I've got a 95 Cavalier with a 2.3L that always starts great but runs on 2 or 3 cylinders until it runs for a minute or so then it smooths out and all four kick in. Fresh AC plugs, new boots and all new plastic in the ignition were recently installed. Any suggestions on what might be causing this rough running when the engine is cold? Once it warms up it runs great.
Vic
2 OR 3?? how do you know its running on 2 or 3? missing? just cus its running rough doesnt mean its only running on 2 ...OR 3 cylinders
coolant in oil? a head gasket can do that, but a cancellation test or a compression test will tell you.
cheek the ohms on the injectors too.
Chris
'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08
.rough when first starts up then smooths out after it goes into closed loop...im gonna go out on a limb here and say bad o2 sensor....................unplug the 02 in your manifold and run the car..then get back to me..see how good a guesser i am lol
That's a very good point about the head gasket as I have noticed occasionally that I get a fair amount of white smoke coming out the exhaust when it's cold and it does require frequent topping up of the coolant. Are there any cooling system sealants worth bothering with or am I stuck pulling the head and replacing the gasket? I understand that it's an expensive and complex job to remove the head on a 2.3L.
Vic
scott (section8cav) wrote:.rough when first starts up then smooths out after it goes into closed loop...im gonna go out on a limb here and say bad o2 sensor....................unplug the 02 in your manifold and run the car..then get back to me..see how good a guesser i am lol
I would head opposite of that.
If it runs good when it hits closed loop, then the O2 must be great.
Could be running too rich in open loop. One cause could be bad regulator or pinched return hose.
Could be running to lean. One cause could be bad fuel pump.
Need to figure out which and head from there.
sig not found
O2 sensor is good and doing it's job properly, it's more the plugs aren't firing as they should. I clearly remember what a bad O2 sensor acted like and that was different, quite different.
Vic
well you said youve been topping off your coolant...does that not raise a red flag with you like it does me?? how bout you pull a couple spark plugs out while the engine is cold and take a look at the top of the pistons..if they look really clean or you see a PUDDLE of coolant lol the gasket is probably leaking...not uncommon with 2.3s
That makes sense Scott. Do I need a special flashlight to look into the spark plug hole or can I see with a regular flashlight?
Vic
Mine runs on 2 or 3 cold too. BUT i use e85, and it doesnt like cold. lol
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Dont really need a "special" flashlight....but a small one would probably help...like one of those little LED lights work well
Thanks Scott, you're always a big help.
Vic
