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1998 Saturn engine choking out


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saturnftw
Novice

Jul 14, 2011, 4:30 PM

Post #1 of 9 (5056 views)
1998 Saturn engine choking out Sign In

Problem:
-About 3 weeks ago my Saturn SC2 4-cyl 1998 engine started choking/cutting out almost to a stall and then would go back to idle every once in a while when I was standing still. The car also would get very hot if I had to stay still for long periods (Stop lights in town). The engine getting hot seemed to make this problem worse to were now it will choke/cut out for a tenth of a second while driving at any speed at random times (does it less at higher rpms and sometimes hardly at all). I can every once in a while smell gas in my car and it sometimes revs all the way to 3500 RPMs when I start it.

-The overheating was due to the fan not working, however now it is working and I still have problems with the car getting hot in town(which in turn makes the choking/cutting out worse). This could be that it is just too hot out, or maybe its a result of the problem.

Things I have done so far
-Replaced the Coolant Temp Sensor
-Replaced the spark plugs
-Cleaned the throttle body
-Replaced fuel filter
-Replaced Catalytic Converter

Engine Codes
- When I had the codes read the ones that came back where
P0420 DTC Code - Catalyst System Efficiency Below Threshold (Bank 1)
P0117 Engine Coolant Temperature Circuit Low Input
P0125 Insufficient Coolant Temperature for Closed Loop Fuel Control

My thoughts
- My thoughts as of now are that it is the upstream O2 sensor or the EGR valve due to the smelling gas and too high of idle at the start of the car. I am mechanically inclined enough to replace anything with little trouble, I just don't want to throw parts at my car.

I am just needing this car to last another couple months when I get a new one. ANY thoughts or even a possible cause would be very nice.

Thanks


(This post was edited by saturnftw on Jul 14, 2011, 4:38 PM)


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Jul 14, 2011, 4:34 PM

Post #2 of 9 (5054 views)
Re: 1998 Saturn engine choking out Sign In

Which model and engine size?





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saturnftw
Novice

Jul 14, 2011, 4:39 PM

Post #3 of 9 (5049 views)
Re: 1998 Saturn engine choking out Sign In

All that writing and I forgot that, fixed it. Its a SC2 4-cyl 1998.

In Reply To


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Jul 14, 2011, 4:49 PM

Post #4 of 9 (5041 views)
Re: 1998 Saturn engine choking out Sign In

Pull the connector off the coolant temperature sensor. Inspect the terminals in the plug for corrosion. If you see corrosion replace the connector( part #12117087).

Don't attempt to clean it. Solder the pigtail wires and use heat shrink. Don't use wire nuts, butt splices, scotch locks, or twist the wires together and wrap electrical tape around them.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Jul 14, 2011, 4:51 PM)


saturnftw
Novice

Jul 14, 2011, 4:53 PM

Post #5 of 9 (5035 views)
Re: 1998 Saturn engine choking out Sign In

I actually replaced the connector also when I replaced the sensor; however it was with a used one so it could be bad as well. Is there anything else that could be the problem?


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Jul 14, 2011, 5:00 PM

Post #6 of 9 (5032 views)
Re: 1998 Saturn engine choking out Sign In

There could be, but you really need to know that the PCM is getting the right voltage signal from the coolant sensor depending on actual coolant temperature. The coolant temperature input is critical on that engine and can cause the symptoms your are describing.

You may need to get hold of a scan tool that can view data stream information. You can look at the coolant temperature parameter to see what the computer is seeing. You can also view other parameters such as fuel trim, MAP voltages, injector pulse width to get an idea what is going on.

The last thing you want to worry about is the P0420 code when you have a drive-ability issue. Misfires, wacky sensor readings, and fuel management problems can fake the OBD2 software into believing that your catalyst is inefficient.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Jul 14, 2011, 5:06 PM

Post #7 of 9 (5027 views)
Re: 1998 Saturn engine choking out Sign In

Was the old temp sensor cracked? Was the old connector corroded or full of coolant?

There is another possibility that if the sensor was leaking into the connector cavity it could push coolant up through the wiring and into the engine controller. I'd pull the connectors off the engine controller and make sure there isn't any coolant in there. Don't laugh because it does happen.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


saturnftw
Novice

Jul 14, 2011, 5:08 PM

Post #8 of 9 (5025 views)
Re: 1998 Saturn engine choking out Sign In

Ok thanks, the problem did start soon after I replaced the coolant temp sensor. I will try and check all things related to it.


saturnftw
Novice

Jul 14, 2011, 5:12 PM

Post #9 of 9 (5023 views)
Re: 1998 Saturn engine choking out Sign In


In Reply To
Was the old temp sensor cracked? Was the old connector corroded or full of coolant?

There is another possibility that if the sensor was leaking into the connector cavity it could push coolant up through the wiring and into the engine controller. I'd pull the connectors off the engine controller and make sure there isn't any coolant in there. Don't laugh because it does happen.


The old connector had some corrosion on it. The new one on there is not corroded (that I can see).






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