02 WRX to 98RS Swap Question

Hey everybody! Been a while. I am currently dealing with a problem that has me stumped.

Car is a 98 2.5RS with an 02 WRX engine/trans/diff swapped in. I had iWire merge the harness for me. First test fire went extremely well. Fired first crank! Super stoked, then this happened.

The issue is that I can now not get it started and it keeps flooding out. Cranking with gas pedal to the floor to deflood results in occasional pops out the exhaust but no life. Pulled the plugs, cleaned/dried them out, spun it over and left it open over the weekend and did not help.

I've made sure I connected all the electrical connectors, vacuum lines, etc...

Really racking my brain on this one. Anyone able to help a brotha out?

Thanks and it's good to be back!
Pic for attention:

 

I unfortunately lack logging capabilities at the moment.

 

when you tried to re-start it after letting things dry out, did you have the pedal to the floor again, or did you let it re-flood?

 

I had the foot to the floor when I tried again to avoid flooding it again.

 

Did you let off at all to see if it would pop? When the pedal is to the floor on start up, it should basically disable the injectors IIRC

 

Yep That's the idea. Cranked it for 10 seconds with the pedal fully depressed initially to build up a little oil pressure. Then cranked it again for 15 seconds starting with the pedal fully depressed then letting off.

 

did you verify that you have spark as well? does your harness/ecu set up still utilize an immobilizer?

 

I have not yet been able to check for spark. Been working by myself lately. I will try and check tonight when I get home.

I am not 100% sure on the immobilizer situation. To my knowledge, I didn't think the 02 WRX utilized one?

 

I don't remember, honestly, if they did or not.

 

I believe the throttle to the floor thing is only on DBW cars, but not 100% on that. Immobilizer came into play on 05+ STi. Bugeye definitely didn't have them.

What was done/changed between the time it was fired to the second attempt to start it? Any CELs?

Edit: Also, did you turn it off after the first start on your own or did it die?

 

Pretty sure the pedal to the floor works on the 02 ECU.

Nothing was changed prior to the second attempt.

I did turn the engine off myself. It was running like a champ too

 

WOT to clear a flood is true of almost all fuel injected cars, certainly all fuel injected Subarus.

Nope, no immobilizer in 2002.

I'm assuming when you pulled the plugs, they were noticeably wet, yes? So we're basically 100% sure that it's a flooding issue.


The assumption that it is, indeed, flooding, doesn't seem to make sense with the fact that it's not solved by the clear-flood procedure. I would start with a medium code reader (or OBD II dongle for your phone), and look for any DTCs, I'd also look at the coolant temperature in the ECU, if it thinks it's -20*F it'll dump fuel in (although clear-flood should solve that, at least temporarily). Next I would pull the vacuum line off the fuel pressure regulator, and look for fuel to see if the diaphragm has punctured, that can wreak havoc, although typically mostly just on the one cylinder...should still run. Then I'd be looking for vacuum leaks, hoses disconnected, etc.

You might try a capacative discharge to clear the ECU of anything it may have learned in that first startup.

If all that doesn't turn up anything, I'd check the cam timing.

 

Thanks Chux! When I pulled the plugs they were indeed quite wet.

I will throw my code reader on it tonight and see what's there.

Good idea on the FPR. I will have a look at that as well.

I will do another double check to make sure I have everything connected. A boost leak test would also help I'm sure.

 

So new update. Got home and for s&g tried to start it. Started right up like a peach. Ran it for 10-15 minutes to bleed the cooling system. Ran like a top the whole time. Shut it off for 5 minutes, started again but with a little throttle work. Once again ran fine. Shut if off again.

Now, sounds like it's flooded again and won't start. Done for the night.

Couldn't find my code reader (of course) but noticed cel is on the cluster. As is ABS and airbag(none hooked up). Checked for and it appears to be just fine.

 

Key on, but engine off, all those lights should come on to verify their operation, regardless of any fault codes.


Well, the fact that it started rules out mechanical trouble, anyway. So that's good news.

Still kind of lines up with coolant temp sensor. The ECU might think the engine is colder than it really is (though maybe not by much), and it's very slowly flooding itself. Still seems like it would run rough, but maybe not, and with a code reader, it's free to check it.


