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2007 Saturn Relay Minivan 3.9L V6 FWD 45k miles experiencing rough idle and hesitation on acceleration. Over a period of months (possibly years) the driver has made trips of 5min. or less to and from school, twice a day.
I suspect EGR valve issues but I’ve looked on alldata for any information concerning the EGR valve, but it has nothing to offer (it only gives the ‘book time’ for repair and replace.) I even tried to look at the power distribution schematic in efforts to see how the valve is powered so I an force the valve to operate but couldn’t find anything. Does this vehicle even have an EGR valve? What other things should i consider in efforts to diagnose and make a repair? I plan on also pulling a spark plug to see actually what is going on inside the cylinder. I have not physically looked at the engine myself as the vehicle is currently 420 miles away in lovely Evansville, IN.
Thanks in advance.
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Take a look at the throttle body may be dirty.
clean the MAF check for vacuum leaks. you could
mist the wires/coil packs with water in the dark
and see if any arcing going on.I would not go for the EGR first thing. The main reason is that the only way EGR can effect idle is if it’s stuck open and that doesn’t happen very often. If I were you I’d be looking to the ignition system first thing. That can effect the idle as well as cause a misfire on acceleration. You can use the methods in the above videos to check that out.
excellent suggestions by everyone btw.. thank ya’ll.
based on eric’s suggestion, i’ll check the easy stuff first and not dive head first into the EGR system, which usually is not a user friendly project to put it nicely.
i almost forgot about checking for MAF related issues specifically. Since I will not have a scan tool available, i’ll back probe the 5 volt reference and signal lines to see what i’m getting. i’ll also disconnect the sensor to see if i can induce a check engine light (which should eliminate the PCM as a possible cause). Also, I could back probe the signal wire and gun the engine and see if I get over 7,000 hertz. I’ll also pull the MAF and hit it with some brake cleaner. I’ll also attempt to examine the intake snorkel for possible air leaks. Other issues such as vacuum and voltage leaks will also be checked, but they will probably be lower on my list of priorities.
Now that I think about it.. a good scan tool sure would make this diagnosis a hell of a lot easier.. :dry:
Btw, there are no TSB’s related to the aforementioned performance issue.
being that the vehicle is driven frequently for short durations i suspect a lot of carbon build up in the engine. although there is no CEL, i didn’t suspect a misfire condition right away; however, i will of course break out the spark tester and hook up the ol’ fuel pressure tester just to see if the engine is getting everything it needs. also, a good spark plug inspection should give me some insight into the fuel/air mixture. and since i’m in there, a good throttle body cleaning will be in order.
one thing i just thought of also is the possibility of a failing catalytic converter. as a trial and error method, i’ll pull an upstream O2 sensor to see if I can get an improvement in peformance. (i am hoping the computer will either omit erroneous/non-existant O2 data, or will resort to open loop operation.. in either case i’ll be able to test vehicle performance)
based on ya’ll suggestions, i’ll attempt a diagnosis and repair on this vehicle at some point in the near future and will hopefully be able to add a successful repair for eric’s vast database o’ vehicle fixes. :side:
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