Deleting SAI

rovercanus

rovercanus

Well-known member
Apr 24, 2004
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I'm currently getting faults for the secondary air injection on my 2004 4.6. I've replaced the solenoid with no change. Current faults are on banks 1 and 2.
Instead of replacing parts in a system that has dubious qualities to begin with, I am considering getting rid of it.
I'm thinking I will need an earlier non SAI ecu and sink it with the BCU. The scan tool I have will do this.
I will also need blanking plugs for the heads which I believe PT has found in his research.
Has anyone done this successfully? Actual part number for earlier ecu would also be helpful as well as informatio about loosing any functionality of the later ecu's
 
jafir

jafir

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May 4, 2011
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Northwest Arkansas
Things get a little murky here. I had a 2003 non-sai 4.6L disco ECU in my hands once (I sent it to the UK for one of the tuners to examine) and it was the same part number as the SAI ECU.

Normally the SAI and non SAI have different part numbers. NNN640 vs NNN460 or something like that. But this one just had the non-sai programming loaded on the SAI style ECU, and it appeared to be original to the vehicle. Even microcat suggested it should use the non-sai ECU, but it didn't.

One thing I forgot to check was which fuel pump a 2003 with no SAI uses. I know they older vehicles don't have a DMTL pump and instead have a leakage sensor in the fuel pump. If the newer ones are setup the same way, you'd need the fuel pump too, as well as wiring it into the ECM.

I think I saw that Marty was selling a 4.6 D2 engine that didn't have SAI. If I were you, I'd check and see if he still has the ECU, and if he does, buy that. Then you'd know it has the optimal tuning for 4.6.... the 4.0 computers should work fine though, but why not get the best you can find? Maybe he can confirm how the fuel pump/evap system is setup on a non-sai D2 also.
 
mbrummal

mbrummal

Well-known member
Jan 23, 2009
2,894
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Willow Spring, NC
http://www.318ti.org/forum/showthread.php?t=24726

Reading the RAVE on this subject should let you figure out exactly what you need to do.

I think the biggest difference is the LR ECU checks to make sure the valves don't leak so you would need to trigger the relay off of the SAI valve output, not the blower output. I'm also not positive exactly what voltage the ECU is looking for but you should be able to figure it out with a little trial and error.
 
seventyfive

seventyfive

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Jan 3, 2010
4,280
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over there
Walter don't waste your time unless you have access to a t4 or auto logic. Even an auto logic may not be able to change ecu settings....a lot of functionality has been deleted from auto logic due to lawsuits.

Even if you get an ecu it's going to need keyed and matched to the bcu.

Physically you only need a non lev2 fuel pump. The fuel tank pressure switch is built into the fuel pump since the lev1 does not have tank leakage detection. Which means you'll need to run wires to the fuel pump for that input...the wiring may actually already be there you'll have to pull the rear carpet and check
Then I think you'll need the tank vent valve which is in the engine compartment.

It's been a long while since I actually looked into this so I may be wrong you may just need the fuel pump put a 4 liter ecu in and just see what faults you get then fix those faults.

But like i said if you don't have access to a 4.6 ecu and a t4 don't waste your time. Just put sai back in. I ran a 4.0 ecu on my 4.6 and it didn't seem to matter.
 
rovercanus

rovercanus

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Apr 24, 2004
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Thanks Mike. I may have a 4.0 ecu in my pile and I may be able to sink it to the BCU but as of now maybe I'll just roll up my sleeves and fix it.
Mike Brummal has an intriguing idea to fool it but if I'm going to do anything it will probably be just to get rid of the whole thing.
Thanks again guys.
 
seventyfive

seventyfive

Well-known member
Jan 3, 2010
4,280
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over there
What fault codes?

Check the vacuum lines from the upper intake manifold plenum to the plastic vacuum reservoir to the change over valves. Check to verify they hold vacuum from the plenum.
 
rovercanus

rovercanus

Well-known member
Apr 24, 2004
9,651
246
seventyfive said:
What fault codes?

Check the vacuum lines from the upper intake manifold plenum to the plastic vacuum reservoir to the change over valves. Check to verify they hold vacuum from the plenum.
Click to expand...

I'd have to look again Mike. I have checked the vacuum lines but I feel that the pump itself may be on it's way out. It's starting to scream at times.
Like I said, I'll dig into it more when the light finally pisses me off real good. It just really sucks on my brand new engine. It's running great and nice and cool.
 
rovercanus

rovercanus

Well-known member
Apr 24, 2004
9,651
246
All the haters come out...
Jeff, I'm going to get those water balloons that you can fill up 40 at a time with a garden hose and wait outside your office. Is there a spigot outside your office?
 
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