Subaru Impreza 98 --> 2002-ish

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kb1gtt
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Subaru Impreza 98 --> 2002-ish

Post by kb1gtt »

I've been to scared to drive it for some time. I bought it from someone that ran out of $. It's using some really sketchy electronics, and makes way to much power for such a sketchy setup. I'm looking to resolve those issues :) Here's the basic specs.

Optima yellow top
H&R Springs
AGX Struts
2003 WRX 2.0L engine with ~30K miles on it
VF39 Turbo
Pink Injectors
Blitz Turbo Timer
CAI
Greddy FMIC
Turbo XS BOV
Perrin Uppipe
Turbo XS Downpipe + Exhaust
Prodrive Axleback
UTEC ECU
WRX Front Brake rotors and calipers
WRX Sway bars
Steering rack bushings
STi V2 Rear disc Brakes and calipers
JDM STi Version 2 transmission (brandy new insides!!!)
Rear 4.11 Diff
ACT Clutch
Lightweight flywheel

http://rusefi.com/wiki/index.php?title=Vehicle:Subaru_Impreza_WRX_2003
Last edited by kb1gtt on Sun Aug 27, 2017 9:48 am, edited 1 time in total.
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Re: Subaru Impreza 98 --> 2002-ish

Post by AndreyB »

And now you have to disclose for how long this beautify is sitting parked and roll towards the garage filled by shame :twisted:
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Re: Subaru Impreza 98 --> 2002-ish

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I'ts been a shameful couple years that it's been sitting. I move it when I started building the garage. However it's been sitting for far to long. Someone stopped by a couple months ago to inquire if I'd sell it. I told them no :) I still plan to make it go and go well.
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Re: Subaru Impreza 98 --> 2002-ish

Post by kb1gtt »

I think I've finally getting around to fixing up this suby. The garage is mostly done, and I plan to put the suby inside shortly. Now that I have a nice place to work on it, I think I'll start making it better. I've been really hesitant in running it, as the wiring is a mess. Messy isn't so much of the concern. I'm really more concerned with the liberal use of those crimp vampire connectors used on power devices like the fuel pump, alternator, ect. A .1 ohm resistance will create excessive heat which can result in fire, which can take the toy away from me all together. So I have been waiting until I can re-wire it, and get a better system into it.

The ECU is currently sitting under the passenger side carpet where the feet go, but I believe in many vehicles it's behind the glove box. While the car is technically a 98 Impreza, that car never came with a turbo. The guy that had this before me got a 2002 WRX wiring harness and motor. Then spliced together the existing harness and the old harness. He was looking to get the controls of the new and keep the windows controls and gauge controls and such of the original. I'm OK with not doing that, and remove the wiring all together. I expect this to be a track only vehicle.

Here's a picture of a wiring mess I'm looking to replace. That's the alternator wiring. Yuck.
alt_wires.jpg
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Here's another ugly picture near the gas tank, inside the cabin. High probability of flames near the fuel tank starting inside the cabin, how can that be bad. Oh, it also use some very small wire that gets hot as the fuel pump has been upgraded for more flow.
fuel_pump_wire_mess.jpg
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Below are the sensors I can easily see. I hope to get an existing harness such that I can connect into the existing spark plugs and existing sensors, then wire them to my own ECU. I'm going to avoid using the existing ECU connector, as the wires connected to it are very questionable.
MAF.jpg
MAF.jpg (1.08 MiB) Viewed 17009 times
Ooops hit the max number of allowed attachments and ran out of time this morning. I'll post more about it this evening.
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Re: Subaru Impreza 98 --> 2002-ish

Post by kb1gtt »

Here are the other pictures of the sensors I want to interface with.
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near_TPS.jpg
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TPS.jpg
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Re: Subaru Impreza 98 --> 2002-ish

Post by AndreyB »

How about I promise to figure out parking situation around my new appartment so that I can buy a test vehicle and you maybe wire up the starter and spin the engine on this red forgotten suby if you feel so? :)
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Re: Subaru Impreza 98 --> 2002-ish

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I'm kind of thinking Frankenso will be a good plaftform for this suby. So I'll probably be considering this in the near-ish future. Hobby goals are currently to do a bunch of stuff with the power supply, Frankenso, then clean out area in garage, then start playing with the red play beast.
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Re: Subaru Impreza 98 --> 2002-ish

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Red suby made it in to the garage today.
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Re: Subaru Impreza 98 --> 2002-ish

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A small step for a suby a giant leap for rusEfi.
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Re: Subaru Impreza 98 --> 2002-ish

Post by kb1gtt »

Continued from here http://rusefi.com/forum/viewtopic.php?f=3&t=736 I'm first hoping for connectors for the spark plugs and crank angle sensors. Pictures shows above. While I can technically cut the wires in this harness, as you can see, the harness is very questionable, and I hesitate to use it at all. Longer term I'm looking for connectors for knock, TPS, ect.
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Re: Subaru Impreza 98 --> 2002-ish

Post by AndreyB »

Image
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Re: Subaru Impreza 98 --> 2002-ish

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Some progress on the suby, ambient temperature finally got up to 10F (-12C) and I got through my snow removal duties. After getting to play with the red suby, it looks like my wiring is shot and can't be used. I was hoping part of this harness was going to be use-able, but it appears the connectors are just to far gone. Blah, I'll have to re-wire pretty much the entire car = blah for labor efforts.

