Rough Idle
Thread Starter
6th Gear
Joined: Sep 2006
Posts: 6
Likes: 0
Rough Idle
So..my girlfriend called me today saying her car is "running rough when she's stopped".
So it's a rough idle, also when cruising at a constant speed there is a hesitation in the car...after a little reading a question asking (she regularly lets the tank get to the reserve point) is there anyway to know whether it's the fuel pump?
My first guess was going to be wires.
Also, around 90K miles on a 90.
Thanks!
So it's a rough idle, also when cruising at a constant speed there is a hesitation in the car...after a little reading a question asking (she regularly lets the tank get to the reserve point) is there anyway to know whether it's the fuel pump?
My first guess was going to be wires.
Also, around 90K miles on a 90.
Thanks!
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Could be alot of things mate.
How long since the fuel filter has been replaced?
Check the plugs and leads.
Check the cap and rotor
Check the igntion control module
Check to see if it happens in open loop as well as closed loop.
Check the EGR function
Check the AIR function
Check to make sure there is no leaks on the left hand exhaust manifold allowing air to be drawn into the exhaust stream
Check for vacuum leaks
Check the MAP sensor
Check the O2 sensor
Clean the throttle body and IAC path very thoroughly
Ohm test the injectors
Check the fuel pressure
Start with those and get back to us.
How long since the fuel filter has been replaced?
Check the plugs and leads.
Check the cap and rotor
Check the igntion control module
Check to see if it happens in open loop as well as closed loop.
Check the EGR function
Check the AIR function
Check to make sure there is no leaks on the left hand exhaust manifold allowing air to be drawn into the exhaust stream
Check for vacuum leaks
Check the MAP sensor
Check the O2 sensor
Clean the throttle body and IAC path very thoroughly
Ohm test the injectors
Check the fuel pressure
Start with those and get back to us.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Case is right, it could be many things causing the problem. The list he made is of things that could be causing the problem you described.
It sounds like a spark or fuel delivery problem from the "running rough" and "constant speed there is a hesitation". I would check the connection of the spark plug wires on the plugs and distrubitor cap. Also replace the spark plugs if you don't know when they were last changed or at least pull them to compare cylinders. Ohm test the spark plug wires one at a time (stick one lead in one end of the wire and the other lead in the other end....wiggle them and it should be around 5,000 ohm/foot).
Check the injector coil resistance with an ohm meter. They should ohm close to each other and not less than 10 ohms cold or hot. Use a fuel pressure guage to check for fuel pressure leakdown after the engine has run and been shut off. A fuel pressure guage can also help rule out a weak/dying fuel pump. Replace the fuel filter.
Hope your handy with tools.
It sounds like a spark or fuel delivery problem from the "running rough" and "constant speed there is a hesitation". I would check the connection of the spark plug wires on the plugs and distrubitor cap. Also replace the spark plugs if you don't know when they were last changed or at least pull them to compare cylinders. Ohm test the spark plug wires one at a time (stick one lead in one end of the wire and the other lead in the other end....wiggle them and it should be around 5,000 ohm/foot).
Check the injector coil resistance with an ohm meter. They should ohm close to each other and not less than 10 ohms cold or hot. Use a fuel pressure guage to check for fuel pressure leakdown after the engine has run and been shut off. A fuel pressure guage can also help rule out a weak/dying fuel pump. Replace the fuel filter.
Hope your handy with tools.
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Thanks mate. The reason the list i left you is like it is, is because from what youve said, it could be any of those items and more. If you can tell if its related directly to closed loop operation (as in it only does it in closed loop, and not in open loop) you can cross off a fair few items on that list. Until you know, its best to have all bases covered.
Thread Starter
6th Gear
Joined: Sep 2006
Posts: 6
Likes: 0
i'm fairly handy with tools...just not with a domestic-especially a high end domestic. Always have driven rx-7's and now a WRX.
I know it's a delivery problem of either fire or fuel just from experience of driving.
Pulled the plugs this morning- yeah they are getting changed as soon as i run to the store. going to go ahead and change the fuel filter while i've taken the day off (can't hurt right!).
After that since it's my girls car it's prob off to a dealership. I flub up my car it's mine.
Her's- yeah..mom and pop buy their princess a vette and her b/f messes it up
I know it's a delivery problem of either fire or fuel just from experience of driving.
Pulled the plugs this morning- yeah they are getting changed as soon as i run to the store. going to go ahead and change the fuel filter while i've taken the day off (can't hurt right!).
After that since it's my girls car it's prob off to a dealership. I flub up my car it's mine.
Her's- yeah..mom and pop buy their princess a vette and her b/f messes it up
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Thread Starter
6th Gear
Joined: Sep 2006
Posts: 6
Likes: 0
Spark plugs were BAD. Only time i've ever seen any with that much carbon build up was on a 92 toyota paseo i used to own that the valve stem seals were shot and it dumped oil straight to the plugs.
Replaced those and started much easier and idle's beautifully.
Haven't taken her for a spin again (noticed the belt is a ltitle worn so to the shop monday for that).
Replacing the air/fuel filter tomorrow while i've got it on jack stands.
Replaced those and started much easier and idle's beautifully.
Haven't taken her for a spin again (noticed the belt is a ltitle worn so to the shop monday for that).
Replacing the air/fuel filter tomorrow while i've got it on jack stands.
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Racer
Joined: Jul 2004
Posts: 389
Likes: 2
From: Howard Beach, NY
does she sputter out of the tailpipes?
Spark plugs were BAD. Only time i've ever seen any with that much carbon build up was on a 92 toyota paseo i used to own that the valve stem seals were shot and it dumped oil straight to the plugs.
Replaced those and started much easier and idle's beautifully.
Haven't taken her for a spin again (noticed the belt is a ltitle worn so to the shop monday for that).
Replacing the air/fuel filter tomorrow while i've got it on jack stands.
Replaced those and started much easier and idle's beautifully.
Haven't taken her for a spin again (noticed the belt is a ltitle worn so to the shop monday for that).
Replacing the air/fuel filter tomorrow while i've got it on jack stands.