The other thing to check, would be fuel trims. Maybe it's getting some bad information (presumeably from the oxygen sensor) that's telling it to add fuel.


What's the history of the engine before the swap?

 

Those lights were on while it was running.

I will try and pickup a reader today from work. For the life of me, can't think of where mine would have gone!

Good call on the fuel trims. I have not replaced the O2 sensors since I've owned the car/engine.

As far as history of the engine. I owned the WRX it came out of for 2 years. Ran like a top for most of that time. Last time I tested the compression, all cylinders were within 3 psi of each other. 117-120 if I recall correctly. When I pulled it for the swap, did all new gaskets, timing belt, water pump, thermostat, oil pressure sender, pcv valve & all new vacuum/coolant hoses.

 

Sounds good, only the upstream sensor has an effect on the fuel trims.

Any medium quality (or better) code reader will be able to read the short- and long-term fuel trims, which would tell you if it's trying to add a bunch of fuel beyond the default tune...

 

Cool. Like I said I will try and borrow one from work and get a better idea as to what's going on in there.

Thanks again Chux for all the help!

 

Borrowed a scan tool from work. Currently have a P0031 cell for the front O2 sensor. Shows 0% on both long and short fuel trims.

Engine temp sender shows 82 degrees and intake air shows 84 degrees. So that appears to be fine. Anyone have a known good front O2 sensor I could try?

 

Good luck with that! I'll be paying close attention to how this turns out.

I recently had my motor out for a handful of things. Long story short, I got a P0031 when I fired it up for the first time. Most likely due to a few damaged wires on the sensor (at least I think). Both damage areas are too close to the end to repair them, plus the sensor is probably original w/ 190k+ on it.

So, bought a new "Denso" one on eBay for $70, as opposed to the $200+ they get at Subaru. Mine even has the Subaru logo on the box! So whether it's a cheap knock off disguised as the good stuff is yet to be completely determined.

However, I put the new one in (even tho the wires are like a foot shorter than the original) and tried it. P0031 went away and was replaced with a P1130 (open circuit). So now I'm in troubleshooting mode trying to figure out wtf is going on.

My apologies for the slight thread jack, just wanted to share my very recent (current) experience.

 

You can test the O2 sensor with a multimeter if you want. Generally a good idea before just replacing it. Let me see if I can find the Ohms for a subaru O2 sensor...


EDIT:

Can't find a value for Subarus specifically. If you're getting infinite resistance (or zero) though, the heater circuit is bad.

 

I've seen a few instructionals online about testing it while it's already hot and still plugged in. However, I don't have those cute little probes that stick into the back of factory connectors. I did check resistance across the sensor itself with the clip unplugged and it did at least register some resistance, so it's not "dead", or so I'm assuming.

 

There's a few different ways to test an O2 sensor and which way you do it depends on which code you get/what you suspect broke in the O2 Sensor. I should have been more clear in my first post that I was referring to checking the heater circuit (which the code indicated), which has a spec-ed resistance generally.

Every Subaru I've worked on is a 4 wire (as are most vehicles). Newer vehicles may have more wires for more features, but they'll all still have the basic 4 wires. Go to an old enough car, and they'll have 2 wires.

The OP's code was for the O2 sensor heater circuit, which is generally the two wires that are the same color. This circuit is similar to an incandescent light bulb in theory, except instead of light, it is designed to just produce heat (to help bring the O2 sensor up to temperature). In my experience, this is how almost every Subaru O2 sensory fails (unless you have a mechanical failure- e.g. the sensor is snapped in half). There should be some resistance between these two wires, indicating that the heater circuit is still working. Infinite resistance (or no resistance, some cheap meters display infinite as zero for whatever reason) means that the circuit is fried, similar to when the filament in a bulb burns out and breaks. No way for the electricity to travel through it.

You can also test for 12V power and ground to the circuit (via the connector that is on the body side, not the O2 sensor side).

