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351w EFI install

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lonesouth

lonesouth

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Was figuring on running without a vent, since I'm using the stock tank and using the stock vent port as the return. I'll see if I can put a check valve T into the return. Or if I can find a spare gas cap, drill a hole in it.
 
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lonesouth

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The fuel filter which was included with my BC Broncos fuel line did not have a flared connection to mate correctly with the hard fuel lines. The result is what felt like a tight connection, but was not air tight. I believe this leak is what caused my pump to not work in the location I had. I ended up bypassing the rear 3/8 hard line and filter, and running rubber hose from the tank to the pump, then from the pump to the front hard line. This put the pump in roughly the same location.

As I've said elsewhere, I think I would have been better off getting custom lines made locally, or bending/flaring my own lines.
 

Timmy390

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I'm running all AN fitting with the only rubber being on the return near the tank.

For HP filter http://www.summitracing.com/parts/tnk-ff-10-kit

I did bend my own hard lines. $110 for the 37 degree flair tool (I bought a good one Ridgid that will do SS lines) Line bender from HF worked well. Already had a tube cutter also from HF.

Tim
 
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lonesouth

lonesouth

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Got everything put together and drove it. I can't say that there is more power, yet, but the throttle response is instantaneous. I also went ahead and ordered a fuel check valve to put after the HP pump. I finished up most of it around 10pm, so I decided I had time to weld in the O2 bungs. One of the bolts on the drivers side exhaust flange refused to come off, so I had to weld that one into a less than ideal location. Not too worried though, since I plan on having the whole exhaust redone later to a single exit.
 
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lonesouth

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One issue that I have noticed, is that there is a moderate hesitation when going to wide open throttle. I can mash the gas, and there is about 1/2-3/4 second delay until is gets going. less than full throttle is instantaneous.

Thoughts?
 
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lonesouth

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Can't believe it has been a year since I got this done. Overall I'm happy with the results. Cranks after about 6 revolutions, and every time. The throttle is just a little bit touchy, but manageable. I still need to install my C4 kick down cable. Still have the hesitation when going straight to WOT, but again, not a big deal. Still haven't replaced the exhaust, not something I need to spend the money on, though I really don't like how loud it is.
 
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lonesouth

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FAST IDLE

This has always, since I made the switch, idled fast. By fast, I mean around 1k RPM. There are no other driveability issues, other than the hesitation going WOT, but that really doesn't concern me.

Trying to set the idle, I was only able to get the TPS down to 1.11 volts. I drilled out the holes and there doesn't appear to be any more adjustment I can make. With the IAB unplugged, it will idle down as low as I want, but as soon as I plug in the IAC, it jumps back to 1k, regardless of where idle was set with it unplugged. Other than this, the idle is smooth and drops back down as expected. No hunting nor surging, just fast.

Thoughts? Not sure if it matters, but this is 93 t-bird, not mustang.
 

chuzie

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Diagnose the iac and circuit. I've had that same problem. Iac was sticking open.
 

dclack

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Sounds like you need a new IAC valve. Mine idled high until I changed the IAC. Do you have an extra one you can test with?
 
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lonesouth

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Thinking more about this, the IAC is being opened by the ECM when it is plugged in. The valve must be closed when not plugged in because the idle drops significantly. Once the IAC is plugged back in, the RPMs shoot back up to 1k. Just a theory, I think the ECM is seeing 12v at pin 10 for the AC and is causing the IAC to open to compensate for the expected AC load.

I don't think this is TPS related because the IAC is not in play off idle, with the throttle opened, which is what a >1v signal would say.

Lastly, when else, other than the AC, does the IAC get opened?
 

chuzie

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Dashpot mode when you let off gas to cruise to a stop and cold start.
 

EFI Guy

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FAST IDLE

This has always, since I made the switch, idled fast. By fast, I mean around 1k RPM. There are no other driveability issues, other than the hesitation going WOT, but that really doesn't concern me.

