View Full Version : Open Loop Required?


C5X2C
03-15-2005, 06:23 PM
My Tuner has told me that because of my cam he has to keep me in Open Loop to get a good tune. Is that right?

Upgrades include:

AFR 205 milled .024
224/228 114 LSA
LGM LT with random cats
FAST 78mm Intake
30lb Fuel Injectors
LS6 ported Oil pump
Performance Dampner

It was running very rich, warm idle and warm starting proved to be an issue. I thought it could be tuned correctly using the O2s.

under_construction
03-15-2005, 06:40 PM
You should be able to run closed loop with that cam, lookup Tony Mamo's AFR car , similar (if not the same) cam. Many are running far bigger in closed loop (230-240 duration). Leaning out the idle range VE will help both problems.

Another_User
03-15-2005, 09:08 PM
Lies, all lies! I really need to go into the tuning business. Especially now that I have all the kinks worked out of my tune. If I can tune a hotcam on a 112 LSA to run smooth as heck, then that cam can be tuned.
:)

Black02SS
03-15-2005, 09:34 PM
It can be done. I had stg2 TEA heads, a 224/224 112 CC, Fast 78MM, ect and it was running fine in closed loop.

MIGHTYMOUSE
03-15-2005, 10:05 PM
sounds like you should find another tuner.. theres no reason

i run closed loop everywhere exept at a hot idle because it will hunt on me with the small injector pulses i have.

C5X2C
03-16-2005, 10:15 AM
Thanks for the Advise. We'll see what my Tuner has to say about it!

Another_User
03-16-2005, 06:10 PM
Thanks for the Advise. We'll see what my Tuner has to say about it!
Yes. Please tell us what he says.

C5X2C
03-18-2005, 10:20 AM
We had a fruitless discussion and then he started many of his comments with "50,000 idiots on the Forum", this and that, and I restated that I wanted a steetable tune without going Open Loop. He agreed to take a look again.

He ran a smoke test (?) and validated that were no vacuum leaks and the FAST intake was sealed well. There also didn't appear to be any exhaust leaks, at least up to the cats.

What he did notice was the PCM was continually adding fuel to the drivers side because the O2 was reading lean. This is why after a short time it was running so rich and having idle and start issues.

He commented that the issue could be the length of the LGM LTs and placement of the O2 sensors which he does not prefer and then stated that he seen more rwhp with the Kooks. I don't think that would only effect one side of the engine.

He stated:
Could be the O2s, but he replaced them with the H/C upgrade.
Could be the lifters, but they were replace also.
Could be the coil packs, he replaced #2 and #3 with the H/C upgrade.

He suggested that we replace the remaining 6 coil packs and see if that fixed the problem.

I would hope that there would be a more diagnostic resolution that would isolate the weak link without just replacing stuff.

Comments?

:usa:

Squintz Palladoris
03-18-2005, 10:28 AM
You Need another tuner.

Cal
03-18-2005, 11:52 AM
Ditch your tunner and buy a pair of Vette rear O2's. That cam isn't that big but it will always be a little rich at idle with any cam.

MIGHTYMOUSE
03-18-2005, 12:59 PM
What he did notice was the PCM was continually adding fuel to the drivers side because the O2 was reading lean. This is why after a short time it was running so rich and having idle and start issues.



precisely the reason you WANT to run closed loop. if it was closed loop the computer would auto correct and the actual air fuel woud be dead on. if the 02 is reading lean when it is not actually running lean then you have a bad 02. it will throw a code and you will want to replace.

i would also get your money back from buying coils.. they dont just 'go bad' when you change a cam.

Another_User
03-18-2005, 02:19 PM
Your O2 location in your longtubes are probably screwing you. I have seen logs from two different people with longtubes whose O2s made the PCM do the exact same thing. And one of the guys replaced the O2s....I think he did it more than once too if I recall correctly. I think the people making longtubes need to reconsider their O2 placement. I don't think I will ever get longtube headers for my car because of that very same issue. Those longtubes may force you to do an open loop tune. Your cam won't.

Cal
03-18-2005, 05:21 PM
Yeah, running long tubes makes the O2's run cool; they are much farther from the engine. That's why I sugested the 'Vette rear O2 sensors, they have higher wattage heaters in them. Bosch part # 13111 from Autozone or Checker. They are expensive, but well worth it. The other thing is make sure your headers are sealing VERY well. There are negative presure pulses in there that will suck in fresh air and fool your O2 sensors, making the PCM inject fuel you dont' need.

Another_User
03-18-2005, 05:34 PM
Has anybody successfully done an O2 relocation yet?