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#1 |
Board Member
Join Date: Oct 2005
Location: Calgary, Alberta
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![]() Hey Crew
The 16v turbo has been idling rough for some time. Started doing preliminary investigations yesterday before pulling the head (hopefully tonight). Compression check came up 145/150/150/150. Had a look at the plugs and thought the difference between them is pretty interesting, but I don't have a lot of experience reading plugs. I did some reading online, but I still don't feel like I have a confident idea what would explain this. Setup is stock B234 with 16T running Fred's 16v chips @ 12lbs boost on Saab APC. green giants, stock FPR. Have been running 3" AMM which does have it a bit lean at onset of boost. Cyl 1 is at top of image, 4 at bottom. ![]()
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1991 940 - stock b234+t -retired http://forums.turbobricks.com/showthread.php?t=243308 1989 760 - T5 +T5 swapped http://forums.turbobricks.com/showthread.php?t=341191 Last edited by 940 16 valve; 09-18-2017 at 08:53 PM.. |
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#2 |
PV Abuser
![]() Join Date: May 2004
Location: St. Louis
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![]() Photobucket ate your pic.
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'63 PV Rat Rod '93 245 16VT Classic #1141 |
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#3 |
BRANDSCHUTZVORSCHRIFTEN!
![]() Join Date: Dec 2002
Location: mont, AL
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![]() did you drop one? why is the gap closed on the one on the left? (at least on the left of the pic I could see)
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"They bum rushed them in their own crib, they drank all their beer, they partied with their ladies and they left with the trophy" Now with in-house Dyno tuning! Megasquirt Tuning! Plug and play LH 2.4 Megasquirt, now with stealth mode! |
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#4 |
They see me trollin'
Join Date: Dec 2008
Location: Cold Lake, AB
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![]() Plug reading doesn't work very well when the plugs have 50k miles on them.
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'88 245 - 2JZGTE VVTi | MS3X ECU, MS2 TCU | GT3582R-HTA | Staged simultaneous dual fuel | 590whp 580ftlbs 1968 Furd Rustang fastberk | 2JZGTE VVTi | MS3X ECU | PT6776S | 4L80e Microsquirt TCU Sloppy Transbrake | 3.73 8.8" rear end 1981 Piper Cherokee Archer II | All stock |
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#5 |
Board Member
Join Date: Oct 2005
Location: Calgary, Alberta
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![]() Great catch, I did drop one, and recall thinking good thing I'm not reusing them.
Also a good point, the car sat for quite a while so the plugs are quite old, and probably have around 5000 miles on them. Interested in thoughts on what can cause 2 cylinders to look so different than the other 2. |
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#6 |
BRANDSCHUTZVORSCHRIFTEN!
![]() Join Date: Dec 2002
Location: mont, AL
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![]() the intake manifold if it's the b234f one
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#7 |
Newbie
Join Date: Feb 2009
Location: The Pitt, 15147
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![]() Fred's chips are old school. Have you checked for vacuum leaks? Sounds like you've had the setup for awhile.
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'93 944 T - #TrophyVo '00 XC70 SE - Slow '11 XC90 V8 - Torque Monster |
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#8 |
Board Member
Join Date: Dec 2015
Location: Lublin, Poland
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![]() Is everything lookin' fine?
https://i.imgur.com/NLaUJul.jpg https://i.imgur.com/8GsUM50.jpg https://i.imgur.com/KMdHEYK.jpg |
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#9 |
Board Member
Join Date: Jan 2011
Location: hillpoint
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![]() The only time I have read plugs is a full pass then stop engine and read the plugs with no idle time. But I would say your plugs look fine
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#10 |
Board Member
Join Date: May 2014
Location: Saskatchewan, Canada
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![]() I think the point has been made that if you are trying to get a mixture read on the plugs they need to be fresh plugs and the plugs need to be pulled immediately after the full speed or part speed pass that you are trying to do the mixture assessment on.
That said, the insulator tips on #1 and #3 look reasonable. Depending on when they were pulled out of the engine (after a full throttle run or after 10 minutes of idling?) #1 looks like it might be a tad on the rich side of 14.7 and #3 a tad on the lean side of 14.7. Its hard to tell; but, #2 looks like it has some serious deposits on it compared to the others. Its hard to tell the color. If it is shiny and blackish then you may have excessive oil consumption on #2. If its not shiny and its dark you may have some fuel fouling / running rich which is lowering the combustion temperature. The reduced combustion temperature can result in deposits not burning off the insulator tip in normal operation. #4 is obscured by the Photobucket advertising. Have you had your injectors cleaned and flow tested? #2 might be flowing more than you expect. Get the injectors cleaned up if they have never been cleaned and flow tested and then put a new set of plugs in and then do a full throttle run (if possible) and pull the plugs. That will give you an idea as to whether your full throttle fuel mixture is balanced (I am assuming that you have a wideband for monitoring the aggregate AFR of the cylinders). Put the plugs back in and drive for a few hundred miles and see if the deposits re appear on #2. |
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#11 |
Board Member
Join Date: Dec 2015
Location: Lublin, Poland
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![]() They have +/- 300 miles 80% running on full throotle (20T @ 1,7 bar boost).
Injectors have cca 1000 miles (bosch 440cm3). But because of their bargain price I will check them anyway. What Im thinking about is this little yellow deposit, Ive never had this before. Will make better shot of #4. |
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#12 |
Board Member
Join Date: Apr 2013
Location: Cornholio, OR
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![]() Cant read plugs saturated with oil.
Todays pump gas does not color the plugs like the pictures in the old books. Any coloring on todays gas is too rich or oiling, a greyish ash like deposit is all you get when things are right. Look for changes caused by temperature, blueing or burning of the ground electrode, how far the heat comes up the threads. Those plugs are not worn, note the sharp corner still present on the center electrode and no erosion on the inside of the ground electrode. The yellowish brown deposits are a cylinder that was not firing right, did not get hot enough to burn off deposits. Compression and leakdown test before teardown? Or some further diagnostics before teardown, like swap injectors, plugs, & wires/coils
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I don't know who I am when I am somebody else. |
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#13 | |
Board Member
Join Date: May 2014
Location: Saskatchewan, Canada
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![]() Quote:
80% x 300 miles = 240 mile at wide open throttle? Most engines would be worn out after 240 continuous miles at wide open throttle. If your plugs came out of the engine right at the end of a high speed run I would expect them to be a darker tan. Even emission controlled engines tend to operate at lower AFRs at wide open throttle at the horse power peak. Last edited by 142 guy; 11-19-2018 at 12:43 PM.. |
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