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Discussion Starter · #1 ·
Any ideas or experience with this would be appreciated.

My '97 Saturn stumbles on acceleration, 4 Cyl twin cam. When I step on gas pedal from a stop it stumbles once or twice before it picks up speed and runs good. Also does this when cruising at a steady speed and give slight pressure on pedal to just creep up to a higher speed. No check engine light or other dash idiot lights come on. Scanned OBD II and no codes.

Checked for loose connections at firewall and most anyplace I could reach, just wiggled wires really, not very in-depth testing. Could really be anything I guess but hoping someone might have some experience along these lines. Personally I'm thinking fuel related. Could be fuel pump relay or pump or computer perhaps cam sensor even throttle sensor I suppose.

I could spend a lot a money swapping out parts with out knowing the cause. I have a company van I use during the week so I guess I'll just drive locally until I figure this out. Have SAFECO road service so I"ll run it and see what happens, get towed in on them if need be.

DUH Just thought of this - I'll get some Lucas Injector cleaner. I would think if it was an injector I would be getting a check engine warning light though.
 

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Discussion Starter · #3 ·
Should have mentioned changed plugs in November. Could be a spark plug wire issue. I'll have to spray some water on the wires and see if it stumbles.
 

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It could also be such things as TPS (throttle body sensor).
I believe that car has a MAP instead of MAF. (manifold absolute pressure-mass air flow). Maybe that.
Another problem that seem to come up with these cars is Temperature sensor.
There is a guy by the name of Rich Pin, who is one of my favorite u-tube guys seems to do alot of work on the Saturns. Check him out.http://www.youtube.com/user/richpin06a#p/u
 

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It could also be such things as TPS (throttle body sensor).
I believe that car has a MAP instead of MAF. (manifold absolute pressure-mass air flow). Maybe that.
Another problem that seem to come up with these cars is Temperature sensor.
There is a guy by the name of Rich Pin, who is one of my favorite u-tube guys seems to do alot of work on the Saturns. Check him out.http://www.youtube.com/user/richpin06a#p/u
IMHO when ever you have a issue with a Saturn the FIRST thing you replace is the temp sensor!! they do go bad, and on these cars they seem to control EVERYTHING!! May not be the issue you are having now, but odd are if you havent replaced it yet, you will be preventing a issue down the road!!
 

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Discussion Starter · #6 ·
My brother just purchased a used Saturn that was running poorly, he changed the temp sensor and it runs like new. I noticed yesterday that when cold it runs good, warm it stumbles. I'll put in a new temp sensor and see if that helps.
 

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My friend chased a continuous fast idle problem on a 99 Saturn last week--no codes were stored,no check engine light either,but it refused to go below 1200 rpm and that made it fail inspection...the owner was having a hard time driving it in city traffic ,it was a standard tranny too,and he said driving in Boston was a real challenge when the engine would rev up to 2500+ when you put in the clutch!...the only other "abnormal" thing he noticed was the temp gauge was only going up to 1/4,when previously it was going up halfway--so he thought maybe its thermostat was sticking open,but it had excellent heat..

My friend went to a junkyard he dealt with often,and the owner let him "borrow" anything he wanted to try to see if it fixed it--he swapped the entire throttle body,the computer,EGR valve ,and inspected every wire and sensor on the engine for damage--it still ran at 1200 rpms!..the only thing we noticed that didn't look perfect on the engine ,which was as clean as new ,was a drop of coolant oozing from a sensor on the side of the cylinder head..when we pulled the plug off it,it appeared one of the pins on the sensor had corroded off,and was now stuck in the plug...as soon as he took the plug of,the engine slowed right down to 600 rpm--replaced the sensor and plug,and it was like new again...we were surprised it never set off the check engine light or set any codes though!...now that sensor will be suspect #1 on any Saturn that he works on in the future!..
 
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