Hello Everyone,

 

this has been an ongoing issue, I've been working on it at NASIOC but not getting too far with it so I thought I would try another forum.

 

I drive a 2002 Impreza TS.  Over the past 2 months, it has been misfiring when starting.  It clears up on it's own ater about 10 seconds and only does it when it's cold.  Runs like a champ otherwise.

 

Things I have done so far:

Checked the plugs

Replaced the wires (two wires had very high resistance (cylinders 3 and 4) cyclinder 2 was above spec but not overly high, cylinder 1 was within spec.

Cleaned the IACV

Metered the Ignition Coil (input pins 1 and 2 had high resistance, around 2mohms, all other combinations were open) Output 3 and 4 metered approximately 13.6kohms while 1/2 metered 12.5kohms)

Checked for a leaking injector (did so by letting the car sit and pulling the plugs to check for the presence of moisture/smell)

Exhaust for smoke/smell (smells bad, but does not emit white or blueish smoke nor does it smell sweet)

 

The misfire has been isolated to cylinder 3 and 4.  Only one at a time.  Codes thrown have been p0304, p0303, and p0420.  The 0420 popped up with the 0304.

 

The car ahs also been having issues with the heat going in and out and overheating.  I believe this is all under control now and is not of primary concern.  That said, On Saturday the car overheated and boiled over.  The following morning, it would not start.  I reset the ECU and it started up fine.  Ran well all day and started this morning.  Now, it will not start again.  It cranks and attempts to turn over but never quite makes it...It backfires every now and then....I'm leaning towards an ignition coil, but I'm not entirely sure and I don't want to throw $150 at it if that's not the problem.

 

The headgaskets were replaced about 12000 miles ago and the car has 77k on it.

 

Thank you

The heating problem and the boil over don't sound good to me. I suggest you have a block check done to see if exhaust gases are getting into the coolant. Also check for an intake air manifold vacuum leak.

The heating problem and the boil over don't sound good to me. I suggest you have a block check done to see if exhaust gases are getting into the coolant. Also check for an intake air manifold vacuum leak.

 

The overheating/loss of heat I believe was caused by the leaking water pump and a bad thermostat.  Both have been replaced and I believe I finally got all the air out of the system.  Hopefully there will be no further issues on that front...

 

I did not find any vacuum leaks, though it's not impossible.  I purchased a new Ignition Coil today to see if that fixes the problem.  Hopefully it will.  I had a friend suggest it could be a cam position sensor or crank shaft position sensor.  Seems like either one of these would throw a code if it were defective...Maybe not though

did you get a "good" coil pack, like an OEM one or Beck Arnley one? 

did you get a "good" coil pack, like an OEM one or Beck Arnley one? 

 I purchased a BWD/Intermotor.  i generally go with Beck/Arnley but in this particular instance they got terrible reviews and were burning out in a couple months.  This one was more expensive and feels of very high quality. Time will tell.  I replaced it and the car still would not start.  I noticed the plugs were soaked in fuel after attempting to start the car so I assumed there was no spark in the cylinder...Since everything else was new I purchased new plugs and it started right up.  we'll see how things go from here.

Update.  The car seems to be having issues starting again, though it has never failed to start.  It now will start fairly easily, runs a little rough though better, and then the rpms remain unstable.  They seem to fluctuate between 1200-1700.  I have not let the car warm up recently or driven it anywhere due to a fear of it not starting when I need to return home.No codes right now...

Why did you check the plugs and not replace them?

Plugs can carbon track and foul easily when cold.

 

Have you checked fuel pressure?

Does it have new air and fuel filters?

maybe the timing belt has slipped a tooth or 2?

maybe the timing belt has slipped a tooth or 2?

This is possible.  I did have to pull the timing belt a little while ago to replace the water pump.  Though the issue was happening prior to doing so.  I'll check it this weekend.

 

Why did you check the plugs and not replace them?

Plugs can carbon track and foul easily when cold.

 

Have you checked fuel pressure?

Does it have new air and fuel filters?

I did replace the plugs, wires and ignition coil.  i checked the air filter and it was clean.  The fuel filter has not been changed recently.

check your overflow if theres bubbles you still have HG issues. The 303 and 304 could possibly coolant leaking into your cumbustion chamber from failed HG's. But once started the car will run but will run rough at idle at a stop light for example. IF the heads were not properly machined or the heads not torqued properly you may have HG issues.

check your overflow if theres bubbles you still have HG issues. The 303 and 304 could possibly coolant leaking into your cumbustion chamber from failed HG's. But once started the car will run but will run rough at idle at a stop light for example. IF the heads were not properly machined or the heads not torqued properly you may have HG issues.

I have checked for the bubbles in the overflow and found absolutely nothing.  I have noticed that when I put in the new plugs the car cranked right away the first time.  The same went for when I cleaned the MAP sensor and reset the ECU.  And then the next time it was started it had an issue.  I have noticed no white smoke, but I am no expert in what burning coolant looks like.  I have noticed the exhaust smells absolutely terrible.  I wouldn't say it is "sweet" though.  Nor does it have the sulfur smell I have heard can be caused by raw fuel being dumped on a cold catalytic converter.  I don't remember it every smelling quite this bad in the past though.

