MMMGIRL

I have a 97 DX with a completely stock y7 under the hood. issue I'm having is sometimes on cold start it will bog down and cut off once or twice before it will stay running, it also sporadically misses or bogs under acceleration. It's throwing a code for 1-4 misfire but it's random, it's not continuous. Tried a new dizzy but no improvement, ran a compression test at WOT operating temp and cylinder 1 was 120, 2 was 125, 3 was 145, and 4 was 175. However, cylinder 4 plug thread was wet with oil I'm going to assume there was oil in the cylinder and that cause the compression spike.. based on that one issue I would lean towards rings but the car does not smoke at all.. Of course replaced plugs as well with no improvement, also replaced valve cover gasket and tube seals. What is the correct compression for a Y7 at WOT operating temp and any ideas where to start? Previous owner had apparently replaced the head gasket at one point because there is copper spray all over it, pcv hose was also taken off and a bolt clamped on it where the valve would go. I have corrected that however car obviously has extremely bad blow by beforehand... just looking towards some guidance. Thanks.

mk378

Stalling out instead of idling when cold could be the IACV or FITV (active below 60 F). For the general misfiring, have you replaced the spark wires? They can go bad and you really can't tell by looking. I think the FSM says 135 psi minimum compression to consider the engine good.

MMMGIRL

I plan on picking up some wires and throwing them on to see if it improves at all. Engine has around 200k I would assume, previous owner took cluster out and replaced it with a em1 cluster.. last cardiac mileage report is somewhere around 160k a few years ago. Correct me if I'm wrong but 96 up don't have a FITV.. I plan on removing the IACV tomorrow and giving it a good cleaning as well.

civicservice

Do you mean that you get misfires from cylinder 1, 2, 3, and 4 at various times?

fsm states at least 135 psi with max variance of 28 psi for a new engine. Did you run the test on a hot or cold engine?



Why not re-run the compression test both wet and dry?

MMMGIRL

Engine was at operating temp at WOT. It's throwing a misfire code for 1-4 and a multiple misfire code.

Jimi Hondrix

Don't throw any more parts at it without testing first. You have a random misfire code so first off try resetting ECU and drive it a while to see if returns. Sometimes random misfire codes can be a matrix-esque anomaly that goes away and doesn't return after an ECU reset. If it (random misfire) does return it may even show itself a single cylinder misfire code..either way at that point it's time to do a power balance test by disconnecting each fuel injector harness one at a time while looking and listening for a drop in idle. If, one or more cylinders does not drop in idle there's an issue with either spark, fuel or compression.

You also need to repeat the compression test using a dry and wet (one tablespoon of oil) method as shown in video below. Your compression numbers show cylinders that are over 10% difference in PSI from each other and that's not good. Make sure the battery is fully charged before dry compression test to allow for optimal cranking. After dry test hook up battery charger wait 30 minutes and do wet compression test ..post numbers here. Never approach repairs by parts replacement first... download a free service manual and test as much as possible first.