Mechanics

MY CAR RUNS ROUGH

1995 Saturn SL2 • 72,000 miles

Engine is a DOHC
I had this car since new, always done normal maintenance. Have been using StarTron in gas becuse of ethanol this passed year. At 61000 miles repaced EGR valve and Ox Sensor and car was OK then. Car runs rough, somtimes near stall, but hasn't as yet.
I have the following error codes

74 Soft Flag
Coolant temp/transaxle temp ratio error

53 Soft Flag
Electronic spark control over max value

27 Soft Flag
Ouick QDM fault

Please help
Avatar
Billlhc
January 5, 2012.



Lets start with the code 74 you want to replace the coolant temp sensor for that code. There is two sensors screwed into the cylinder head right bellow where the upper radiator hose goes on. The top one has one wire that one is for the gauge. The bottom one with two wires is the one you want to change that one tells the computer what temp the coolant is. Also inspect the inside of the connector going to it if the terminals are blue or green instead of silver you will have to replace the connector also. So are you flashing the codes out or are you using a scan tool?If its a scan tool can you read live data what rpm the codes set etc?


Saturntech9
Jan 5, 2012.
Thanks saturntech9. Ordered a coolant temp sensor, should have it next week. I don't have a scan tool, have Autoxray Code Scout 2500 to read codes.


Tiny
Billlhc
Jan 6, 2012.
You ordered the sensor they didnt have one it stock?So was the connector terminals to it corroded?


Saturntech9
Jan 6, 2012.
I first replaced the coolant temp sensor and inspected the connector with a magnifying glass and it looked good. Also tried cleaning the connector with a tiny drill bit, I still had the car running rough. So I found a Saturn parts supply on internet and ordered both a genuine GM coolant temp. Sensor and connector. This suppler has slow shipping but I finally got them the other day and installed the parts. I still have the same problem rough running and once the car is warmed up, it is near stall or seems to stumble at idle. I have cleared the codes on scanner and drove the car about twenty miles, but scanner does not show any error codes, how long does it take?


Tiny
Billlhc
Feb 2, 2012.
So you changed the bottom sensor with two wires going to it?What were the exact code numbers that you had that you cleared?


Saturntech9
Feb 2, 2012.
I changed the bottom sensor and its connector with the two wires. The codes before were 74, 53, 27 Thanks


Tiny
Billlhc
Feb 2, 2012.
So it idles rough and also runs rough while driving down the jerking etc?


Saturntech9
Feb 2, 2012.
The car runs well when first started, but seems somewhat rough when warmed up when at idle. When at a stop light I have been shifting to neutral so it idles faster and then does not sound like it would stall out. The car seeems to run well at normal speeds, but does not seem exactly right. When I accelerate it goes well, does not misfire or breakup on hard acceleration. In reviewing some posts on 2CARPROS that pertain to my problem, someone suggested that BOSCH Plat. Plug can foul, I put them in about 20K miles ago, maybe I should change to NGK. What do you think.


Tiny
Billlhc
Feb 3, 2012.
Iam the one that suggested that bosch platnuim plugs foul in those engines because they do. Replace them with ngk copper plugs and see how it runs. How are the spark plug wires?Have inspected the coil towers where the plug wires go on?Its real common on those cars for the towers to corrod.


Saturntech9
Feb 3, 2012.
I put about 100 miles on the Saturn since replaced the parts and now it runs like a top. Since I didn’t want to experiment, I replaced the Bosch Plat. Plugs with NGK, new plug wires and both coils. One coil had oxidized terminal. The spark plugs ground bent arm seemed to be eroded away on the end which seemed like widening the gap. The Bosch plugs had about 15K miles on them. The old coil look to be better quality than the new ones so will keep the old coils and clean up the terminals if I need for future use. I have attached pic’s of spark plugs and coils.
Thanks for all your help!


Tiny
Billlhc
Feb 15, 2012.
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