Bought a 2003 Impreza RS with 2.5 Swap, Flying Blind...

[bluesteel1973]

Hey everybody newb and reaching out to community for any help or suggestions.

 

I bought a 2003 Impreza with a 2.5 engine swap, with what I'm told looks like a fresh rebuild.

From what I can tell, it is a 2005 Forester motor.

I bought it as a project, and it was priced well.

Ok, it runs, goes into gear (AT), and "drives", not well.

I figured it might need an ECU flash with a different tune, but when I was throwing on the CAI piping, I saw that there was no MAF.

I went ahead and purchased a new one, and I cannot find the MAF plug anywhere.

Is this something that should be near where the stock one was or in a different spot because of the other motor? I can't find any plug that looks that size.

Additionally ABS light is on, and brakes seem spongy.

I appreciate any help or advice in advance.

BTW, its NA now but I'm planning on adding the stock WRX turbo setup, which I have.

[1 Lucky Texan]

that car likely has a MAP

 

mushy brakes are most frequently from air in the lines so, strat with a good flush/bleed.

 

many people complain of soobs having a spongy feeling when actually, the pedal travel is just a tad longer than other cars. But, if you still have a problem after a bleed, start by looking for stuck calipers or cracked caliper brackets or associated bolts. Then, if that's all good, it may be time to investigate new rubber or stainless steel lines at the wheels or a master cylinder brace.

[bluesteel1973]

that car likely has a MAP

 

mushy brakes are most frequently from air in the lines so, strat with a good flush/bleed.

 

many people complain of soobs having a spongy feeling when actually, the pedal travel is just a tad longer than other cars. But, if you still have a problem after a bleed, start by looking for stuck calipers or cracked caliper brackets or associated bolts. Then, if that's all good, it may be time to investigate new rubber or stainless steel lines at the wheels or a master cylinder brace.

Thank you very much for the reply. I'm not really familiar with a MAP vs MAF. What should I know or look for?

Where should I begin as far as why it seems lack power or that fuel air mix is off, an ECU flash?

 

The brakes do feel like they may just need a bleeding, but since the ABS light was on, I figured it could've been associated, while they may be unrelated.

[1 Lucky Texan]

there are sensors at each wheel and a pump so, there very well could be other issues with the ABS. Since the car is new to you - it's worth checking the charging system too as low voltage will often show up in the ABS system first.

 

Is the check engine light on? getting the codes and posting them here is often helpful.

 

was that engine rebuilt with multilayer steel headgaskets?

 

more details about the car/engine/swap and specifics about how it's running/driving poorly will help. There are guys here with tons more experience than me , I just read a lot, so, they can probably guide you better.

[bluesteel1973]

there are sensors at each wheel and a pump so, there very well could be other issues with the ABS. Since the car is new to you - it's worth checking the charging system too as low voltage will often show up in the ABS system first.

 

Is the check engine light on? getting the codes and posting them here is often helpful.

 

was that engine rebuilt with multilayer steel headgaskets?

 

more details about the car/engine/swap and specifics about how it's running/driving poorly will help. There are guys here with tons more experience than me , I just read a lot, so, they can probably guide you better.

Thanks again for taking the time to read and post.

Check engine light is on, I will pull codes again, I know there are a couple generic O2 sensor ones, maybe an IAT as well. I'll scan again though.

 

Unfortunately, I have no history on the vehicle whatsoever. I know nothing about it.

It looks like kind of a hack job although it seems that all the electrical accessories etc in the car seem to be working.

 

I also discovered last night that the rear drive shaft is missing! Not sure why the PO would've removed it, because I wouldn't think an engine swap would necessitate changing or even removing.

[lmdew]

Quick fix for Torque Bind, a fixable transmission problem.  Search Torque Bind and you will fine lots of good info.

[Fairtax4me]

O2 sensor codes will usually put the ECU in Open loop which may cause low power.

 

Need to pull the codes and figure out what it needs to correct those first. If there are still power problems after that then you can proceed with other diagnostics.

 

MAF would typically be plugged in somewhere over on the passenger side near the fender.

 

Check the hood for the VIN sticker and the Emissions routing label.

Compare the VIN to the car to see if the hood is original. If so, check the emissions label diagram on the hood for a MAP/Baro sensor. This will tell you if the car has a MAP or MAF based fuel system.

You can also try googling the location of the MAP sensor on that engine.

Another thing you can do is post pictures of the engine and someone here who knows the setup Bette may be able to tell you what's what and if anything is missing.

 

 

 

MAP based fuel systems use a pressure sensor on the intake manifold or throttle body to measure intake vacuum. These make adjustments to fuel delivery based on changes in vacuum which will change depending on throttle opening and engine speed. Its a bit less accurate than a MAF system, but they have fewer issues and the response to changes is a bit quicker since there is very little delay between throttle opening and when the computer changes fuel delivery. This is also refered to sometimes as a "Speed Density" system.

