Sputter at Idle and Lower RPM
#1
Racer
Thread Starter
Sputter at Idle and Lower RPM
I bought the car over a year ago with 42K and it ran great except it would sputter erraticaly at Idle and low RPM. I just flushed and serviced the cooling system witch was like brown mud water (Bars Stop Leak?) Or is this normal for a car needing a flush? Now at 47K it still does it. I replaced the Opti with new MSD Opti, New blaster coil, New plugs, Fuel filter, Fuel pressure is within Specs. Havent changed wires or fuel injectors yet. My concern is I might have a bad head gasket, or worse a cracked head causing antifreeze to enter the cylinder resulting in this symtom. Is there any way test for this condition. The car accually runs great but when I pull up to a stop light it runs a little rough and up to 1500 RPMs you can hear a slight sputtering out the exhaust. There is no white smoke and my coolant stays full and doesnt seem to be going any where. Could this be wires or fuel injectors or worse?
#2
Burning Brakes
Have you cleaned the Throttle Body and IAC pintle lately? They seem to collect gunk on them after time and need cleaning at about 40K or so. It may be something else, but this may be something to rule out.
#4
Racer
Thread Starter
The coolant was muddy brown before the flush? But I dont
recall rusty threads when changing the Plugs? Will look into
both these ideas, Keep ya posted.
recall rusty threads when changing the Plugs? Will look into
both these ideas, Keep ya posted.
Last edited by RetroTA; 10-31-2006 at 10:22 PM.
#5
Melting Slicks
Member Since: Nov 2002
Location: 1993 Quasar Blue 'vert Scottsdale AZ
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If the head is cracked or bad gasket, you should have water in the oil. Sounds like the previous owner may have put those stupid GM pellets in the cooling system. Flush, flush, flush.
#11
Not sure this will help but check the EGR valve. I have 1995 with high miles. EGR valve opens during rich fuel conditions to reburn exhaust gas. If it sticks open just a bit, you could have sputtering at low PRM's - e.g. causing a bad vacuum leak from the exhaust. I had similar issue. changed out the entire fuel Tank Sending unit, fuel pump assembly and strainer, as well as fuel filter. I also tried the Seafoam. Turns out a shot of carb cleaner to the EGR valve fixed the prob pretty quick. Not sure that was the final fix, but I no longer have the problem. Pretty easy to replace if you need. Manual should show you how to test and repair/replace. glad it's gone, I was thinking about the ECM and Fuel Injectors next....
#12
Drifting
Not sure this will help but check the EGR valve. I have 1995 with high miles. EGR valve opens during rich fuel conditions to reburn exhaust gas. If it sticks open just a bit, you could have sputtering at low PRM's - e.g. causing a bad vacuum leak from the exhaust. I had similar issue. changed out the entire fuel Tank Sending unit, fuel pump assembly and strainer, as well as fuel filter. I also tried the Seafoam. Turns out a shot of carb cleaner to the EGR valve fixed the prob pretty quick. Not sure that was the final fix, but I no longer have the problem. Pretty easy to replace if you need. Manual should show you how to test and repair/replace. glad it's gone, I was thinking about the ECM and Fuel Injectors next....
#13
Drifting
Well, so far, no one asked, so... is the service light on? Are there any stored codes?
The brown gunk in the coolant is likely from the factory SOP of using those pellets in the cooling system- IIRC there was an issue with porous heads... anyway, a compression test should diagnose a head gasket problem, and if there are combustion gases getting into the cooling system, I would expect to see bubbles in the coolant.
The brown gunk in the coolant is likely from the factory SOP of using those pellets in the cooling system- IIRC there was an issue with porous heads... anyway, a compression test should diagnose a head gasket problem, and if there are combustion gases getting into the cooling system, I would expect to see bubbles in the coolant.