Toyota Celica Supra Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
793 Posts
Discussion Starter #1
My friend, Crash, just bought an 85 supra 5mge 5-speed. It starts hard, and when it does idles very poorly and choppy. When revved, it sounds like it is missing on one, possibly two, cylinders under about 3000rpm, after that it seems to quiet down and work alright but power is lacking. Checked timing, seems fine. No leaks in intake or vacuum I can find. All wires have spark. There seemed to be excessive noise coming from the area of the head, but I couldnt pinpoint exactly where. Could this be a screwed up valve or lifter? I dont know much about internal engine/head stuff so I am clueless here as to what it might be. Im going back on Saturday afternoon to check it out, any help would be much appreciated.

-Ken
 

·
Registered
Joined
·
129 Posts
Could be that a valve is stuck. Could be that the injectors simply suck, fuel pressure could be too low, there could be a vacuum leak somewhere and certain cylinders are running too lean because of a bad gasket or cracked port/runner.

If it is running so bad then I would suggest you just take it apart and search for the problem rather than risking complete desctruction of something valuable.
 

·
Registered
Joined
·
1,374 Posts
Sounds like one or more of the fuel injectors may be at fault. That's my thought since you describe it as jumpy and poor idle but levels off at higher RPM's.

One or two cyliders are getting no combustion so the others must take up the slack. Obvious when it's idling. At speed the faster momentum is helping to swing those dead pistons causing the engine to level out...or so it feels. The lack of power is still evident since it's not firing on all 6.

That's just my guess.

Checkin' out the halls makin' sure the coast is clear.
Scott
 

·
Registered
Joined
·
40 Posts
:wink: I had a similar problem with my 82 P-Type when I bought it 5 years ago...I pulled the valve covers and found at least one cam lobe was going flat and others were severely worn, along with the corresponding rockers.
Replaced that side cam tower assembly, rockers and lifters(adjusters) and the problem fixed...The whole thing (used) cost me less than $100 to fix.
Hope this helps, D-
 

·
Registered
Joined
·
247 Posts
This may sound dumb but did you check spark plugs, plug wires, and distributor cap and rotor? It's amazing how many things just doing that will fix. Not to mention it's easy and cheap.

Always start with the basics.
 

·
Registered
Joined
·
73 Posts
Also, check to see if it's getting fuel. Mine had very little power, specifically up hills and if it's not the ignition system it could be the fuel filter. See if it needs a new one.
 

·
Registered
Joined
·
793 Posts
Discussion Starter #7
It is a BHG, no compression on 5&6. Gonna fix it in a couple of weeks. Thanks for all the suggestions!!
 

·
Registered
Joined
·
191 Posts
NO compression, head gasket...That will cause it to run horiblty.. and check your timing belt too.. since you gotta pull the head you might as well change it,, if not it might slip, or even worse tear and there goes your motor.and take a close look at everything total head and piston..look for cracks...

But i also have 85 , supra , 5m-ge, with miss at idle till at least 2200 rpm, but if i rev it up quik it appears too be gone, and there is alot/ not tons of soot on my tail pipe, im thinkin flat lobe, (intake side) , bad injector,s, no check eng lite.oy ya every thing is new , plugs cap rot, fuel filter, wires, i checked for vac & intake leaks but,, N/A. help would be nice.. THANX moon
 

·
Registered
Joined
·
566 Posts
moon said:
and check your timing belt too.. since you gotta pull the head you might as well change it,, if not it might slip, or even worse tear and there goes your motor.
I know some engines are designed with critical piston/valve timing, to where if the timing belt broke the piston would slam into the stopped/open valve, causing major issues. Does this comment mean our 5mge engines are designed this way?
 
D

·
Guest
Joined
·
0 Posts
Thats one goodthing about toyota's, when the t/belt goes it just stops. No damage to any valves or pistons. :lol:
Dick B.
 

·
Registered
Joined
·
247 Posts
Timing belts going won't hurt anything, if you have an engine with a timing chain however and it manages to break you're screwed. The engine with chains are interference engines and those with belts are non interference, at least that's how Toyota does it.
 
1 - 12 of 12 Posts
Top