Fitech Tach wire connection Q

[Jp76]

Hey Guys - I am still battling a bogging issue with my 76. The Fitech guys finally got back to me and said my log showed a Fault code 36, which is interference. They suggested that I wrap the tech wire with heat shield:

First - any thoughts on this? Is this just Fitech trying to get me to leave them alone, or might this simple solution help?

Second - I have an MSD 6a box, where my tach wire is connected to - could this be part of the problem at all.....interference of some sort?

Thanks!!

 

[Devo73]

I don't know much about the fi tech, I'm running a Holley Sniper, Id try changing out your distributor cap, mine was running pretty crappy and I tried everything and decided to change the brand new cap cause it was the only thing I hadn't tried and it's been great ever since, I think having that ECU out front right next to the distributor on a Ford is a recipe for trouble

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[Jp76]

Thanks! Yeah, it might be time for a whole new distributor anyways. It rund fine until it heats up a bit, and then the RPMs go wonky. Coming to a stop, it will want to die. When I park it, the same thing happens at idle - almost dies, then RPMs jump up high. I will try the cap and maybe wrap the tach wire. See what happens. Thanks!

 

[Devo73]

I bought some of that emi resistant tape off Amazon and covered all my wires with it, idk if it worked cause the cap was no good, good luck!!

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[Jp76]

update - still happening. seriously considering going back to a carb and using the POS Fitech as a paper weight.

 

[Devo73]

I was right there with the sniper man! Just hold out a little longer, chase down the possible emi, does the fi tech have software you can put on your computer so you can view datalogs? You can also take the belt off your alternator, see if that cleans it up some, do you have a fuel pressure gauge so you can verify you have constant fuel pressure, is your power sourced directly at the battery? Just some things to consider, you get that thing running good you won't want to go back to a carb!!

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[Rusty_S85]

You have the RPM signal for the FI tech coming from the MSD box?

You have no interference then. That is the preferred method of hookup as it is the cleanest rpm signal available.

If you have a GM HEI style dist they recommend running a filter or a MSD to clean up the signal as HEI style dist`s have a very dirty signal.

I think they are blowing smoke up your rear right now with that. They told us the same thing about the problems we had with a blazer that was hard to start as it was just flooding out on crank up. Told me to wrap the signal wire in foil to ensure no interference.

Found out the problem a few weeks later after it came back from the body shop, the optima battery didn't have enough cranking amps which was throwing the system off making it hard to crank once we solved that it was just a simple tune on the cold start fuel setting.

 

[Jp76]

Devo - thanks, yeah it is super frustrating; I am gonna exhaust all possibilities and really dont want to go back - appreciate the other ideas to check.

Rusty - thanks, I may need to check into the battery. It is newer but has had some issues.

What's odd is that it runs fine for a bit. then after driving for 10 mins, it has the issues. I have a return line and electric in-tank pump, so it should not be vapor lock. Also, since it runs great for a bit and is super-predictable for when the issues will start, it cant be a dirty fuel filter. Maybe a pressure issue in the pump (hope not - Pain in the arse to drop that tank).

One more question though if I did decide to go back to a carb - with the electric pump in the tank, would the pump simply run once the key is turned to ACC, and then the regulator would manage it for crank and run? Worrying about flooding if the pump just runs without a return like there is now. Thoughts?

Thanks!!!!!

 

[Jp76]

I was right there with the sniper man! Just hold out a little longer, chase down the possible emi, does the fi tech have software you can put on your computer so you can view datalogs? You can also take the belt off your alternator, see if that cleans it up some, do you have a fuel pressure gauge so you can verify you have constant fuel pressure, is your power sourced directly at the battery? Just some things to consider, you get that thing running good you won't want to go back to a carb!!

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So the Fitech has power direct to the battery, with the ground to the throttlebody, but I also grounded it direct to the negative terminal of the battery as well as the frame (can never have too much ground on these things). I have an in-tank pump that came specific for EFI applications and is used all the time with Fitech (Wildhorses Sherman), so I assume it has enuff pressure, but i should probably check. Since it runs fine even under load and acceleration for a while, I wouldnt think there is an issue there, but you are right and never know. More to come!....

 

[idus25]

HAd the same issue. I ran my MSD 6a heavy power wire opposite side of tach wire. That is enough to get away from radio noise. Make sure no heavy power wires, like fan or any accessory are no near the tach wire.

 

[Devo73]

Good luck man!

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[Jp76]

HAd the same issue. I ran my MSD 6a heavy power wire opposite side of tach wire. That is enough to get away from radio noise. Make sure no heavy power wires, like fan or any accessory are no near the tach wire.

Thanks - I am going to go through everything to make sure I have covered everything - appreciate the reply!

 

[Rusty_S85]

Devo - thanks, yeah it is super frustrating; I am gonna exhaust all possibilities and really dont want to go back - appreciate the other ideas to check.