Here's how I connected my CAM, it goes through the E1/B20 engine connector, then the E15 connector on the CAM sensor, it has been 100% disconnected from up stream components, and was originally tested when connected to the Frankenso board, with the same results as noted below. The DMM claims 1.742k ohms between red and black wires, not connected to the frankenso, just red and black.
CAM.jpg
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suby_cam_noisy.png
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Here's how the crank looks, it's better but still very noisy. The DMM claims 1.622k ohms when connected to the green / white as well it was connected to the Frankenso.
Crank.jpg
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suby_crank_noisy.png
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Both VR sensors are measuring the same ohms, so perhaps the sensor is some how broken. I really shouldn't have this much noise on the line. The ohms is also not un-reasonable, but is a bit high for most VR sensors, which implies a bad connection. However I don't know the expected ohms, so I don't know if I'm really measuring high or if it's with in specification.
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Re: Subaru Impreza 98 --> 2002-ish

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I see no other way to fix the subys wiring, other than to gut it entirely and start from scratch. Which is kind of frustrating.

I took the CAM sensor out and clipped onto it with the scope. I got a very nice and clean signal when I waved a wrench in front of the sensor. I then re-installed it into it's position sensing the CAM, then I disconnected both engine harnesses (which disables spark, fuel, solenoids, ect) I then cranked it over with the scope connected. Ch1 was one lead, CH2 was the other lead, both scope probe GND straps were connected together and connected to the frame near the sensor. However I still get a noisy as hell signal. Best guess is that starters brushes must be making some noise. I really need to find a new battery for this DSOQuad. Mine blew up like a balloon, and I stopped using it before it popped. There is a chance this noise is coupling in through the USB and laptop GND's. The laptop was floating relative to the car.
CAM_no-engine-harness_direct-clipped.png
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I guess I could have tried capturing it to see what rusEFI would consider a noise pulse vs what I see on the scope. However I really want to make it better on the scope first.

Any how, still fighting with noise issues caused by a really sketchy wiring done by a prior installer.
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Re: Subaru Impreza 98 --> 2002-ish

Post by puff »

is the cable from vr shielded? what if you connect the scope directly to vr cable (GND & CH0)
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Re: Subaru Impreza 98 --> 2002-ish

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Yes cable is OEM shielded twisted pair. I used a alligator an clip to GND it as the GND was broke when I cut the cable. I originally cut the wire and connected Frankenso R0.2 to it. I got many noisy pulses in the digital sniffing. I then connected the scope and saw a huge amount of noise. I've been trying to isolate that noise and remove it from the equation. To do this I've been working my way closer to the sensor and sniffing in a variety of ways, as well I've been disconnecting harnesses to remove potential noise sources.

This engine is an engine swap, which uses 2 different harnesses. The harnesses were spiced together with these scotchlok connectors.
41WttNxCnmL._SL500_SS100_.jpg
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That is a blue one, and I used to joke about how the fellow used brown connectors (blue and red that got hot) I just learned that they actually make these connectors in the brown color. Point being it's some really dodgy wiring.

I have sniffed in several different ways, which includes direct connecting the scope to the sensor. I still get the noise. My plan is to remove the existing electronics even more. I plan to remove the starter battery lead, then connect my battery power direct to that and use a relay to engage the starter. This will prevent powering the existing ECU and existing radio, ect.
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Re: Subaru Impreza 98 --> 2002-ish

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This red beast is still an electrical nightmare. But I got out there and did some testing today. The short version is that if you have a suby, with after market ECU I would suggest a 1.6kohm to 2.2kohm 1 watt resistor be installed at the ECU or just inside the ECU. This loading resistor will help get a better electrical signal to the ECU. See below for a slightly more detailed analysis below.

In this case, the slow cranking pulses are above 85mS, so the MAX9926 zero-crossing threshold will self adapt to about 4mV to 30mV, typically 15mV. The chip typically self adapts to 33%, so when in these low cranking RPM situations, you want your VR signal to be at least 30mV * 3 = 90mV, which is 180mV peak to peak. By adding a resistor to the circuit at the ECU, you can decrease the effects of noise. However if you put on a loading resistor with small ohms, you can also prevent slow RPM tooth detection. In my case, I have a very noisy signal, and I'm looking to decrease the noise by adding a loading resistor.

I was hoping that I could minimize the noise and get valid readings from my suby with questionable wiring. I set out to see what ohms of impedance I could put on the VR to minimize the noise, and decrease false tooth detection.

