Rough idle & accel.

[DRFT24O]

Could some one tell me what could be causing my 1991 240 to shake at idle when the a/c is off. The engine causes the car to shake, to the extent that its shaking your whole body, I feel kind of stupid when im at a light and the whole car is shaking. Only does this when at idle with a/c off. When I drive and floor it, the power comes on but its not consistent, or smooth. After about 4.5-6k rpms I can feel the cam come on and it pulls harder, but the power is just not smooth. Ive already changed the fuel filter, spark plugs, and checked the plug wires. The car has 90,000 miles on it, it cant be because it needs an oil change can it? Thanks for the help.
Oliver

[mrmephistopheles]

After about 5-6k rpms I can feel the cam come on

Holy shit! We have VTEC?!

[ALTRNTV]

Holy shit! We have VTEC?!


hahaha... are you sure you have a 240 and not a Honda? j/p KA's (assuming you have that) don't have VTEC type cam lifting..so I don't know what you mean by the cams coming on... KA's pick up power around 4k-6k, so that's probably why you felt that harder pulling

[DRFT24O]

Holy shit! We have VTEC?!
Haha..Yea i know its not vtec, thanks, i use to have a b16 in a hatch i know vtec. Im saying this is the "aggressive cam" coming on so thats what Im assuming im feeling. I thought the 91's have that? Still need some suggestions though..

[Id-]

there is no aggressive cam :) 91s got the dohc motor but one doesnt come on or anything; one is for intake, one is for exhaust; no timing or valve event changes...

if you're having the trouble you say you are, i'd bet its an ignition problem of some sort; did you replace the cap and rotor on the distributor?

[DRFT24O]

there is no aggressive cam :) 91s got the dohc motor but one doesnt come on or anything; one is for intake, one is for exhaust; no timing or valve event changes...

if you're having the trouble you say you are, i'd bet its an ignition problem of some sort; did you replace the cap and rotor on the distributor?
No I didnt..

[aznpoopy]

if you're having the trouble you say you are, i'd bet its an ignition problem of some sort; did you replace the cap and rotor on the distributor?

agreed... 1. check timing and 2. cap+rotor.

3.5+ is the powerband but short of a turbo we dont have anything that really 'kicks in' at a certain rpm. at least my car doesn't.

[YellwMonky]

doesn't the KA have a second butterfly ? maybe that's what he is feeling...

[mrmephistopheles]

the secondary butterflies are for idle smoothness, so yes, there's a possibility he's feeling the effects of them not working. This is, however, unlikely for the fact that 95+ KAs did not have that secondary butterfly system.

[aznpoopy]

oh shit!

vtec! it's faaast!!!

[Dweezil]

bad battery or bad ground, that's my guess.

[DRFT24O]

the secondary butterflies are for idle smoothness, so yes, there's a possibility he's feeling the effects of them not working. This is, however, unlikely for the fact that 95+ KAs did not have that secondary butterfly system.
im a bit confused...what does the 95+ KAs not having the secondary butterfly have to with me feeling the effects of not having mine working? Also I dont know how to explain to you guys but im telling you after 5k you can feel it pull harder. I gave me friend a ride who has a 300zx turbo, and he said he can definetly feel the power come on up top. :cool:
BTW, just to clarify, when I say "rough idle", i mean the rpms are fine, its just the whole car will shake.

[DRFT24O]

im a bit confused...what does the 95+ KAs not having the secondary butterfly have to with me feeling the effects of not having mine working? Also I dont know how to explain to you guys but im telling you after 5k you can feel it pull harder. I gave me friend a ride who has a 300zx turbo, and he said he can definetly feel the power come on up top. :cool:
BTW, just to clarify, when I say "rough idle", i mean the rpms are fine, its just the whole car will shake.
If the 91 240 doesnt have a different cam profile, then why do i see s14s change to a s13 exhaust cam in intake? :squint: just curious

[mrmephistopheles]

im a bit confused...what does the 95+ KAs not having the secondary butterfly have to with me feeling the effects of not having mine working?
I was inferring that since they don't have that system, the fact that yours might not be working is irrelevant, since it'd idle pretty much ok without them even being there.

[DRFT24O]

I was inferring that since they don't have that system, the fact that yours might not be working is irrelevant, since it'd idle pretty much ok without them even being there.
Oh ok, gotcha! Anyways, I will see about checking the rotor and cap, and ill keep you guys posted. BTW last night i swapped radiators from another s13, FYI you can use a radiator from an automatic, youll just have 2 connectors on the bottom of the radiator that wont connect to anything. :2f2f:

[Id-]

oh shit!

vtec! it's faaast!!!


vtec!!! holy shit thats fast!!! :Ownedd:

[Id-]

No I didnt..


its cool; its a piece of cake to install; can get the cap and rotor for a KA from autozone :)

[DRFT24O]

good, theres one right by my house, any idea what it goes for?

[AAA240SX]

List price for Bosch Dist. Cap (KA24DE) is $17.10. You can get that around $8-10.
List price for Bosch Dist. Rotor (KA24DE) is $12.99. You can get that around $5-7.

That's if you go to AutoZone, Pep Boys, Murray's, Advance, or any other discount auto parts store.

Your car sounds like it is suffering from hesitation/stumble.

This is a general list of items that could cause this in any car (no particular order):

Worn or defective spark plugs
PCV hose air leak
Air flow meter
Intake valve deposit
Exhaust gas sensor
carbon canister
fuel pressure
fuel pressure regulator
Injector
injector circuits
ignition coil and circuits
Transistor ignition unit
ECU harness connector
ECU power supply & ground
ECU
AAC valve
Air regulator
clogged idle screw
Battery
alternator
EGR
Temp sensor
Temp sensor connector
Throttle position sensor
Idle switch
Cone Air filter
Crank angle sensor
Fuel temp sensor
Speed sensor
Incorrect timing belt installation
Crank Angle sensor and circuits
Ignition Timing

Knock these items down one by one...and ur set.

[DRFT24O]

Geez thats a list. Ill start with the cap and rotor.
Thanks.

[AAA240SX]

I know, sorry i didn't narrow it down. But yea, definetly start with those two (they're the cheapest). From there if there are any problems cycle down my list, I just made it out for the worst situation...knock on wood...