Looking for diagnostic help...


Car sat for months before had time to take it for inspection. Changed to stock exhaust, went for inspection, passed. Sat for a couple more months before road registered it. Started fine, drove fine. Didn't run car hard, just normal A to B driving. As I was backing up into a car spot, idle went extremely rough. On the way home, same rough, rich idle, misfiring. Sounded like a Subaru boxter engine. CEL came on solid at first, then flashed so pulled over & towed home. Have a Brockway Engineering reader display but it wasn't working like it normally does, it did not show any codes and I was unable to manually check for them.


no time to work on it so disconnected batt, left town for few months. upon return, plugged in the durametric. all codes had already been cleared from disconnecting batt. Fired up the car and it was running normal again. Drove it around the block, no codes, no misfires detected on durametric. Boosting fine as if nothing had happened.


What do you guys think is the problem?


Possible OBD2 sensors accidentally mounted in reverse (when shop swapped to the stock unit)
- could this cause cylinder to be flooded? (de-cat exhaust system w/accompanying tune)
- and perhaps reason car is working normally after cylinder/plug dried out?


Changed to new OEM coils & NGK plugs 4 years (10k miles ago)
- can coil packs failed intermittently?
- fouled plug?


Thanks for your help!

 

Sounds like limp mode you went too. Since you have a lot of upgrades you need to change your coils every 20k a
nd plugs every 10k miles. Other then that might had some bad gas.......

 

There's no such thing as "bad gas." It's one of those things a lot of people point to when they have weird problems, but it's a myth. It's possible to get some sediment in your tank if you fill up at the same time or soon after a tanker fills up the tanks at a station, but that's it. Otherwise the gas you get is going to be good. And getting sediment from the tank is unlikely unless you fill up at a station with old pumps/tanks since all modern stations have multiple filters in the lines to clean the fuel between the tank and your car.

It is possible for gas to get old and not work as well, almost entirely due to water getting into the fuel (and to a tiny extent due to stabilizers "wearing out" or the fuel mix becoming non-optimal/unstable), but it's not going to cause the car to go into limp mode in the short time you had your car stored.

So....
A weird problem like this with no codes is impossible to diagnose, and nobody can tell you what the problem is without those codes.

 

Since you weren't driving it hard prior to the incident, it seems to me like a coil failed. On different german cars (Audis, BMWs) coils have indeed failed intermittently for me.

 

thanks for comments. Regret not connecting the durametric before disconnecting the batt.

 

Could be a boost hose that came loose.
Something similar happened to me when I installed my sport exhaust.
I did not make sure one of the boost hoses "clicked on" and it came off.
Mine was also in limp mode and had a "whooshing" sound.
I connected the hose properly and all was fine.

 

I agree, check the boost hoses from the turbo to intercoolers. Also, maybe the flange bolts holding the muffler are loose. Generally, from my limited experience with these cars, it seems that the issues are simple fixes. But expensive unless you do the labor. Or have really talented friends....

 

Thanks guys, I wish that was the problem. My IC hoses are modified and utilize clamps rather than clip on type. Have had IC hoses pop off before this was distinctly different. Note also that the issue came backing up into a parking spot vs WOT. And somehow resolved itself (albeit likely to be temporary), don't think IC hose pop off would do that.


My guess is one of the cylinders wasn't firing. Only way I can describe it is that the engine revs were off, for those familiar with a Subaru engine, sort of pulsing rhythm rather than the normal 996tt, which is linear. And I could smell more than usual level of un-burnt fuel.


Will start by changing coils as well while in there for the plugs.

Could it have been a MAF related issue?


Any other areas to check?


Thanks!

 

Sometimes it's an act of God,,
I have had a similar experience in my years of ownership after it sat also for awhile but after I did the battery disconnect it cleared up and no problems again.

 

maybe your first lambdasensors are old and send out a bad information

if the failure comes back...disconnect your before cat o2 sensors and the failure must go away...a test without any costs

 

If the engine noise changes your misfiring on 1 or more cylinders. It will also cause the idle to be horrifically rough. My guess is something was causing misfire. Odd that it went away but not totally implausible.

 

don't know where to begin trouble shooting an "act of god" haha...


yes idle was violent.


Will start by rechecking the ob2 sensors, re-new coils/plugs ... and see from there. Revert with results if any. thanks!