DTC's Present: Direction Needed
 

Hi, my 02 SL1 has largely been a pretty decent car, but it has some issues I need to correct before my wife has to resume using it as her daily commuter car. The DTC's present are:

- P0301 Cylinder 1 Misfire
- P0507 Idle Air Control System RPM Higher Than Expected
- P0410 Secondary Air Injection System

By order of elimination, my intent is to begin by looking for a vacuum leak, checking/replacing the ECT sensor, and then possibly replacing one or all fuel injectors if needed. I could definitely use some experienced input.

With the engine running, spray some throttle body cleaner around the #1 cyl (closest to serp belt and pulleys) intake manifold runner where it meets the head----ALL thE WAY AROUND AND BETWEEN 1 and 2.

If the rpms rise, you've found your "vacuum leak" which in turn causes the increased idle and misfire on that #1 cyl.

The problem is that part of the intake manifold gasket has gotten partially "sucked in"
to the head and thus the seal between the head and I/M is compromised. Very common on the SOHCs of this era.

Happens at #1 b/c I/M bolt pattern does not provide enough support near #1.

Resolution: Replace intake manifold with a stiffer one than the original to keep this from happening again.
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P0410 -- Sec Air Inj Sys

There is a great video by richpin06a that walks you through diagnosing the Sec Air Inj System:

https://www.youtube.com/watch?v=dIrmkxj6wJE

Richpin has a huge catalogue of Saturn related videos on Youtube covering all kinds of stuff,

Derf is right on. With the exception of checking the spark plugs, especially #1, I would guess that it is the intake manifold gasket. Felpro makes an updated design that has metal inside the gasket that addresses the issue.

I can't tell how glad I am to have some real direction to follow here. I'll keep you guys up to date on how it goes.

The best way to do the job from underneath the car. Drain the coolant first. There is the radiator drain, and a 10mm bolt that is right under the thermostat housing that drains the rest.

After spraying throttle body cleaner around the vicinity of cylinder #1 there was a noticeable jump in the RPM. So, now I get to replace the intake gasket. It only took two tries for me to get the right part because even after specifying that I had a SOHC, they ordered one in for a DOHC. I thought something was off when the box they handed me seemed a little short.

As for the P0410, it turned out to be a bad relay. Once I get the intake gasket replaced I'll have to see if there is anything else I need to be concerned with as it pertains to the air pump. I'm afraid to admit that code has been present for a while.

Once again, thank you all for the input and the recommendation about accessing the bolts from underneath.

It really isn't a bad job. I did it on my 01 last year. I'm trying to remember if there are any tricky parts, but I think it was fairly straight forward.

I was finally able to get back to fixing the car, and so far there is a significant improvement in the idle. It is sitting where it should be now. Hopefully nothing new pops up when I take it for a test drive.

On a side note: I was really surprised and amazed by how much carbon build up had occurred inside of the intake manifold. Cleaning that thing out turned out to be quite the chore.