Ok, my wife has a 2000 saturn SL2 with about 120,000 miles on it. About two weeks ago, it had a really rough idle right after cranking and at stop lights and such I thought it was going to cut off (no SES lights). We got home and I was going to take a look, but forgot and the problem was gone the next morning and I completely forgot. The other day the SES light did come on so she calls and is all worried. I send her to autozone or the like and get a code read. Don't remember the code number but it was something to the effect of "misfire on cylinder one." The plugs and wires were replaced about 6 months or 20,000 miles ago so I doubted that was the problem, but just to rule out the cheapest solution I changed the plug in cylinder 1 with the same brand as was in the other 3. No change. So, I bought an ignition coil and replaced the one that fires that cylinder. No change. What's left?

A few more symptoms. After stopping, if you let up off the brake but don't hit the gas, there is some jerkyness like it is missing, which makes sense b/c of the code. Also, the SES light comes and goes, but tends to come on after periods of idling. Once the car is moving there is no noticable misfire.
Thanks for any help

ok, now what kind of wires and plugs do you have one it? although new they can be the issue. not all parts are just as good as the other, now and days you have to spend money for quality. ive dealt through many cases working in a shop. but also it could be the coolant temperature sensor (only get one from a dealer). common issue. but then too ive known of intake gaskets leaking vacuum but i think thats only on the sohc models.

it can also be the valve cover leaking oil on the plug fauling it out, but im sure you would have noticed that. now im going to stick to most likely bad wires or ects.

also you didnt happen to notice if the plug had oil on the tip? piston rings are known for seizing up due to carbon and letting oil past.

I actually have the plug I took out of cylinder one with me now. As far as I can tell, the plug looks normal. In the past hour or so, I've come across quite a few posts lambasting the plugs I put in there 6 months ago (Bosch Platinum 4202). Is it true that Saturn + Bosch= problems?:banghead: I just found the recipt for the wires and they are autolite professional series.

The plug itself looks good to me, everything is clean with about 1.5 turns of what is probably carbon on the bottom of the threads. Now that I look at it a bit closer, the insulator at the top of the plug where the wires attach is a bit discolored. At the very bottom just before where the nut begins, the insulator has turned a bit brown (almost the color of oil, but not slick so I'm assuming it's not oil) and it lightens up as it moves toward the tip. Is that a sign that the plug is getting too hot?

Actually, I just scraped at the brown on the plug insulator with a knife and it appears to be like a glaze that chips off. I'm guessing oil that has been baked onto it for 6 months? But how would oil come into the top of the engine there? The top the engine is clean, so it didn't run down into the plug that way and the plug didn't have wet oil on it when I pulled it out.

Either way, I would guess that unless these bosch plugs are just terrible for a saturn that the replacement I put in would have taken care of it if the plugs were the problem. But , I might change them anyway if you think that could be it just b/c they are cheap and easy. NKG?? Seems to be what people recommend. Platinum or no, I think the ones that I took out before were, but can't remember.

Thanks for the help, I'm open to suggestions as long as things don't get over my head or tools and it's probably a lot easier to get over my head than my tools. This has been a really good car for my wife and this is the first time it has ever given any trouble (well ok, it has had an exhaust leak I am putting off fixing for awhile). The original plugs and wires had been in there for 100,000 miles so I decided it was time since they reccomend a 30,000 mi interval on plugs for this car.
Thanks again.

ok yes, bosch plugs are horrible and pretty much any car. euro cars seem to be fine with them but american and japanese dont like them. go with ac delco rapidfires or ngk v-power. i would also say denso u-groove but i havent tested them yet, i only will give out the good products that ive tested. now your car is probably burning oil, so if no oil is in the plug well, then id say that brown color might be coming from inside the cylinder. id say go buy the new plugs. and those wires have been pretty good, so i dont think they will be an issue.

i will also suggest an upper engine soak, piston soak. there are many different products to try. ive used marvel mystery oil and didnt see much of anything. im going to try seafoam tonight, gm and saturn both have their own upper engine cleaners too. but in order to does this, you pour the fluid down on top of the piston. fill it to where it completely covers the piston, if you have quite a bit in there, then before you start you will need to turn it over (with rags in plug holes) to shoot most of it out. you should let it soak for 24 hours, but id say 12 hours so pretty much over night. also some guys like to do it when the engine is pretty hot. they will pull the plug pour it in and hurry and put the plug back in so it really works in. i havent tried that method yet.

