Possible Engine Misfire

[GMFan]

I have been having an issue the past few months where my 2001 Saturn SL has a sputtering exhaust. At idle, especially when the car is warm, the exhaust will repeatedly "burp"...sorta like a muscle car except it sounds more like forceful air coming out the tailpipe. I believe the engine may be missing, but I'm not 100% sure.

The muffler and exhaust pipe do shake a little when the exhaust sputters. The sputtering happens every second or two.

The car has 118,675 miles on it and it received new plugs/wires and a big tuneup around 88,000 miles.

I have sprayed brake cleaner around the exhaust manifold...no change. There is no CEL or SES light on at the moment.

I have replaced the throttle position sensor, fuel filter, tried fuel system cleaner etc. Engine coolant temperature sensor was replaced at 100k miles.

What would be first on the list of things to check for diagnosis?

Thanks.

 

[StevieC]

Could be the following:

1) Slight vacuum leak or other un-metered air leak into the engine causing a lean condition

2) 02-Sensor not functioning properly causing a lean conditon

3) Sticking EGR valve that is staying slightly open. (Try Disconnecting)

4) MAF or MAP or both not functioning properly.

5) Poor compression on one or more cylinders

6) Worn cam lobe not opening the valves fully

7) Poor injector spray pattern on one cylinder or dirty injector.

8) A plug and or wire is breaking down or grounding out

9) Weak spark on one cylinder because of a coil that is breaking down

10) Plugged Catalytic converter

11) PCV Valve sticking and creating too much pressure in the crank case.

12) It's a Saturn with many miles and it's just tired.

 

[Popinski]

Aren't Saturns known to have Throttle bodies and MAF sensors that get easily clogged/dirty? You should clean your throttle body and MAF sensor..

 

[GMFan]

StevieC, perhaps my best approach/gamble would be to look into the EGR and O2 sensor first?

Popinksi, forget to mention throttle body was cleaned at 100k...wasn't too dirty when I cleaned it.

My engine has started to use more oil than it used to...but it's a Saturn thing. I 3,500 miles on my current OCI and I've added close to a quart.

 

[StevieC]

Try PCV valve if equipped (Can't remember)

Check the compression with the engine fully hot. Pull the spark-plugs/wires off and pull the fuel pump fuse and crank with compression gauge attached to 1 cylinder at a time. All cylinders should be within 10% maximum of each other (Eg: 150 - 135)

Then try disconnecting the EGR and snap the throttle a few times. Make sure to plug the vacuum leak if yours is vacuum controlled (Can't remember) and see if it goes away. (may produce CEL)

Then try disconnecting the 02 Sensor (Upstream only) and snap the throttle a few times and see if it goes away. (may produce CEL)

If it goes away with the EGR, it's bad. If it goes away with the 02 sensor you either have an un-metered air leak around injectors intake manifold (Brake cleaner test), a bad MAF, a bad MAP (Don't know what your car has), a vacuum leak somewhere (brake cleaner on all the lines). If none of those the 02 sensor is the culprit.

Good Luck!

 

[The Critic]

Older Saturns don't have MAF sensors, at least mine doesn't.

The spark plugs are supposed to be replaced every 30,000 miles according to the manual, so you are due.

Have you checked for any exhaust leaks?

 

[PandaBear]

how does the brake cleaner test work?

 

[StevieC]

Originally Posted By: The Critic
Older Saturns don't have MAF sensors, at least mine doesn't.

The spark plugs are supposed to be replaced every 30,000 miles according to the manual, so you are due.

Have you checked for any exhaust leaks?


I'm assuming he has checked the basics because this is more of an advanced forum for oil junkies and wrench heads...

Originally Posted By: PandaBear
how does the brake cleaner test work?


If there is an air leak into the engine and you spray brake cleaner or WD-40 or carb/choke cleaner or combustion chamber cleaner (Has to be one of these) in the area it will cause lots of white smoke to pour out of the exhaust as the engine burns this chemical spray.

Make sure to generously soak the suspected areas...

Helps to rev the engine at 2,000 RPM while doing this as well because if the leak is big enough you will hear the engine start sputtering and drop in RPM while doing this.