Testing the actual Sensor portion is the most difficult portion. The resistance of the last two wires changes with the temperature of the sensor it self, so testing for resistance there is not too useful. Instead, check to see how volts (or mV) it is putting out when it is warmed up. A torch works, but letting the car get up to operating temp and then testing it is the best way (not always possible when the car doesn't start...). Some use a torch to try to test the O2 sensor then, which can be done if you are careful.

For my 05 Outback, the front O2 sensor should be between 0-0.9 Volts. As a general rule, the voltage of the sensor should vary as the car is running (as the different voltages tell the ECU to put different amounts of fuel in). In my experience, again, when an O2 sensor fails this way, it pegs out and turns the fuel trims all the way up. If you have an O2 sensor code and your fuel trims are at your max, this is generally how the sensor failed and the first thing to test. That requires having a scan tool that has live data displays though too.

 

After doing a bunch of electrical tests and running the scan tool from work, pretty much deduced that the O2 sensor heater circuit is fried. Also found that the main relay in the vehicle is fried on one side. Doesn't send full voltage to the front O2 sensor connector. Have one of each on order and should hopefully have them by Wed. Will update with more then.

Thanks again to everyone. Somehow keeping me from setting the whole shebang on fire

 

How did you figure out the relay side of it? And is it a "special" relay or would a universal 5 blade style work?

 

Soon...

 

@ShortytheFirefighter

 

FSM calls for a voltage reading of 10V+ on pin 2 on the front O2 sensor connector with the key in the on position. I was getting anywhere from 3-6V. Pulled the relay and did the tests on that. No connection between pin 3&5 or 4&6 (Can't remember which one off the top of my head right now).

It is a fancy 6 pin relay. Link Here ----> https://www.amazon.com/Standard-Motor-Products-RY56-Relay/dp/B000C7ZVH8

 

Woohoo! Thanks for the insight. Something else to check tonight.

 

Update. Threw the new parts in last night and tried starting it again. Nothing appeared to have changed. Still floods out.

I am at the point now that I think it is wise to seek the help of others.

On that note, anyone down for a little roadtrip to come and help me get this old girl up and running for good? Can provide food and beer!!!

 

I'd say yes but unfortunately I think this one is definitely over my head.

 

UPDATE:

Been a while as I got sidetracked with getting my Jeep ready for a work event.

I have since replaced the Crank Position Sensor and the Cam Position Sensor And Installed a new Front O2 Sensor.
Sent my injectors out to Porter Mufflers for a clean and they all checked out good.

Still NO start!!!!!!

Anyone have any possible idea what this thing is doing? Literally driving me nuts over here.

Appreciate any insight anyone can give. Insert support group comment here ----->

 

Since i've been debugging my ECU and wiring swap a lot of things like this have been on my brain.

One thing that comes to mind, can you test the Idle air control valve?

If it's not opening while cranking your going to be starving the engine of air, and you'll get lots of fuel. One simple test is give the car 5-10% throttle while cranking and allow some air in.

This may be a long shot, but not being familiar with all of what you've tried, it's the first thing I can think of.

-Eazy

 

I am not sure what tests are available for the IAC.

I have tried all manner of throttle positions to no avail. Only real difference is with throttle wide open, where eventually I will get a pop from the exhaust.

 

I have verified spark. Good strong arc on all 4.

I figured I would swap plugs for MAPP torches

 

So did a bit more testing. 3

Tried unplugging the MAF but no dice.

Also tried with the intercooler removed and the MAF unplugged, still nothing.

Open to any other suggestions. Literally braindead now. Just can't think of where to go next. Any help is much appreciated!

 

Maybe a long shot but was the fuel pressure regulator ever checked?

 

It was visually inspected for what it's worth.

 

Have a new FPR on its way. Will report back with update.

 

Have you checked the ignition and main relay? I had a similar issue on a Subaru and Mazda and both times it was a relay.

Mike

 

Mike, I have already replaced the main relay as one side was burnt. I have a new starter/interlock relay coming as well since that one fried from all the cranking I've done so far.

 

UPDATE: Got the new relays installed and double checked all the connections once again. Tried starting yet again to no avail. I have uploaded a video to try and better explain what it is doing.


Any help is greatly appreciated! If this doesn't work, I will resort to bribing people to come over with beer/food to take a look