Ok, sounds good. I'll change out the plugs asap. May be a few days, I have to work all weekend and it's raining anyway. I'll let you know how it goes. May even get a chance one afternoon to try the soak.
Thanks again.

ngk is best since they fire at the right temp for saturns.

I'll try those. Before I go buy, would you recommend platinum plugs for this car? I hear contradicting reports.
Thanks again.

your going to find lots of people saying no on platinums. ive tested platinums and normal coppers, its all about what kind you get. ive had no issues with platinums, been very well. ive even dared to buy the splitfire triple platinums, and had everything go very good with them but the gap did spread over time.

THERE ISNT ISSUES WITH PLATINUMS IN SATURNS! there ive said it. ive tested them. i havent tested gold, nickel, or iridium. i wont test the gold ones, and nickel isnt appealing to me, so ive got iridium to do. i also have a set of denso u-grooves to test out.

i'm too tried to get into the platium thing now...

if you in fact have a SL1 with the SOHC motor a cylinder 1 missfire is a common problem caused by a leaking intake manifold gasket. the DOHC motor did not share this problem

No, it's the sl2 with DOHC. Thanks thought. I still haven't done anything else to the darn car. Being lazy I guess.

THERE ISNT ISSUES WITH PLATINUMS IN SATURNS! there ive said it. ive tested them. i havent tested gold, nickel, or iridium. i wont test the gold ones, and nickel isnt appealing to me, so ive got iridium to do. i also have a set of denso u-grooves to test out.
yes there is. they won't work eventually. yes some people haven't reported problems. Yet. 90% of stories that i hear about putting platinum plugs in a saturn turn out bad whether it's codes you haven't heard before, misfire, or bad gas mileage. your manual says not to use them. the experts from Chilton's and Haynes say not to use them. This is a quick tech explanation by barnowl from www.saturnfans.com. on why.
http://www.saturnfans.com/forums/showthread.php?t=70203

well i think that is crap. thats saying that like dis ignitions cant use platinums. wasted spark isnt a fact for platinums not working in saturns. its just people buy junk plugs, thats all.

3000gts have wasted spark, and from factory use platinum plugs. wasted spark is not why, junk plugs.

Hopefully somebody will still be looking at this post, because I am just now getting back to do a follow up. Finally bought some plugs, stayed away from platinum b/c it appears there is no use and may be bad (can you say can of worms?) Got the delco rapid fires. Put them in. No help. SES light still comes on, mostly after idleing several minutes (drive throughs and long lights). Once up to cruising speed for a few minutes, light goes of. Still jerky if you let off the brake and don't hit the gas. Feels like a misfire, but not sure. Definitely no problems with the plugs fouling. All four looked clean when I took them out. As I've said, the wires are still about 6 months old.

Now, I didn't have the computer reset after I put the plugs in, but I assume that this is moot because the light keeps coming back on. Is that right? Haven't been back to have the code read after the new plugs, but probably still the same misfire cylinder one code. I'm starting to lean towards sensor malfunctions. Thoughts?
Thanks.

have you done a compression check on the cylinder then?

I just purchased a 1995 SC2. upon driving it home i found that it has pretty much the same troubles, when i step on the gas it seems to stumble as well as when stopping at a light if i dont keep the RPM above 2000 it will just stumble and stall. I plan on taking it in to get it diagnosed ASAP. I will let you know what they say! I'm gonna check the compression in the next couple days. I also put in new plugs and wires earlier today.

I was just browsing the internet at work, and apparently the brown stain I mentioned earlier was the corona stain that is mentioned on the NGK website http://www.ngkntk.co.uk/technicaltips/coronastain.asp. Good to know I guess. Haven't done a compression check, but hope to carry it somewhere to have it done soon. I'll keep you all up to date. Just went by autozone the other day and had the codes checked and reset and it is still the p0301 cylinder 1 misfire.

I just returned from my local Saturn shop...:screwy: They discover that my problem is a couple of things...:banghead: These consist of the 2/3 coil pack giving a fluctuation of resistances. Apparently it was all over the place. Next was the ECT Sensor and connector are giving incorrect readings. Also the valve cover is leaking slightly allowing small amounts of oil into spark plug 4. I got them to price out the parts directly from them and here is what they said:
ECT Sensor-$20.40
ECT Connector-$54.68
2/3 Coil Pack-$103.62
Valve Cover Gasket-$61.81

I'm gonna call around cause i am sure i can find everything for cheaper.
I will let you know how it all goes after i fix it all up. Hope this ends up being all thats wrong!:banghead:

go figure, but dont cheap out on the coil or ects. you need to buy either original equipment or very good aftermarket, coil wise msd or original (gm 2 tower coil pack). now the ects the only thing you can do is buy the original. it needs to be brass tipped, not plastic. typical problem with them. parts store ects like never work.

