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CRANKING FUEL

The fuel requirements during cranking are very far from the speed density calculated amount. Thus, the fuel is not using that equation during the time between stall and about 450 RPM. The main factor determining the amount of fuel needed is the engine temperature (very cold requires several times as much fuel as a warm engine), as the fuel wall film needs to be applied, and the cold engine parts will cause most of the fuel to cling to them as a liquid, and not take part in the in-cylinder combustion. The various intake manifolds and engine sizes are also going to affect the amount of fuel required. In order to help the engine start much more quickly, the system also injects a large squirt “Prime Shot” from all of the injectors a few moments after the key is turned on. If the prime shot is not desired, such as if just the radio is to be turned on – pressing the throttle fully open prior to and while the key is turned on and while the fuel pump primes, will cause the Prime Shot to be cancelled.

Prime Fuel Mult = The prime injection will fire the injectors after key on to help make starting much quicker.

Crank Open TPS Mult = If the throttle is opened above this (and below about 50% for clearing flooded engines), the fuel injection is increased. This is to help start the car if the calibration is not yet finalized for starting. Also, the open throttle lets in much more air than just a closed throttle, so the extra fuel is sometimes needed to balance the extra air to deliver a burnable mixture to the cylinders.

Prime Shot Delay = If the engine is not cranked directly after key on, the software will wait a few seconds before injecting the Prime Fuel to allow time for the fuel pump to purge the throttle body of vapors, and get full fuel pressure to the injectors.

Prime Crank Revs = If the engine is cranked directly after key on, the software will wait a few revolutions to allow time for the fuel pump to purge the throttle body of vapors, and get full fuel pressure to the injectors.

CRANK IAC Mult = The IAC is opened an extra amount during cranking to allow more air into the engine for faster starting, and extra torque to spin the engine against thicker cooler oil. Adjust this to get good starting without excessive overshooting after starting.

Crank Fuel 20F = At cold engines, the default calibration increases the fuel injected by a very large amount. However, different engines and manifolds will show different needs. Adjust this to get good starting response.

Crank Fuel 65F = At cold engines, the default calibration increases the fuel injected by a large amount, however, different engines and manifolds will show different needs. Adjust this to get good starting response.

Crank Fuel 170F = At warm engines, the default calibration decreases the fuel injected by a large amount. However, different engines and manifolds will show different needs. Adjust this to get good starting response.

Afterstart 20F = This is the exact same value that is found in the Fuel Control section. It’s here again to help find it quickly when adjusting the fueling just after the engine is started.

Afterstart 65F = This is the exact same value that is found in the Fuel Control section. It’s here again to help find it quickly when adjusting the fueling just after the engine is started.

Afterstart 170F = This is the exact same value that is found in the Fuel Control section. It’s here again to help find it quickly when adjusting the fueling just after the engine is started.

Warmup 20F = This is the exact same value that is found in the Fuel Control section. It’s here again to help find it quickly when adjusting the fueling after the engine is started and the engine is cold.

Warmup 65F = This is the exact same value that is found in the Fuel Control section. It’s here again to help find it quickly when adjusting the fueling after the engine is started and the engine is cold.

30 comments on “CRANKING FUEL

  1. This product comes with no instructions to explain how to adjust the crank. I have had this product for a couple of months and can’t get it to crank easily when at running temperature. If there are instructions please send then to me. Disappointing priduct.

    1. The two things you need to adjust are as follows.

      IAC Steps:
      Turn the driver’s side throttle adjustment screw IN (clockwise) half a turn to start with, with that done turn the key on and go to dashboard and find TPS and make sure it reads zero. If not, then shut the key off and wait for the numbers to go black then turn the key on again. Once that reads zero start the vehicle and find IAC Steps on dashboard. This number needs to be within 3-10 at warm idle. If the number reads zero then slowly turn the screw OUT (counter clockwise) until the IAC steps reads between 3-10. If the number is above 10 then shut the vehicle off and turn the screw IN as stated above and repeat the process until the IAC steps are between 3-10.

      Cranking fuel adjustments:
      With the key on go to the Go EFI Tuning menu, find Crank and Warm up. There you will see three cranking fuel selections. For cold starts add or subtract fuel from Crank fuel 65f, for hot starts add or subtract fuel from crank fuel 170f. Changing these settings should help with your start up issues along with setting the IAC. A good starting point is to change the settings in intervals of 10 to find which way you need to adjust the system to work better.

