CE light & hesitation/stumbling problems.

[Xylob]

99 Subaru Legacy Wagon Outback

2.5L engine

 

For just over a year now the "CHECK ENGINE" light has been coming on randomly and staying on for random amounts of time - a few minutes, a few days, a few weeks... Also the car sometimes hesitates/stumbles when cold (as in the engine is not yet up to normal operating temp).

RTFM and it says either the emissions system is jacked or the gas cap is jacked.

This all started shortly after the car passed the state emissions test with flying colors! So I took the gas cap apart and cleaned it meticulously as well as the filler neck etc etc.

Whatever. At first I thought the light was just coming on after I gassed up so the dirty as hell seals on the cap must have been the culprit (except part of the emissions test is to check the gas cap and ensure it seals properly, but I digress). It still kept happening.

So I took it to the Subaru dealar and asked them why my ****ed "CHECK ENGINE" light was on. They charged me $120.00 to hook it up to their computer and told me it was a "ghost code", they cleared it and it won't be a problem again.

A week later the CE is on again. YAY! I just ignored it for the most part - or at least tried to. It was really eating at me.

 

Eventually I took it back to the dealer and explained the whole story to them.

They hooked it up to their computer again and then their "Lead Technician" told me that the error code means "There is a massive carbon build-up in the left head which is blocking the EGR valve. If you don't replace the heads it will ruin your engine. $3,000.00 to replace one head, $5,000.00 replace both.".

I have to call 'bull************' on this. Where is the exact location of the "Massive Carbon Build-Up in the Head Sensor"?

I didn't have $5,000.00 to dump into this car that's only worth about that anyway (if I'm lucky!).

Not to mention that in the 2 years previous I'd dumped $4,000.00 into it first replacing the viscous coupler then replacing both of the head gaskets.

And oh by the way - if it has such a massive carbon build-up in the left head shouldn't that have been identified a few months earlier when they had the ****ed heads pulled off the engine?

Besides, "massive carbon build-ups" in the head don't come and go. I may not be an ASE certified mechanic but I've got a good grasp on the basics of internal combustion engines and I understand simple physics. If there was in fact a "massive carbon build-up in the left head which is blocking the EGR valve" it wouldn't just go away for a week. Or 3 weeks. Or a month.

So I tell 'em I don't have $5K, just reset the light and then ask about the hesitation/stumbling - he tells me "that's just how it is with these cars. Most cars in fact. Cars just don't run right until their up to temperature."

Seriously? This guy is their freakin' "Lead Technician"?

So I gave them another $120.00 and went home. The CE was back on again before I got home (less than 2 miles away), but it went out the next day and stayed off for more than a week.

I guess the "massive carbon build-up" went on vacation.

 

Today as I was leaving work it started to hesitate/stumble again - but much worse than it ever has.

Then I heard some muffled thumping from the engine compartment. WTF? Did I just lose a belt?

Pulled over, belts good. What the hell, it's cold out - I'll let it idle for a few minutes to get warmer. The idle is cRaZy! Wildly jumping between 3000 RPM and 200 RPM. No rythm or pattern to the fluctuations, just craziness.

It eventually settles down and warms up a bit - runs fine.

 

Throughout this entire ordeal I have never noticed any misfires (though I do understand they can be easy not to notice), no loss in power/performance (other than the already mentioned hesitation/stumbling when cold), and no loss or change in fuel efficiency (I track my gas mileage meticulously).

 

Anybody know WTF is going on here? O2 sensor would be nice & cheap to fix, but it was replaced less than 18 months ago...

 

TIA!

[zzGUY46]

Have you ever read the CEL yourself ??? or at a parts store like Autozone?

[Xylob]

I don't have an OBDII reader, but I did hear a commercial on the radio yesterday for AutoZone or Advance saying they can pull the codes for free - I'll have to check it tomorrow.

[OB99W]

Please be sure to get the actual code(s) ("Pxxxx", where the x's are numerals), not the code definition(s).

[Xylob]

OK - went to AutoZone and got the codes pulled:

P0400 Exhaust Gas Recirculation Flow Malfunction

P0463 Fuel Level Sensor Circuit High Input

 

The first one is fairly specific, the second not so much - but could certainly be a symptom of the first.

 

I still don't see why the dealership automatically jumped to the conclusion of "massive carbon build-up in the head" - wouldn't it make more sense that the EGR valve is damaged/failing?