Rusty - thanks, I may need to check into the battery. It is newer but has had some issues.

What's odd is that it runs fine for a bit. then after driving for 10 mins, it has the issues. I have a return line and electric in-tank pump, so it should not be vapor lock. Also, since it runs great for a bit and is super-predictable for when the issues will start, it cant be a dirty fuel filter. Maybe a pressure issue in the pump (hope not - Pain in the arse to drop that tank).

One more question though if I did decide to go back to a carb - with the electric pump in the tank, would the pump simply run once the key is turned to ACC, and then the regulator would manage it for crank and run? Worrying about flooding if the pump just runs without a return like there is now. Thoughts?

Thanks!!!!!

If you go back to carb, you can run the fuel pump you just will have to wire it to key hot. I would recommend using a relay to have the fuel pump load off the ignition switch itself.

You will also need a pressure regulator to drop the pressure down from 45 - 55 psi down to 6 to 10 psi depending on what carb you run.

Also return line would be preferable. A mechanical pump can dead head against a needle and seat but I wouldn't try to dead head a electric pump against a pressure regulator. Can build up heat in the electric pump and heat up the fuel if not just out right burning the pump up.

 

[bronkenn]

Try wrapping the distributor cap and the front of the Fitech unit with tin foil to see if that stops any interference. I did this and it worked well until the problem was figured out.

 

[Jp76]

Try wrapping the distributor cap and the front of the Fitech unit with tin foil to see if that stops any interference. I did this and it worked well until the problem was figured out.

Think I will try that - I might do a total learn reset on my ECU and start fresh. I am not doing timing control, so is there a value that I need to set manually during initial setup, or should the unit auto-learn my idle timing? Thanks!

 

[Jp76]

Try wrapping the distributor cap and the front of the Fitech unit with tin foil to see if that stops any interference. I did this and it worked well until the problem was figured out.

OK, I foil wrapped the front of the TB and Distributor, and the tach wire going to my 6a box is wrapped in heat wrap and lifted off of other wires. It started but was a super high idle, because I had the TB drivers side screw in quite a bit. I adjusted it out, and it fired up again but noticed the IAC steps were high. I played with that screw, but the IAC steps are jumping all over the place at idle and the idle goes from about to die to revving. Any next ideas? I did a log of it and even a video of the screen while it was idling.

Thanks!!

 

[Jp76]

Update - I wrapped the front of the TB and Distributor and really had to play with the front screw on the TB to even get it started. It runs super rough - idle is all over the place and the IAC steps jump around from 30 to 0, then it corrects itself. Got me going back to basics and thinking about vacuum leaks.

Question (silly one, but what the hell) - everything looks great with Vacuum connections from the distributor, brake, etc., all other ports plugged, but the PCV valve sticking out of the oil filler cap on the Valve cover (drivers side) is very loose and can even pull out of the cap. Would this be enough to cause the very rough idle and therefore confuse the Fitech computer? In other words, I am trying to dial in a computer that is confused, because there is a vac leak, so it will never run anyways. I am going to replace, but any suggestions on if there is something specific I should replace with? Should I get a brand new cap with fitted PCV? Anything else while I am doing that - this is an area I never think of......?

 

[Rusty_S85]

Got another one in today, hard cranking FItech said the screen going blank during cranking is the ignition wire is key hot but not hot in crank. checked it wire is hot in crank as well. its yet another faulty FITech computer which requires the throttle body unit and the hand unit to be mailed in for repair.

 

[Jp76]

Got another one in today, hard cranking FItech said the screen going blank during cranking is the ignition wire is key hot but not hot in crank. checked it wire is hot in crank as well. its yet another faulty FITech computer which requires the throttle body unit and the hand unit to be mailed in for repair.

Yep - mine went back to them before it even cranked over for the first time - faulty wiring in the TB. Bad part was that I purchased it on sale and it sat brand new in a box until my rig was out of Body and Paint. By that time, they said the warranty was no good, even though the seal was never broken on the box. They grudgingly fixed it, but it still has never run right. In their defense though, this last issue is possibly just a common vac or timing issue....at least I hope so.

 

[Rusty_S85]

Yep - mine went back to them before it even cranked over for the first time - faulty wiring in the TB. Bad part was that I purchased it on sale and it sat brand new in a box until my rig was out of Body and Paint. By that time, they said the warranty was no good, even though the seal was never broken on the box. They grudgingly fixed it, but it still has never run right. In their defense though, this last issue is possibly just a common vac or timing issue....at least I hope so.

That's how they are. They only try to work with us because we bought 5 of them from them as a shop and we are installing them but we are at the point of just not even dealing with them. sat on hold for 30 minutes today to be told the screen is blanking out during crank cause its losing voltage on the key hot wire under crank. Which it was not sat on the phone again for another 30 minutes before I hung up and said screw it.

And to think I thought about using them for my 306 build but now I am going to stick with carbed.