What'd I break? - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 02-21-2014, 08:29 PM   #1
Elite Member
Thread Starter
iTrader: (17)
 
Join Date: Aug 2007
Location: Fort Myers, FL
Posts: 2,791
Total Cats: 130
Default What'd I break?

I've got about 1500 miles on my built motor, I'd gradually bumped the power up to where it was making around 300whp. Last weekend after about an hour drive, I got into it and could hear it detonating really bad. I drove around a minute and it seemed fine. I rolled into the throttle as I watched the wideband, as it came into boost it'd go to 15:1 and start to hear knock again. I babied the car back home; swapped the fuel filter, checked fuel pressure (good), and swapped the plugs.

These are what I pulled out:

Left to right: 4, 3, 2, 1:


Left to right: 4, 3, 2, 1:





After putting the new plugs in I pulled 5 degrees of timing from my timing map (that had previously been fine). Let the car warm up, and started to make a pull. It knocked exactly the same so I let out of it and brought it back home.

I'd been considering swapping to E85 so I drove 12 miles to the nearest station, topped off, and added fuel to the tune. The car was reading rich, so again I attempted to roll into the throttle with the same result, horrible detonation. I drove back home and pulled the plugs to find

Top to bottom: 4, 3, 2, 1: cylinder 4 smells of well cooked oil







So I pulled the head

Cylinder 4 (No holes, yay!)









Head

4:


3:


2:


1:



So given those results, what is the prognosis? Anything you see here that you'd say is definitely the source of the oil? Greatly appreciate any suggestions.
Attached Thumbnails
What'd I break?-before1.jpg   What'd I break?-before2.jpg   What'd I break?-6e464a1a-b80b-4471-bf61-ce700bab2abe.jpg   What'd I break?-block4-1.jpg   What'd I break?-block4-2.jpg  

What'd I break?-block4-4.jpg   What'd I break?-head4.jpg   What'd I break?-head3.jpg   What'd I break?-head2.jpg   What'd I break?-head1.jpg  

What'd I break?-head4-2.jpg  
pdexta is offline   Reply With Quote
Old 02-21-2014, 08:39 PM   #2
I'm Miserable!
iTrader: (1)
 
Join Date: Aug 2011
Location: SWFloriduh
Posts: 114
Total Cats: 9
Default

Running out of fuel under power ?
Boris is offline   Reply With Quote
Old 02-21-2014, 08:41 PM   #3
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,198
Total Cats: 2,584
Default

weird, it looks like 1st time around 1 and 4 were lean and possibly detonating, then 2nd time around 2 and 3 were lean
also 4 kinda looks like it had a bunch of blowby
possibly 1 as well
18psi is offline   Reply With Quote
Old 02-21-2014, 09:31 PM   #4
Elite Member
Thread Starter
iTrader: (17)
 
Join Date: Aug 2007
Location: Fort Myers, FL
Posts: 2,791
Total Cats: 130
Default

Quote:
Originally Posted by Boris View Post
Running out of fuel under power ?
I should have plenty of fuel and it seemed fine before, but I'm definitely going to pull the injectors out of the rail and look them over.

Quote:
Originally Posted by 18psi View Post
weird, it looks like 1st time around 1 and 4 were lean and possibly detonating, then 2nd time around 2 and 3 were lean
also 4 kinda looks like it had a bunch of blowby
possibly 1 as well
Ehh, now that you mention blowby, I did blow the dipstick out last week. It only happened once, so I was hoping it just wasn't pushed in all the way to start with, but probably not a good sign.
pdexta is offline   Reply With Quote
Old 02-21-2014, 10:17 PM   #5
Slowest Progress Ever
iTrader: (26)
 
thirdgen's Avatar
 
Join Date: Oct 2007
Location: The coal ridden hills of Pennsylvania
Posts: 5,812
Total Cats: 186
Default

What is your ignition setup like? Cops? Coils? Tell me more...
thirdgen is online now   Reply With Quote
Old 02-21-2014, 10:20 PM   #6
Slowest Progress Ever
iTrader: (26)
 
thirdgen's Avatar
 
Join Date: Oct 2007
Location: The coal ridden hills of Pennsylvania
Posts: 5,812
Total Cats: 186
Default

I failed to look at your sig...I was seeing 1&4 looking different than 2&3 so I assumed that if 1&4 fire at the same time perhaps weak spark on that side? But you have cops that fire which cylinder when?
thirdgen is online now   Reply With Quote
Old 02-22-2014, 10:12 AM   #7
Elite Member
Thread Starter
iTrader: (17)
 
Join Date: Aug 2007
Location: Fort Myers, FL
Posts: 2,791
Total Cats: 130
Default

I've got Toyota COPs on an otherwise stock ignition. 1/4 & 2/3 are paired so they fire at the same time. I suspected I had an issue with the wiring on them. I pulled the wiring all apart after my last drive and it looked solid to me. That's when I pulled the plugs again and saw the oil on cylinder 4.