 

I looked into the EGR valve initially and checked a repair manual (Chilton probably?) and the description of removal kinda indicated that by taking the EGR valve off the head you risk ruining it - easier (maybe even cheaper) to replace than to repair?

 

AutoZone has a new EGR valve for $170.00, but from reading the repair manual I don't have the tools/facilities to replace it myself... and even though I far more mechanically inclined than most of my friends I think I'd rather pay a pro to do it right than ************ it up myself for free, then have to pay a pro to fix my mess.

Shouldn't be more than an hours worth of labor, right?

[OB99W]

OK - went to AutoZone and got the codes pulled:

P0400 Exhaust Gas Recirculation Flow Malfunction

P0463 Fuel Level Sensor Circuit High Input

 

The first one is fairly specific, the second not so much - but could certainly be a symptom of the first.[...]

Actually, P0400 isn't all that specific, and an inaccurate gas gauge reading resulting from a sensor circuit fault (P0463) isn't going to lead to an EGR problem. Replacing the EGR valve without further diagnosis wouldn't be the most prudent step. For more insight, see http://endwrench.com/images/pdfs/Emissions.pdf .

 

EDIT: There have been several threads concerning P0400, so doing a search in this forum for that code might help. Also see http://www.vcertt.org/news/11-02.pdf .

Edited March 25, 2010 by OB99W

[Xylob]

I think it's the gasket on the EGR valve?

 

Pulled the BPT - 'clean' but wet inside.

Pulled the EGR (dropped the top not and lost it somewhere in the engine compartment!! @$#!#$!!) and very wet inside. As in water dripped out of it. Not buckets, but I certainly didn't expect any, so some was not what I was expecting.

Pulled the gasket off and it was soaked.

 

I'm going to try to clean the EGR out and clean the gasket off (it's FILTHY).

None of the parts stores in town have a new gasket and can't get one for a week (WTF?!).

[GeneralDisorder]

You don't need a new gasket - just reuse it.

 

Condensation (water) is natural by-product of combustion - it would seem that perhaps your EGR system isn't fully blocked by this carbon build-up.

 

Check the ports for carbon. And put a vacuum line on the EGR valve and suck on it to see if it opens and closes properly. The CEL is only indicating that there is no flow in the EGR system - that could mean a carbon build-up in the head, valve, or any other portion of the EGR passages.

 

In all likelyhood, it's going to turn out that the dealer tech was correct (dealership's rarely lie about this stuff). Though I don't see why you would need to *replace* the heads - a good cleaning will remove the carbon and they can be reinstalled. Carb cleaner or an aluminium safe hot-tank will remove the carbon or at least soften it so it can be washed out.

 

The bit about it ruining your engine is probably a bit of an exageration. EGR's aren't even used on many EJ engines. You could remove the thing and live with the code - it probably wouldn't affect the engine mechanicals ever.

 

If it's only been a few months since the HG job - you should complain and if you don't get any satisfaction at the dealer go to Subaru directly.

 

GD

Edited April 3, 2010 by GeneralDisorder

[Xylob]

hhmmmmm.....

my main concern is passing the state emissions test next month - if it can't pass I can't renew my tags which means I'm without transport.

 

Like I said before, there has been no change in performance or fuel efficiency since this started with the exception of the one time it freaked out with the erratic idle and the occasional hesitation/stumbling before the engine gets warm.

 

I can get the valve to operate via the vacuum line and the diaphragm appears to be in good condition.

 

The BPT is a bit of a conumdrum to me, but it seems to be OK.

I found a new gasket at a dealer on the other side of town - $6.00. The wife will pick it up for me after her bridal shower this afternoon. If it were expensive I'd probably pass, but $6 is no biggie. The original is quite nasty.

[Xylob]

removed the EGR valve (I can't believe I lost that damned nut!)

removed the BPT

bought 2 new nuts (8mm, 1.25 pitch BTW)

cleaned the EGR with an old toothbrush, a can of intake/manifold cleaner, and canned air (being careful not to get any cleaner on the diaphragm)

cleaned up the head where the EGR & gasket mount

cleaned up the gasket to find that it is badly deformed/warped

had the wife pick a new one up at the dealer on her way home

installed new gasket, the EGR valve, and the BPT

 

car did not want to start. finally turned over just as I was about to give up, stumbles, hesitates, coughs out a cloud of white smoke, smooths out...

NO CHECK ENGINE LIGHT!!

 

Drove around for a bit, ran some errands, took it back to AutoZone - NO CODES!