Jump to content

Welcome to Ultimate Subaru Message Board, my lurker friend!

Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.

We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!
  • Say hello and join the conversation
  • Subscribe to topics and forums to get automatic updates
  • Get your own profile and make new friends
  • Classifieds with all sorts of Subaru goodies
  • Photo hosting in our gallery
  • Meet other cool people with cool cars
Seriously, what are you waiting for? Make your life more fulfilling and join today! You and your Subaru won't regret it, we guarantee** it.

* The joy of participation and being generally awesome constitutes winning
** Not an actual guarantee, but seriously, you probably won't regret it!

Serving the Subaru Community since May 18th, 1998!

Guest Message by DevFuse

- - - - -

XT6 Backfiring problem...HELP

  • Please log in to reply
4 replies to this topic

#1 SSJupB


    New User

  • Members
  • PipPip
  • 19 posts
  • Lakewood, CO

Posted 20 September 2003 - 07:03 PM

I wanted to ask you guys for advice so please help.

Heres the problem:
When the engine is cold I start it up and the engine will sometimes want to die and I have to give it some gas and it will backfire. Then it will do the samething sometimes when I just started driving it when I am sitting at a stoplight for example. But when I am sitting at a stoplight it doesn't backfire.

I took it to a shop and they told me it probably just needed a tune up. Well I got a tune up and it really did help but...it still does it sometimes, not as much as before though. So I took my car back to shop to show them what I am talking about. But of course the car will not do it when it is being looked at. So that didn't work.

Please tell me your ideas what you think the problem could be.


#2 JonOfScio



  • Members
  • 713 posts
  • Corvallis, OR

Posted 20 September 2003 - 08:12 PM

possible leak in the intake somewhere (the hoses, ect.)

Just look at the air filter box, the hose running from that to your engine, and check your exhaust for leaks. I think maybe it's a leak.

How BIG is the backfire, is it light? Do you get a whispy sound when you push the gas down that you don't get when you lay off the gas?

Mine made a noise that was pretty hearable (blown exhaust gasket) and backfired just a little. You may want to run some FI cleaner through your car (fuel injector cleaner)

#3 Skip


    Flatuous Blather

  • Moderator
  • 8,991 posts
  • Latrobe, Pennsylvania

Posted 20 September 2003 - 08:17 PM

the key here is the back fire, I will assume you mean under the hood as in through the intake system.
This indicates a lean mixture, sounds like the ECU does not know the engine is cold. This indicates a problem with the FI coolant sensor.
These do go bad but most times they just need the contacts cleaned.

I think I know your next question - Where is it and how do I get the contacts cleaned?

I do not have my factory service manual handy but if you have no other response I'll promise to dig it out of the library.

#4 SSJupB


    New User

  • Members
  • PipPip
  • 19 posts
  • Lakewood, CO

Posted 20 September 2003 - 11:23 PM

Well I put FI cleaner in about 3 weeks ago.....didn't help. And the backfire noise isn't extremely loud or quiet....but if you are near the car you can hear it. I'll look if theres a hole in the intake hose....but I don't think there is because I sealed that up about 6 months ago. But i'll check in case.

SKIP...thats sounds VERY possible.

#5 asavage


    Eat, Live, Breath Subaru

  • Members
  • 338 posts
  • Port Townsend, Wash. 9836

Posted 21 September 2003 - 01:24 AM

Spark Plug Wires!

They're often not replaced as part of a tuneup, and they get leaky and can be the cause of misfire into the intake tract.

Skip is correct, a lean condition can exacerbate this, but with a modern ignition system in good condition, lean misfire doesn't (isn't supposed to) occur; instead, you just get a power loss.

I am (I really am!) trying to get my Loyale wgn whipped into decent shape for my friend without spending as much as is my wont. This car had had a tuneup recently, I have the receipt, but they didn't replace the plug wires, and I vacillated over whether I should.

As a test, I grounded a long screwdriver with a clip lead, then with the engine running, I ran the tip over the wires, ends, spark plugs, and all over the dist cap. When I brought it near the coil top, it drew an arc. I shut off the engine, then removed and carefully cleaned the wire end, boot, and terminal. Retested, no arc.

Next day, I decided to reset the timing. I plugged in the D-check connector, warmed up the engine, removed the bellhousing plug, loosened the dist and connected the light. I decided to back off the timing a few degrees, so I put a shop rag on the cap, and with my gloved hand, tried to rotate the dist. I got zapped hard!

Thirty seconds later, I was on the phone, ordering a new wire set.

What galls me is that the day before, I couldn't get an arc to a solid ground, but next day it zapped me through a clean, dry shop rag and a layer of latex!

I guess I'm just a magnet for automotive abuse.

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users