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Open Loop tuning

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Old Oct 9, 2011 | 06:53 PM
  #1  
TPI-Formula350-'s Avatar
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Joined: Aug 2003
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From: Long Island New York
Car: 89 Formula 350
Engine: Forged 385 H/C/I
Transmission: 700R4-4300 Stall-lockup
Axle/Gears: BW 9 Bolt 3:70
Open Loop tuning

I get a lot of surging in open loop and it gets much smoother once it goes into closed loop. I've been told to make some adjustments in the "Open Loop AFR% vs Coolant temp" table. The surge seems to follow the AFR on my wide band gauge. In OL the AFR is in the 12-13's and surges as the AFR surges, once it goes into closed loop and the AFR settles near 14.7 the surging is very slight. When looking at the OL AFR% vs Coolant temp table I see above 46*(68*-241*)the value is 12 until it gets to (262*-306*) then the value goes to 21.48.
The other night was in the low 40's and the car surging was worse then normal on cold start up. I took a look in the table and the value jumped from 12 above 68* to the 20's below 46*...so do I need to lower these values and if so by how much? The IAC counts are in the low 50's when the cars warm, thats as low as I can adjust it and still get 4.5 volts on the TPS at WOT and .55V at idle.

Last edited by TPI-Formula350-; Oct 9, 2011 at 07:01 PM.
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Old Oct 10, 2011 | 10:42 AM
  #2  
RBob's Avatar
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From: Chasing Electrons
Car: check
Engine: check
Transmission: check
Re: Open Loop tuning

I don't think that with the AFR in the 12-13 range would cause it to surge. The varying AFR may be the result of the surge.

If you can smoke the intake it would be helpful in eliminating any vacuum leaks. They are tough on a MAF car as it is un-metered air.

The injector compensation values are important. I see Accel injectors in your sig. Unfortunately it is near impossible to get the compensation values for them.

Looking at $6E I don't see any idle compensation SA. You may need to work on the main SA table in the area around idle. Adding a little more SA as the RPM lowers. And conversely remove some SA as the RPM goes up.

Then flatten a bit on the MAP axis.

I would work on getting a good hot idle, then work on the cold idle.

RBob.
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Old Oct 10, 2011 | 01:26 PM
  #3  
TPI-Formula350-'s Avatar
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Joined: Aug 2003
Posts: 1,644
Likes: 4
From: Long Island New York
Car: 89 Formula 350
Engine: Forged 385 H/C/I
Transmission: 700R4-4300 Stall-lockup
Axle/Gears: BW 9 Bolt 3:70
Re: Open Loop tuning

I had checked the intake with a smoke machine a few months back and it didnt show any vacuum leaks
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