2002 Saturn L300 • 135,000 miles

My car will crank fine, then idles a little rough meaning the RPMs jump from 300 to about 1500 in a slow sporadic fashion. It will idle like this for a few minutes (maybe 5) then even out. If I put the car in drive or reverse during the first five minutes when it is cranked it immediately conks out. I can cranked it right back up without a wait and try again.

If I crank it, then rev it to about 3500 RPMs for about 10 seconds, then bring it to 1000 RPMs, and while holding the gas at that level put it in reverse or drive I can get it going on the street and usually do not have a problem after it runs for a mile. Acts fine afterwards.

In the last three months that I have had the problem I have had it conk out on my while driving at about 30 mph on three occasions. Each occasion was a couple of weeks apart.

What I have done so far:
I replaced an 02 sensor after it came up bad with a code check.
I have cleaned the MAF sensor and replaced the air filter.

Current Codes I have right now are:

August 15, 2012.

Scan it again if the same codes pop-up, try erasing it and then clean out the Idle air control valve and EGR/PCV valves and test the throttle position sensor-to include a fuel pressure check-

Aug 15, 2012.
Just to add to this the code P0128 is a bad thermostat really common code on those cars.I have replaced a lot of thermostats for that code. As far as a idle air control valve the car doesnt have one. It has a throttle servo that uses the throttle plate to control idle speed. Also as far as the tps there two of them if there is a problem with on it will set a code for it which you dont have. As far as the code P0405 that is for a egr valve low sensor voltage a sticking egr valve wont set that code. Also the code P0102 is for mass air flow sensor low signal voltage.I belive the P0405 and the code P102 are related and have a issue with the 5 volt refrence going to them. Do you have a scan tool that reads live data?

Aug 16, 2012.
Well, I cleaned the ERG, but couldn't get to/find the PVC valves. I need to find a multimeter to test the throttle sensor.
I also found a cracked tube that I have replaced. I am only getting code P0102 (MASS OR VOLUME AIR FLOW A CIRCUIT LOW) now. The car conked out while in park idling for about 2 minutes. It is still going up and down with the RPMs.
I went to Advanced Auto Parts and used their scan tool to read the live data here are the results: TROUB CODE P0102
CALC LOAD (%) 3.5
MAP("HG) 13.6
COOLANT ( F) 198
ST FTRM1(%) 0.0
LT FTRM1(%) -0.8
ST FTRM2(%) 0.0
LT FTRM2(%) -0.8

When I chose Read data this is what came up - the car was idling in park.

CALC LOAD(%) 3.5
MAF(LB/M) 0.17
MAP("HG) 15.1 (this number has a down arrow by it)
COOLANT ( F) 178
IAT( F) 129
IGN ADV ( ) 14.0
ST FTRM1(%) 26.6 (this number has an up arrow by it)
LT FTRM1(%) -0.8
ST FTRM2(%) 22.7
LT FTRM2(%) -0.8
VEH SPEED(MPH) 0 (this number has a down arrow next to it)
O2S12(V) 0.380
O2S22(V) 0.350

Not sure if this helps figure out the issue. If anybody wants to give me more specifics of what to do with the live read I will definitely go back to the parts store to borrow one.


Aug 17, 2012.
The pcv is a box on that one car dont worry about cleaning it.I dont know why you cleaned the egr valve a dirty egr valve isnt going to set a code P0405 because a egr low voltage isnt caused by a dirty egr valve. Its caused by a wire issue bad egr valve etc. But the reading your looking for isnt in that live data your able to get with that scan tool your using. You need to see the egr voltage with the engine off and the key in the run position.

Aug 17, 2012.
I cleaned the EGR valve because the first person replied that I needed to. I am not well versed in car repair. Instead I am a computer guy. I can take your phone completely apart and put it together without a thought, but I look at a car engine and get a little lost at the view! Haha.

The only code I am getting now since I replaced the cracked tube is P0102. No more P0405. I even reset the codes yesterday a few times while driving. I was able to drive 10 miles with no service engine light coming on. The code P0102 only occurs during a fresh crank when the engine is running bad.

Do I still need to see the EGR voltage with the scan tool due to the code P0102 or does this look like a MAF sensor replacement is in need?

Thank you so much for the help so far. Definitely going to donate!

Aug 18, 2012.
I posted the trouble tree for the code P0102 I would follow the trouble tree since there are no other current codes. ALso for the code P0128 that code will come back its a slow setting code sometimes. Its a bad thermostat its not a fun diyer replacement you have to remove the upper and lower intake manifold to replace it. ALso lets try this while its idling take a screw driver handle and lightly tap on the mass air flow sensor see if that changes the way it runs. ALso which hose did you replace?When you donate make sure you donate to this question so I get credit. ALso let me know when you do and thanks in advance for your donation.

Aug 18, 2012.
Thanks for the tree, I will check that out. It actually wasn't the entire hose, it was the rubber tip of the tube. An employee at O'Reilly's cut me a new tip which worked well.

I attached two pictures showing the location of the hose (circled in red). In the closer image the tip looks gray because I wrapped it tight with duct tape until I could get to the auto parts store to replace it.

I have heard the thermostate is a pain - dealer wanted $400 to do it since it would take so long. I have also heard the thermostats are flaky and require replacement quite often. I hope not as I am going to set a day to replace that and the belt at the same time.

I will be sure to donate to this specific question and will let you know how following the trouble tree works. I bought a OBDII to USB ElmScan 5 from Amazon so that I can get more info without having to drive to the auto parts store every time. The code reader I have just reads and erases - no info on the screen or anything.

Aug 18, 2012.
Its common for that short piece of hose to split I have seen it split many times. Also I wouldnt say the thermostat fails over and over again I havent really had to replace them over and over again on the same car. You have to becareful not to split the intake boots when removing the intake manifold and putting it back on. Also when removing the upper intake make sure you dont loose the oring in the lower intake manifold that seals againist the upper intake. Are you talking about replacing the timing belt?

Aug 18, 2012.
Nope, no timing belt. Had that replaced by the dealer at 98,000 miles - currently at 133,000. I was too scared of screwing something up by replacing the timing belt. I have a Haynes repair manual now and feel better about making more repairs these days though.

I meant I was replacing the serpentine belt. I have heard that is a semi-easy one to do.

Aug 18, 2012.
Yeah you remove the air box support the engine with a jack remove the upper engine mount jack the engine up.I do that makes it easy to get access to the belt to replace it.

Aug 18, 2012.