FiTech EFI tuning - Vintage Mustang Forums
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post #1 of 22 (permalink) Old 07-08-2017, 03:20 PM Thread Starter
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FiTech EFI tuning

Hi everybody, my name is Jon and I have 73 mustang convertible with an 89 5.0 bored out to a 306. I just installed a FiTech EFI and fuel command center. The car started great initially but was ideling at about 1500 rpms, I fiddled around with it and had it down to about 800 last night. This morning I started it and the engine is now surging between 1500 and 3000, and IAC is stepping around 150.

Also, I can't get the CPU to save my changes.

Any advice is welcome.

Thanks,

Jon
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post #2 of 22 (permalink) Old 07-08-2017, 03:38 PM
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Are there any vacuum leaks? What is the idle set at on the handheld?

-Brett
1968 fastback 351w
1986 Iroc-Z
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post #3 of 22 (permalink) Old 07-08-2017, 03:52 PM Thread Starter
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Thanks for the reply Boom.

I'll check for leaks. The handheld is set at 800. The engine "pulses" between 1500 and 3000. I find it odd that the command center gets grounded, but the throttle body does not.....
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post #4 of 22 (permalink) Old 07-08-2017, 07:00 PM
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I know my Fitech doesn't like to idle very low until its warmed up. When I first fire it up in the morning it goes to 1500-ish but then settles around 1000 after a minute.

I drive mine everyday. Has then unit had time to learn? Are the basic settings all correct in the handheld?

-Brett
1968 fastback 351w
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post #5 of 22 (permalink) Old 07-08-2017, 10:31 PM Thread Starter
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You ar a genius Boom! It's not perfect, but I went for a drive and let it "learn" and now it at least seems normal. Thank you, more to come.
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post #6 of 22 (permalink) Old 07-08-2017, 11:42 PM
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Glad to hear you got it working.

-Brett
1968 fastback 351w
1986 Iroc-Z
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post #7 of 22 (permalink) Old 07-09-2017, 10:15 AM Thread Starter
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Well....got up this morning and she started right up, i let her run for a bit while I was tidying up some wiring etc. and she just up and quit! Now I can't get it to fire back up.....any thoughts?
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post #8 of 22 (permalink) Old 07-09-2017, 10:19 AM
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Quote:
Originally Posted by SiouxFalls73 View Post
Hi everybody, my name is Jon and I have 73 mustang convertible with an 89 5.0 bored out to a 306. I just installed a FiTech EFI and fuel command center. The car started great initially but was ideling at about 1500 rpms, I fiddled around with it and had it down to about 800 last night. This morning I started it and the engine is now surging between 1500 and 3000, and IAC is stepping around 150.

Also, I can't get the CPU to save my changes.

Any advice is welcome.

Thanks,

Jon
Hi Jon, glad you got it running. Here are some things I learned putting a dual throttle body system on my hemi charger which might help you get it running even better.

The ECU does not save ALL settings from the handheld even if you "sent" them from the handheld until you power off the ECU for about 30 seconds. (Key off, wait for all dashboard values to go blank, then changes are saved)

Cold idle RPM is not necessarily what you set for idle RPM. You can check this by referencing "target" RPM on page 2 or so on the dashboard. It gradually falls to your set RPM as the coolant temperature comes up.

No ECU learning occurs until the coolant temperature reaches 130 degrees.

The ECU requires a minimum of 10 volts. Most B+ circuits on our older cars have a significant voltage drop during starter engagement, down to 6 volts or so. You must grab key on 12v near the ballast resistor, on a circuit that doesn't drop during crank.

I'll agree with the previous poster that the most likely cause of your idle surge is a vacuum leak. I didn't have a vacuum leak before I put the Fitech on, so I disconnected and plugged heater box vacuum controls and hideaway headlights, as well as the brake booster and I STILL had a leak. Found it in a very unlikely place. The Fitech throttle body to intake manifold mounting flange is just a hair less tall than the carburetors I removed. Check the studs in your intake manifold and make sure you are not tightening the throttle bodies to 16 ft lbs against the unthreaded middle of the mounting studs since the Fitech mounting "ears" are less tall than the carb you removed. Put a die and thread the middle of the studs down further, or add a washer at all four corners.