I've definitely got some underlying cause that suddenly made the car run poorly, but my main concern at this point is identifying the hole between where oil is supposed to be and where oil is not supposed to be.
pdexta is offline   Reply With Quote
Old 02-22-2014, 10:32 AM   #8
Cpt. Slow
iTrader: (25)
 
curly's Avatar
 
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 12,109
Total Cats: 518
Default

When were the valve seals last replaced? Oil doesn't ignite well.
curly is offline   Reply With Quote
Old 02-22-2014, 12:00 PM   #9
Elite Member
Thread Starter
iTrader: (17)
 
Join Date: Aug 2007
Location: Fort Myers, FL
Posts: 2,791
Total Cats: 130
Default

Valve seals were done when the motor was assembled, about 1500 miles ago. There's not any way to check them without at least pulling the cams is there? It'd be awesome if that was the problem.
pdexta is offline   Reply With Quote
Old 02-22-2014, 12:05 PM   #10
Cpt. Slow
iTrader: (25)
 
curly's Avatar
 
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 12,109
Total Cats: 518
Default

Nope. In fact I'm pretty sure you could take them out and look at a used one that was sealing well and a used one that was leaking and have no idea which is which.
curly is offline   Reply With Quote
Old 02-22-2014, 12:23 PM   #11
Elite Member
iTrader: (21)
 
Join Date: Jun 2007
Location: Rochester, NY
Posts: 5,688
Total Cats: 560
Default

Looks like lots of oil in #4. Rings or valve seals?

Did you compression test it?
rleete is offline   Reply With Quote
Old 02-23-2014, 05:18 PM   #12
Elite Member
Thread Starter
iTrader: (17)
 
Join Date: Aug 2007
Location: Fort Myers, FL
Posts: 2,791
Total Cats: 130
Default

I didn't compression test it, probably should have I guess. I just felt like that much oil in the cylinder is going to distort numbers a lot.

I've got no experience at all in this stuff, but I keep looking at that top right oil passage hoping it had somehow found it's way into the cylinder.

pdexta is offline   Reply With Quote
Old 02-24-2014, 11:38 AM   #13
Elite Member
iTrader: (12)
 
Join Date: Nov 2009
Location: Harpers Ferry WV
Posts: 1,521
Total Cats: 20
Default

Oil will cause detonation like a champ. You obviously have oil in cylinder 4 did you check the head gasket to see if it has a hairline crack on that cylinder or possibly a void going to the oil passage?
Sean is offline   Reply With Quote
Old 02-24-2014, 12:43 PM   #14
Elite Member
iTrader: (5)
 
Join Date: Dec 2010
Location: Raleigh, NC
Posts: 1,970
Total Cats: 49
Default

purely speculative based on the fact that where oil is burned, it tends to look whitish/tanish on my spark plugs (and online pics/reading)...I would think the top left valve seal is a likely culprit.

if you puke oily substance out of your tail pipe after letting the car sit, its probably a valve (seems more likely to happen with exhaust valves too). I noticed that hard running, then letting the car cool off, then starting it up, my car will "puke" some blackish substance. Initially I was thinking carbon build-up + condensation, but I am more convinced its oil sitting inside my valve and getting shot out on startup especially since it still happens after getting a new cat.

Mostly speculation on my side and a lot of reading online, but...If one spark plug has the "oil burn" build-up on one side, its usually the side closest to the valve that is leaking. If its pretty uniform, its usually not from the valves (I suppose it could be all the valves...), but piston/rings/maybe gasket??
Seefo is offline   Reply With Quote
Old 02-24-2014, 04:35 PM   #15
Elite Member
iTrader: (13)
 
Join Date: Dec 2006
Location: Taos, New mexico
Posts: 5,703
Total Cats: 237
Default

I wish you would have at least done a leakdown test like i recommended in your thread. That can really help diagnose things before you tear them apart like this. It's really hard to tell from the looks of it but I'd have the head checked first since its off anyways at this point.
Fireindc is offline   Reply With Quote
Old 02-24-2014, 05:55 PM   #16
Elite Member
Thread Starter
iTrader: (17)
 
Join Date: Aug 2007
Location: Fort Myers, FL
Posts: 2,791
Total Cats: 130
Default

Yeah, with that much oil I figured the results would be skewed, plus I was really expecting to see a hole in the piston anyway.

A friend suggested pouring oil in the cylinders and seeing if one leaks through quicker than the others, I'm gonna try that tonight. If that checks out I'm going to clean it up and slap it back together. I bought a cometic headgasket, apparently they're reusable so I'll give that a shot and see what happens.
pdexta is offline   Reply With Quote
Old 02-24-2014, 06:13 PM   #17
Elite Member
iTrader: (13)
 
Join Date: Dec 2006
Location: Taos, New mexico
Posts: 5,703
Total Cats: 237
Default

Yeah, the oil really would have skewed a compression test - but a leakdown test at ~100psi should push past the rings even with oil helping to seal them. It would also clearly tell you if you have a valve issue going on or not.
Fireindc is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 59 Yesterday 09:00 PM
Re-Spring Tein FLEX or replace? Mazdaspeeder Suspension, Brakes, Drivetrain 21 10-03-2015 07:45 PM
New personal best 1/8th mile tehzack Dynos and timesheets 10 09-21-2015 07:30 PM
High-lift cams, SUB, new valve job = lifter tick? Der_Idiot Engine Performance 14 09-16-2015 10:30 PM
'92 tune, built motor whinin MEGAsquirt 0 09-15-2015 09:37 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 06:57 PM.