Great way to find un-metered and vacuum leaks!

 

[CourierDriver]

go for the simple,,pour stabil gas treatment in the tank, 3 oz should do it if u have water in tank, i went thru this with my van. O2 senors usually do not die out, 90 percent of them that are returned to the factory r ok. If that does not do it, place 3 cases of C4 under car and lite it off, u wont need anthing else.lol

 

[StevieC]

Yeah you should probably just use a mechanic in a can and some snake oil while you are at it.

Forget about ever replacing parts or diagnosing things properly these magic cans of "Stuff" can fix anything...

 

[moklock]

Did you try spraying around the intake gasket as well?

 

[beast3300]

I think: intake gasket.

 

[CourierDriver]

sounds like a lot of part changers in here.

 

[GMFan]

Started the car up to go to work this morning and as I stopped to look for cars passing my car made a quick series of rapid loud popping sounds. I looked at my dashboard and I saw the Service Engine Soon light on...so whatever happened at that moment tripped the light.

This will hopefully lead me on the right path. I have been waiting for this light to come on for a while now...

I will get the code read and report back...hopefully it isn't too elusive or vague.

 

[StevieC]

Not necessarily, it might show a 02 Sensor Lean but it could be because of a vacuum leak causing it to be lean.

Hopefully though it does lead you in the right direction...

 

[GMFan]

Was in Ohio for the weekend so I couldn't post earlier, but it turned out the code was for a misfire on cylinder #1. Turns out that spraying brake cleaner does in fact change the idle noticeably.

At first I tried changing the spark plug wires but that didn't fix it. I sprayed brake cleaner again really focusing on the #1 cylinder and sure enough the idle changes.

I bought new AC Delco copper spark plugs today to change after the gasket is replaced. I will replace the coolant with universal coolant...I am weary of the GM Dexcool.

Thank you all for the help.

 

[StevieC]

Good to hear you got it sorted out...

 

[onion]

Originally Posted By: GMFan
Was in Ohio for the weekend so I couldn't post earlier, but it turned out the code was for a misfire on cylinder #1. Turns out that spraying brake cleaner does in fact change the idle noticeably.

At first I tried changing the spark plug wires but that didn't fix it. I sprayed brake cleaner again really focusing on the #1 cylinder and sure enough the idle changes.

I bought new AC Delco copper spark plugs today to change after the gasket is replaced. I will replace the coolant with universal coolant...I am weary of the GM Dexcool.

Thank you all for the help.


FYI, most 'universal' coolants are essentially the same thing as Dexcool. This has been hashed and rehashed over in the Coolant forum.

While I'm personally no fan of dexcool, and DO agree with you wanting to get away from it, your options are limited and difficult these days. G05 is my preferred coolant for most applications, but it can be difficult to find and/or expensive depending on which version you get. Conventional green is still available, but again- hard to find. And sometimes of questionable quality IMO.

If you use universal, you can just top off and go... seeings how it pretty much IS Dexcool. But if you switch to something else, make sure you thoroughly flush the system.

 

[GMFan]

onion,

When I went to AAP to pickup the spark plugs I had in my hand a gallno of Peak anti-freeze but I decided to put it back on the shelf as I was uncertain. I would flush the system first before putting the new coolant in.

I do have Prestone 'universal' yellow coolant that is around 6 years old. It has been opened and only has a bit taken out. It has been stored in a garage. Can I use this stuff or is it past its shelf life? I'd rather use it in my car than keep it around looking for a place to dispose of it.

By the way, interesting to know that dexcool is close to the typical thing. I do have a jug of Preston Dexcool as well that has only a bit taken out (I have used this for top-offs).

Which one would be better to use....or should I pickup a new jug of Peak or AAP coolant?

Thanks.

 

[Merkava_4]

Originally Posted By: GMFan

Which one would be better to use....or should I pickup a new jug of Peak or AAP coolant?


I use Prestone Dexcool in my Buick and have never had any problems with it. I like it mainly for the red color. I've got a very slight leak in my heater core and the leak was easily evident by the red stains it produces against the background of silver coils.