125shifter

The lamba sensor is just telling the tuner or the ECU what the AFR. Once the tuner has mapped the ECU, he doesn't need the info anymore and unless you're running closed loop, the ECU doesn't need the data either.

You should check your AFR again when the weather has changed to make sure your air temp correction is right.

Of course it's nice to have especially on a turbo car to make sure all is running right.

DonE

Joe told me that too. For whatever the reason (cams, cam timing, injectors, etc), the car likes to idle between 1050 and 1250 and I can adjust to that range. Any lower and its unstable - lopes, rough, etc. Any higher and I'm not comfortable because temps start to creep up quickly in traffic. It also likes AFR's in the range of 12.5 to 13. Any higher and its rough and won't hold rpm (hunts), any lower and it bogs off the line.

A.Wayne

Hello Don,

13.-12.3 is too rich , the hunting , bogging just means your tables are not yet setup correctly, so you are using an initially rich mixture to cover this up. Being that rich of a mix at idle and cruising it is not good for the oil /motor etc. for idle try and keep it in the 13.7-14.2 range and the same for cruising or a little richier 13.4-13.9 say above 3000rpm but 12 's for cruising is not good.
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DonE

Cruise is 14.5 right now, depending on kPa (less than 70). I can not get the idle to 14 - it idles best at 12.5 - 13. On the other hand, I see your point. I'll try again since its just a matter of pulling fuel out.

Dknebes

Don, I used your numbers for idle and fuel enrichment. After my car is warmed up I can feel the difference on initial throttle response and it does idle well however it oscillates on idle when it is started cold. I did not start it again cold or get to drive it much but will do it this week. My car is idling at about 13.8 and idles rough at 14.0 and above.

DonE

I had to set my timing at 10 degrees at idle, 13 at 1500 rpm and 18 at 1850. With 72lb injectors, at idle, the inj on time is 1.45ms (but this appears to be too rich). Also, I set the idle with the throttle plate (engine up to temp) to hold idle at 1000 rpm with the IAC closed and disconnected. The idle is now held more easily with the software.

PorschePhD

The goal is to get the car to idle with the plate cracked slightly and once the idle is maintained allow the software to correct the idle with in +/- 50RPM. Anything more and the ability to control gets a little loose causing the car to hunt.

You really want idle AFRs about 13.5 or leaner if you can get them. Depending on the injector you are using this may not be possible because of drip or a poor pattern.

Lots of great advice in this post.

The last car I did had 72# injectors and idled about 14 with no hunting. At cruise I ran it as lean as I could before the motor would start getting crabby. Around 14.2-14.5 or so.

DonE

The idle is not hunting right now, but if I lean too much, it gets "crabby" - rough, stumbles a bit, hunts, etc. I'm told that the 72lb Siemens injectors don't like to get lower than 1.1ms or they dribble. At 52psi fuel pressure, I should be able to raise the AFR's at idle a bit.

Dknebes

Don, I am running 95lb injectors and with the full sequential injection it idles fine as at a/f 13.8 but at a/f of 14.0 it starts to run rough. I still have a cold start problem with rough and oscillating idle for the first 10 to 30 seconds and settles after I blip the throttle a bit. I think it is to rich or to lean hard to tell, my a/f meter does not start to read immediately. I may have to play with the 20 second enrichment.

DonE

It is my opinion that these air cooled motors like very rich conditions when cold. Of course being in Tampa, you most likely don't see "cold". I would experiment with a richer setting because you said you blip the throttle a couple times and it settles. If your enrichment is set up like mine, blipping the throttle will immediately introduce a couple of ms more of fuel which it seems to like. If it were too rich, the motor would stall or stumble badly. I've read where AFR's in the 5 or 6:1 area are not unusual for cold start conditions in horizontally opposed engines. The fuel does not atomize well with the cold intake and tends to be droplets that fall to the bottom (actually the low-side) of the cylinder.

In any event, I would recommend bumping the 20 second enrichment by 20 or 30% over what you have now and see how that works.

95lb injectors - yow.....

PorschePhD

This probably has more to do with the spray pattern.

Keep in mind that if this is a cold startup then 13s and 14s will be too lean depending on the outside temp.

Dknebes

I am probably at 12.2 a/f cold start and have adjusted the warm up enrichments to hold there till it is warm then it ramps up to 13.8 a/f at idle. I will try and run my 20 second start up at 11.5 a/f and see if that helps

fast951

The 72# injectors do not operate well at anything below 1.5-1.7ms This is why you have to richen it to get close to the min duty cycle where they operate well. Another thing to try is to increase the injectors open/close time which is a variable related to the injector size and style.

m42racer

The 72# injectors do not operate well at anything below 1.5-1.7ms This is why you have to richen it to get close to the min duty cycle where they operate well. Another thing to try is to increase the injectors open/close time which is a variable related to the injector size and style.
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Do you mean the phasing to the crankshaft degrees. If so, good point. This timing has a huge difference in Idle, and many other factors. Then it can be mapped to the closing or to the opening or both. Depends if the system can support such control.

DonE

I worked on the idle yesterday and have it nailed at 1050 rpm, 14.5 AFR. The injector on time is about 1.37ms and timing is 9 degrees. I also tried the O2 sensor in closed loop above 2000 rpm and below 100 kPa. It's really running well with these parameters.