Small 16g with 660cc injectors tuning question

[Jdiddy2k4]

So I have put a small 16g on and at around 10psi I am already running lean on the wideband at around 10.6 so I let off the gas. I have some denso 660cc injectors that aren't installed yet and I have a couple of questions. My fuel system is stock, however I have the 660cc injectors as stated earlier and an evo 8 fuel pump ready to be put on.

Would it be possible to put the injectors in and tune it somewhat with my safcII and logger just so the car isn't running lean, so I can get it to a friends house to get the fuel pump installed because I don't even want to attempt that install?

 

[hdoerr]

10.6 to 1 isn't lean. 11.0 to 1 is optimal so you actually could lean it out a bit.

 

[kottyking]

Why dont you wanna attempt putting in the fuel pump. It's not too hard. I cant get the link to work but go to vfaq.com>fuel>fuel pump install> 2g AWD.

 

[matthewdesigns]

So I have put a small 16g on and at around 10psi I am already running lean on the wideband at around 10.6 so I let off the gas.

That a/f ratio looks great if you are on at least 91oct gas. Might even squeeze it a little closer to 11:1 if you are on 93+. I usually run about 10.6-7:1 on pump 91. 11:1 might be optimal on hdoerr's car, but you'll need to log to see what actually makes more power for your car.

I have some denso 660cc injectors...Would it be possible to put the injectors in and tune it somewhat with my safcII and logger just so the car isn't running lean,

Yes, but I'd look at the wbo2 more than the logger...just pull fuel until you are back to stoich at idle. You'll probably need to start with about a -30% LO adjustment on the afc. That will get you close for idle and part throttle.

so I can get it to a friends house to get the fuel pump installed because I don't even want to attempt that install?

The pump is really no more difficult than the injectors. If you are going to do those yourself, then might as well do the pump too. And rewiring the pump while you are at it is a good idea.

 

[Jdiddy2k4]

Ok thanks for the clarifications. I was under the impression that anything below 11:1 was running lean. So just to clarify....the higher the number the more lean it is? and the lower the more rich?

So when I put the 660cc's in then I will need to take out fuel at idle until I get it down to the stoich number of 14.7 or so

 

[spyderturbo007]

Stoich is 14.7:1 and anything above stoich is lean and anything below stoich is rich. Stoich is where you want to be during light cruise and idle situations. This allows for maximum gas mileage by consuming all of the fuel during the combusion cycle. During WOT runs, you need to be richer than stoich to protect against knock.

To give you an example, the 2g target AFR, on the 2.1g/rev airflow map, is 9.5:1. Most DSM's like to run a little leaner at WOT. Somewhere in the neighborhood of 11:1, depending on the car.

 

[Jdiddy2k4]

ok thanks now I get it. Now I don't know if this is classified as a tuning problem, but during my short drive to autozone I was at a light and then all of a sudden I went down to 10 on the wideband when it is supposed to be around 14.7 and the entire drive after this happened the wideband was reading rich even under cruise conditions and I looked at the logger and the front o2 was not fluctuating around the numbers and the wideband was not either for the rear o2, but as soon as I turned off the car and restarted it was back to normal. So I am guessing it is time to change out the front o2 or do I have a bigger problem?

 

[JeffGST]

If your car went to 10:1 during idle, then the ECU is going into open loop. One of the reason for this is that your ECU is giving up on trying to maintain 14.7 to 1 because the fuel trims are so far off. Another reason could be that you may have been overheating the motor. There are a hundred reasons why the ECU would go into open loop.

Closed Loop = Idle/Part Throttle conditions = ECU is using Front O2 for feedback
Open Loop = Whenever not in Closed Loop = Front O2 is ignored, and the ECU uses the MAF and the fuel maps to control the injectors

What are your Fuel Trims at? What was your coolant temp when this happened?

 

[Jdiddy2k4]

Hmmm I don't know what the coolant temps and stft and ltft were. I guess I will get the logger and see if it does it again and report back with the temp and the fuel trims. Should I just start a log as soon as I am idling at a light so I can catch the full act? The temp gauge was sitting exactly where it is supposed to sit, but who knows. The fuel system is still stock so I haven't messed with any fuel trims as of yet either.

 

[Jdiddy2k4]

ok I got to capture the coolant, stft, ltft, tps, front o2, and rear wideband 02. At the end this was when the light turned green and I pulled into a gas station to shut it off and reset the trims. I don't suppose this would have to do with my rear heater circuit CEL would it?

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Edit: It just happened again as I was at cruising speed on the highway, I got into some boost and the stft reset and the wideband went back to fluctuating around 14.7. Today is the first day that it has happened. I put the wideband in last night, and took an extensive drive stopping at lights and none of this happened. So based on your answer I would say it is either the stft or front o2 making me run rich. How would I go about fixing this?

 

[Jdiddy2k4]

Looking under the hood today I noticed that the vacuum hose that goes on the FPR was off for some reason. Would this affect my rich at idle condition? It doesn't happen all of the time. I will be replacing the o2 sensor tomorrow so I will report back if that fixes the problem

 

[Lonnie gandee]

Looking under the hood today I noticed that the vacuum hose that goes on the FPR was off for some reason. Would this affect my rich at idle condition? It doesn't happen all of the time. I will be replacing the o2 sensor tomorrow so I will report back if that fixes the problem

Thats definately a problem.. If that hose was popped off, it wouldnt affect your idle.... Just your wot... ANd you dont want that... Put a zip tie or something on it...


Well, it would affect your idle, cause thats a vacuum leak...

I'm surprised you didnt lean it out, and blow it up... That vac line tell the regulator what to do.

It raises fuel pressure on a 1 to 1 scale with boost... ## lucky your only runnin 10 psi..

Fix that.. Then go log.... TPS-o2/both-timing advance/// ANd get a log with some wot in it... Your TPS will say 100%...

 

[Jdiddy2k4]

Ok got the o2 sensor hooked up and the car seems to be better now. It went to 10 at idle once for like a second(I think when the fan kicked in at the light), but the o2 sensor got it back to hovering around 14.7 Now I can move on to actually putting on the 660cc and fuel pump. Thanks for the help everyone

 

[Jdiddy2k4]

Ok got to installing the 660c injectors and tried to get to tuning and I had the first NE Point at -15 to get the car up to operating temp and I disconnected the negative to get both trims zeroed out. Now when it got to operating temp, I am supposed to go to the first NE point which is 1000rpm and hold it in this range and then wait for the STFT to adjust and try to get it to zero out when added to the ltft?

 

[matthewdesigns]

It's the LO setting you want to adjust to compensate for idle and part throttle, and -15% is probably still going to be fairly rich. 660's need about -30% adjustment to be in the ballpark for idle/part throttle.
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