Jump to content
HybridZ

#6 fouling


Recommended Posts

FPR is after the the tail . I could split the batch. I have the hot running to the fuse box , just got lazy because MS said it was okay to run all 6 with one hot. Need to get sequential going , but this should work unless the demand can’t be met with a bigger engine . I do have some kind of oil issue from a seal or something . Maybe get away with swapping intake valve guide seal on #6 will help

C5AA3210-BA7C-4D9C-97A5-D1C557E8103F.jpeg

Link to comment
Share on other sites

Well after trying about everything I could think of I pulled the head . I definitely have an oil control problem . Since this is a fresh assembly I must of got something wrong or something failed. I tried different valve guide seals on this build, but examining one of them I couldn’t say if it failed . Removing the head revealed a oil film on 4,5,6 with 5&6 being the worst. Maybe oil control rings broke, failed ? 

Im going back to the Ford valve seals, but really should pull a piston - ugh. 

Just weird it happened on the last three . Or is possible it’s just #6 and engine vacuum is dispersing it between the closer runners ? 

Learning a lot in this build - the hard way

Link to comment
Share on other sites

Just going back to injector wiring for a moment. Yes it's fine to run all injectors off of one Power Lead. But that goes through a Relay direct from the battery. But the ECU triggers injectors by grounding. And you should be using BOTH injector driver banks with that. Even if using Multi Point ( all injectors fire at once ). 

 

 Batch fire requires one bank of cylinders ( usually 1,2,3, )  firing from Bank A and the other Bank ( 3,4,5 ) firing from Bank B. But remember it's the ground side of the injector drivers that does the triggering. 

 

Once you have the injector wiring corrected, choose 2 squirts alternating as Tony mentioned. . That will enable batch fire. 

 

Multi-point is the least desirable method, particularly with larger injectors. The " Water Hammer " effect gets pretty bad. will cause spikes in actual Fuel Rail pressure. Batch fire is much better and of course true sequential injection is best for emissions quality and smooth idle.

 

Negligible difference in power output at WOT between Batch Fire and Sequential at high RPM though. Everything is just happening so fast.

 

Sequential does reduce available time to inject fuel over a 720 degree combustion event because it is Timed injection. By about 30% if memory serves me correct. If IDC are getting high, you can reduce them by switching to Batch Fire. Just an interesting but possibly irrelevant point in your situation. 

Link to comment
Share on other sites

 

Okay - turns out I have an oil issue . Oil is getting into to cylinders 4-6 , progressively worse from 4 on . The oil is diluting the charge and causing a misfire - especially in 6. 4&5 seems to be able to burn it off . 
I removed the intake to check for vacuum leaks to find an oily film in the runners 4-6 . Runners of intake and head both had oil film. 
First suspect was/is the valve stem seals. I tried a different kind on this build vs my L24. Visually they looked fine . They took a lot of persuasion to install and thought maybe I used too much . Last seals were a Ford seals , which were difficult because they are finicky as hell to install. 
Actually replaced #6 seal while head was in motor - ran motor and still have same results . Not being able to pin this down I decided to pull the head and look at the guides and anything else . Getting good at this now I guess - 1 hour later the head was on the beach . But no smoking gun found . I ordered more seals anyway.

Decision time now . Do I go deeper and pull pistons or throw all new valve seals on and reinstall head and keep fingers crossed ? I was getting ready to leave town and really wanted an answer so I dropped the pan and pulled 6.

Still no smoking gun - as far as my experience(novice) eyes can tell. Got on the phone to my machinist - but didn’t hear back yet. My inspection was very quick , so when I’m back in town I will scrutinize closer . 
Just trying to determine source of oil . I was expecting to see a collapsed expansion ring or another failed ring . There was marks on the bores on the thrust side that were fairly significant visually  , but nothing you could feel.

I have an extra assembled f54 flat top short block sitting there untouched by amateur hands  with 110k miles with perfect wear in the bores . Also pulled a couple of bearings and everything looked spot on. Depending on what I find or not find it might be the next plan. With the head off it makes assembly decision equal. 

Though this is frustrating , the hobby of engine building will have these outcomes I guess . Not being a stock engine makes this more of a challenge . Missing the L24 right about now because I enjoy driving my car - a lot ! I was hoping for more engine swap and tune - not engine swap and troubleshoot . Hopefully I learn from my mistakes 

Link to comment
Share on other sites

7 hours ago, Leon said:

I'm not familiar with the EFI stuff but where is the PCV valve located on that manifold? Are there any other possible oil paths into the intake that you haven't explored, outside of the stem seal and piston rings?

PCV is basically located on the bottom center of the n42. 

https://images.app.goo.gl/s7MedL1SofYUqDMXA

 

It actually looks biased towards front . I run through oil catch can to the PCV . I also think the #4 would get most of the junk being close to the PCV .

Link to comment
Share on other sites

Can you post more pictures?  wide view of all the parts removed, close up of others.  Much easier to view something, then trying to diagnose by what someone says.  Not trying to be an ass, just was frustrating when customers would only state what they think was wrong, but would never ride along with us technicians to better express what they heard or felt.

Link to comment
Share on other sites

Well there was no smoking gun that I found . I pulled #6 piston to find oil around the top ring , but the second ring was pretty clean . Tends to make me believe the oil was coming from the top . I only replaced the 6 intake seal earlier , but since have changed all the seals back to the Ford seals . Inspected the piston and threw it back in . Haven’t fired it off yet - will keep my fingers crossed . 

Link to comment
Share on other sites

I like @Leon's theory that points at the PCV valve as the potential source of the oil. The problem seems to start directly downstream from its entry point in the intake. And you mentioned that there's oil in the intake runners. It would take a LOT of intake reversion to push oil out to the intake if hte source was the valve seals.

 

An easy test is to block the pcv hole in the intake, and run a hose from the pcv up under a windshield wiper. Not that there should be much blowby, but you'll see whatever there is instantly that way.

Link to comment
Share on other sites

  • 5 months later...

Well guys , my best answer is that I found some scoring on the valve stem on #6 intake valve around the seal area of the stem . 
I moved on to my 3.2 build and P90 head since that head was ready . Funny thing is that #6 still had a different burn with the new engine , but not oil fouled - what kind of luck is that . Once I went full sequential on my EFI - it seemed to help . I think now it’s an intake design flaw . It’s something I could tune out with injector trim possibly , but I’m going to run it . The N42 intake will go away shortly with something else . 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...