Robtuned with 16g! Working out the kinks...

[free5ty1e]

Hey peoples!

My 94 ss is finally robtuned! Been sitting on the robtuned z5 ecu for almost 2 years and had most of the parts for a while too.

At first, had a major issue with the fuel pump relay and even sometimes the rad fans cycling on and off rapidly and clicking themselves silly... and sometimes fuel pump would be completely off. Seems to have been a broken resistor on the ECU. Once resoldered, its been running and driving mostly great!

The 16g turbo is also in, had to sneak the 90 degree silicon elbow thru the intake manifold runners but it's in!

Its currently on stock boost control, which I know is not recommended, but it will pull nicely to 10-11 lbs. I havent given it the beans (lol thanks top gear) just yet, because its showing some other issues I need to work thru first.

First, it loves to stall when I let off the gas and step on the clutch at a stop. It seems to want to idle at like 650ish, which is lower than im used to. I wonder if I have a vaccuum leak somewheres...or if maybe my iac valve needs some help.

Then, ive seen it throw an engine code and the cel stays on. Do I pull codes from the robtuned ecu with the d check connectors still? Same procedure and codes?

While spooling up the turbo once, bout 6psi it appeared to hit fuel cut or something. ..it bucked and lost power and the cel came on and stayed on. I need to see what codes it has stored.... a bir after this happened, on the same drive, the cel went off and I boosted 10lbs just fine.

Hmmm....perhaps my old jecs maf may not be a pristine specimen.

Thoughts?


Thanks guys!

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[James614]

First, it loves to stall when I let off the gas and step on the clutch at a stop. It seems to want to idle at like 650ish, which is lower than im used to. I wonder if I have a vaccuum leak somewheres...or if maybe my iac valve needs some help.

I have this same issue, though oddly only with a BPV that opens properly. With the old one that was stuck closed due to a blown diaphragm, it idled flawlessly. I've been over everything vacuum-related and can't find anything (especially considering you can pull one of the small vac hoses off completely and it'll only have a very minor effect on the idle). I've got a 2.25" pressure tester on the way so I can REALLY test for leaks, hopefully something will pop up then.

That unexpected fuel cut thingy happened to me once too. That was over 2 months ago, it seems to have been an isolated incident.

And yes, the procedures for reading codes via the black connectors remains the same. The green + black connectors still cycles all of the relays and motors. And the codes are the same, too. It really is just a stock ECU with Rob's custom ignition and fuel maps, and whatever else he changes like the fuel cut, idle, etc.

[free5ty1e]

Cool, thanks man!

I'll pull codes this weekend and try to figure out more of what's going on here. Kinda in the dark at the moment.

So, the bucking / fuel cut thing seemed to only happen during partial throttle while boost built up > 6psi or so; every WOT pull felt fine @ 10ish PSI.

Today, the bucking / fuel cut thing happened during a WOT pull, about when it spooled past the 6psi mark (this big 16G turbo spools a bit slower than I had hoped for).

Also, one thing that concerns me: I ordered Launch Control on this tune. Yet, at a stop, I can rev up to 6500 RPM (did not attempt to bounce off that rev limiter). Am I just running on a normal EJ20G Z5 ECU at this point?

Could the repaired resistor actually be required to be broken in order to enable the tune? Did I disable the RobTune itself by repairing the broken resistor?

If that's the case, I wonder if my particular tune itself has an issue. I'm definitely afraid to raise the boost until I know what the crap is happening.... hoping for a bad MAF or something dumb like that. But it's seeming more and more to me like I need a new RobTuned ECU. This one clearly has issues.

[James614]

Cutting that resistor tells the ECU to run the code from the chip instead of the standard code. So yeah, you disabled the robtune, lol.

[free5ty1e]

Lol indeed my legacy thinks its a stock wrx wagon at the moment.

Rob is gonna give me some email help soon when he gets back home, in the meantime it doesn't appear to be knocking or anything horrible; think its ok to drive the car like this for now or should I park it until I get the robtune figured out? As I understand it, ive already gone thru all the steps to convert over to a stock ej20g ecu so maybe ill just run a bit rich for now?

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[James614]

You probably won't hurt anything, but I'd park it if you can. It should just run rich, but why drive the car when its not running right? Plus you'll waste a ton of gas.

[free5ty1e]

Good points. In the garage it goes.

[free5ty1e]

Finally had half a chance and pulled codes to see what was stored from this behavior. All it had was code 45 - atmospheric sensor.

When the check engine light comes on, remember, it bucks and goes into fuel cut. Yet it is not something that happens repeatably on every pull. Partial throttle or full throttle, it's happened to both and it's not happened to both. I've had good WOT pulls almost to redline. So I'm wondering if I have some sort of intermittent connection here to the atmospheric sensor or something?

I also still have my FCD wired in place, which is just a voltage clamp on the MAP sensor signal to never appear to be pushing above 12 PSI (and I've watched the light, it's never clamped yet), but it doesn't need to be there and so I am going to remove it and patch the MAP signal back straight through to see if that helps things on the next test drive.

I'm still running as a standard WRX EJ20G ECU, the RobTune is still disabled.

