the ignition and fuel system with a fine tooth comb. The low voltage at the injectors was a problem with out a doubt, I don't know if they had anything to do with the miss though. The short could have existed for a long time with no one knowing.

I do know that when I put a fresh set of injectors in the car would not start until I ran a fresh 12v wire bypassing the short.
If the wire was disconnected/no fire, as soon as I reconnected it, fired right up.

At least I can confidently say those systems are good as new now.

I will be taking the cover off tomorrow morning once the temps get high enough not to freeze my fingers. For eveyone following, expect pictures of the issue by afternoon.

On a side note, I will probably be needing at least a shim and hopefully nothing else, I know SHOSource sells them used but if anyone is feeling generous donations are welcome (;

 

[stangeater]

It's a 5mm. When you do put the socket in the hole, tap it in with a hammer just to make sure it's seated well.

Exactly what I do! This works great!

 

[vortex2450]

Found it!





Shim in the exhaust side of the cylinder jumped out, I inspected the shim, the top of the valve, and the lobe, everything is clean as a whistle, a lot of relief after finding the shim just laying there.



All the fuss over this thing. 93rev2sev you were completely right from the get go, the injectors were a problem and threw a wrench in tracking this down quicker but it was an ejected shim.

Ok, so bare with me, I can't explain how relieving it is to see no damage from the issue.

As for fixing this, is it not reasonable to just turn the cam and baby the shim back where it needs to be? Wouldn't it just be like what your doing 23 more times in a valve lash?

EDIT: I turned the engine over and the valve itself seems to be stuck open, I tapped it lightly with no luck, looks like I'm going to have to pull the head... No celebration quite yet after all..

EDIT: Had my dad turn the engine over while I watched the valves, it goes down when the lobe touches it but doesn't come all the way up, essentially sticking halfway through it's motion, I dont' hear the piston touching it which is good.

What am I looking at here? A broken guide? Broken spring? Or just a carbon build up ?

 

[kevinspann]

My guess would be a broken valve spring, but I'm not SHO smrt like lots of others here.

 

[stangeater]

I wonder if the lack of movement could be from the build up of the fuel that's not been combusting in that cylinder??? Hmmm. So glad you found that shim!!

 

[93rev2sev]

That's exactly how mine acted. The valve is either bent, there's too much carbon on the stem to allow it's normal range of motion or the spring is broken. Here was my solution:

Stripped and junked.

 

[vortex2450]

I wonder if the lack of movement could be from the build up of the fuel that's not been combusting in that cylinder??? Hmmm. So glad you found that shim!!

I'm with him, I'm going to go to Napa pick up some Marvel Mystery Oil (snake oil and some sea foam while I'm there, hopefully it's just carbon. I'll drive it around and see what I get after about 100 miles.

Here's my reasoning..

shims pops out-> miss starts-> cylinder begins to run rich-> unburnt fuel being forced out a halfway open valve-> unburnt fuel and gunk begins to clog the valve head/seal-> valve only moves halfway up because of blockage but still allows air through.

And 93rev2sev, your option is 100% not an option here, this car is in great condition.

If the sea foam and marvel don't clear it up my next move is in fact pulling the head.

So my questions regarding that are..

A) Can is simply take out the camshafts, and loosen the large hex bolts to take the head off?

or am I looking at having to completely tear down the engine?

 

[93rev2sev]

The only luck that's left is the luck associated with trying to free up that valve.

If it's a broken spring, consider yourself lucky. Pull the cam, repalce the spring, shim it back up and be on your way. If it's anything else, you're hosed. Shop for a replacement engine. You can get engine and have it installed for less than the cost of replacement heads that have been cleaned up. I'd value a set of cleaned up (degreased, re-lapped valves, new valve stem seals) heads at about $400.

 

[93rev2sev]

I'll drive it around and see what I get after about 100 miles.

Do NOT drive it.

Pull the cam and see if it's a broken spring. If not, get a new head and beg, borrow or steal a loaner car to drive and some help getting the head installed.

Edit: if you drive it and the valve pops closed, then you are going to ruin the cam and the bucket when the lobe comes around to open the (now) fully closed, unshimmed valve.

 

[vortex2450]

Do NOT drive it.

Pull the cam and see if it's a broken spring. If not, get a new head and beg, borrow or steal a loaner car to drive and some help getting the head installed.

Edit: if you drive it and the valve pops closed, then you are going to ruin the cam and the bucket when the lobe comes around to open the (now) fully closed, unshimmed valve.

Well I put the shim back in and put the engine back together for now because it's really wet outside and I don't need moisture getting where it doesn't belong.