I have a friend who is a parts dealer so i hope to get good prices out of her!
Thats is the only way i would "cheap out".
I defenatly want to increase preformance so i plan to get the best for what i can afford. The prices i stated are strait from the Saturn Dealership i took my car in to get checked out.

Well I've come across a mystery hose connector. I made an appointment to have the compression checked monday, but thought I would go ahead and get some cleaner and clean the throttle body and check for a vacuum leak. So, I cleaned the throttle body (which by the way was extremely dirty). After that, I reassembled the air ducts, and went around the engine spraying the throttle body cleaner listening for a difference in the sound. I found a spot where the engine would rev a bit if sprayed and looked expecting to find a bad hose. Instead, I found what looks to be a connector where a hose should be, but is not. Facing the engine from the front of the car, the connector is on the side of the motor almost directly behind the spark plug for cylinder 1, but is just slightly to the right of there. It is under and to the right of the support bracket for the power steering fluid reservoir. What the devil is that connector for, because try as I might, I cannot find another connector for a hose anywhere and can't seem to find the right place in the haynes manual to find it.

I wouldn't get that MSD coil pack unless you REALLY want to, not much better than stock if at all.

Well I've come across a mystery hose connector. I made an appointment to have the compression checked monday, but thought I would go ahead and get some cleaner and clean the throttle body and check for a vacuum leak. So, I cleaned the throttle body (which by the way was extremely dirty). After that, I reassembled the air ducts, and went around the engine spraying the throttle body cleaner listening for a difference in the sound. I found a spot where the engine would rev a bit if sprayed and looked expecting to find a bad hose. Instead, I found what looks to be a connector where a hose should be, but is not. Facing the engine from the front of the car, the connector is on the side of the motor almost directly behind the spark plug for cylinder 1, but is just slightly to the right of there. It is under and to the right of the support bracket for the power steering fluid reservoir. What the devil is that connector for, because try as I might, I cannot find another connector for a hose anywhere and can't seem to find the right place in the haynes manual to find it.


i dont want to take any guesses on it, but are you able to take a picture of this?

Unfortunately not, no digital camera right now. I went by autozone to see if they had any idea, but it was a no go. Best description I can give is that it is a metal tube pointing straight up. It looks like there is a 2 inch rubber hose that connects to the back of the engine block right beside this thing and it comes straight up from beside that hose maybe 2 inches set back from the side of the engine. It actually appearsto be connected to the engine at almost the same place as the bigger hose. Or coming from the other direction, it is just to the left of the throttle body but closer to the engine. Also, I stuck my finger over it when the engine was running and it has a pretty strong vacuum to it. Sorry I can't be more specific. If I can't figure it out, hopefully the guy at the repear shop will have an idea.

BTW, it seems like the problem with the rough idle is getting steadily worse over time. I drove it to the part store today to see if they had any idea about the mystery connector and I think it is worse. Let you know how the compression test comes. If it is poor compresion, would we expect valves instead since the plug looked clean? Either way, I suspect either one is beyond my time or talent level.

:banghead: Well i have now replaced the coil pack and ECT sensor which the Saturn Shop told me where malfunctioning, and the problem is still there. I am planning on doing a compression test on it tonight. Gotta get the heaters going in the garage cause its so damn cold up here. :disappoin Unfortunatly these malfunctions had nothing to do with my issue.

Unfortunately not, no digital camera right now. I went by autozone to see if they had any idea, but it was a no go. Best description I can give is that it is a metal tube pointing straight up. It looks like there is a 2 inch rubber hose that connects to the back of the engine block right beside this thing and it comes straight up from beside that hose maybe 2 inches set back from the side of the engine. It actually appearsto be connected to the engine at almost the same place as the bigger hose. Or coming from the other direction, it is just to the left of the throttle body but closer to the engine. Also, I stuck my finger over it when the engine was running and it has a pretty strong vacuum to it. Sorry I can't be more specific. If I can't figure it out, hopefully the guy at the repear shop will have an idea.

BTW, it seems like the problem with the rough idle is getting steadily worse over time. I drove it to the part store today to see if they had any idea about the mystery connector and I think it is worse. Let you know how the compression test comes. If it is poor compresion, would we expect valves instead since the plug looked clean? Either way, I suspect either one is beyond my time or talent level.


id say there is a vacuum leak right there. something should go to that.

and mkary, where did you buy the ects? and did you get the connector for it?

