keeweechris

Thanks man, much appreciated.

Thanks everyone for your help. Turned out to be #3 coil. Running smooth as silk now.

This is promising... last fkn cylinder (#4), swapped coil and plug, idling mostly normal... no shudders and dropping rpm. Will take for a test drive tomorrow. All cylinders 150psi compression, which is good. Is there any harm not having the fuel filter core inserted for a short blat?

Doesn't seem to run any differently, which is weird. Also, if I try to start it without MAF plugged it, it fires up for a second or 2, then stalls.

Thanks man, yeah, it seems like a bit of mahi, but hopefully I crack it. Got cylinder 2&3 done (compression 150psi, no change when swapping out coils and plugs), then got bored and tried the fuel pump, haha. Will get onto 1&4 tonight. Tried removing alt belt, but it still ran bad without the alt. Thanks for the idea though. Thinking about it this morn, it seems like something not right with closed loop system. It gets going well on boost and above 2000rpm. So I've got to understand whats involved in closed loop running... O2 + TPS + MAF I guess. But I've swapped all those... scratching head a bit.

Swapped fuel pump and removed fuel filter... no change. Jeees. Gotta be coils, plugs, or injectors! Or headgasket or valves.

Just a regular stock GTB twin turbo engine bay... stock BOV, stock airbox (K&N panel), everything clean a tidy, replaced intake pipe 3 months ago, and all vacuum lines. Was running very nicely after that.... smooth and 11/15psi boost. Yeah, all subaru's I've owned have had that slightly irregular idle, where it shakes ever so slightly every so often. But this is not that. It shakes constantly, changes exhaust tone, and misfires/stumbles on partial throttle anywhere between idle and 0psi. Then under boost it takes off and has no noticeable problems. I'm wondering now if it has some headgasket or valve issue. Leakdown will reveal that I'm hoping. Doesn't seem to be knocking. Data for "Knock Correction Advance (degrees)" and "Knocking Signal #1 (On/Off)" was all zero's for the time I logged it on cold idle the other day. Gotta find time to swap out the coils and plugs and injectors systematically, to rule them out. And fuel pump. Hoping it's one of those!

rpm fluctuates (like a misfires every second or so), and hesitations when accelerating or coasting from idle up to 0psi. On boost it appears to be ok.

Nah, stock BOV. Yeah, that's why I logged data from the ECU. I seemed to be getting realistic data from the MAF sensor, but keen to hear your opinion. Here is MAF data on cold idle: And here is the O2 sensor & RPM. It's all over the place, and shows the idle speed flapping around too. I logged heaps of data, but it's hard to show all on one graph. Let me know if you want to see any other data. Cheers Chris

Cambelt all good still... Well, all cams line up. Can't see crank, but seems unlikely that it skipped a tooth, being wrapped in cambelt 270degs. Will focus now on coils, plugs, injectors, comp/leakdown, then fuel pump.

I haven't tried starting it without MAF though, but was curious how to force it into Open Loop. Are there map values for lower revs? I'll try this anyway, because if the bad idling (misfiring) sticks around, I guess it proves it's mechanical, fuel, or sparks, not sensor-related..?

Haha, yeah, bit of a gamble. Came off a BH5B (same engine) at 255,000km. No, comp and leakdown is on the list. No smoke/smell from oil filler, and only a moderate puff puff puff of air, so rings are prob ok I'm guessing? I'm pretty new to this. I'll have to get set up for a leakdown test.

Well, I did open one cam belt cover to check the belt wasn't damaged, but didn't check if it had skipped. Good idea though. Can you check without talking the centre cover and pulley off? I kinda figured because there was a very clear point at 0psi where it started running well, and it boosted nicely, that the cambelt/timing was all good. Never experienced a belt with 1 tooth off before. And the problem is getting slowly progressively worse. But hey, no harm in checking, thanks! I've got a cheap SCA boost gauge, and that looks to match the readings the ECU is seeing. What do you mean by "borderline"? Is -60kpa/18inHg not quite right? What's it a sign off? Smoke tested again yesterday, and couldn't find any leaks. Yeah, no change after swapping to pick-a-part MAF. The MAF's (mine and pick-a-part) look very clean though. So I figure the problem is somewhere else. Gotta try the easy stuff first though, right.

