Well of course with a boost controler set at 10 psi .

A few moths ago I got my engine rebuilt. Happy with it so far, runs strong. Currently I'm running all that set up with an HKS FCON piggy back ECU. Running rich as hell which is good and all, but I venture into saying that it is running too rich. Kinda an over kill especially after I keep reading about how the stock ECU compensates enough fuel if we stay at 10 psi.

Here's my situation: I want to put my cat back on, remove the HKS F-con and PASS EMISSIONS. Therefore my only mods are a light streetport and a DP. Which at some point I'll want to re-install the straight pipe. But do I really need the ECU? Again, I really don't care to boost past 10 psi.

I'd rather keep the cat on than to be running THAT rich. I know that my best option is to get a PFC and get it tuned. But I really don't want to spend $1200 + tuning $$ so I could just run a midpipe. Seems silly.

Comments apreciated.

 

If you can actually keep it at 10 psi with the midpipe WITH NO SPIKING, then it's reasonably safe. If you still have the stock cat-back and intake, they may provide enough restriction to maintain 10 psi, even in colder weather. Otherwise, just get a used Pettit ecu for $400 -- you should know that as long as you've been here.

BTW, running really rich is bad for the car. You will carbon up your rotor chambers, which can kill a motor as well and certainly will hurt your chances of passing emissions.

 

Not tryin to be a smart a$$, but you probably have read it before here is a good way to prevent the spiking from occurring. spiking

 

Thanks guys.

Yeah I'd figured that is wasn't good to be running that rich.

 

I think you're an idiot. No offense though...

 

One thing to take into consideration is that with that street port, you will be shoving more air into the engine for a given boost level. So the street port increases your chances of running lean.

This is different than what happens for the DP/MP/intake where if you hold you boost down to stock levels you really aren't pushing anymore air into the engine and shouldn't run lean.

Don't be penny wise and pound foolish. If you spent the $$ for the street-port on the engine, it would make sense to at least get on a dyno w/a wideband O2 and find out.

-b

 

THe mild street port was the reason for my concern even though it's only ported on the exhaust side. And yes I'm scheduled to be Dynoed next week

 

:

Personally I wouldn't put a stock ECU on my new ported rebuild

 

exhaust side?! i thought it was customary to NOT port the exhaust side and only port the intake side. especially with twins.

 

Here is something interesting I found on the web today, about what the stock ecu can handle, I am not sure how factual it is...

http://www.wvinter.net/~flanham/wlan.../3modrule.html

 

What you mean you're not too sure how factual it is? Wade was the first to really test and prove that the 3-mod rule was bogus. Many of us other guys have since validated his testing with wideband testing of our own.

 

If I had a dollar for every time that Rynberg had to tell someone to keep their boost at 10 psi with the stock ecu ..............

 

my friends have run straight pipe w/o pb or ecu upgrade and they have leaned out and poped

 

Not at 10 psi, they didn't.

 

Anytime a mid-pipe comes into play, the stock ECU is not a good idea.

Regardless of what PSI you're capable of generating, CFM is another story.

The volume you are flowing at 10 psi on the stock intake and exhaust tract is not what you're flowing at 10 psi with a modified intake and exhaust tract.

Forget about PSI, CFM is really what matters.

The stock ECU has maps for stock flowrates. Don't screw around - get a PFC.

 

I certainly agree with you that running a midpipe with the stock ecu is a really bad idea. However, wideband testing with the stock ecu and midpipe at 10 psi still indicate very rich A/F readings (below 11:1).