05 LGT idle (good times)

Guys I just want to say hello, although I am not new to the subie crowd this is my first legacy and I really want to love this car like I did my WRX. I just bought the car and it was running like a top for the first week, then I had this crazy idea I would wash the car. So full disclosure I also washed the engine. I consider myself a car guy. I did all my own work on my WRX that I use to race, I have built several comp. rock buggies and recently put a LS1 in my FJ62. I'm just telling you this so you understand I did not fill up the air box with water or any thing stupid like that. Now here is where I need a little direction. I too have fallen to the rough idle problem know to the LGT. Mine started the day after the wash which is why I don't believe water was the culprit but I am not ruling it out. The idle started suddenly while sitting at a stop light and only seems to manifest after the engine has reached operating temperature. I have read most everything posted on this matter and have found that not one specific thing fixes it every time. After the recent purchase of the car funds are a little tight and if I can help it I would like to avoid throwing parts at the car. I have injectors on the way as this seems the most likely culprit, and the plugs have been changed in the last 10k. Any help in reaching a diagnosis would be much appreciated.

One more thing I hooked up a snap on versus pro scanner to it and I could not get anything from the ECU other than the serial ID, it would communicate with the trans, airbag, and ABS module fine but no ECM

Had the same problem updated my solus and got full function back

Good to know. Thanks for the help.

1. Clean the Maf, reset ECU, beat the balls out of it

2. Spray Carb Cleaner around the TGV/IM and see if idle change

3. Remove intercooler and inspect for leakage at end-tanks

4. Perform Vacuum test

5. Perform compression test and hope for the best

6. Perform Leakdown test " "

Oh yea, check the oil, learn how the dip stick reads, keep the oil topped off.

 

Some one here say's these things use oil.

Unless you have gone through and ziptied all the problem vacuum lines mentioned on this board, if you used any serious pressure at all while washing, you probably just knocked a line loose.

 

Especially since you can correlate this to the wash day. Check the T connector under the intercooler.

After closer inspection I am pretty sure the tmic is failing, so I have a fast motorsports replacement on the way. I went ahead and replaced the plugs, since the service records show about 20k on them, I ohmed out the fuel injectors and the read in spec, but they could still be dirty, it's funny you mention driving it hard, if I do get down on it a little the next time it comes to idle it seems to be fine, but the problem returns shortly after. As much as I would love to drive the piss out of it everywhere I go I think the boys in blue may become irritated. Guys thanks for the help with this so far.

What did you gap your plugs at? A shop tried to give me .044. You need .028 for turbo model. If not that i would check ground straps for corrosion. Good luck

After closer inspection I am pretty sure the tmic is failing, so I have a fast motorsports replacement on the way. I went ahead and replaced the plugs, since the service records show about 20k on them, I ohmed out the fuel injectors and the read in spec, but they could still be dirty, it's funny you mention driving it hard, if I do get down on it a little the next time it comes to idle it seems to be fine, but the problem returns shortly after. As much as I would love to drive the piss out of it everywhere I go I think the boys in blue may become irritated. Guys thanks for the help with this so far.

 

Keep in mind an after market tmic runs poorer on a Cobb Stage 2 tune.

 

What made you think it's failing?

If not that i would check ground straps for corrosion. Good luck

 

I am certainly not a Subaru expert, but as a hobby I have a some vintage cars that I restore to drive and show at club events.

That being said; if I get caught in the rain I wash the engine compartment and undercarriage, and electrical gremlins often pop-up afterwards, especially when using a strong corrosive cleaner like Simple Green.

As was mentioned above, clean all grounds and add some dielectric grease, also do the battery terminals.

Also un-mate and re-mate any connectors that you suspect may have taken a good blast of water, you may also want to put a bit of dielectric grease in those.

Checking the vacuum lines is also sound advise, I changed the intake gaskets on my LGT and I was stunned at the number of vac lines on that car!

It was like mid seventies early emission control cars all over again...

 

http://legacygt.com/forums/attachment.php?attachmentid=146723&d=1364623647

 

Paul

I gapped the plugs at .029, the tmic has oil blow by seepage around the lower part of the passenger side of the crimp

I am not planning on running a tune on this car, it is my daily driver and I need it to get the best mpg possible.

Does any one know if a injector can Ohm out OK and still be bad?

I am not planning on running a tune on this car, it is my daily driver and I need it to get the best mpg possible.

 

Not true, I get better mpg at 280whp then the car did stock, as long as I keep my foot out it.

 

Get the car tuned, the factory tune is not near perfect. It can cause burnt valves.

Does any one know if a injector can Ohm out OK and still be bad?

 

Yes, it can still be bad. Checking the resistance in Ohms only verifies that the electrical coil inside the injector is within spec (which is also important). But if the injector were clogged/obstructed/not spraying properly, testing the Ohms would not pick this up at all.

I'm sure the tune will come, I just bought the car and keep telling myself I'm not going to tune it , just drive it like a normal person who does not love their car.

Update, I kind of broke troubleshooting protocol and changed the plugs even though I had not confirmed they were causing a problem. The TMIC was suspect so I had planned on changing it out anyway, I also cleaned the MAS. As of right now the car is running great and I feel like the boost has returned which I believe confirms the loss of pressure from the TMIC. I have only had the car for a few weeks and have not had the opportunity yet to install the proper gauges so I am not sure of the exact change in boost pressure before and after TMIC swap but it is defiantly noticeable.

Update on this, so after further complication and a little frustration with the car running great for a few days and then like crap I finally got a new code (P0021)

After a little more research I decided to replace the OCV for bank 2 (driver side) car runs great now and has been for the past few week so I think we have a winner here. Side not I did try to clean it first with out any luck, my recommendation is if you find yourself in a similar situation just go ahead and replace it. From the info I found if the cleaning works for you it should only be considered a band-aid, as the OSV in on the way out.

Thanks for the update. My car was doing the same thing and before I got around to attacking the problem it stopped, but recently returned so now I'm back into trying to get it fixed and will check this out as it actually stalled the other morning it idled so low. Really is a laundry list of possible causes.