 

With a MAF system there is an air flow sensor which measures the mass of the air flowing through the intake tube. These give a more accurate calculation for the A/F ratio, but have a bit of a delay between throttle opening and when the MAF registers a change in air flow. The MAF sensor will usually be attached to the filter box on the fender, and have a long intake tube from the MAF to the throttle body.

[bluesteel1973]

O2 sensor codes will usually put the ECU in Open loop which may cause low power.

Need to pull the codes and figure out what it needs to correct those first. If there are still power problems after that then you can proceed with other diagnostics.

MAF would typically be plugged in somewhere over on the passenger side near the fender.

Check the hood for the VIN sticker and the Emissions routing label.

Compare the VIN to the car to see if the hood is original. If so, check the emissions label diagram on the hood for a MAP/Baro sensor. This will tell you if the car has a MAP or MAF based fuel system.

You can also try googling the location of the MAP sensor on that engine.

Another thing you can do is post pictures of the engine and someone here who knows the setup Bette may be able to tell you what's what and if anything is missing.

MAP based fuel systems use a pressure sensor on the intake manifold or throttle body to measure intake vacuum. These make adjustments to fuel delivery based on changes in vacuum which will change depending on throttle opening and engine speed. Its a bit less accurate than a MAF system, but they have fewer issues and the response to changes is a bit quicker since there is very little delay between throttle opening and when the computer changes fuel delivery. This is also refered to sometimes as a "Speed Density" system.

With a MAF system there is an air flow sensor which measures the mass of the air flowing through the intake tube. These give a more accurate calculation for the A/F ratio, but have a bit of a delay between throttle opening and when the MAF registers a change in air flow. The MAF sensor will usually be attached to the filter box on the fender, and have a long intake tube from the MAF to the throttle body.

Hi, thanks for the reply. I have searched lots on the internet and have seen where it is, on various cars, though it does vary.

Bear in mind I have a 2003 RS impreza, with a 2005 2.5 forester motor. I don't know whether the MAF harness would be the original impreza harness and exit location or wherever it routes on a forester.

 

Either way, I can't seem to find a plug that large anywhere.

The hood is a CF hood so no diagrams, not that it would matter due to the different model motor.

Very frustrating...

The car did not even have intake plumbing when I bought it.

The car starts right up ever time and is strong, but there is much unplugged I suspect.

[Rooster2]

It is customary in a motor swap to stay with the wiring harness that is in the car. I don't know of any subtle changes between the motors, but if need be. If the wiring to the motor was not identical, I wouldn't be surprised if the intake manifold off the original motor was bolted onto the swapped in motor. That way original factory wiring is kept in tact.

 

The Impreza and Forester are built onto the same chassis, with the same 2.5 motor, so would expect all parts location to be the same. So, don't think of these 2 vehicles as being that much different. They really are not.

 

If it were me, i would check the basics fires. Pull out a spark plug or 2 to see what shape they are in, or perhaps just replace all spark plugs, so you know they are all good. Add a bottle of Chevron Techtron, or other good injection cleaner product. Put in the good stuff costing $7 or $8 per bottle. Don't waste your money buying cheaper injector cleaner. The cheap stuff doesn't work well. With injector cleaner you get what you pay for. Drive car for a while to see if drives better.

 

Post all codes here. Fixing code makers always helps a car run better.

 

Keep us posted on your progress............Rooster2

[bluesteel1973]

It is customary in a motor swap to stay with the wiring harness that is in the car. I don't know of any subtle changes between the motors, but if need be. If the wiring to the motor was not identical, I wouldn't be surprised if the intake manifold off the original motor was bolted onto the swapped in motor. That way original factory wiring is kept in tact.

 

The Impreza and Forester are built onto the same chassis, with the same 2.5 motor, so would expect all parts location to be the same. So, don't think of these 2 vehicles as being that much different. They really are not.

 

If it were me, i would check the basics fires. Pull out a spark plug or 2 to see what shape they are in, or perhaps just replace all spark plugs, so you know they are all good. Add a bottle of Chevron Techtron, or other good injection cleaner product. Put in the good stuff costing $7 or $8 per bottle. Don't waste your money buying cheaper injector cleaner. The cheap stuff doesn't work well. With injector

cleaner you get what you pay for. Drive car for a while to see if drives better.

 

 

Post all codes here. Fixing code makers always helps a car run better.

 

Keep us posted on your progress............Rooster2

 

 

 

Thank you, that's kind of what I figured as far as keeping old harness, though I was under the impression that the RS was a 2.0 motor.

I am going to change all the plugs and use the ones suggested for boosted vehicles as I plan to throw on a small turbo and boost no more than 9 lbs, I was also given some 440cc 3920 injectors, and a new unisia Jecs fuel pump, so might as well throw them on too.

 

It almost seems like the PO eliminated the harness and MAF...

