Rough idle (misfire?) no codes

2004 wrx 156k 2.0L bullwinkle tune, 665cc injectors, 1 step cold iriduim plugs, dp, up pipe, perrin tmic, (silicon inlet, tgv delete this summer along with cleaned injectors and new orings and fuel lines). Also had a problem when reinstalling the engine where coil plugs were reversed on 1 & 3 and a loose harness connector which gave a MAP sensor code - all fixed. I also smashed the O2 sensor during the install so I put in my old one with 100k+ miles.

The problem seems to be more common recently and with colder days. Starts fine, then after start up fuel enrichment (I'm guessing) starts to shake and misfire, stutter on light acceleration. Also the exhaust pops occasionally on deceleration in gear. However, in OL it seems fine - no stutter or bucking. Might smell like it's running rich, but I have and exhaust leak at the rear catalytic converter so it's hard to tell.

Being as it's cold out I want to spend as little time working on this as possible. I intend to clean the MAF and at least check the injector connections and visually inspect coil packs and plugs. Like title says, no codes so I don't know where (cylinder) to start. Possibly the old O2 sensor is not right, but voltage readings are 3.7V while driving and 3V at idle (a little high?) so initially it doesn't seem faulty. Possibly rich due to spark plug/coil?

 

When was the last time the plugs were done? I see you have the one step colder iridium plugs. How much boost are you running?

 

Plugs were changed summer before last so 2016. Running maybe 19-21 psi boost on a vf39.

 

Id start with the plugs.

 

yeah, that scares me. I'll have to check though.

Trying to find spark plugs - BKR7EIX-11 Iridium IX -locally (Rochester) with no luck. Is there and equivalent plug I should look for?

 

Will I have any problems if I have to replace plugs with regular BKR6EIX (not one step colder) plugs?

 

Is there a reason you want to replace it with iridium vs just doing platinum plugs? Turbos are hard on Iridium plugs. Not to mention then Iridium plugs are expensive as hell and in person experience the "pre gap" they come with is all over the place in terms of being the gap size you should be running for your plugs. are you on pump gas or e85.

 

Pump gas - 91 non oxy kwik trip gas
I was thinking at the time I did turbo upgrade 8-10 years ago colder plugs were a good thing. What did I know then? Being as it was tuned on this type and heat range plug, do I need to keep them consistent or can I move to other plugs?

 

Ok I can tell you right now that non oxy is NOT a good gas to run in these cars. With that mix they run its effectively the same as running 87 pump gas or worse in some cases. The ethanol they put in modern gas is a good thing for our cars in terms of running temps and knock control. Id stop using that none oxy as soon as you possibly can.

 

My understanding is oxygenated premium (5-10% ethanol) is like 89 non oxy with the ethanol bringing the octane up to 91-92. Granted the ethanol does have cooling and predetonation benefits. However, more BTUs exist in the 91 non oxy thus less fuel is needed for a given horsepower required.

Perhaps you are suggesting I should top off with a little e85? Maybe I need to look at BP, Kwiktrip doesn't have any oxygenated premium gas down here.

 

@jmyhre05 can explain this better then I can so perhaps he can chime in on why 91 non oxy is not a good thing for these cars.

 

You do not want the -11 plugs. If you have them in there now, that could be the source of the issue (unless you gapped them correctly before installing). I believe the difference between BKR7EIX-11 and BKR7EIX is the -11 is a 1.1mm gap (.043"). You want something closer to the .028" - .030" gap. The regular BKR7EIX plugs should come closer to the gap you're looking for.

Also agree that the non-oxy fuel is no bueno for turbo cars. This is more used in small engines (snow blowers, lawn mowers, etc)...things that potentially sit around. It is supposed to help alleviate "gumming" up carb issues. Turbo cars like the ethanol. I wouldn't reccomend dumping some e85 on top of the non-oxy. Just run the tank down while babying the car and then fill it up with 91 or better (I usually use 92 or 93 if it's available...generally from BP).

 

More reason to put in the de-capped injectors and go e85...
Picking up spark plugs and compression tester after work.

 

Good luck fingers crossed for good news.

 

You'll probably have similar roughness with de-capped stockers because the flow rates of decapped aren't always equal. I had that idle issue with my car when the fuel trims were a little off and the warmup map was wrong. The car swings the trims one way to lean out (responding to the o2 being rich) then the other way for the opposite reason.

I still have a little of that when the engines cold because its been tough to nail the e85 blend map. Most notability, when I'm stopped at the second stop light after work, the car feels like it shakes because the idle is low (since its past the cold start warmup period) and the trim is swinging ever so slightly (only about 2%, but I can still feel it). No roughness increments, no per cyl knock increments, steady rpm, just a little shutter.

