10:1 Commanded afr at startup

[Admiral Jedi]

'03 Cavalier Ecotec. Supercharged, blower cams.

When I start the car (regardless of temperature), it will idle at 14.6-14.8:1 for a few seconds, then I watch as the commanded afr goes down slowly to 10:1. After letting it sit there for a few moments, the car slowly changes its commanded afr back up to 14.6:1.

Also: when I'm decelerating in gear, the car will go lean like it should during DFCO. Very often when I push in the clutch, the rpms will fall and the motor will eventually stall out. I don't know if this is a cam related issue or something in my tune. Stock cams are going back into the car sometime this week to see if that helps.

Any help would be appreciated.

My computer is being dumb and not letting me upload files...I'll keep working on it.

[pjk91]

i think it has somehting to do with when you change the map sensor and rescale it in the table, because my car does the same thing. there is probably something else that needs to be adjusted when you rescale teh map.

[Admiral Jedi]

I'm using a stock map sensor with the stock maps.

The Jbody ecu can't be scaled.

[oldskool]

I know i mentioned this on JBO, but i'll say it here for good measure too

The correct way to resolve would be to have access to the open loop table that controls commanded AFR at warm up/idle. There are two quick ways to "solve" the problem otherwise. Change the OL/CL engage temperature so that it enters closed loop more quickly after start up, and take it easy on her till she warms up.

The other option is to lean out the idle VE table so that its not so pig rich when its warming up and still in open loop commanding 10:1 AFR. I have noticed this same occurance and my set up is much different than yours. Like I said before, there's no reason to be wasting that kind of fuel on warm up - just drive off and take it easy on the throttle until it warms up.

Do you have any CEL's with the stalling issue? Does it go extremely rich when you push in the clutch? Have you modified the non-PE spark advance tables in the lower MAP cells at all? I have no experience tuning for different cams, but someone else may be able to chime in on that one.

[Admiral Jedi]

^ I have tried changing the OL/CL settings so it goes into closed loop almost immediately. It still does it.

I will try altering my idle table though.

[imphat0260]

I got your email... I also repsonded to it after looking at your file... Your VE tables are all out of wack.....

[oldskool]

^ I have tried changing the OL/CL settings so it goes into closed loop almost immediately. It still does it.

I will try altering my idle table though.

So does it go into closed loop? If so, what are the actual AFR readings? If it IS going into closed loop, it can command whatever it wants, but it should achieve 14.6:1. My car still commands stupid rich AFRs, but since it goes into closed loop almost immediately, the O2 sensor takes priority over the commanded AFR/VE table.

The idea behind changing the idle VE is to lean it out obviously, but if all other things are correct (injector constant, multipliers, ect), it will be lean relative to commanded AFR. I would just subtract 2 percent or so from the idle table until it is where you want it to be in open loop. Until we get control of everything that's going on in open loop, these are the best tuning "band-aids" i can come up with

Do you have a tune file and a log file with Wideband logged handy to post up?

[blackeco]

I got your email... I also repsonded to it after looking at your file... Your VE tables are all out of wack.....

x2, send your stock file.

Also it looks like you have changed idle spark tables?

[blackeco]

So does it go into closed loop? If so, what are the actual AFR readings? If it IS going into closed loop, it can command whatever it wants, but it should achieve 14.6:1. My car still commands stupid rich AFRs, but since it goes into closed loop almost immediately, the O2 sensor takes priority over the commanded AFR/VE table.

The idea behind changing the idle VE is to lean it out obviously, but if all other things are correct (injector constant, multipliers, ect), it will be lean relative to commanded AFR. I would just subtract 2 percent or so from the idle table until it is where you want it to be in open loop. Until we get control of everything that's going on in open loop, these are the best tuning "band-aids" i can come up with

Do you have a tune file and a log file with Wideband logged handy to post up?

There should be no problem getting the car to idle correctly with what HPT has given us. Assuming the injector constant is correct it should ide fine. If not it could be a faulty sensor or another issue.
I think he has just created more problems for himself by what has been done so far. I would recommend putting all the VE and spark tables back to stock. You should then be able to adjust injector constant until it idles correctly.

Once the car is idling fine then you can begin to work with VE tables to add fuel for boost. In fact the easiet thing to do would probably just ditch the current file. Edit a variant of the stock file with the VE offset you need. Make sure the VE table values default and go from there.

[imphat0260]

There should be no problem getting the car to idle correctly with what HPT has given us. Assuming the injector constant is correct it should ide fine. If not it could be a faulty sensor or another issue.
I think he has just created more problems for himself by what has been done so far. I would recommend putting all the VE and spark tables back to stock. You should then be able to adjust injector constant until it idles correctly.

Once the car is idling fine then you can begin to work with VE tables to add fuel for boost. In fact the easiet thing to do would probably just ditch the current file. Edit a variant of the stock file with the VE offset you need. Make sure the VE table values default and go from there.

I said the same thing in the email.... You could poke an eye out with those VE tables.....

[oldskool]

I have not seen his tune file - did he post it in another thread? Or just email it to you guys?