I still am waiting to hear back from Rob after he told me he was out of town a couple weeks back, so hopefully I'll be able to get my RobTune up and running at some point in the near future

[free5ty1e]

Update: got my replacement RobTune ECU in the mail yesterday! Gonna try and get it swapped out this weekend and compare the two boards while i have them out.

Fcd is also gone now. Been running 12psi on ej20g ecu. Seems to be working decently, although cold starts appear to be something this setup struggles with. I regularly have to start this one twice after it dies or fails to catch the first attempt.

Meanwhile i go start my stock 92 ss and it fires right up on the 2nd crank like my 94 used to on the stock ecu.

I hope the robtune starts a bit better

[free5ty1e]

Update: Managed to get the old EJ20G ECU out (the one with the RobTune v1.0 "disabled" from the "repaired" resistor) and prepped the new RobTuned v1.1 ECU for installation. Here are photos of the old ECU. Note the lack of a chip socket pin poking all the way through where the arrows are pointing; this pin was making intermittent connection and causing the issues with the tune when enabled. This ECU worked just fine as a stock EJ20G ECU.





I've contacted Rob and asked if he could give me a part # for this chip socket so I can order a replacement and fix this ECU for another Legacy.

In the meantime, I also got the new Robtuned ECU up and running in my '94 SS. Drove it to work today, wastegate is only letting me build 12 psi of boost and then tapers off; clearly I need to adjust the wastegate arm but the car drove GREAT! Off-boost drivability was the best its ever been; peppy and responsive! Started up a bit better than the stock EJ20G ECU in the cold morning, but still required two attempts to get it going.

[James614]

Yeah, driveability vs the stock ej20g is just night and day. Makes you wish rob's tune could just come stock on our cars, lol. Your fuel economy should beba tick or two higher also.

[free5ty1e]

Hrm... new problem since ECU install. Gave it a little boost yesterday, then when i went to shift it pegged at redline. Kicking the accelerator appeared ineffective. I had to turn the key off and back on in order to regain control. Yikes.

Its tough to suspect sudden mechanical issued with the accelerator... this has happened twice now, every time i build some boost up the car slams to redline as soon as the clutch is in.

Could this be something like the ecu manupilating the cruise control cable for some reason? Perhaps the IAC valve is being commanded to hold wide open even after the throttle is shut?

Any ideas?

Also: yikes!

[James614]

The cruise has its own computer. If its an electronic problem it wouldnt be the ECU (at least I couldn't imagine how that would be the case with a mechanical throttle plate). But without the cruise turned on, the computer should not be active to effect anything. Regardless, to rule it out you could unhook the cruise cable from the throttle body.

I had this happen during an autocross with my stock ECU once, in-gear when I got on the brake. But it lasted only a few seconds. I think it happened very briefly a couple of other times, but only for a second or so after lifting. It wasn't enough for me ever to get an accurate assessment of what happened.

[wtdash]

Hi,
Two things I've seen.
1. ON mine, the BPV was attached to the TMIC and I had a vac hose catching on the throttle body 'actuator' (whatever it's called) that the throttle and Cruise cables attach to - it's what actuates the butterfly valve in the throttle body. This was UNDERNEATH so I didn't see it......but since you have a FMIC, maybe you don't have anything near there??
2. When BOTH my EJ20G and EJ22T ECUs were first installed, I had the high RPM issue - it took a few 'warm-ups' and drives for it to 'learn' the idle.


Also, I'm not clear on your 12psi?? You should have an EBCS or MBC to control boost w/the Rob-tune and w/the TD05 and 550's you can run 18 PSI. If you have the stock BCS connected, you're running whatever the stock PSI is on your version of the EJ20G ECU.... on that Z5 you had b4 it would be about 12.5.

U8, 2C - 1993/1994 WRX - 11.47psi
W6 - 1993 WRX RA - 11.47psi
W9 - 1994 WRX RA - 11.47psi
SA (STi chipped) - Ver1 STi (Sedan and Wagon) - 14.94psi
SB (STi chipped) - Ver1 STi-RA - 13.64psi
SC (STi chipped) - SAME AS Z4 - Ver2 STi Wagon - 12.78psi
Z4 - 1995/1996 WRX - 12.78psi
Z5 - 1995/1996 WRX-RA - 12.57psi
6K - Ver2 STi Sedan - 13.34psi
7K - Ver2 STi-RA - 13.19psi
Prodrive UK ECU (Prodrive Chipped) -- SAME AS 6K - 13.34psi
1C, 3B, V9, V5 - All WRX Wagons 10psi, dropping to 6.8psi
V7, 7D, 6D - 1993 to 1996 UK/Euro 11.47psi

And BTW, the cold-start issue is just part of the EJ20G's tuning. Rob specifically told me he doesn't touch the cold start tables in the ECU's tune, so the Rob-tune has no effect on it....unfortunately.

Td

[free5ty1e]

Ok.. one of the reducing couplers had to be doubled up to adapt the sizes, and apparently one had just worked its way into the throttle body. Not caused by the ecu.

My intetcooler piping is deteriorating after 9ish years... hacked together out of what i could find, which was not all silicone. Also, my hks ssqv bov apparently is leaking now (smoke test). Im stuck at 12 psi because i cant get my piping to hold any more right now. Im just finding this out...was wondering why i could turn my mbc all the way up and still not build more boost....