I also noticed e85 is more affected (viscous) by colder fuel/tank temp, and cobb doesn't have an injector latency map based on ambient temps. Not that that's important to this thread, but it is worth noting if you want to go to e85. E85 flow seems to change based on temp and I believe that's why I see the swinging despite all of the preemptive tuning work I did this fall.

... As for the de-capped, I would suggest after market if you have the cash. And if my $0.02 is worth anything here, I would check plugs but you may not want to rule out dirty injectors or evap.

 

I haven't flashed the tgv delete start up fix (fuel enrichment). I did remove all the tgv cel codes when I deleted them this summer. If all else fails this weekend, I'll flash that change in the tune.

 

I did TGV deletes too. Are you modifying the map yourself? cobb or os?

 

os, pulled the bullwinkle tune and removed cels/dtcs

 

Let me know if you want any tables to reference. For TGV, I'm pretty sure I got cold crank right on my car... which was a combination of a few OS maps, form posts, and a few weeks of trial and error.

 

Drove home after picking up spark plugs and milk. Ran fine. A little stumble at start up and cold idle. Then no issues after leaving O'Reilly's to home. Thinking tuning cold weather related issue.

 

Bad gas can do it to. Like condensation in it and what not.

 

Have learned a lot about this stuff over the last year. 91 non oxy should be just as good at detonation resistance as normal ethanol 91 basically but in real life testing in the Midwest that is not the case. It probably tests closer to 87 octane. Stay away. Your car pulling timing can be something your feeling. Could also be many other things too. Spark plug, coil pack, injector, a loose connection, ect.. With these cars it's good to work with a tuner shop since there are so many good ones locally that specialize in these to help diagnose stuff like this. Have seen people throw lots of parts and time at cars For simple stuff at times.

But it sounds as if your getting misfiring just under idle mostly and not WOT? No flashing check engine light? 90% of the time we see those symptoms it ends up being valve lash and pitted exhaust valves. You can do a compression test and they'll test good too. Sometimes they'll take more cranks to make full compression but other times it'll be 100% normal. Leak down some times will show it, other times you'll have to vacuum test the heads. If that's the symptoms your getting then it's most likely time for a full valve job.

But looking at data logs and feeling it in person helps diagnose and rule out most things. Could be a dozen+ things.

 

So some of you are telling me it could be as simple as bad gas/bad plugs, or tuning, the others are preparing me for the worst and say possible valve job.
Being as I've just spent a boatload of money on the family acadia and still don't trust it. I hope the subaru is a simple fix.

 

It' a Subaru. You have to always be prepared to use the 5 gallons of gas and a road flare fix. Good luck to you.

 

We're pulling for ya!

 

Compression on all cylinders on very cold engine was right around 62-67 psi. I'm not concerned. The iridium plugs I pulled looked clean, no soot or oil or heat marks. All gapped about.030. I put in ngk g power platinum plugs at stock heat range. Also cleaned maf, may have found vacuum leak in inlet. Took it for a drive, no issues but it was 28 degrees out. Maybe try tomorrow when cold again.

 

Might want to check your compression tester, lol 62-67 is VERY bad even for a cold engine. Maybe you didn't disconnect the fuel pump and washed the cylinder walls during the test, and they'll come back if that's the case. Doubt that's accurate, so see how it does tomorrow.

 

Yes, I didn't trust the tester completely either. however, each cylinder was similar to each other. Probably forgot to disable the fuel pump, and my battery was getting weak.
If the rough idle returns in the cold, I'm going to try flashing some of the tgv delete warmup enrichment tables I found. Basically running rich in CL fueling target compensation ECT. Any suggestions beyond those would be great.

 

Monday update:
Saturday (25-30F, cloudy, snowy) changed plugs, cleaned MAF, did a poor job checking compression (but was consistent across all cylinders). Went for a drive seemed fine, but it was 28 degress out.
Sunday (0-5F, windy, sunny) I flashed the updates to the closed loop fuel target comp - and primary base enrichment. Seemed to run okay, problems not completely solved, i.e. some exhaust popping on deceleration.
This morning (-5 to 0F, light wind), starts up fine, no stumble no "misfire" at initial startup, then once that's complete it acts a little rough, some flashing CEL at idle (likely misfire), couldn't read it with my cheap scanner I had along (was only on for a few seconds at cold idle). Drives fine, accelerates fine, holds speed fine. Only exception is exhaust popping on deceleration (foot off throttle, in gear). Once I get into town (I live out in the country) it's up to temp, but idle is still rough and seems to be searching - no more flashing CEL . I also notice the boost gauge moving a bit more than usual from -0.06 to -0.05mPa (-9 to -7 psi) - maybe nothing just noticing everything right now. Low rpm drivability is better than it was last week (around parking lot).

