I have hyundi coupe 1600, when damp it seems to not fire on all cylinders, i took it in, they changed the plugs and points?? run better for a week or two, now it has started doing the same thing. Once it has warmed up it fires on all cylinders and is fine

NO YEAR TOLD... 1993 TO 1996?
CORRECT NAME (NO SPACE BEFORE C)
Hyundai Scoupe? ALL 4 BANGERS ARE 1,3,4,2
EXCEPT BOXER ENGINES (PANCAKE MOTORS)
IS THIS A SPARK QUESTION?
OR CAM TIMING QUESTION.?

• • 1.5L Sirius I4
  • 1.5L Alpha I4
  • 1.5L Alpha Turbo I4

Try the standard for a 6 cylinder. 153624. That's what I always use.

when you say not firing have you removed the plug and checked for spark across the plug points. If you haven't done that then do so as misfiring can also be from faulty injector( blocked tip or faulty electronics)

check the injectors and make sure there is fire on those plugs in 3 and 4

Replaced the MAF sensor - nothing. Took it to a authorized toyota shop & checked compression which check out good and put the computer on. Computer read mis-fire on cylinder 1, and then multiple misfire (like it would jump around). We went ahead and replaced the fuel injector on cylnder 1 - did not solve problem as when we hook the computer up, misfire seemed tp stay at idle and seem better when running high RMP, but check engine light is on as it never went away. Went ahead and replaced the coil pack to cylinder 1 - nothing. what am i missing?

To much gas going thru the exhaust. probably the #2 miss fire. Before you change plugs, make sure you have fire to cylinder #2. You could have a bad coil or ignition module. Also check the condition of the plug wire. You can change these if you like , but it may not be necessary.

youre p0300 code is radom miss fire,usually cause by bad wires or bad coil pack,p0304 indicates missfire at cylinder 4,cause bad wire or plug.p0335 indicates crank sensor circuit malfunction can cause all of the above,because its part of the timing position for the spark at the plugs,iwould check crank sensor if its within specs!

I think the auto-lite plugs are probably your problem. yes it sounds like mis-firing. That's one of the few times the check engine light flashes. I'd suggest changing the plugs to a NGK plug, that's the ONLY plug we use in our Audi's and VW's (work at a VW/Audi shop). Try that, and it should take care of the rough running, if not, it will probably need coils too.

Four cylinder is
1 3 4 2

Have you tried moving the spark plug and/or lead to another cylinder to see if the misfire moves? If it doesn't change, i.e. No. 3 cylinder still misfires i'd carry out a compression or cylinder leak test.