 

The car runs flawlessly once the rough idle clears up for the first start.  No loss of power, MPG seems to be the same....The upper radiator hose seems to be under quite a lot of pressure, even after the car has cooled down overnight.  So much to the point it will spew coolant if the cap is popped while the engine has sat overnight.

Do a cooling system pressure/leak down test on it 

Going by what you say about the hose pressure I still suspect you may have a headgasket issue and suggest you have the coolant sniffed for exhaust gases. Checking the fuel pressure regulator should be done also as Fairtax4me already suggested. Checking the coolant temperature sensor operation for the ECU may be a good thing to do also.

My wife was behind me while starting it today and said it was blowing large amounts of white smoke while it was trying to start and after it started, then it cleared up.  So it looks like it's a bad head gasket...What would cause a premature failure?  I did them about 15k ago...

Not prepping the heads or block deck properly...too much warpage on the heads or block...or not torqued properly with the original bolts 

Not prepping the heads or block deck properly...too much warpage on the heads or block...or not torqued properly with the original bolts 

 

All this can happen several thousand miles after the fact?  Either way, they definitely seem to be bad.

Dropped valve guides on ex valves a'm seeing this a lot lately pull header look at guides see if they have moved down

If the old bolts were used they could of stretched enough to do this 

If the old bolts were used they could of stretched enough to do this 

 

I used new bolts on both sides.  However, on one side I did reuse the bolts after setting a gasket that was defective.  The car was never driven on them though.  Only cranked once so they were technically still new.  The main issue has been on the other gasket though.

had a 07 impreza yesterday misfire codes 02 codes had 4 out of 8 ex guides droped one the end was smashing against the valves both sides Mide you 0 smoke and ran not to bad. This is becoming a comen problem

have been using ARP head studs on all ej engine nowdays only way I can guarantee headgasket jobs is only 100 more than buying stock bolts and worth every penny

had a 07 impreza yesterday misfire codes 02 codes had 4 out of 8 ex guides droped one the end was smashing against the valves both sides Mide you 0 smoke and ran not to bad. This is becoming a comen problem

 

I'm going to be taking the heads to a shop to be resurface and checked out as soon as I get the cash to pay for it and the time to disassemble.  I'll post up what I find...

 

have been using ARP head studs on all ej engine nowdays only way I can guarantee headgasket jobs is only 100 more than buying stock bolts and worth every penny

 

I'll definitely look into that.  The ones I used were about $60 per side.

That P0420 code points to a failed or clogged catalytic converter. The misfire could be from a bad 02 sensor. Check this site out for details: http://www.p0420.com/

 

My 99' Saab 9-3 had a bad 02 heater code for front and rear 02 sensors. Car ran fine otherwise and didn't need e-check for 1.5 years so I left it alone. Eventually, I developed a random engine misfire P0300 that happened very infrequently and would clear up in 5-10 seconds then not return for weeks. I thought it was fuel or sensor related, but never thought it was from the O2 sensor's heated element. Eventually the misfire got worse and was happening more frequently, and would eventually start acting up within the first 10 minutes of starting the car or within the first 2-5 miles and start bucking badly and loosing power. I was running the car catless briefly (with a anti-foulers stacked in rear O2 to trick ECM into thinking the cat was there, so no CEL for it) and it was misfiring, I put it in neutral, revved to 3k (this would usually clear it) and instead it let out a huge backfire    that literally blew the muffler apart at the seams! Looked like somebody stuck a cherry bomb up in it.

 

Anyways, what I finally discovered was the rear/secondary O2 was shorting out internally (the casing was peeling and sort of cracking which is common when they get too old) and not only causing the random misfire (P0300), but was the reason for the backfire as well. Thankfully the cat wasn't in the car at the time, as I believe the backfire would have damaged it in many ways. The ecm wasn't detecting anything else either, other than the failed heater element. Unfortunately O2's for Saab aren't cheap, but I replaced both and it solved the issues.

 

Not saying yours are bad, but you never know. If your cat is clogged (could be ruined from previous head gasket failure) it could be causing overheating as the EGT's could be very high which can be bad all around. I'd pull the piping down, and inspect the honeycomb for melting or breaking (if need be, cut the pipe on a straight section before the cat if it allows full view of the substrate, then buy some exhaust pipe couplers from Auto Zone and weld them back by slipping over the joint). It should look like a screen if OK. If melted, it'll look like a glob of melted glass. It's also possible only part of the honeycomb is damaged, or only 1 cat is bad, both scenarios WILL allow the car to at least run, and in some cases it's hard to notice while driving, but very possibly can be causing your issues. If they are bad, make SURE you figure out what caused their failure in the 1st place before haphazardly replacing unless you want a repeat failure. My guess is they were heavily contaminated, run too lean too long, fuel additives (I never use fuel additives for this reason as even "safe" additives can destroy the honeycomb if not mixed correctly and it can take awhile to catch) etc.

Edited January 29, 201412 yr by Bushwick

P0420 does NOT 'automatically' point to a bad cat conv. Though, a lot of people have probably been sold cats.

 

read here first before swapping any cats based solely on a P0420; http://www.subaruoutback.org/forums/66-problems-maintenance/49537-p0420-diagnosis.html

I bet a good amount of those cars with misfire codes and 420 code is a bad valve guide causing it