Engine/car loud?

[usinjin]

It's role is to preheat the catalytic converters so they can do their job right away on cold starts. Interesting that with the MS45.1 DME, the SAP has a MAF to monitor air flow.

If you eliminate the SAP system, you'll need to code out the SAP and the secondary O2 sensors... same as if you were putting headers on the car.
Also, If your state has emissions tests, It will most likely fail even though you have cats due to the fact that those two entries will be non-functional when they read from the OBDII port.

In Texas, it varies by county. I am in a county that does a safety-only inspection (no emissions).

Mafia, I am not sure if this is the same subject or not, but maybe someone would help me to understand something. My understanding is that the SAP system is only there for emissions reasons--feeds air into exhaust manifold on cold starts and runs for just a minute or so. There are many, many explanations of this system on the internet and I've read many of them.

However, a new shop I recently took my car to said that the slight engine roughness that has plagued me for so long is due to the fact that I most likely have carbon buildup on my SAI valve. I take this to me "secondary air intake valve". But again, isn't the functionality of this valve limited to the few minutes of the car warming up?

Is it possible that the shop means the Idle Air Control Valve?

[PetesZ]

I’d check that or the disa.

May also be time to clean your mass air.

Typical issues with your ccv should show smoke and or lost oil

[usinjin]

I’d check that or the disa.

May also be time to clean your mass air.

Typical issues with your ccv should show smoke and or lost oil

I'll check my DISA. MAF was just replaced. No smoke or oil loss from what I can tell--indy shop is insisting carbon is built up in the engine. They quoted $2200 to pull the head to scrape it out (ahhh no!) or just cleaning the "check valve". Still not exactly sure what they mean by this.

Is it normal to have to do a "carbon scrape", or could that be solved with Seafoam?

[Sockethead]

If there is enough carbon buildup on the valve they talk about, it could keep the valve from closing all the way letting air back into the engine. You could temporarily remove the SAP, block off the hole in the head with a block off plate and see if your problem goes away. You'll get a check engine light but if you put the SAP back in after the test and clear the codes you should be good.
When was the last time you changed your spark plugs? This can cause rough starts too...

[Newjack]

If there is enough carbon buildup on the valve they talk about, it could keep the valve from closing all the way letting air back into the engine. You could temporarily remove the SAP, block off the hole in the head with a block off plate and see if your problem goes away. You'll get a check engine light but if you put the SAP back in after the test and clear the codes you should be good.
When was the last time you changed your spark plugs? This can cause rough starts too...

This is good advice, I would start here.

[usinjin]

If there is enough carbon buildup on the valve they talk about, it could keep the valve from closing all the way letting air back into the engine. You could temporarily remove the SAP, block off the hole in the head with a block off plate and see if your problem goes away. You'll get a check engine light but if you put the SAP back in after the test and clear the codes you should be good.
When was the last time you changed your spark plugs? This can cause rough starts too...

I understand your test, and I want to understand why it would lead to sub-par engine performance--if the valve doesn't seal correctly, does this mean exhaust gasses could leak from that intake line back into the engine?

Edit: also, evidently our cars don't come with the vacuum line on the check valve (from what I see at realoem). Why is this?

[Sockethead]

That valve hanging open would be the same as having an exhaust manifold leak. Not only would that make the engine louder, it could potentially throw the mixture off since the air leak would be before the O2 sensors

[usinjin]

Well, I replaced the valve with a new gasket and the Turner Motorsports stop plate, and the problem and noise persists. Seems like it might be something else.

The noise sure sounds like some sort of leak. It's not constant, but it gets louder at times under low/moderate acceleration. I'm definitely feeling a loss of power as well, and my fuel economy has dropped about 5 mpg.

I ran a Seafoam treatment through the brake booster and the intake. This seems to have helped smoothed the car somewhat, but it's not the root of my problem.

Interestingly enough, when I pulled the brake booster line, the engine seemed to run BETTER than when it was connected. It idled slightly faster and stronger. I thought it was supposed to idle worse when disconnected with such a large vacuum leak??

[PetesZ]

Try a smoke test. Did you pull the electrical connect to the SAP?

[usinjin]

Try a smoke test. Did you pull the electrical connect to the SAP?

Smoke test is next, as soon as I can rig something up. SAP connection was disconnected.