The compression was checked this morning. Shows 150 psi on all 4 cylinders. Lower than the spec 180 to 190, but w/ 120,000 mi I think it is normal. They couldn't figure out where the vacuum line went either so that is confusing. Could that single missing line be the cause of all problems, because I would think a vacuum leak would cause a p0300 or something similar? The repairmen mentioned that sometimes these things are plugged so they went ahead and plugged it up with some tube and a bolt. I'll get it by the dealer sometime to check it out. I told my wife to drive around today and see if it acts any different plugged up. I'll let you know.

They did mention that the mystery connector comes striaight up off of the same connection as the intake manifold if that helps any.
Thanks

Got a chance to take the car by the dealership today. They were nice enough to tell me what the mystery hose went to no charge. Apparently, when these cars were sold in the colder northern climates there is an extra electric air pump mounted behind the head light and a vacuum line went from there to this connector. In the south, they just capped the line and it was done. Apparently, my cap dry rotted and broke off. I drove it about 30 miles today and my wife another 40 and capping it off has taken care of the rough idle completely. The guy at the dealership said that the bolt and hose should be fine and not to worry about buyin their cap. Hopefully, the misfire code was just an artifact of that, although it still doesn't make complete sense. Maybe the injector for cylinder one is slightly clogged and it was amplifying the effect of that leak, who knows. I'll let you know in a week or two, but think I have it taken care of. While I was there, I went ahead and picked up a PCV valve (still had the original) and the Z tube that goes from the air intake to the valve cover which was badly cracked. Any suggestions for other maintenance items I should do. I plan to change the fuel filter and transmission fluid in the next few weeks, neither of which has ever been done to my knowledge.

too bad you didnt notice that vacuum port before. when i noticed you said that, i figured there was your problem or at least one of them. but its good to see compression is matching across the board, seems a bit low though. im too lazy to go back through the posts, but did you do a piston soak? it sounds like the valves are not seating due to carbon. im not sure on the newer engines, which im sure they are about the same, i think below 180psi service is needed. probably just needs a good piston soak and a strong fuel system cleaner and/or true injector cleaner (not stuff you buy in a bottle to put in your tank).

Yea, it stinks that I didn't see that before, but it was hidden a bit and no vacuum lines went back there so I wasn't really looking there for an obvious leak. Oh well. I haven't done the piston soak yet, but hopefully will get to it. I've read that some people use the seafoam by sucking it up through the vacuum lines via the PCV valve. Ever heard of this? You're right, it recomends service if below 180 with normal being 190 psi. The local auto repair shop has an injector cleaning service, but I'm not sure what brands they use. Do your recommend these. I know it is one of those where they attach some pressurized chemical to the fuel line and run it through. Are any of the fuel additive treatments worthwhile really? I've also heard of seafoam in the gas tank.

ok the piston soak may help, but it seems like there is carbon build up around the valves which is what is bringing the compression down. running seafoam through a vacuum line while its running helps clean the intake and pretty much the valves, it does nothing for the rings. doing both may help greatly, but understand doing the seafoam through the vacuum line will cause it to stall if you put in too much at a time. you have to go slow and you wont need a funnel, the vacuum will just suck the fluid right in. now doing the injector cleaner at the shop, where they use the chemical cleaner hooked up to the fuel line, is the best way to go. it can be pricy at some places, but worth it. now to keep them running good after that, i would use seafoam, marvel mystery oil, or lucas fuel treatment. i have used them all, and all seem to do well. i have even mixed seafoam and lucas for a potent mixture, which my dad told me worked extremely well, just dont want to overdue the mixture.

ok and before i forget, if you plan to do the piston soak, do it right before you are going to do an oil change because it will leak down to your oil and could have carbon deposits floating around. marvel mystery oil, main one guys use, seafoam, or gm tec(top engine cleaner)-another one guys use- are the main things to use for the piston soak. you can also do this while the engine is still warm, pull the plug pour the fluid in and then stick the plug back in. ive done it and ive heard of a few other guys, just dont do it while its HOT, let it cool a little bit and just in case you have a hot spot, it wont ignite the fluid. now just let that stuff set quite a while, i normally do 24 hrs since i have the time too, but id say about 12 hrs should be good but keep a check on the level so it doesnt completely drain down before hand. also, dont fill the cylinder up with a bunch, or you will have to crank it with rags over the wholes to clear out most before putting spark to it. just make sure that pistons are completely soaked maybe like 1/4" deep or a little more.