The second slightly less likely reason for RPM surge at idle is a dirty RPM signal to the blue wire on the Fitech ECU. You should, but may not, have a fault code if this condition exists. Route the blue wire as far as possible from coil, spark plug wires and other potential sources of electrical interference.

The ECU is grounded by the engine block. Check and make sure you have a grounding strap block to battery, battery to frame, and block to frame.

Your IAC steps should be 3-10 on a warm engine. These will not be valid until you fix the vacuum leak/dirty RPM signal. Work on that first, then set your IAC.

Hope this helps.

Ray
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post #9 of 22 (permalink) Old 07-09-2017, 10:22 AM
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there's a whole thread on tuning the fitech here. i dont have one yet but check your ?IAC? setting? i think bumping it all the way down to 0 takes care of that. But im probably wrong.

http://forums.vintage-mustang.com/mo...justments.html
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post #10 of 22 (permalink) Old 07-09-2017, 11:41 AM
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Quote:
Originally Posted by SiouxFalls73 View Post
Hi everybody, my name is Jon and I have 73 mustang convertible with an 89 5.0 bored out to a 306. I just installed a FiTech EFI and fuel command center. The car started great initially but was ideling at about 1500 rpms, I fiddled around with it and had it down to about 800 last night. This morning I started it and the engine is now surging between 1500 and 3000, and IAC is stepping around 150.

Also, I can't get the CPU to save my changes.

Any advice is welcome.

Thanks,

Jon
Before you beat your head against a wall call FiTech. My friend was ready to rip it all out ,trash it,then kill me for ever mentioning FI and giving him a ride in my FAST injected FE Mustang.
He called them after beating his head against the wall for 2 weeks. After over 30mins on hold and half way through describing what was going on the TECH interrupted him and asked what the file code ( I think thats what is called) was. The TECH said oh ,give me your email and I'll send you a new file . Down load installed,base setting reset turned key it fired and settle right to idle,properly set up the IAC and tht was that. He is now just makng slight tweeks here and there for cold starts but no tuning problems at all.
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post #11 of 22 (permalink) Old 07-09-2017, 11:49 AM
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OP My friends unit did just like yours idle perfect then suddenly jump to 3000 rpm for 30sec to a minute then drop back to idle rpm. I'm not sure but if you got your system from Jegs or Summit make a call those parts warehouse for quite a while.
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post #12 of 22 (permalink) Old 07-09-2017, 12:53 PM Thread Starter
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Thanks everyone, I will definitely be giving the tech center a call tomorrow. It's just crazy that it finally started running quite well, and then it just quit and won't start back up.

I did, btw buy the kit from Summit Racing

Last edited by SiouxFalls73; 07-09-2017 at 01:10 PM. Reason: More info
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post #13 of 22 (permalink) Old 07-09-2017, 07:23 PM
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Originally Posted by SiouxFalls73 View Post
Thanks everyone, I will definitely be giving the tech center a call tomorrow. It's just crazy that it finally started running quite well, and then it just quit and won't start back up.

I did, btw buy the kit from Summit Racing
Be prepared to power it up so you can give them the software code,or whatever it is called.
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post #14 of 22 (permalink) Old 07-12-2017, 11:37 PM Thread Starter
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Hi everyone,

I got the new codes from FiTech and following their instructions I was able to upload without issue. The car still seems to surge between 1200 and 3000 rpm with an occasional sustained 3000+ rpm. I can't locate a vacuum leak around the throttle body, but i did notice a small puddle of fresh coolant under the car.....can my reviing surges be related to this?
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post #15 of 22 (permalink) Old 07-13-2017, 09:27 AM
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Could be related, but it should definitely be fixed anyway. Have you checked the TPS/IAP sensors that they are working properly? How long are you letting the car run while it does this surging?

-Brett
1968 fastback 351w
1986 Iroc-Z
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