Weak cyl Prob FOUND

Sean Krupa

Sean Krupa

Moderator
Re: Weak cyl Prob FOUND

Glad you found the problem Don!

My Ty just had a Issue with #1 Piston hitting my Intake valve couple months ago. I was in Boost for about 1/8th mile and engine shut off. Got it started and sounded like a Rod knock. Found out the piston kissed the valve and bent it. So #1 Cylinder has something goin on for us huh.
 
Don W.

Don W.

Stab it and steer it
Re: Weak cyl Prob FOUND

Quickstop [UK] said:
Is that a cracked ring land? I've never seen one before but am familiar with the idea behind it.

Can you really weld it back together? /gullible. :dunno:

Quick diagnosis! Good work!
Click to expand...

Naw, I was joking. Sometime my jokes don't sound like jokes. Yes that is a cracked ring land. Actually the two lands between 1st, 2nd, and the oil ring. When I pry on them they bring the rings with them so I haven't removed them yet. Once out I'll post another pic.

With all the comments it would seem that #1 does run lean. Seems odd to me.
 
neildemo

neildemo

Administrator
Re: Weak cyl Prob FOUND

So question if Cylinder number one runs lean all the time . Is it possible to install like a 40# injector on the 1 cylinder which would provide more fuelling ?
 
dgoodhue

dgoodhue

BuSTeD 4.3
Re: Weak cyl Prob FOUND

Typically 3 & 4 run lean because of the intake manifold. You wouldn't want a completely different sized injector to compensate for the lean cylinders it would be too large of a variation. If the injectors were flowed, you could move them around to compensate for leaner injectors. It would probably be helpful to be reading plugs if someone was go this route.
 
Don W.

Don W.

Stab it and steer it
Re: Weak cyl Prob FOUND

To properly read plugs you'd have to pull them at the end of a pass or a FT dyno run. A couple of burnt fingers later you could tell. IMHO Installing a single larger inj would cause more problems that it might cure. Rough idle, plug fouling at idle/cruise.

It would be interesting if someone has ever put 6 o2 sensors on one of our motors. Steve Morris are you out there? :lol:

Dave, why do you think 2 & 4 run lean? In our engines the cyls fire from back to front. Back pair, middle pair, front pair. No idea what difference that might make. Especially under boost. The off center of our throttle body could muck up the flow I suppose but I doubt it. If I did my math correctly there are always 2 intakes open somewhere through about 1.8 turns of the crank. My simple brain has trouble imagining one getting cheated. Just my opinion.

Math: Intake is open for 220* x 6 cyl = 1320*/720 (since it happens through 2 revolutions of the crank.)

Off to the machine shop. I'll post what happens.
 
D

Damian

Member
Re: Weak cyl Prob FOUND

I believe it has to do with the coolant flow, not running lean. Doesn't the water flow start at cylinder 2, work it's way to 6, then 5 and finish at 1? If it does, that's a lot of time for the coolant to heat up by the time it hits cylinder 1.
 
Don W.

Don W.

Stab it and steer it
Re: Weak cyl Prob FOUND

Damian said:
I believe it has to do with the coolant flow, not running lean. Doesn't the water flow start at cylinder 2, work it's way to 6, then 5 and finish at 1? If it does, that's a lot of time for the coolant to heat up by the time it hits cylinder 1.
Click to expand...

Flow starts at the front, cyl 1 & 2, flows toward the rear and up into the head then forward to the outlet at the front of the head, to the t-stat then on to the rad. The two banks are separate. IOW 2,4,6 on the pas side and 1,3,5 on the drivers side. It appears just from looking at it flow from the block into the head is determined by holes n the head gasket.
 
Quickstop [UK]

Quickstop [UK]

Combating adversyty.
Re: Weak cyl Prob FOUND

Thanks Don, I didn't think a simple weld would work. :tup:

I guess noone has tried running 6 O2 sensors off each exhaust pipe respectively? That would be definitive.

Also, can't the Holley control individual injectors on difference cyclinders? What are your AFRs like Don? Maybe you need to sacrifice .1 or .2 to get a bit of cooling across the board.

Hope you get it fixed soon - or go filled block. No coolant, no issues right :D
 
Don W.

Don W.

Stab it and steer it
Re: Weak cyl Prob FOUND

Heh, heh... 8 o2 sensors are used all the time in the pro ranks. Also done with piston powered aircraft. 4 & 6 cyl common. Not to many 8 cyl out there but they do exist. I'm sure it's been done. You could do it on our engines, just bring your wallet.

To be determined on the mixture.

I did learn one thing though for you high powered engine guys who might be following this. If the top compression ring looks polished where it meats the land they you are detonating. Didn't know that.

Parts are coming overnight. Reassembly should begin Wed.
 
RealFastV6

RealFastV6

@jb_and_his_coffee
I've never seen 6 or 8 x O2 sensors but I have seen Buicks with 6 x EGT probes for this purpose.

Intake design has everything to do with unbalanced cylinders. Just because it's pressurized doesn't mean it doesn't flow like any other naturally aspirated intake.

I tend to agree though that #1 wouldn't be the "leanest" cylinder just based on looking at the intake. Far more likely that you've got a clogged injector.


Sent from my iPhone using Tapatalk.
 
Don W.

Don W.

Stab it and steer it
Re: Weak cyl Prob FOUND

So it's fixed. Fired the truck today. Sounds about the same. Did a "test crank" without fuel and at least now it cranks the same on each cyl. :tup:
 
D

Davemc1963

93 Ty Owner
Re: Weak cyl Prob FOUND

Going back to the plug reading. Rather than just checking the mixture (afr), how about the plug heat range? Could try running colder plugs.
Another thing to consider thinking outside the box, is, if the previous posts are correct and not all cylinders are 'equal' as you would expect with regard to cooling, would be to run a colder plug on the 'two'? hotter cylinders. Just because it isnt the normal practice, dosen't mean it wouldn't work on our oddball trucks.
Reading the plugs would determine if the heat range is correct or not, in addition to the afr. Too hot of a plug can cause pre-ignition by glowing red hot.
Compared to old school tuning with big cams and carbs, plug heat range dosent get mentioned much these days, although the afr control with efi in closed loop mode is infinitely better. Just a thought.
 
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