racecar

SD tune with a decent cam and headers. I turned off my LTFT to see how good my tune really is, and it's great all throught the rpm range. There is a problem at idle. It starts at 14.7, then just keeps dropping 14.6, 14.5, all the way to 11.7 in about one minute. The scan looks like the O2's are seeing a lean setting. I am thinking with a cam and headers, the O2 are just not seeing enough signal, they think there is no fuel in there and keep adding, but the wideband is showing rich. So now what Do I just go to open loop and set the idle without STFT or LTFT?? I am planning to install a MAF sensor so I can get through state inspection. Can I run a MAF with open loop. I suspect this is a common problem with cam and headers?
Ideas?

ND2RACE

Possible bad O2s, command open loop and see how it goes. There's no reason to run OLMAF unless you want to, but it is possible. This isn't usually an issue, your O2s will work just fine regardless of the cam and headers. Is it both banks? If your wideband reads rich I doubt that its wrong, usually if there's a problem with a wideband it will go lean (exhaust leak, ect.). Does the car seem to be running rich? or are you just judging off the wideband?

Patrick G

iTrader: (14)

Make sure your O2 switchpoints are set at 450mv across the board. Make sure you have no leaks anywhere near the NBO2 sensors. Any exhaust leak will have you chasing your tail. Are your VE tables tuned off your STFTs or WBO2 sensor? If you tuned VE table off your WB, try tuning it off your S-Trims instead. I also noticed that you have SVO injectors. You'll need to run the Ford voltage offsets for your injector timing. The stock table won't give you the fueling you need.

jimmyblue

iTrader: (11)

An idle AFR that starts OK when you come down from
hot cruise, and then drifts like that, says a sensor heat
problem. Possibly, or not, compounded by age / crust.

racecar

ND; Yes I am reading from my wideband rich at idle, it is in one bank. If I look at the scan, both banks of OEM O2s are active and read about the same so I think both are good.

Patrick; I have been experimenting with O2 switching today, I have smaller numbers in there now, it's better, but still unpredictable, I will try the 450. I Have been tuning the VE in SD with the wideband for a year and it is good. Now with LTFT turned off, the wideband is really steady at 14.3 cruising. Ford Injector voltage?? Got any numbers for that?

My WOT and mid are great, I just need to get this idle consistant so I can add the MAF and pass state inspection. I have CATs, so if there are no codes, I should be able to pass, but if the idle goes down to 11/1, the DEQ test guys may small a rat. I have never tried to get this car through the inspection, they may freak out when I pull in there, so I would like the idle to be right in case they want to plug in for a sniff test.

Hey Jimmy; my wideband and OEM O2s say the same thing, something overheating ??, anything is possible. Thanks guys, I'm going to set the switching to 450 and plug in the MAF, and see what happens.

You guys are the greatest..

Slowhawk

iTrader: (12)

Sounds like it is learning a rich setting.Probly the STFT.The injectors should work fine with the stock setting and not cause your problem.

I'm surprised you have to put the MAF back on for inspection. Ma. is second to California and we get pass inspection with no MAF's, No 02's, no nothing really(no codes and ready tests working 100%).Just need the Cat shells and a decent exhaust.

racecar

With no MAF, if I set the code to 3 No Error Reported, the car won't start. I have to set it to 2 No MIL light to get it to run, but if you plug in, there is 0101 or 0102 code.
Is that normal on a 99 C5??
That's what I ran into when I first SD tuned. Maybe I should experiment with that. Yes, for DMV, they just plug into OBD, no codes, history present, you are good. With this race car, they may have a cow when I show up.

racecar

As Patrick recommended, setting the O2 switching to 450 seems to be the magic number. I had them lower and it did not work as good. At 450 I had to raise the numbers in my VE table because I had it way leaned out. Idle is better, A/F still drops from 14.5 to 13.6 before it stabilizes.

Whenever I reprogram, it takes the tune a while to stabilize. Why is that, is the computer still learning something even with LTFT off.?

FRUSTRATED T/A

iTrader: (13)

https://ls1tech.com/forums/fueling-i...y-engines.html
might help a littel

Slowhawk

iTrader: (12)

Luckilly those are not the SVO-30 or 42lb injectors.

racecar

Oh Fudge, Mine are SVO 30 LB are they OK? I saw that other post that showed the SVO next to an LS1. The SVO had two streams, the LS1 was like a fine shower.
Do I need new injectors?
What would be a good LS1 replacement 32lb that will not require adaptors.

FRUSTRATED T/A

iTrader: (13)

yea i forgot the last post where is said 39 and 23lbs injectors opps.

He says its only the 39 and 23's. So your 30's should be fine i guess. I have the 42s and im tring to get ahold of him to have mine cleaned and i want to ask if the 42 are this way also.

Could fuel be vaporizing more while running higher rpm, then the runner walls cool down not vaporizing as much at idle. I believe theirs tables for it, i would think though the amount would be so small not to make a big difference. Just putting it out their.

racecar

I had to make my own MAF chart using data from an 08 Corvette. After a few changes of 20% overall leaner, it works pretty good. It is easier to street drive with the MAF.

With the MAF installed, the idle is better and more stable, but the idle still wants to go rich. This is strange. When the WB A/F is at 14.0, the NBO2 are reading lean, and STFT are adding more and more fuel. It keeps adding until the wideband is showing 12.2.
If the WB is accurate, why do the NBO2 think it is lean at idle.??

jimmyblue

iTrader: (11)

I still think you've got a NB O2 sensor heat problem.

racecar

The Innovate manual shows how to build a heat sink around the WB O2 sensor if it is mounted close to the header. That may be worth trying on my NBO2s in my headers. Do you think that will help.

FRUSTRATED T/A

iTrader: (13)

I would agree its a wide band or o2 sensor. Long tube headers have so much more area to allow them to cool off, mybe their just not hot enough. If your header arnt coated i suggest mybe trying wrapping them, or a better sensor.
where is your wide band placed? Although your wide band wont cause it to add lift and sift values, so o2 sensors like said before.

racecar

My headers are thick ceramic coated so they should be holding the heat. The WB is back in one pipe, after the CAT. NBO2 are lean, WBO2 is rich.
When I first put headers on years ago, I got codes at idle for insufficient O2 activity, so I keep thinking this is a common problem with headers.
I'm going to check out Jimmys theory tomorrow about the NBO2 overheating, If I let it warm up for a minute then let it idle, it should be OK because the NB is not hot at that point.

racecar

I checked the Injector msec on the scan, and at idle it's at 1.9. The Short Pulse Limit is set at 3.9. OK, maybe this is why idle is rich, the short pulse adder is adding fuel.
I set the short pulse adder to 1.5, the idle is better now, it's around 13.2-13.6, and holds pretty steady there. I lowered my VE in the idle cells from 32 to 30, that did not make much difference. I am going lower the VE to 29 or 28. Does everyone else with a cam (233/239) have such a low number in their VE at idle??? Is there a limit to these SVO 30 lb injectors, maybe they cannot go any lower?? Any ideas... I would like to idle at 14 or 14.5 so I don't foul plugs.

tomz28

iTrader: (20)

i have had the same thing going on with my car. i looked the switchpoints on my car and the are still stock. cant wait to try this out

racecar

Hey tomz, I set the switchpoints to 450, it seemed to help keep the idle A/F consistant.
Now I am leaning out the VE table a little more each day and driving for a half an hour. It
is still rich 13.4 at idle. I think the weather is getting warmer every day and with my SD tune, I am leaning it out and the result is net. With the LTFT turned off and no MAF how long do I need to drive to see results, it should be instant right???