Cheers, yeah, I did that. Each injector I unplugged caused the engine to change the way it ran, but surprisingly it did keep running, just. Yeah, I was hoping removing 1 injector wouldn't make any difference. I got a coil and injector from pick-a-part yesterday, so will spend the week swapping each out in turn. Fun job huh.

Changed MAF, crank & can sensors, no difference. On to spark plugs and coils now.

Got RomRaider logging data. Do these Crank and Camshaft values look odd to anyone? I expected consistent on/off/on/off data for both, or something with a pattern. This was when idling, and data has 16ms resolution. Thanks in advance for any help.

Thx! Any ideas on what to test for now? Injectors... Any way to check if they're happy without whipping them off and flow testing? Do the above results prove the AFM is ok, or is it worth getting my hand on another one?

Any Legacy GTB guru's out there?

Can anyone interpret these values I got from FreeSSM this morning? With ign on, engine off: TPS 0.48v foot off, 4.26v foot to floor AFM 1.02v MAP -1kpa IACV 115steps Coolant Temp 22deg A/F Corr 0.0% Ign Timing 10deg Diff pressure 1.96v Neutral pos switch behaving Idling from cold: Timing hovering around 17-18deg. Revving 2000rpm, ign timing rises up to 35deg IS THIS NORMAL? "Front O2 rich Signal" on-off-on-off... SHOULD IT BE CYCLING LIKE THIS?? Knocking Sig off IACV 52steps, then dropped to 28steps after ~5min TPS 0.44v (foot off pedal) A/F Corr hovering around -4 to 0% Temp rising normally to 60deg after about 5min MAP -60kpa AFM 1.2v. (2v when revving at 3000rpm) IS THIS IN THE RIGHT RANGE?? Thanks!

All good, thanks anyway man.

Well, ECU reset did nothing. I also cleaned the AFM, which did nothing. Hesitates and tugs at light light throttle, no matter what rpm, if I'm cruising on the flat. But when applying a bit more right foot, it runs/accelerates smooth. Also remembered that the old O2 sensor was quite obviously light grey, almost white. I've heard coolant is bad for it, and causes it to turn white. But I'm pretty sure it doesn't consume coolant. Thinking at this stage either AFM, or injectors. Any other ideas?

OK, thanks very much, that would be very appreciated. It's this one, just in case you have a few different ones: If you can get the actual sensor out of the housing, that would be easier to ship.

Yeah, I need to borrow a good AFM to cross that off the list. Are you in Auck by any chance? I removed the intake snorkel a few months back, so stock airbox takes air from inside guard. Think that would lead to AFM going bad?

Just realised what I haven't done is reset the ECU... doh. Will do that when home tonight. Before replacing the O2 sensor, it popped code 32 (O2 sensor), so maybe it also stored some setting which mucked up the idle/mixture. I haven't reset the ECU since before the O2 sensor swap.

Kia Ora's Just after some ideas on how to diagnose an erratic idle on a '99 GTB RevB. It's had that common minor shudder while idling for years (subaru thing?), but recently after a long trip it's got much worse. Doesn't stall, but tacho (dash) fluctuates between about 500-700rpm, and stutters and shudders every second or so. Feel like it will stall. No difference whether engine warm or cold. Once revs are >1500, runs and boosts well. Things I've tried: -Intake leak test (smoke). Nada. -IACV - cleaned, and replaced with another from pick-a-part, but no difference -AFM - Cleaned, but not tried with another yet (I need to get my hands on one) -O2 sensor replaced with new (old had open circuit heater) -All intake and vacuum piping checked & replaced about 3 months ago -Air filter checked/cleaned -BBOD cleaned and checked -Boost solenoid (guard) checked and cleaned -Injector plugs look fine -Spark plugs replaced a few months back Since it runs well under power, I figure fuel pump is ok? But it's on my list to replace the fuel filter soon. I've got FreeSSM+VagCom hooked up and can get live values from the ECU/Sensors, if that's any help? Thanks fulla's!