I have no problems driving, idling, or exhaust popping when it is above some given temperature which I'm guessing is about 15-20F. I have issues for sure if it is 5F or below.

Tonight I might clean off the O2 sensor. I don't want to pull injectors until I get more orings. I could try new premium fuel or mixing in 1-2 gallons E85 (should be around 5-10% EtOH total and push it up to 92-93 octane depending on % EtOH in the e85 which could be as low as 50%) Though, this could lead to more start-up issues. I'd rather concentrate on one change at a time.

My laptop needs more RAM if I'm going to do any logging. (old windows XP with maybe 1GB ram, but likely 512kb). I can probably send or post my current map (not log) to someone if they're interested in looking at it.

 

All good things to do but I would recommend redoing that compression check or taking it somewhere like JM and having it redone. If the cel is flashing then it is detecting a missfire. Better to resolve that sooner then later for the health of the motor. Especially if it is determined it just needs a valve job no reason to trash the rest of the motor in the mean time.

 

Yes Stock BPV. Target boost is probably 19 or 20 psi. I haven't done any WOT pulls at all in a long time. I drive this thing like an old man.

 

Drove home from work with one stop for milk. Car ran perfectly - temperature was 15F.
Here is my current map https://drive.google.com/open?id=1zGRpGEbTKdFQc9a2gaNCmnaQUJC0tmaH
Can someone knowledgeable look to see if anything is out of the ordinary - likely concerning fueling, warm up, closed loop and possibly IAT. Thanks!

 

I can glance at the map sometime this week but a logs are gunna be worth more than anything

 

log from tonight short idle, drive for 2-3 miles, short idle
https://drive.google.com/open?id=1cz8wfvZtFJ2jbGWKLCEi0cX_37Bh4aBa
I wanted to look at my MAF again - not only is the brass insert in the housing not holding tightly, but the o ring was crimped and if I remember correctly, not the exact right size o ring.

 

I noticed in my map that I posted that most of the DTCs were turned off. So I turned on the misfire codes for 1-4 and reflashed (also changed the fueling for TGV deletes back to "normal"). Low and behold I finally got a CEL this morning - though it was running pretty good, just some idle stumble. P0302 - cylinder 2 misfire. Now to swap coil packs to see if it follows.

 

Update: P0301, cleared, P0302 again, cleared. Changed fuel filter. runs poor on coldest days, better when warmer out. I just had a terrible idea... Timing belt tensioner. When it's warm out it applies adequate pressure, when it's cold out, not so much or it sticks causing timing to be off. Timing belt, pulleys, tensioner were changed about 30k miles ago. hopefully I can get to it easily enough to check. Could use Blackozone's help or someone in the Rochester, Stewartville area...

 

Temperature would not have that effect on the timing belt tensioner. Plus if it skipped a tooth it would not skip back to where it was based on temp.

 

My thought was if it's loose, the timing would be off, it wouldn't have to skip a tooth. If there's not enough tension, it would be loose by definition. But maybe you're right.
I'd hate to fire the parts cannon at it. Maybe I should just bring it in to the dealer. Needs airbag recall done anyway.

 

Or take it to JM as many of us have suggjested. Above dealer level support for diagnostics and in house tuning if it is determined to be a tune issue (after all this time i doubt that)

 

I'm in Rochester/Stewartville. JM is quite a trek for me especially with a poor driving car.

 

Do you trust your dealer locally? Do you have AAA? AAA is $100ish a year. Would cover your single tow if you decided to just have it flatbed towed up this direction.

 

No, I don't trust the local dealer (Clements Subaru). I don't have AAA and insurance doesn't cover tow - found that out with the Acadia. I'm down to one running car for my family and it has 290k miles on it - and nearly bald tires. I was hoping I could diagnose and fix this myself (usually reliable for most repairs) in order to save some money due to having to pay to fix the Acadia and needing to save for another family hauler. Money is tight right now. Sorry for emoting, but I feel like I'm chasing my tail on this one.

 

Not a problem. If money is tight money is tight nothing you can do about that. That said did you ever do the leak down check on the motor to make sure you did not have a head issue. I know you had performed a compression test that was questionable on if the numbers were reliable or not but either I missed where you reported back on the leak down or?