Here is what my suby signal commonly looks like while cranking. Please note, this is probably not the typical. the prior owner did some really messed up wiring, it's a 98 with a 2002 engine harness. The battery has been relocated to the trunk, and I have many brown scotch connectors. This wiring is very sketchy and bad. I don't drive this thing, as it's just waiting to catch fire. I need to gut it completely and wire it properly. However I have not gotten around to doing that yet.
620ohm_5ms_0.3Vpp_noisy.png
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The above is with a 620ohm resistor across the VR.

Here is what my noise looks like with the key on and not cranking.
620ohm_no-crank_1ms.png
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You can see that as soon as I start cranking, I get massive noise issues. As well you can see that even with a 620 ohm resistor, I'm still getting about 480mVp-p which is more than the required 180Vp-p. You can see the noise floor is very low, so this noise is not from ambient stuff, it's from the car. Also the hood was open, and the scope was placed outside the car near the front passenger fender. Such that the wires were as far away from potential noise generating wire as possible. The shield was connected to the frame ground, so the shield should be mostly functional. Also I have disconnected any devices I can get my hands on. However there are many things buried in the engine.

Here's a picture of where I captured the signals. I'm showing the scope probes on 10X and that I'm on that side of the wiring connector. When I did the testing, I ran the wires 180 degrees from how shown, such that they went over the fender and left the engine bay right there.
Setup.jpg
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Any how, despite my attempts to keep the noise down, it's still there for me. I don't see enough of a change from 10k to 2.2k to prevent false tooth detection's. To me it does look like the 10k is more noisy than the 2.2k. As well it looks like 620ohms is less noisy, and I expect that lower ohms will decrease the effects of the noise.

So I wonder, how low in ohms can I go? I really don't know. It depends on a bunch of details which I do not have. I don't know the gaps, or inductance of the VR, etc. I don't know how many mJ of energy the VR will produce at full RPM. I know a 1/8 watt 620 ohm resistor, could handle about 9Vrms, so about 12Vp-p. I expect VR's to typically get up to 50vp-p ish. So I would think that 40Vrms ^2 / 0.125W = 13k ohms is all you can get out of an 1/8 watt resistor. I would expect a 1W could handle 1.6k ohm. However I don't know the voltage that would be produced by this sensor at full RPM, so that's just guess work. It would be handy if I could get this sensor spinning at 6kRPM, then I could measure it's voltage and make good suggestion for what size resistor it could handle.

Any how, the conclusion I would make from this is that if you use a 1.6kohm or a 2.2kohm resistor, you want to install it across the leads at the ECU or if you can inside the ECU. This will help decrease the electrical noise and will help prevent noise from generating false triggers. I also know you can electrically go down to 620ohms and you would still have sufficient signal for the MAX9926 to detect, however you are likely hitting thermal limits when you go below 1.6kohms. If do install a loading resistor, I suggest using a 1 Watt resistor, and that you provide it with thermal cooling. Granted you aren't going to be full RPM all the time, so you would probably be OK with a smaller resistor. However keep in mind you may end up doing engine braking as you are heading down a mountain or long hill, and it would suck if it overheated. Also there really isn't a difference between 1/2 watt and 1/8 watt, so you might a well spend the extra $0.50 and get the 1W resistor.

Also for archival purposes, and to leave a bread crumb trail for kb1gtt here's my notes of this testing.
Subaru_Crank_Sniffing.7z
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Re: Subaru Impreza 98 --> 2002-ish

Post by sleepingAwake »

Posting to subscribe, offer my help if I can be of any at some point and to say thanks for the detailed information.

--- I'm kind of a Subaru nut.
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Re: Subaru Impreza 98 --> 2002-ish

Post by Rhinoman »

That's the worse VR signal I've ever seen, where is the noise coming from? surely that's not straight out of the VR sensor? Can you remove the sensor and spin it with a drill or something? that way you could measure the output voltage and determine what current you need to lose and what resistance you need.
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Re: Subaru Impreza 98 --> 2002-ish

Post by kb1gtt »

Wires are bundled in the engine, I'm to lazy to tear the engine apart. I'm sure this is coupling from near by wires buried in the engine. Probably that flapper valve thing, or with the dodgy wiring, perhaps a pinched wire or rouge scotch connector. That emissions valve thing has not been deleted yet. I have no idea why the guy I bought this from put on a STX turbo but did not remove the air restriction is beyond me. I would guess he didn't have the $ for the delete plates. There are many oddities with the security system, and lots of things blink and do odd things. I understand the UTEC ECU modification device was programmed with a gameboy. It's really a dodgy system.

I could buy a sensor and spin some metal near it, My Millwakee 5378-20 drill claims to do 2500 RPM, it's a hammer drill and does 40,000 BPM on the hammer pulses. Any suggestions on were to get a cheap crank wheel? Perhaps one on loan? I could mount it in a drill and do a mock up system which would allow me to take measurements and figure out which resistor and what ohms could be used.
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Re: Subaru Impreza 98 --> 2002-ish

Post by sleepingAwake »

Which one would you like or both?
Pm an address and I'll send them your way
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