      1. I have the IAC within the 3 to 10 limits. I have increased the crank adjustment twice in increments of 10. It will usually crank on cold start within the first 3 to 5 attempts. It is better. I will keep adjusting. Thanks for the email.

        1. Did you ever solve your problem with the hard crank. I’m having the same problem. Takes several attempts to start cold but once it starts it runs good until it is shut off. Then it won’t crank unless I pour a little fuel in top of throttle body. Then runs fine again. I’ve adjusted cranking fuel all the way to 60 and still no luck. Believe it or not, I’m not a total idiot when it comes to these efi units. I have installed several of the competitors but really wanted to try this unit for the price point. I have about 5 units sold if I can ever get the first one figured out. I’m almost to the end of my rope and considering a carb. It is a brand new 496 strokes for a very high end build. I knew it would take some tweaking but the start issue I can’t let the customer have to deal with. I have went through all the IAC steps and adjustments and still no start after warm. Crank and die, crank and die

  2. i have a nayuraly asperated chrys 340 600 hp unit. have istalled comand center . is there a vacume line to be istalled from com ctr to throttle body. if so, where do i hook it on the throttle body. ported or full vacume

    1. The regulator should be hooked up to manifold vacuum.

  3. I have been trying to get my EFI 4 600 to start without fighting with it for over a month now with no success.. IAC Steps is within 3-10, Have played around with the crank fuel, added and subtracted with no luck. Once I get it started, it runs great. Took it for a good 1 hour drive tonight. It ran perfect. Pulled into driveway. It idled perfect. Turned it off, and then tried to start it and it wouldn’t start. Coughs and chugs and almost starts but no luck.

    What next?

    1. Check for 12 volts to the white wire on the system during cranking. Feel free to give us a call and we will go over some adjustments if your do have voltage during cranking on the white wire.

      951-340-2624

  4. Hi Bryce,

    You were right, I had inadvertantly connected the white wire to ACC instead of IGN on the fuse panel, and was dropping to 0V when cranking. I have now hooked it up to IGN, but when testing voltage noticed that it dropped to 10V when cranking. Is this OK? If it is OK, it is still not starting any better. It will eventually start but I usually have to press the gas and fight with it for a while. Once it’s started all is good, until you turn it off again.

    1. Have you adjusted the throttle using the following steps? If so you will need to play with the cranking fuel.

      Turn the driver’s side throttle adjustment screw IN (clockwise) half a turn to start with, with that done turn the key on and go to dashboard and find TPS and make sure it reads zero. If not, then shut the key off and wait for the numbers to go black then turn the key on again. Once that reads zero start the vehicle and find IAC Steps on dashboard. This number needs to be within 3-10 at warm idle. If the number reads zero then slowly turn the screw OUT (counter clockwise) until the IAC steps reads between 3-10. If the number is above 10 then shut the vehicle off and turn the screw IN as stated above and repeat the process until the IAC steps are between 3-10.

  5. It said its supposed to get rid of the gas smell, but my still smells like gas, is there a way to adjust the AFR? Other than that great product an i had nothing but good luck with it besides that,

    1. You have full control of your AFR settings. They are in Go EFI Tuning. It is called AFR Targets.

  6. I’m working with a Ford 390. Struggling with my cold starts here in Kansas. How much should we expect to add in order to make this work. I’ve gone from the -24 on the Crank 65F to positive 14 with no success. I’m looking for some assistance with what numbers to aid in my cold starts.

    thanks,
    Chad

    1. What is your distributor base timing set to? Also can you give me some information on your engine.

  7. My base timing is set at 10, it’s a 390 with a. Mild cam and I high rise intake manifold. When it’s warm it runs great idles great so I don’t think it’s a timing issue, I think its initial fuel issue. Default for 20F is 0 and 65F is -24. From reading on the site I need to adjust the 65F correct? What direction should I be headed towards -34 or towards -14, -4, + 4, etc? Thank you for the help.