CODES:

P0851 PARK/NEUTRAL SWITCH CIRCUIT LOW

P1518 STARTER SWITCH CIRCUIT

P0512 STARTER REQUEST CIRCUIT

P0137 O2 CIRCUIT LOW VOLTAGE BANK 1 sensor 2

P0138 HIGH VOLTAGE

P0502 VEHICLE SPEED SENSOR A- CIRCUIT LOW INPUT

P0503 " " INTERMITTENT/ERRATIC/HIGH

P0113 INTAKE AIR TEMPERATURE SENSOR 1CIRCUIT HIGH INPUT

P0037 HO2S HEATER CONTROL CIRCUIT LOW BANK1 SENSOR 2

 

 

Yeah, just a few...

[1 Lucky Texan]

I'd be tempted to clear those and see what comes back.

 

if voltage is actually wonky - that can cause 'spurious' codes to set. so, thoroughly check the battery and charging circuit.

 

also, I'd imagine it would be easy to miss some ground connections with an engine swap so - google up some images and try to locate all the grounds and confirm they are good.

[Rooster2]

Suggest, if you have not done so..........do a google search for "2002 subaru maf location." This will give you access to several sites, and even to a link for MAF sales sight on line with pictures. Maybe the talk and pixs will help you.

[1 Lucky Texan]

the MAP sensor may look something like this;

 

 

look for it plugged into the intake mani - sorta behind the alternator under the 2 spark plug wires at the coil.

 

I think (just based on googling some images)

Edited December 9, 2014 by 1 Lucky Texan

[bluesteel1973]

the MAP sensor may look something like this;

 

 

look for it plugged into the intake mani - sorta behind the alternator under the 2 spark plug wires at the coil.

 

I think (just based on googling some images)

Ok, thanks that is what it is and is present. The word boost on it threw me, and I didn't really know what a MAP was anyway, only familiar with MAF.

[bluesteel1973]

Thank you everybody for your help pointing me in the right direction. I had a few delays with the weather and holiday chores. The header has a badly pinched pipe on both side that has got to be killing my air flow tremendously. And since I recently found out that my impreza is also missing the rear drive shaft, might that play a role in it feeling very sluggish on acceleration? It is in F W D mode now. I got a manual rear drive shaft locally for a good deal, and supposedly you can adapt it to work on a AT if you swap the yoke section at the tranny end. I have no idea how the last section aka yoke, output shaft, propeller etc. If anyone has any suggestions, I'd be grateful to hear them. The AT shafts seem to be hard to find locally. If I could post pictures, I could more easily convey what I am dealing with.

[bluesteel1973]

Quick fix for Torque Bind, a fixable transmission problem.  Search Torque Bind and you will fine lots of good info.

And this may be the very reason that the PO removed the driveshaft, you think that's likely? Thank you for that, I will start looking into that as well, I saw a few related postings in searching for the AT MT conversion or driveshaft interchangeability. Thoughts?

[Fairtax4me]

No need to swap yokes. The rear half of the driveshaft is the same for auto or manual. Just unbolt it at the center flange and bolt the rear section onto your car. Be sure to pay attention to the way the yokes are oriented. If the rear section is 90° off it will cause vibration.

 

The driveshaft has nothing to do with the sluggishness. The crushed exhaust pipe could cause that if the actual pipe is crushed. The heat shields on the outside of the y-pipe can be pretty badly bent and not affect the pipe inside.

[bluesteel1973]

No need to swap yokes. The rear half of the driveshaft is the same for auto or manual. Just unbolt it at the center flange and bolt the rear section onto your car. Be sure to pay attention to the way the yokes are oriented. If the rear section is 90° off it will cause vibration.

The driveshaft has nothing to do with the sluggishness. The crushed exhaust pipe could cause that if the actual pipe is crushed. The heat shields on the outside of the y-pipe can be pretty badly bent and not affect the pipe inside.

Thank you for the info, maybe I simply don't understand or didn't explain my problem very well. Ok, so I have an AT with no drive shaft at all going to the rear. I have only the small yoke piece just to prevent ATF from spilling out.

[bluesteel1973]

Anybody have any experience swapping driveshafts from an MT to AT any if the swap that mine has with the forester motor would factor in, although I don't see why it would. Or should I start a new thread? Once again, thanks to everyone for their input.

[lmdew]

I think the length is different.  If you have one, it's easy to check, just jack up the rear get it on jack stands and then try the drive shaft you have.  Slide it into the trans, see if the mid bearing bolts up.   Bolt it to the rear dif.  It will either work or not.  If not, you will see what you need.

 

Yes torque bind is likely!

[bluesteel1973]

I think the length is different.  If you have one, it's easy to check, just jack up the rear get it on jack stands and then try the drive shaft you have.  Slide it into the trans, see if the mid bearing bolts up.   Bolt it to the rear dif.  It will either work or not.  If not, you will see what you need.

 

Yes torque bind is likely!

Ok, thank you very much. I can't seem to figure out how to get the last section of propeller shaft from AT, I will start a new post.

I think that torque bind is almost a given now based on circumstances, thanks for that. Looks like it can be relatively easy to resolve.