i looked up code 74 and it said misfire cylinder #4...

so i did a compression test and i got about 240 239 230 240 on my stock 99 gsr motor? anyways...

should i be worried?

doesn't seem like it's running any differently? but it couldn't have just been a random CEL going off...

 

those are very good compression results. i got 220, 200, 220, 220 not to long ago.

Your results will vary depending on the quality of the tester you use and how it is calibrated.

All you want is your numebrs to be close together.

I wouldnt be worried about a misfire.

DId you recently change what gas you put into the car? That will sometiems cause a misfire.

 

I personally would check the fuel injector function in the fourth cylinder. Also there could be a fouled spark plug in that very cylinder.


Possible causes of a misfire detected in one cylinder.

Fuel injector clogging, fuel/air leakage
Fuel injector circuit open or shorted
Spark plug carbon deposits, fouling
Leaking/open ignition wires
Distributor malfunction
Valve clearance out of spec

 

hmmm... those are a wide range of possibilities.. i don't think i have the time to check each and every one... well as for my comp. gauge... i used to have around 220 i believe a few years ago when i checked... but i don't remember stepping on the gas all the way last time i tested (resulting in 220)

edit: and yes, i've been switching between 89 and 91 octane (due to the insane gas prices)