98layinframe

I searched and searched but all the threads Im seeing involve check engine codes.... but there's no codes stored in my computer!? I checked it with a scan reader and no codes to display. Only other thing the car acts weird about is the high idle when cold starting, and then little lower idle when warm.

The cars a stock 97 civic dx with an entirely stock (other then a goofy intake) Y7 motor thats having a random what seems like a misfire. The car only has this miss when at low rpms and under load... for example when pulling out from a stop light. It might do it once in first, then shift in to second or third at low rpms and then give it gas, that's when it shudders 2 or 3 times then its fine.

Its almost like the car is loading up on fuel? If I rev it to say 3 or 4 grand first, then start going under throttle shifting at 5-6K rpms its perfectly fine.


So random seemingly miss fire?
NO check engine codes
Only does it from a stop when starting off.
stock motor
pulled the plug wires, no oil around them.. bone dry.

NotARaCist

iTrader: (1)

Standard, or automatic? A miss will (almost) always throw a CEL.

98layinframe

standard.

And yeah thats what I thought too.. which is why im confused whats going on. It feels like a miss since the car seems to hesitate and loose power during those brief miss's for a few seconds?

It has a new clutch, flywheel, both axles, and the timing belt all less then ~500 miles ago... doubt that should matter though? It was doing this issue before those parts were replaced.

NotARaCist

iTrader: (1)

I was actually going to mention your clutch, but you've already covered that. When you replaced the clutch, you replaced the pressure plate as well, correct?

Three more things for you to test. You'll need a voltmeter and a spark tester. What voltage does your battery read across the terminals with the car off? Again with the car running? What color is your spark?

TomCat39

Have you pulled the spark plugs to read them? They sometimes can give you a clue, dry fouling, oil fouling etc etc.

Could be ignition related, could be alternator related, could be ECU, could be O2 sensors, could be any number of things.

I think I would first rule out the ignition system. If you google "How to Test the Igniter, Ignition Coil Accord, Civic, CRV, and Odyssey" the first link you get should be a really great write up of the full process of testing your ignition system. This guy has some really great write ups on diagnosing Hondas, everything from the no start, to cylinder balance tests, to head gasket tests and more. I found his resources invaluable. That article is at easyautodiagnostics while the other articles are housed at troubleshootmyvehicle. Some great step by step how to's ruling out each piece until you find the bad part.

Good luck.

B_Swapped93

cap and rotor or just in need of a full tune up. if there's no codes I doubt it's a misfire check that the tps is to spec.

romerosi

A misfire will not always set a light . it only sets if its bad enough to damage the cat. rule of thumb if wires and plugs look good is to check the valve adjustment. also check the ground wires on the thermostat housing, ive seen them come loose and cause all kinds of problems with hesitation and misfires ,

B_Swapped93

Where do you get that idea ? a misfire is a lot more damaging to the piston/sleeves then to the cat....detonation.

Chriser0

Mine did this a few months ago. Cap rotor and plugs. Mine did not set a check engine light

romerosi

because a misfire sends unburned fuel into the cat which is hot enough to ignite the fuel and causes the cat to super heat. there is a very slim chance a misfire will cause engine damage.

B_Swapped93

Just stop now....I wonder why a couple hundred dollar CAT is more valuable then a couple thousand dollar(when new) engine, can you explain this ?

NotARaCist

iTrader: (1)

Misfires induces detonation, and coats the cylinder walls with unburnt fuel, causing cylinder wash. How exactly are either of those things not damaging to a motor?

Nightwing22

^im with this one

romerosi

im just explaining why the check engine light isn't on. im not a Honda engineer. misfires are actually very common and normal. most of the time you wont even notice. I am a Honda tech and I have spent hours on the phone with American Honda about the topic. the worst ive seen from misfires is carbon build up on the oil rings causing oil consumption

romerosi

and misfires will not cause detonation, it will prevent it , why do you think when tuning boosted set ups they shoot for 12.1 a/f ratio. also they don't care about the few hundred dollar cats, they are worried about emissions .

xXDUNNKILLED1XX

Don't forget ignition coil it cause a misfire in my first cylinder and I had to change it and a while back my cat was clogged and cause a misfire in the 4th cylinder if I remember right, and it wouldn't hurt to do a pressure test on your fuel pump and change its filter.

HondaMotive

map or tps sensor.