Thread: misfire like a MF

well....today was the day to finally turn the key. i did, and she ran. finally i have a boosted b13. only to my dismay, i have a misfire. i ran the car after the swap and put 37 miles on it running fine back in june. then it started misfiring. we determined it was a bad injector. it was replaced with new 555's. now a few months later, today in turning the key, we decided it was just a completely foulded plug so we replaced it. nothing. the wires are new, but i tried an old one, still nothing. the distributer is also new. there is spark. its now dark outside and i need new ideas to try tomorrow. please help

plain and simple, find the cylinder thats misfiring, swap the injector with another from a different cylinder and go from there. Could be an injectors, especially if you didnt run it hard before you lost the cylinder then its something simple, engines just dont lose cylinders for no reason. And if you dont have blowby coming from the breather i would almost definitely say injector.

Hope this helps.

i will try that. i was thinking of trying that. although they are brand new 555's. if i swap the misfire in cylinders when i swap the injectors, then i have a bad injector out of the box. unlikely, but possible.

im almost positive now thinking of it that the plug we replaced today wasnt irridium. would that have anything to do with it? it only cost $3. irridiums are like $12.

plugs are plugs, the one you replaced should fire. Have you checked your cap or rotor. I had this problem before, turned out to be 2 things. 1 was a leaking injector and 2. one of the contact points in the cap broke off.

it shouldnt matter, a spark plug even basic should fire the cylinder. Is the cylinder a constant misfire or is it just every so often or when driving it

also you might have damaged the oring on the injector when you put it in. when you pull the injector check the oring to make sure its not cracked or torn anywhere on the upper or lower o rings

i will pull the injector tomorrow. the injectors are new. the cap and rotor is new. all the plugs except the one we bought today have 37 miles on them. the wires are new. in searching i read a boost leak is possible, but the plug is wet when i pulled it. i dont think its a boost leak. its just not firing. its a constant misfire, i havent even driven it yet. i plan to go over a few things tomorrow as my buddy put on the already (at the time) ordered injectors, cap, rotor, and wires while i was in the hospitol back in july.

what ECU are you using? Its a long shot but my friend had a Calum and it ran on 3 cylinders. We swapped the ecu into a different car and it had the same problem. Turned out one of the injector circuits was bad on the ECU. Had to get it fixed.

mine has the same thing right now my distrubitor is not trowing spark im going to try the stock ecu back I was running a Calum ECU

it is a calum realtime. but it ran for probably about 30 miles back in june when we swapped when it began misfiring. would the curcuit just go bad? it did run, not for long though.