    Chad

    1. Increasing the number gives more fuel while decreasing gives less fuel. This is the correct adjustment.

  8. I have a 30002 throttle body with the 40003 fcc. I’m having an issue with starting on cold mornings (50 degree F and less). It stalls immediately. i have to give it a little throttle, starts and runs smoothly afterwards. warm days it starts perfect. My engine is a 1968 reman ford 302 (set to 305 on engine tuning) with stock heads, edelbrock performer 289 intake, hedman shorty headers, GM HEI distributor mechanical base set to 14degree @ idle max out to 34degrees @ 4200rpm, with a 20degree max vacuum advance connected to manifold vacuum. the engine runs outstanding, no spark knock, great throttle response. my iac @ idle when at running temp is @ 9 @ 800 rpm. It’s just this 1 little thing on cold morning starts. i can shut it off after letting it warm up and she starts right up with less than one rotation of the crank. I do let the pump prime up before starting.

    1. All you will need to do is lower your cranking fuel at 65 degrees a little. By you opening the throttle you are allowing more air in which is making your starting AFR leaner. By decreasing cranking fuel you are leaning out the AFR as well. Try lowering it by about 7.

  9. Ok here is one for you. making my head hurt. I have a chevy 355 and selected 3 for the cam. im running a tach input off of a jacobs ignition system and a msd 2 wire dist. It’s not locked out not running timing control. I have the IAC set at 6 and the cold crank is good having trouble with the hot crank. this has happened twice now. i have adjusted the hot crank by 10 to help with cranking. after i have set this went to crank it and the injectors never shut off had to turn the pump off and pull all the spark plugs. it hydrolocked the engine. after pulling the plugs and turned the engine over blew all the fuel out. put the plugs in and went to start it and it started great. drove the jeep and it drove great. shut it off and let it sit for 30 min. temp was 167 degrees and went to start it again and it flooded the engine again. What is causing the injectors to fire with the engine hot. i checked the white wire and have 10.2 on the cranking voltage. i dont under stand why its flooding the engine with so much fuel that i have to pull the sparkplugs out. the hot crank is set at -47 now but im leary about starting it again.

    1. This sounds like you are getting a false RPM signal when the key is on but the engine is not, can you look at the RPM on dashboard the next time you are in the car and let us know what you see, you can also call us and we can discuss this over the phone if you wish.

  10. How long does warmup fuel last if I increase the settings at 65F ? Does the system increase fuel until the coolant temp is at 150F ?

    1. The crank and warm-up settings are a gradient so setting them affects the map as a whole. they gradually move up through the fuel enrichment as the car gets hotter. To define the amount of time they affect the sytem simply find the middle point between the 65 and 170 and that is around the temp they trade of.

  11. Hi, I have the 1200 power adder with a centrifugal supercharger, everything seems to be fine until I use more than half throttle, the Fitech seems to shut down or cut fuel until I back off, then it comes back too life again. I have only put about 100 miles on it so far so don’t know if it’s still learning or if you have an idea what to alter. It has an Aeromotive stealth tank so fuel delivery should not be a problem. Regards Jason

    1. Check fault codes on the main menu. Its most likely ignition noise.

  12. Hi, im unable to start my motor on cold or warm starts. i have been up and down the with the adjustments on the Crank Fuel 65F and 170f. now if i squirt some fuel down all 4 butterflys it will fire up and run.
    any help would be great. thx

    1. The most common reason for and engine firing and immediately dying is loss of 12 volts during cranking to the white wire of the EFI. This is the key switch on of the EFI kit.

  13. Hey FiTech, here is my question. I just installed your Go Street EFI 400HP with FCC on my CJ-5 with an AMC Inline-6 258 4.2l. First crank the system started and ran! Super impressed! However what I’m noticing now is that when I start the engine, it revs up to about 1700rpm but then goes back down to target idle, is this necessary or is there a setting to change so it doesn’t try to high rev on start? Also when the revs are coming down, it takes about 2 seconds to get all the way down.

    1. Due to the size of your engine you will need to adjust the IAC cranking position. We want it to come to a high idle like 1200-1300 rpm but not that high. The setting is under GO EFI Tuning and then CRANK AND WARM UP. Change the Craning IAC down to about 70-80 and try it there.

  14. I just installed the fire tech on my Chrysler 360 and it starts up and shuts off I have the fuel Command Center what is causing it

    1. The most common is loss of power during cranking to the white wire.