I did pour a little marvel mystery oil in the cylinder itself and the crankcase and fired it up, the miss is definitely sounding different along with the sound of the lobe ticking against the shim. It's not pretty.

Does my reasoning not sound at least somewhat accurate? The miss definitely started with the shim being spit out, because if the shim hadn't of been spit out it would've sounded like i does now, with a moderate ticking at idle.

I'm not saying it isn't possible that the shim spit out and as a result the spring or valve went right behind it....

But I watched the lobe when it pushed the valve down and when the lobe was in contact with the shim it moved very fluidly, would it still move smoothly with a broken spring or a bent valve?



Okay, I'll agree driving it isn't a smart. If I pull the cam will I be able to diagnose anything else besides a broken spring? Like say a bent valve?

Also can you give me a lead on how to pull the cam? A link with pictures is always best but I can work with a vague idea here.

I don't mean to come off brash, it's how I think, and I don't know too much about the heads of this car (yet) so I'm asking as much as I can to get a clear idea of what I could be dealing with..

thanks,
josh

 

[stangeater]

That's exactly how mine acted. The valve is either bent, there's too much carbon on the stem to allow it's normal range of motion or the spring is broken. Here was my solution:

Stripped and junked.

By the looks of that car....you picked the right option. The car he is working on is beautiful, therfore, that's not an option.

 

[93rev2sev]

The general procedure for getting to the valve spring:

Remove cam and affected shim and bucket
Pressurize cylinder to keep the valve from falling into the cylinder
Remove keepers
Remove spring cap
Remove spring

Problem:
You can't pressurize cylinder since the valve won't close. The acceptable method then will be fairly "old school". You will need to feed a length of nylon rope into the cylinder through the spark plug hole while it is at bottom dead center. Once you have a decent length of rope in there, rotate the engine by hand until it stops. This will jam the rope into the valve so it can't fall in. Now you can remove the keepers and pull the spring without fear of losing the valve into the cylinder.

Problem:
You probably don't have a Rotunda SHO head tool kit laying around. You might be able to use a generic valve spring compressor but I've never tried that.

 

[luigisho]

Call Kirk at NESHO and see if he has a head at a reasonable price.

 

[vortex2450]

Well, I don't have any valve-train tools at all, I'm
At this point, I'm going to turn the car on and let it run each day for about 10 minutes with some marvel mystery oil in the cylinder until Saturday, if the doesn't help I'm going to put some Seafoam through the intake.

I probably take the cam off I'm I don't succeed with these shots in the dark and check the spring out. And If I still don't get anything new then I'm pulling the head off.

I'll determine then if I even need a head, I could be lucky and have a stubborn chunk of build up could be stuck in-between the valve and the seat. If not I'll do what I can to tear it down.

At least now we've isolated the issue,
thanks a ton guys.

I'll update if (and hopefully when) the valve decides to get back in the program with the rest of the engine.

 

[Frisbeeguy]

Good luck - we're hoping it works. Time, patience, resolve and cash will get it back on the road.

 

[vortex2450]

Thanks, unfortunately I have all of those but that last one

 

[vortex2450]

SOLVED! but might have bigger problems...

Solved! It's official. :woo-hoo:
Compression checks out. Sounds good.

I did exactly what you said not to 93rev2sev :angelnot:

I put the shim back in it's bucket buttoned it up, filled the cylinder with Marvel Mystery Oil, turned it over a couple times so it would get into the valve.

My instincts were screaming gunk in on the valve seat so I let is sit overnight, took it on a 10 mile round trip to Food Lion and about 3/4 the way back I noticed the car wasn't bucking any more at a stop sign.

I pulled the plug and gave it another serving of Mystery Oil with some Sea-foam as well, just to be sure that that valve would not be giving me any more slack.

I took a video after running the Seafoam/marvel Mystery Oil out.
http://s757.photobucket.com/albums/xx220/vortex2450/?action=view&current=100_2896.mp4




With the miss fixed I can move onto other pressing matters like the exhaust leak at the y-pipe/flex-pipe or the shimmy from a warped right rotor.

but, did anyone else notice that rattling/squeaking noise emanating from the crank pulley? I have not noticed it before..

Is that the dreaded cancer? Or is it maybe just the result of me possibly over-tightening the tensioner pulley?

I did run the car through it's entire power band in 2nd and 3rd right before the video, would that make a difference?

 

[stangeater]

The car does not have crank cancer, the crank, and key are in perfect shape....ask me how I know??LOL You probably just over tightened the tensioner pulley....a common mistake, and it's easy to do.
Good job so far!
Jeff

 

[stangeater]

PS...now that you got it fixed, can I have it back for the same price you paid for it? LOL