Trying to set the idle, I was only able to get the TPS down to 1.11 volts. I drilled out the holes and there doesn't appear to be any more adjustment I can make. With the IAB unplugged, it will idle down as low as I want, but as soon as I plug in the IAC, it jumps back to 1k, regardless of where idle was set with it unplugged. Other than this, the idle is smooth and drops back down as expected. No hunting nor surging, just fast.

Thoughts? Not sure if it matters, but this is 93 t-bird, not mustang.

Thinking more about this, the IAC is being opened by the ECM when it is plugged in. The valve must be closed when not plugged in because the idle drops significantly. Once the IAC is plugged back in, the RPMs shoot back up to 1k. Just a theory, I think the ECM is seeing 12v at pin 10 for the AC and is causing the IAC to open to compensate for the expected AC load.

I don't think this is TPS related because the IAC is not in play off idle, with the throttle opened, which is what a >1v signal would say.

Lastly, when else, other than the AC, does the IAC get opened?

Idle speed shouldn't be more than 750, with no adders in effect like cooling fan or A/C. WOT hesitation probably will not improve much without a tune, the PCM thinks you are still a 5.0 when your engine is a 351.

You should definitely be able to get the TPS a little lower. Is it possible the throttle stop screw has been messed with and it's causing your TPS to read high because the throttle blade is open too far? That could explain the high idle speed as well. But, the first things to check are vacuum leaks, base ignition timing, correct PCV routing, and make sure the IAC is not installed backwards.

The IAC is not just open or closed, it uses duty cycle and opens and closes constantly. The minimum duty cycle is usually ~15%, you will never see less. While cranking to start it will be anywhere from 60-99% depending on temp.

At warm stable idle it will usually run between 25-35%. As soon as you begin to accelerate it will increase for dashpot, that amount varies depending on how much is commanded but 60-70% is typical. When you decelerate the duty cycle will start to drop to bring you back to idle. How fast it decreases varies quite a bit but the idea is to keep it from stalling when coming to a stop.

Also, different types of failures (like MAF or TPS out of range) will cause the PCM to command more air through the IAC as part of a limp mode strategy. So it would be a good idea to do a KOER test and see if anything pops up that may be your cause. If you use the 94-95 Mustang computer, there are a few scan tools out there that can stream live data for them. It isn't great but so much better than relying on flash codes alone.
 

roundhouse

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Sep 5, 2003
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I still have the 5.0 in mine
Haven't gotten around to installing the 351 yet
But I've never been able to get the IAC to work right
Mine idles high and then the dash lot mode kicks in every time you let off the gas to change gears (I have a five speed )

I just ran the wires from the IAC to a switch in the cab
I activate the IAC when the engine is cold, otherwise it won't idle , and shut off the IAC once I'm driving

Everyone on here keeps telling me that it's an easy fix to make the IAC work like it should but I've spent a lot of time adjusting the TPS and lots of other stuff and it just won't work right




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chuzie

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I have a 351 and it run perfectly. Efi guy tuned my computer.
 
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lonesouth

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I pulled codes tonight and got two that stood out, air bypass and MAF overvolt. I don't have any MAF cleaner on hand, but I do have a spare sensor sitting on the shelf. Swapping those did clear those two KOER codes. None of the KOEO codes were of concern, EGR, Purge, etc.

I also bumped the timing to, I think, 12* BTC. Reading up on the timing marks now. I'll push it further if I still have some room.
 
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lonesouth

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The idle is much improved after making those changes. The 1-2 shift has a bit more oomph and comes in around 4,500rpm. Need to check that my throttle is actually going wide open. I suspect that it is not and that I have left some out that could be adjusted. Also need to pick up a new TPS and see if I can get that into range.
 
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lonesouth

lonesouth

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Checked the throttle, and it is going wide open. Going to replace the IAC and see if that fixes the high idle. I bumped the timing a bit more, still not impressed with the power.
 
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