D16Y7 sporadicly runs rough/misfire, no code

[quick86]

So I've got a 98 Civic LX, 5spd Y7 car that is my daily driver... I've done the fuel filter, plugs, wires, cap, rotor all this year... I've also run fuel injector cleaner through it...

Problem: When I drive the car, and this is more frequent in the rain, it will do it once after I fire it up and then not at all the rest of the time it stays running.... The car will run rough sporadically, or just feel and sound like it's losing spark, for which it will do for probably 5-seconds, and then it goes away and all the power in the world comes back. I've noticed when it happens if I push the clutch in and take the load away from the engine while it's doing it, it's not nearly as severe - which to me makes me think that it's losing power. Also, my fuel mileage is below 30mpg, more around 25mpg as of late doing 70mph on the highway approx. 26 miles 5 days a week.

I cannot figure it out. Any ideas???

 

[Szady]

Almost sounds like a bad seal somewhere in the ignition system. Double check your dizzy to make sure theres no water in there, make sure your plug wires arent touching each other, and make sure you gaped your plugs correctly.

 

[quick86]

Still does it, lol. I've done so much with this thing. Fuel mileage has returned, but still has a hiccup when it's cold....

 

[RonJ]

Any CEL codes? What's the current city/hwy mileage?

What brand/type plugs, wires, cap, and rotor did you install? I recommend OEM plug wires and standard NGK plugs.

Have you checked the ignition timing with a timing gun and service connector jumped?

Any noticeable problems with the charging system or battery?

 

[cgpEJ6]

Mine does it too and I have no clue, how is your idle

 

[quick86]

Starting/Charging system are awesome.

Plugs & Wires are from CarQuest, the plug wires are carquest inhouse brand and the plugs, hell, I don't remember.

Idle is fine ----- when it's warm.

No CEL/codes.

I do have a slight exhaust leak (gasket that needs changed) but not enough of one where it's throwing a code for the O2 sensor....

Fuel mileage as of late has been between 30-34mpg, all highway, depending on weather and traffic.

It doesn't get much highway use.

Idle is fine, when warm. When it's cold idle drops way low once, maybe twice --- and when it warms up the idle stays perfect.


I haven't checked timing yet.

 

[RonJ]

Civics don't like generic plug wires and also do best with standard NGK plugs. This is where I would start. Also check the ignition timing.

Also try this night time test:

In the dark, open the hood with the engine idling. Do you see any small sparks jumping from the plug wires or distributor cap. If not, start misting the plug wires and cap with water from a spray bottle. Do you now see any sparks.

Where is the exhaust leak?

 

[quick86]

Civics don't like generic plug wires and also do best with standard NGK plugs. This is where I would start. Also check the ignition timing.

Also try this night time test:

In the dark, open the hood with the engine idling. Do you see any small sparks jumping from the plug wires or distributor cap. If not, start misting the plug wires and cap with water from a spray bottle. Do you now see any sparks.

Where is the exhaust leak?

Done the night time test, numerous times.




The's got a 2-piece longtube header (Some would call it a 4-2-1 I guess), and it's the gasket mating the upper to the lower portion. Not major by any means, just an annoyance. Way better than the cracked manifold that was on it, LOL.

 

[RonJ]

The's got a 2-piece longtube header (Some would call it a 4-2-1 I guess), and it's the gasket mating the upper to the lower portion. Not major by any means, just an annoyance. Way better than the cracked manifold that was on it, LOL.

How far from and upstream or downstream of the primary O2 sensor?

 

[quick86]

uhmm... Well, the gasket is in front of the block and the O2 sensor is behind the motor down low.


I'm probably going to slap some NGK's in her this weekend.

 

[Szady]

Civics don't like generic plug wires and also do best with standard NGK plugs.

Not 100% true. I have Autolite plug wires on mine, and I have zero spark/ignition issues...

 

[RonJ]

Your exhaust leak will never throw an O2 sensor code, though the leak is likely causing the engine to run rich. Fixing the exhaust leak should increase your gas mileage and also potentially prevent destruction of your cat. While this is separate from your hesitation/misfire problem, I'd repair the leak ASAP.

 

[RonJ]

Not 100% true. I have Autolite plug wires on mine, and I have zero spark/ignition issues...

I presume that some aftermarket plug wires work fine. [Edit] Is Autolite the same as Carquest? I still recommend OEM as I know they will work well and last.

 

[AllTracCelica]

I had this same problem on my D16Y8 I went ignitions wires fuel pump o2 sensor the whole nine yards and never found the problem the problem was i had a valve not sticking out. I noticed after they rebuilt the head that the little square on your cluster that says maintence required was barely orange trying to tell me but no check engine light at all. Do compression leak down test. Get kit from harbor freight $50 to find it valves are stuck. I wished i would of done this before wasting alot of money.

 

[AllTracCelica]

One more thing neat trick is take piece paper and put over exaust pipe if it kinda pops little bit like its missing and sucks the paper back not constantly pushing forward just idling than you could also have stuck valve bad seat you name it. This is your most likely issue.

 

[quick86]

I am fairly positive it's not a valve. About 99% so. But anything is possible I guess. NGK plugs are only $2.08/ea at my cost soooo it's not like it's a huge investment.

 

[quick86]

Okay, the best way to describe the issue...


While accelerating normally, the motor kind of falls on it's face between 2000-3500rpms, and then all of a sudden, it's as though you achieved boost and all the power comes back.. It will do it once or twice when you first drive it after turning it on... Randomly though, I will say I do notice it more when its cold and wet... that's why I think ignition system.

It's as though the throttle cable is being snagged on something and then it snaps back to where it should be, or maybe a spring is acting up like it would on a carb...

hmmmm..

 

[quick86]

Driving in today I thought of the best way to describe it -----


It ALMOST feels like a 2-step/rev limiter.....

 

[Sammo115]

starting to have this issue as well. bump for more clues and info.

 

[quick86]

NGK plugs, installed. Haven't been able to drive it much since I just did it 2 hours ago...