Why is my car falling flat on its face?

[imaiami]

howdy,
I've got a 93 legacy turbo wagon manual swapped, which just got a td04 and tmic thrown on it.
At first it was sweet up to about 15psi (somewhere I read the ecu will account for 16psi???)
so after driving for a day I get a complete cutoff at random times....ie falling flat on its face.
I dropped boost to 10 psi with no change...
also checked and changed plugs, which did help a good bit due to being gapped .040, and now .032 or so.
But as the plugs helped a bit of hiccuping, it still will occasionally at wot, w/ only 10 psi, fall flat on it's face.


The codes that are being thrown are 12, (abnormal starter switch signal due to it being bypassed for now)
35, (canister purge solenoid valve) because I broke the darn solenoid so it's bypassed
and 51, (abnormal neutral/ inhibitor switch) because I haven't wired up my neutral switch
so all of those shouldn't cause any havoc to the tune based on what I read.

if the maf is being maxed out or bad 02 sensor or something causing spark/ or fuel to stop, wouldn't it throw a code?

possibly coils going bad?

um I dunno.....any suggestions?


Thanks,
Dustin





a little pic of the not so clenlinessness of my engine bay

[mike-tracy]

Are you running the stock ej22t ecu? It has fuel cut around 12-14 psi, depending on temp and altitude however. What is your vacuum at idle? Also, how about the vacuum hose that comes off the fuel pressure regulator (at the back of the passenger side fuel rail), I've seen the car do funny things if it's leaking air.

[Legacy777]

You really need to make the ECU happy and deal with all the codes before you try troubleshooting anything further. Even if it's an unrelated code the ECU may do some funky stuff.

Did you pull out the TCU and do the MT/AT identifier pin wiring as mentioned in my swap write-up?

https://www.surrealmirage.com/subaru/sw ... rical.html

[imaiami]

yup, stock ej22t ecu.
the 12-14 psi fuel cut could surely be my culprit---shoot, I was under the impression it was all good up to 15psi or so..... I guess even thought I was around 10 it would spike up around that amount......

am I stuck keeping the boost below these levels?
it sure did feel great at 15psi when it decided to work

I did pull out the TCS and do the mt/at identifier pin.. btw thank you for the write up. it helped a lot. I did find however that I have quite a few wire colors varying from the diagrams, so I skipped a couple steps to get her driving.

the pressure line to the regulator does look solid... no pressure leaking.

Thanks for chiming in

[cj91legss]

I'm curious about your BPV routing. What else is that "T" attached to?

[Legacy777]

I did pull out the TCS and do the mt/at identifier pin.. btw thank you for the write up. it helped a lot. I did find however that I have quite a few wire colors varying from the diagrams, so I skipped a couple steps to get her driving.

Try the 92 FSM, the wiring diagrams will most likely better match than the 90 diagrams on my swap write-up.

https://www.main.experiencetherave.com/ ... and_Elect/

[imaiami]

@mike-tracy vacuum at idle is about -20psi

@cj91legss that's just the valve cover breather t'd into that. All the intake hoses were brittle and breaking nonstop, so I just routed it all to the plastic box n made a makeshift S intake connection to use the remainder of the stock intake.

@Legacy777 will do, thx.

[cj91legss]

I would recommend routing the vc breather line. When your bpv releases air, it can go straight to the valve cover.

Sent from my SM-N920T using Tapatalk

[marsh27]

yup, stock ej22t ecu.
the 12-14 psi fuel cut could surely be my culprit---shoot, I was under the impression it was all good up to 15psi or so..... I guess even thought I was around 10 it would spike up around that amount......

am I stuck keeping the boost below these levels?
it sure did feel great at 15psi when it decided to work

I did pull out the TCS and do the mt/at identifier pin.. btw thank you for the write up. it helped a lot. I did find however that I have quite a few wire colors varying from the diagrams, so I skipped a couple steps to get her driving.

the pressure line to the regulator does look solid... no pressure leaking.

Thanks for chiming in

I was running about 16psi stock ecu with a fcd. I had the hks fcd and it worked great for me. I think I picked mine up new for like 110 but you can probably get a used one for 50 or so. I just sold it otherwise I would have helped you out lol go figure

[imaiami]

@cj91legss for sure, it's probably not the ideal plumbing of the breather along with the bov, but I figured plumbed into the intake there's always going to be vacuum there, thus most of the air would go that way.

@marsh27 I very well may give that a shot.

Butt I'm also getting what seems to be clutch slippage when full boost hits, the whole 12psi, while in 4th or 5th gear at low rpm. It's quite odd cuz the clutch is nearly new, and it doesn't give me any slipping issues banging through the gears, or even launching. Nor do I smell any clutch. But when the boost hits the rpm starts running up really fast and then car isn't going much faster. I've played nearly 2k rpm of slippage, but then the car catches up to it gradually (this is of course while just trying to figure if the clutch is roasted) however no clutch smell and then no lack of grabbing anywhere else.

A buddy of mine seems to think it could be center diff, but I really couldn't see how it could slip fully free of the motor entirely.

[mike-tracy]

When the center diff goes, it works fine when cold then has a banging/scraping noise once it's warmed up. I'm not sure why the clutch slips, but if the trans is NA and/or the clutch kit is a cheapo, anything's possible.

[Alphius]

There's no way that the center diff could fail and cause that symptom. I'm going all in on slipping clutch as well, especially if it isn't a turbo clutch. If you have a hydraulic clutch setup, there's a simple way to run an 06+ WRX clutch on an N/A trans however.

Mike, I had a wagon once where the VLSD didn't fail in that way. It failed completely open, so it would roast one front tire from a launch all day long. Lol.

[Turbone]

Wish there was a resolution to his problem, as I'm having the same issue. Car was running fine on a short drive, did a few pulls - no probs. Parked for about 30min and then it would fall on its face at half throttle. I couldnt see or find anything visibly wrong.
Running a Chinese VF39, headers, 3in DP all the way back. Stock inj, Walbro 255 FP, FCD. MSD coil, stock ECU. Cobb intake hose
I changed the turbo to a TD05, replaced the FCD with a new HKS one, installed a new fuel pump. Changed the boost sensor, the TPS and the MAF.
Have a new fuel pressure regulator coming, along with a gauge to check fuel pressure (who's installed one?) I have yet to check the codes, as I just realized I need to connect the plug to do so - DOH

[Legacy777]

Do you have a stock coil pack you can throw in there just as a check? And maybe the plugs?