First ride with boost

[HAMMER]

Where are you sourcing boost for your MPI box ? You might want to try it from the TB's.

I don't have the answer but before you do that you might want to ask MPI what pressure sensor they use in the controller and what effect doing that will have. If the fuel controller is calibrated to read from the intercooler, a continuous pressure source, then exposing it to a vacuum at the throttle bodies could throw its calibration out of whack. Some pressure sensors, I'm not sure in this case, that are designed to read pressure only can be damaged/fail if a heavy vacuum is applied to them.

 

[TurboJamie]

Where are you sourcing boost for your MPI box ? You might want to try it from the TB's.

I don't have the answer but before you do that you might want to ask MPI what pressure sensor they use in the controller and what effect doing that will have. If the fuel controller is calibrated to read from the intercooler, a continuous pressure source, then exposing it to a vacuum at the throttle bodies could throw its calibration out of whack. Some pressure sensors, I'm not sure in this case, that are designed to read pressure only can be damaged/fail if a heavy vacuum is applied to them.

You are a good man to answer his lean spot questions, did you experiance this problem or change in calibration when you added the BOV's to your kit?

 

[gsxr]

I don't want to put on the vac. side , the barb was put in the intercooler by MPI.

First is to try a short ride w/o bov vacuum source hose unhooked, at least I will know if that is the cause.

 

[HAMMER]

First is to try a short ride w/o bov vacuum source hose unhooked, at least I will know if that is the cause

Don't forget to cap the line from the throttle bodies...vacuum leaks are baaaad.

Did you experience this problem or change in calibration when you added the BOV's to your kit?

I can't pin any cause and effect down to one thing because I made several changes at once, Clutching Changes, Bypass Valves, Engine Bay Venting, Intercooler Fan, Cold Air Intake, then adjusted the controller rich enough to eliminate any lean spots. I'm actually way richer than MPI recommends in my Idle/Cruise for my elevations, their recommendation is 0.5, I'm set at 2.0, quite a bit of difference there. My sled won't even run at 0.5 Idle/Cruise, way too lean, and I've had the Accelerator Pump function up to 6 for drag racing but normally run it a 4.

 

[gsxr]

I tried the needle richer ,did not seem to help
but did not try the idle / cruise above 1.0 ,
I did notice it did seem lean at idle until it warmed up !(.5 or 1.0 )
I can try 2.0
The accelerator pump seems good.
This system is sure easier than the carb days !
I will advise .

 

[HAMMER]

Here's one of my old posts for reference:

NOTE: (I have version 11 mapping...MPI is up to version 13 mapping)
These fuel settings are for info only and would only work on an identically setup sled, in identical conditions, so use an A/F gauge to dial in your setup to your conditions !!!

5500-8500 elevation -- 25*F to 35*F

Idle (2)
Needle (4)
Main (4)
Boost (4)
Accelerator (4)
Altitude (6)

12.5:1 AFR at Idle
(Note there may be a dead-spot if engine isn't at full operating temp)

11-12-13-14 AFR Cruise
(Depending on throttle position, rpm, and engine load)

9.8-10.8 AFR Acceleration
(After initial acceleration tapers into 11.8:1 12:1 AFR at sustained wide-open-throttle)

 

[mulot30th]

Here's one of my old posts for reference:

NOTE: (I have version 11 mapping...MPI is up to version 13 mapping)
These fuel settings are for info only and would only work on an identically setup sled, in identical conditions, so use an A/F gauge to dial in your setup to your conditions !!!

5500-8500 elevation -- 25*F to 35*F

Idle (2)
Needle (4)
Main (4)
Boost (4)
Accelerator (4)
Altitude (6)

12.5:1 AFR at Idle
(Note there may be a dead-spot if engine isn't at full operating temp)

11-12-13-14 AFR Cruise
(Depending on throttle position, rpm, and engine load)

9.8-10.8 AFR Acceleration
(After initial acceleration tapers into 11.8:1 12:1 AFR at sustained wide-open-throttle)

12.5-1 is too rich for an idle at operating temp.

 

[TurboJamie]

Here's one of my old posts for reference:

NOTE: (I have version 11 mapping...MPI is up to version 13 mapping)
These fuel settings are for info only and would only work on an identically setup sled, in identical conditions, so use an A/F gauge to dial in your setup to your conditions !!!

5500-8500 elevation -- 25*F to 35*F

Idle (2)
Needle (4)
Main (4)
Boost (4)
Accelerator (4)
Altitude (6)

12.5:1 AFR at Idle
(Note there may be a dead-spot if engine isn't at full operating temp)

11-12-13-14 AFR Cruise
(Depending on throttle position, rpm, and engine load)

9.8-10.8 AFR Acceleration
(After initial acceleration tapers into 11.8:1 12:1 AFR at sustained wide-open-throttle)

12.5-1 is too rich for an idle at operating temp.

ummmm why?

 

[Need for Speed 2]

14.0 to 14.8 at idle use accelarator for quick throttle response not idle cicuit

 

[gsxr]

Talked to Ted , he said to adjust the bov , and see if the studder follows the rpm that the bov opens at !

Tighten the adjuster the higher rpm it opens!

good idea !

 

[HAMMER]

Note that we run an Open-Loop system, so sensor position, type of exhaust system, and condition/calibration of the sensor itself can make different setups give different readings.

Short version:

"In most cases the target wide open throttle A/F ratio for naturally aspirated engines will be between 12.8:1 and 13.2:1 whereas supercharged, turbocharged, and nitrous-injected engines will like a richer mixture between 11.5:1 and 12.5:1"

"Due to the low port velocity and frictional losses Idle mixtures are typically set at a fuel ratio of 12.25:1. Your motor will idle at stoichiometry (14.7:1) or less than stoichiometry but this is very near misfiring and if operating temperatures are not stabilized at a high level the motor will die. For example, operational fluid temperatures can vary from 150 degrees Fahrenheit to 250 degrees Fahrenheit and inlet air temperatures can easily vary 100 degrees Fahrenheit. These variations in temperature all necessitate different mixture requirements in an Open-Loop system so it is far better to keep the fuel ratio in the 12.25:1 region to preserve idle quality and off-idle response"

"There is no magical, absolute, digitized answer to developing your applications fuel requirements. You must drive your machine and a considerable amount of judgment must be placed in such areas as cold start, warm-up, acceleration fueling, idle quality, and drivability. Each motor is different and the calibration will be only as good as the effort you put into it. Much subjective decision making will take place and the A/F ratio meter will not provide you all the answers. Stop watches, elapsed times, lap times and your own opinions as a tester are equally valid"

 

[gsxr]

That being said , I richened the Idle circuit with the bov in the system , the lean spot went away ,
then the idle also settled when cold.

I also tried the original settings with the bov out of the loop , and all ran perfect as well ,

SO now , bov or not , ??????

 

[HAMMER]

 

[gsxr]

I rode the sled approx 5 miles in short spurts.
The sled when cold started , hunted a little and would settle only if I worked the throttle a small amount.
After richining the mode 1 idle / cruise to 2.5 it now starts cold , runs on fast idle till it heats then idles down as it used to.
The lean spot has gone away , I had only tried the mode 2 , thinking it was needle transition !
All seems ok now.

 

[gsxr]

6 more inch's snow , second ride !
Awesome !!!!!!!!!!!!!!!!!!!!!