What about the GS, Ive had a "Catalytic Converter below threshold" code since I got the car, had replaced both down stream O2 sensors but it always comes back, called the dealership about it. And they say they know nothing about it.
Idle Rough
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The TSB was only for the GTs
I have a 2006 GS and the cats were still working fine at 120k miles
How many miles do u have?
I'm at about 175k
Then you just have malfunctioning cats in the header
I mean who knows what happened, when the cats fail they can cause extreme back pressure to the engine which is damaging to the engine, or if they overheat they can break apart and either blow down further into the exhaust clogging the 3rd cat or even get sucked back into the engine and cause damage
Which is why I gutted mine...
I think what my next step will be is to try changing the fuel pump, Ive no idea if its been changed or if its factory. I've heard the fuel filter is built onto it, (Like it being just a filter sock?) Does anyone know how Id be able to check fuel pressure to see if it might be worth going into doing/investing, or what kind of fuel pump would work as a replacement.
With your mileage it’s possible it’s clogged up pretty good
Mines at 150k miles and my fuel trims are around 10% I am guessing because of a fuel supply problem due to the filter in the tank
Would it be best to replace the filter, the pump or the entire assembly, and which would be best as far as brand, I've seen delphi on rock Auto, as far as the entire housing and assembly goes. Which the reason Im suspect of the fuel filter is it startted running a bit better at times running some 91% alcohol through with the gas.
What's your Long Term Fuel Trim on a scan tool?
Ok so that is weird, your long terms should be nearly matching; and yours are way off
Did you get two brand new Denso upstream O2 sensors yet? I want you to do that before anything else
I replaced the upstream sensors. So now all four are brand new. Car is running smoother, but still getting that misfire P0302 code, and have rough idles with fluctuating rpm.
Did you ever do a compression test?
Just did the dry compression test its looking like
Cylinder 1 195
Cylinder 2 178
Cylinder 3 165
Cylinder 4 195
Oof, cylinder 3 is pretty bad, 30 psi difference there is not good
2 really isn't good either if you're concerned about it being perfect or a high performance engine, but would be fine for a daily driver; but 3 is really bad
U sure that you didn't mix up the cylinders and count them backwards? because you said the misfire code was cylinder 2
They're read just left to right while looking into the bay, as the left side is the front of the engine (where timing components are), and the right side is the back of the engine (trans mounts up)
As if they know what they're talking about
No, it's 1234
So you gave me your compressions in backwards order? So cylinder 2 is your super low psi compression cylinder AND the cylinder throwing the misfire code then right? That makes more sense now
All in all, there's not much you can do to fix this except rebuild the engine and rebore the cylinders up to the 87.5mm size and use the Wiseco racing 4g63 stroker pistons and get some stronger rods (150mm) while you're at it, and the engine will be bulletproof and built
Yeah, unfortunately its going past any kind of things I can do with my experience. So I'm just SOL,. Hopefully this post can atleast help some othersif they have these issues. I appreciate the help getting to the conclusion.
I mean if you don't want to have your engine rebuilt, you can always find a known good used one and drop it in
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