Jonthamo

Hi all, new to the forum and new to my 07 SS/SC as well. I've owned an IRL before, so somewhat familiar with the LSJ.

Anyhow, I've got a randomly occurring at startup P0303 on my car. Sometimes it's accompanied by a "system too lean" code as well, I can't remember the P0 number for that one. When the MIL comes on, I can definitely notice from outside the car that it is missing a little at idle, but it does not affect driveability at all. When the MIL is not on, it idles fine. MIL has only come on at startup, never midway through driving. Does not seem to go out on its own. Have not made any changes to the car since the light started coming on.

Car setup: stage 2 pulley, injectors and reflash, factory GMPP exhaust, aftermarket "performance" MAF, custom made CAI, runs the same as a k&n typhoon intake.

Things I've done so far: switched coil #2 and coil #3, cleaned MAF, verified IAT is good. All to no avail. Anything else I should try?

I have a startup and idle log for my car from my scan tool showing both O2 sensor voltages, RPM, temp, and STFT. To me the bank 2 O2 looks a little funny but I have very little experience. If this log would be of use to someone more experienced please let me know and I can email it to you.

Thanks,

Jon

mrbelvedere

iTrader: (3)

sounds like you need to get it tuned

Jonthamo

So the car could be fine for 500km and then intermittently start throwing a P0303 and lean code because of the "stock" stage 2 flash? Yesterday the car had zero symptoms. Who knows what will happen today. It's pretty sporadic.

ECaulk

iTrader: (6)

What is the performance MAF?

If you have a GM Stage 2 tune it needs the stock MAF and stock intake.

mrbelvedere

iTrader: (3)

weather changing on a shitty tune can cause that

agreed probably a zzp can tune

Jonthamo

There definitely was some colder than usual weather when it happened last! (Canada) Did not happen again today, 2 days or 3 in a row without a problem.


agreed probably a zzp can tune[/QUOTE]

I'm pretty sure it's a JET MAF. Either way it's aftermarket, looks high quality and USA made. I don't know the brand of the intake. It looks like a custom made one. No obvious branding and nice welds, I could remove the whole thing and check closely if needed.

You guys suggest getting a dyno tune with these mods?

ECaulk

iTrader: (6)

Getting a tune for the mods you have is the best idea. Get rid of the Jet Maf, go buy a AC Delco maf. Let the ECU actually see the air correctly.

The intake is not as big of a worry if you're getting a tune, who tunes you should be able to make the correct adjustments for it.

Jonthamo

Okay. You don't think it's a fuel issue or anything hey? Even with light on it runs great as long as it's above idle.

I also forgot to mention, I don't know that I'm making full boost. I have an auto meter mechanical gauge. It peaks at 11 maybe 12 PSI. When I bought it, it was way colder outside and made 14-15 psi. From what I remember, a stock SS/SC runs like 12psi doesn't it?? Plugged cat?

mrbelvedere

iTrader: (3)

The cat is not plugged ad check the fuel pressure

Jonthamo

Update: I lost a cylinder on the way home today. Not bagging the car or anything, suddenly lost power severely and the car sounded remarkably like my Impreza WRX. 500m later engine light started flashing. P0304 this time. Cleared codes, switched coils and plugs and same code on startup. Idles VERY poorly and is not driveable. No obvious problems with coils or plugs on all 4 cyls. No engine knock or ticking at all. No metal bits visible through plug holes. Ideas?

Looking for a compression tester to borrow, I think that's the next step.

Sharkey

iTrader: (1)

compression test, if it looks ok do a leak down test. it could also be an injector issue causing it, you can swap the injectors around and see if it follows.

my guess is you have a broken piston.

mrbelvedere

iTrader: (3)

180 to 210 is the spec and sharkey is probably right time for an engine

Jonthamo

okay, thanks for the specs. Will update you guys tomorrow night probably, when I get a chance to run the tests

Jonthamo

Test results:
Cyl 1: 180
Cyl 2: 175
Cyl 3: 80
Cyl 4: 0

Could not find a leakdown tester to borrow, but I'm pretty sure engine is shot. Thanks for everyone who commented, I appreciate the welcome to this forum. It's Saturday, so everyone is closed. Anyone know approx cost to have professionally re-built to stock vs used engine vs cheap ish performance build myself?

Sharkey

iTrader: (1)

no use doing a leakdown test, its shot.

cost to rebuild it really depends on how bad it is. if it just broke a piston and the sleeve is ok, then its not so bad, could toss another piston in, freshen the head and away you go. if it damaged the sleeve your best bet is to just find another motor, especially if you arent planning to make a bunch of power.

you can search for used engines on Car-Part.com--Used Auto Parts Market. if you want to look for stock rebuild items rockauto has stuff. for performance parts ZZP Platforms.

if your wanting to build an engine yourself it really depends on your end goals. a stock engine is more than happy up to 300whp with a blower on it, itll do up to 400 with a turbo swap. to go further a set of aftermarket rods and pistons, head studs and stiffer valve springs are all you really need, neutral balance shafts are also a good idea. around 450hp your starting to play with fire with the weak cylinder walls, there is a member here with better sleeves, or you can go with a zzp girdled block to support more power.

Jonthamo

This is the most appealing solution to me. I would be happy with 240-250whp. This car needs to do 2 things for me: be Canadian winter friendly and maintain resale value without a massive investment. I don't plan on keeping it more than a year or maybe 2 years max.

Correct me if I'm wrong, but the only way to really properly tell if there's scoring is head removal. I have a scope, but it's pretty low-resolution. I imagine you could pull the head, then pull the oil pan and do the pistons while still in the car? Or perhaps it is faster to drop the cradle so a fella can disassemble more efficiently?

Sharkey

iTrader: (1)

you can pull the motor apart and do an in frame rebuild on it if the bores are ok. you will need to pull the head off to have a proper look at the bore.