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Fuel pump control module


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Ah, damn, I see.

 

Cool, I am very curious about it. Careful about the nasioc part. 08+ STI hatch indeed has 22648AA140. Earlier years had a different part number.

 

Interestingly on 08+ the part number seems to depend on wagon vs sedan. Maybe there is a difference in mounting bracket or something like that.

 

The controller I was looking at on NASIOC is an older one that fit pretty much all the imprezas and STIs.

 

I saw that difference in 08 as well as the wagon sedan difference.

 

I figured the older 05-07 one would work fine if it plugs in.

 

We shall see....

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Well GTTuner you Win you WERE on to something and those not pushing a lot of horsepower and needing a lot of fuel (like E85) in a legacy would have never known.

 

Near as we can tell the legacy fuel pump module will only put out a max of 11.75 volts.

 

RAO is correct we do need this part to regulate the fuel pump output for life of the pump and emission etc. on a daily driver.

 

Here is what Cobb Plano emailed me back today after running some tests of cars they were tuning on the dyno.....

 

"I tested the output from a 04 STi today and it was outputting 13.7v. So it may be worth it to get one and see if will out put more. I have the relay wired up except for the wires to the controller so if you want to get one coming to us I will hook it up to the controler and see if we get a higher output."

 

 

I am sending him a Fuel Pump Controller part number 22750AA010 that I picked up on NASIOC for $45.

 

He is going to see if it will plug in to the legacy harness and see if we can get it to work to output closer to batt/alt voltage on max like the STI.......

 

Stay Tuned........Should know first part of next week when part gets to Cobb Plano

Edited by Scooby2.5
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Yep that exact scenario happened to me two years ago. Two STI's on 850 cc injectors tuning for E85 put out about the same HP/TQ as I did and I was at 100-105% duty cycle and they were at 80-85%

 

We couldn't figure out why and here we are two years later trying to tune my car for more HP but can't and now we know why!!!

 

I talked to a guy with the same exact setup as me on a 08 impreza that put down 380/440 to the wheels with no problem.

We got mine to 362/415 and it was at 97% and we couldn't push it any further.

 

This is all on a mustang dyno as well.

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Well the verdict is the STI/Impreza fuel pump module was able to plug right into the LGT harness.

 

Bad news is the module only output 11.9 volts. .2 more than the stock legacy module on the stock wiring harness.

 

 

Good news is that if you bypass the stock wiring harness that seems to drop 1.7-2 volts the STI/Impreza module outputs 13.5 volts to the pump.

 

If you bypass the wiring harness on the legacy module we would get 12.5 volts.

 

So it looks as though the STI/Impreza module does output a bit more voltage on max than the legacy module does if the voltage into the module is correct or more.

 

I don't know why the legacy drops 1.7-2v across the harness but it seems that is the case.

 

With 13.5v going to the pump now by bypassing the harness with a wire and another relay and using the STI/Impreza module they were able to tune my car to 385WHP 425WTQ on the ID1000 injectors and FMIC. The IDC was around 90%

Edited by Scooby2.5
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Ill let you know what they used. I had to leave and Cobb plano finished up the wiring and testing faze.

 

I think they went from the fuel pump relay and ran a wire to the back of the car by the module and placed another relay, then to the module.

 

Ill take some pictures of it this weekend. I told them not to put the interior back together that I tore apart to save me some labor.

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Cool. I just looked at the wiring diagrams of 05 LGT and 04 STI and indeed the plug and pinouts match. The two wires that go to the ECU go to different ECU pins, but that's not surprising - the ECUs are different. I hope Cobb confirmed the ECU has no trouble controlling the pump duty cycle with the Impreza module?

 

Anyway, this is truly great research. The long standing mystery has been solved. But culprit is - what crappy thin wiring harness and cheapo piece of electronics? Geez, Subaru.

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I would honestly think that dang wiring harness has a resistor in it somewhere.....

 

I just can't see the harness dropping 1.7-2v across the wire. Crazy!

 

Only explanation is that or the wiring harness on the Impreza is larger wire.

 

I do believe the module was controlling the duty cycle as that was our goal and they didn't say anything different.

Edited by Scooby2.5
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Yep, good news is a lot of cars used the expensive one so it may not be too difficult to find at the salvage yards

 

Someone needs to test the 08 one with batt/alt voltage running to it and see what comes out.

 

IMPREZA

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'05, April — WAGON 2500CC EMPI DOHC TURBO Fulltime 4WD 5SP Manual transmission WRX Normal suspension

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'05, January — WAGON 2500CC EMPI DOHC TURBO FULLTIME 4WD Manual transmission 2.5XT Normal suspension

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'07, February — WAGON 2500CC EMPI DOHC TURBO FULLTIME 4WD Automatic transmission FORESTER SPORTS Normal suspension

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I looked at the parts database again. So 05-09 LGT/OBXT part # is 22648AA081. Regardless of wagon or sedan.

 

The same part # is used on 08-10 WRX sedan. 08-10 STI and 08-10 WRX hatches use 22648AA140 part #.

 

I don't have part info for 2011 STI sedan, but my guess would be it uses same part # as 08-10 WRX sedan or 05-09 LGT/OBXT.

 

So it would mean 08+ should suffer from similar problems, except perhaps the wiring harness being lower gauge. I don't think 08+ STIs are known from handicapped fueling. Or are they?

Edited by unclemat
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Btw, I am actually wondering if the particular unit on your car was bad/dying and the real culprit is just the wiring.

 

We did test another local 2005 Legacy GT wagon and it was exactly the same as mine.

 

I have a couple of more people that are supposed to test theirs and get back to me.

Edited by Scooby2.5
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Btw, with fuel pressure gauge, this condition should manifest itself with pressure drop (relative to the manifold pressure, of course), correct? I.e. not enough flow -> pressure drop.

 

Am I missing something? I had messed up fuel pump and the car was leaning out at the top. I confirmed the fuel pressure was dropping.

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It would be nice to check the max voltage at the pump, the voltage at the pump relay, and the voltage at the input of the module to see if your harness is dropping voltage across the wire as well.

 

Unclemat I can't remember what was happening with the exception of the needle on the Fuel pressure gauge was fluttering all over the place. Not stable at all.

Edited by Scooby2.5
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Thanks for running this one to ground and I'll be keeping an eye on this for my HTA68 build. Planning to run DW850s or PE850s (have both), but am concerned about topping out the IDCs when they really should be in the sweet spot of their capacity.
- Pro amore Dei et patriam et populum -
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