I pulled out the spark plugs out of my 3sgte and cylinder plugs 1-3 were in normal condition but the #4 cylinder plug was carbon fouled pretty badly. my ignition wires are fairly new and timing is actually set at about 15 degrees btdc so it should be running hotter than anything. The only thing left is to check compression...is there anything else i should check???
Well, you've already covered the bases I would've checked except for one. -was that plug properly gapped?Another possibility but i doubt is- a bad ring or/and valve seal in that cylinder letting in excessive oil. Maybe enough to foul the plug but not enough to make a noticable amount of smoke....???
Put in new plugs and set timing to 10 degrees BTDC and see if it still fouls.
I have new plugs on the way, but I'm going to do the compression test tomorrow. do i really need to disconnect the cold start injector like to book says?
So I replaced the plugs with new BK7 NGK's and set the ignition to about 11-12 degrees BTDC. I warmed the motor up for about 10 mins and pulled the #4 plug. Its has traces of oil on the electrode and on the threads, and the 3 other plugs are clean. This means either oil is getting is through the rings or valve seal correct? what test can I do to verify? right now the plugs are set at .30 for gap
during the compression test, all cylinders were at 150-155 by the 6ish or 7ish crank rotation. according to my manual, those number are within specs. I did the test by myself so I could test the max but its the best i could do.
...it idles really weird. one minute it will be idling fine, then i'll give it some throttle and it will bog down. it will keep running but very crappy, but then I'll give it throttle again and it will run good again???
ya make sure compression is good and deffinatley seafoam it, this will destroy all carbon in the motor its amazing stuff, also maybe check the injectors, be sure they arent gunked, could be getting voltage but plugged and just putting hella fuel in?
I just rebuilt this motor. I have a lot of mods done to this thing but stock ignition and stock fuel system.
so the rings are fine a valve stem seals are fine? and you are using 92 octane? if thats all fine and your using 92 then id say its the injectors or your spark isnt strong enough to ignite fully. Check and make sure your dist and cap have good connection and your wires are good, and be sure the plug isnt cracked or anything, wanna be 100% sure your spark is getting form the dist to the plug with full power, otherwise the carbon will build up
Seafoam is a fuel addative that helps clean a fuel system and burn carbo build up, you can find it at autozone its just as popular as a Lucas fuel treatment although myself and many others would say seafoam is about the best, usually you just pour the can into a full gastake although with seafoam it works best if poured into a vaccum line while the car is running. any vaccum line in the intake plentum/manifold will work on a mr2, on a front engine car a popular one to use is the brake booster hose, although ou'll need someone to hold the throttle open so the car dosent die, the vaccum will suck the sefoam fuel additive throught the motor and burn all the excess carbo buildup in the motor. also note when you do this ou will burn white smoke for anywhere from 5-10 minutes, and deending on how much carbon could be longer and the smoke could be super thick so do not be alarmed whe you see this
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