1999 Saturn SL2



February, 3, 2010 AT 8:23 PM

Computer problem
1999 Saturn SL2 4 cyl Front Wheel Drive Automatic 124800 miles

Recently purchased used with SES light on, mild external oil leak from head gasket area, and a temp gage that did not go over 1/4 unless in traffic.
I had Autozone read the codes, flagged EGR and knock sensor.
Cleaned EGR and light stayed off for a short time.
Light came on again, this time Autozone read P0410 secondary air.
While troubleshooting that I became convinced I needed to clean the air tube to the exhaust manifold. Before I could get to that I washed the engine down and then the fun began.
Car immediately began stumbling during mild acceleration when warm under moderate to heavy loads.
Service engine light came on.
I replaced the spark plug wires. There was a little water in well 1, I dried it out. I replaced the ECTS. Temp gage still reads 1/4 when warm which measures as ~185 degrees.
Codes now read by garage:
P1670 - quad driver
P1671 - Driver 4 Line 1
P0327 - Knock sensor signal low
P1599 - stall detected
P0410 - Secondary air

Found a Saturn quad driver troubleshooter here : -)
-Checked fuses.
-Upshift bulb N/A
-Coolant temp bulb lights up
-I do not know what a 'shift to drive' bulb might be
-Car does not have fog lights but came with a fog light relay. I swapped the fog light relay with the A/C relay and the cooling fan relay and neither helped the stumbling problem.
-I disconnected the EGR and (I think I got the correct gizzmo, if it is under the intake runners for cylinders 3, 4) canister purge electrical plugs, same problem.
-I disconnected the purge vacuum line to intake, same problem.
-Speedo has not misbehaved that I have noticed.

Note: While cleaning the PCV valve I noticed it seems to be made of a thin disk of metal that barely reaches its seat, not beefy and with a sure closure like the PCVs I am used to. Is this normal?

The car is new to me and I would rather keep the repairs on the cheap side until it proves it is not a basket case. So far - not so good. I do NOT live in an emissions test area. I am willing to get the emissions up to snuff if the car seems reliable.

I have a 3/4 of a day into this and I am getting weary. Thanks a bunch for any help you can offer.


Front Fog Lights


Fog Lights


5 Answers


Service Writer

February, 5, 2010 AT 5:01 AM

Remove Exhaust Manifold and clean carbon build up out of air passages on manifold & in head. The small passages in to exhaust ports can be a bugger to open up. Process can take 3 to 5 hours in my experiences. I work on the head ports until I can feel compressed air entering exhaust ports with my fingers blocking the exhaust port openings to exhaust manifold. Make sure the blockage didn't kill the air pump. This should set things right. What happens is carbon block air pump passages in head so computer cant see the o2 running lean when air pump on

Also, you may want to check continuity on the wire from the pcm to the relay and the relay to the pump. Should be around 5 ohms. Is the relay itself ok?

HAving said that this may have damaged the air pump which in turn may have damaged the relay the ecu quad drivers.

The relay may now be drawing excessive current, destroying driver in PCM. Check amperage draw through AIR pump motor.



February, 5, 2010 AT 10:13 AM

Thank you. I will address the more labor intensive recommendation when I get the chance.

Secondary air pump seems to run fine and when I disconnect it from the vacuum switched valve it does blow air. It is vacuum cleaner loud tho when plumbed properly. I guess because it is reaching full speed because of blockages.

I believe that style of air pump fan actually draws less current when not pumping air.

I would like to address the stumbling issue first since it is a safety issue. It started immediately once the engine was washed. Any ideas?

I will check that relay shortly. Thanks!


Service Writer

February, 6, 2010 AT 6:11 AM

By looks of what we have I would go after the knock sensor code.

We can build theories that will say the knock sensor code is a symptom or a source of the code and or performance.

The Knock Sensor resistance should be about 100,000 ohms at 70 F.

If you can't read the pic, I can send it to you.

Not sure what all got washed, but I hope the pcm didn't get wet.



February, 17, 2010 AT 5:22 PM

We dont need to worry about the PCM having gotten wet, they didnt move the PCMs to the engine compartment until 2000. This one should be under the driver's dash.

The carbon clean-out tip was right on. The carbon that was easy to get at clogging the secondary air tube into the exhaust manifold was cleaned out. Some other easy to clean items were cleaned. Also the knock sensor terminal was cleaned. Doing this cleared all of the codes except the quad driver code.

The car runs better but still stumbles during mild acceleration once warm, it occasionally sounds like it backfires, and it occasionally stalls when shifted into reverse. One thing I need to mention is that the quad driver check list I went through above was to a '92 Saturn SL. I couldnt find anything more applicable. This car was manufactured 6/98 but was sold as a 99 so Im not sure what that was about but I digress. We're down to the P1670 quad driver code which showed up after the engine wash. How do I determine what is causing this code?


Service Writer

February, 18, 2010 AT 4:35 AM

I have nothing that says there should be that code for that car with my software, but I will check another software later.

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