83 cylinder not fireing

heschlie · 03-10-2005, 05:52 AM

hi all ive been very impressed with the knowledge ive seen floating around here so i have a question. i just got an 83 supra and the 3rd cylinder is not firing, there is a small amount of oil on the spark plug, and it misses throughout the entire rpm range, only the one cylinder, on the occassion i can see some smoke come out of the exhaust pipe but i havent seen it for awhile, ive been told it could be a valve or piston ring problem, what is it and whats the best way to get jit running good again?

projectsupramk3 · 03-10-2005, 10:21 AM

Have you tried doing a compression test and a leakdown test on it yet? How about replacing/upgrading the plugs and wires?

heschlie · 03-10-2005, 07:36 PM

did the simple maintainence (I.E. spark plugs, wires and such) and still the number 3 is not firing, im getting ready to do a compression check, what is a leakdown test? im pressed for time between work and school so ill try to do it ASAP but im not sure when. if it does happen to be a valve or piston ring problem is it gonna be hard to do? should i go ahead and have the head looked at by a mechanic while it off? let me know when you get the chance.

projectsupramk3 · 03-11-2005, 08:54 AM

Well be sure to post up the compression numbers when you do it. If they are all pretty even it's most likely not a valve or piston problem (unless there is a ton of oil in that one cylinder). Are you sure #3 is getting spark? How about fuel?

heschlie · 03-23-2005, 07:48 PM

ok sorry for the delay had some problems getting around to this, but heres the numebrs for the check starting with the first cylinder.
175
160
0
175
175
170
these are aproximate within 4psi or so the guage wasnt horribly accurate it went from 150 to 180 in about an inch but what bothers me is the 0 on the third cylinder ive heard people talk about low compression but not no compression, do i have a real bad problem? or is this normal?

projectsupramk3 · 03-23-2005, 10:48 PM

Well that definetly sucks, time for a rebuild. Maybe even a good excuse to swap in a 7mgte if you want that kind of power.

heschlie · 03-24-2005, 12:27 AM

well ive been doing some reading and it looks as if its just the valve seats thats he culprit for no compression. if this be the case i just gotta take it out and down to the shop where my dad has the head to our MR2 being gone over after a BHG. so i figure ill have them do a full go over and replace most of the parts with new ones.

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