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Plug swap failed to fix miss on my WRX - looking for ideas

miss WRX intermittent miss

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85 replies to this topic

#1 1 Lucky Texan

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Posted 26 February 2013 - 01:04 AM

My 06 WRX wagon with 43K doesn't see many miles and most of my maintenance is done on the 'time' side of the schedule.

 

It came from the factory with Iridium plugs.

 

Recently, it has begun intermittently making a 'chk' sound and I can feel the car jerk very slightly. No CEL. I waited till the tank was nearly empty, put in some SeaFoam and filled it up. No help, No CEL. It may be on its 3rd or 4th tank so, I doubt it's a fuel issue. I did pull the MAF connector to force a CEL so I could get FreezeFrame data with my scanner. Fuel trims were all low single digits (dunno what else I should look for there)

 

This weekend, I swapped out the plugs. And of course, all four I removed 'look' pretty good. Sigh - well, I have new plugs in even though the old ones probably had another 20K or more life in them.

 

Car still has the miss. It is very random. never seems to do 2 in quick succession, and there could be one, followed by another in 300 yards, or it might be a mile. I have an 11 mile commute on side streets. I have heard it at idle maybe 2 times. I THINK I've heard it decelerating 3-4 times. Of course, at high RPM I can't really hear anything so, not sure if it's happening. But cruising around at 1800 to 3 K or so, it could happen 10-20 times on the way home.

 

so, I figure I may as well ask what you guys what you think. If I were gonna change something, what would it be (crank angle sensor ?) or even take it to a dealer (what would they be able to do?)  I'd really rather not just wait until a CEL comes on or something breaks.



#2 Fairtax4me

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Posted 26 February 2013 - 08:45 AM

Check the plug boots if it has Coil on plug. Also pull the springs or whatever it has out of the boot (you can usually pull the boot off too) and see if they're corroded. Check the output post for corrosion an look for signs of arcing through the boots.
If it has plug wires its probably time for some new ones.

#3 1 Lucky Texan

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Posted 26 February 2013 - 09:23 AM

Check the plug boots if it has Coil on plug. Also pull the springs or whatever it has out of the boot (you can usually pull the boot off too) and see if they're corroded. Check the output post for corrosion an look for signs of arcing through the boots.
If it has plug wires its probably time for some new ones.

 

 

DANG! - wish I had known to do this but, as it happens, I DID see the springs in 2 of the coil packs (one because I was curious, the other because at one point, I thought it would make removing the rear DS coil easier to pull it off)  and they were bright and shiny. None of the rubber 'snouts' were oily ,wet, dirty or otherwise looking bad.  Each coil also had its connector re-seated.



#4 ivans imports

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Posted 26 February 2013 - 10:42 AM

had a 02 wrx that the heads had been done and the valve clearances got messed up was to tight on #4#2 cly made it miss at idle and run rough on hyway had to remove the heads and reclerance the valves and problem was gone seems to be a wrx problem mabee the extra heat from turbo makes the exhaust valves get tight



#5 1 Lucky Texan

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Posted 26 February 2013 - 11:00 AM

how likely would that be at 45K miles? no history of engine work.


Edited by 1 Lucky Texan, 26 February 2013 - 11:00 AM.


#6 Fairtax4me

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Posted 26 February 2013 - 04:49 PM

Doubtful it's valve clearance issue at that mileage.
Fuel trims should be low single digits. 10+/- is fine.

#7 ivans imports

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Posted 27 February 2013 - 10:12 AM

the one i had was hitt in the front and must have had valves changed at some piont. What if it was set to tight from factory ? how long has it missed for. I did have a car with a cracked injector had a hairline crack and was shorting and giveing misfire codes on that hole. was a 02 outback



#8 1 Lucky Texan

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Posted 27 February 2013 - 10:56 AM

the one i had was hitt in the front and must have had valves changed at some piont. What if it was set to tight from factory ? how long has it missed for. I did have a car with a cracked injector had a hairline crack and was shorting and giveing misfire codes on that hole. was a 02 outback

 

 

That's one thing that's frustrating, no misfire code. No codes at all.

 

I read one thread at NASIOC about debris on the end of the crank angle sensor(most of those cars also were higher mileage though). , plus, seems like an easy thing to too check so, I plan to pull it soon. Plus, I will be able re-seat its connector/inspect the cable.

 

I'm not hopeful that will be the problem either, but easy enough to try.



#9 Gloyale

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Posted 27 February 2013 - 11:08 AM

+1 for valve adjustment. Do it before it burns.

I got an 02 in my shop getting a valve replaced right now.

#10 1 Lucky Texan

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Posted 27 February 2013 - 12:27 PM

+1 for valve adjustment. Do it before it burns.

I got an 02 in my shop getting a valve replaced right now.

 

 

I don't want to 'guess' with just 43.5 K miles. Would it fail a leak-down or compression test?



#11 Fairtax4me

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Posted 27 February 2013 - 04:46 PM

Pull the valve covers and check lash clearance.

#12 ShawnW

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Posted 27 February 2013 - 04:53 PM

The plugs-no black in the ceramic/insulator section of the center?

 

A leakdown test would certainly tell you more and give you the piece of mind to replace an injector on the cylinder with the most black in the center of the plug.  I am going to guess cylinder 4 just based on what I have seen in the past few months.  3 bajas, a 1 wrx and 1 turbo forester all with tight clearance on cylinder 4 and 3/5 with a cracked exhaust valve edge.  Over $50 a valve for factory valves too.  



#13 1 Lucky Texan

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Posted 28 February 2013 - 12:29 AM

I did save the plugs, though i didn't number them. I'll look again.

 

about how much would you expect a dealer to charge to check the lash? I'm a little uncomfortable wrenching that deep i think.

 

guess an upside if they don't find a problem would be getting the cover gaskets re-freshed.



#14 Fairtax4me

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Posted 28 February 2013 - 10:35 AM

It's really pretty simple. All you need is a feeler gauge, which you can get for like $5 at any auto parts store. Set the engine at TDC for cylinder 1, check the clearance between the rocker arm and valve stem (between camshaft and bucket on DOHC engine) on all 4 valves for that cylinder. Move to the next cylinder in the firing order, set it at TDC, check clearances, repeat for the next two.
The clearance is the largest gauge or combination of gauges that fits. If no gauges fit the lash clearance is 0 and that's no good.

Just for giggles, try this to see if you can get it to set a misfire code.
Get the engine warm, take it out on a highway or some road where you can accelerate from about 30 up to 60 mph. Get up to about 30mph and put the trans into the highest gear, then accelerate at half throttle or more up to about 60. Repeat several times, then stop the car and turn off the engine. Restart and repeat the process several more times. This usually gets the ECU to detect an intermittent misfire by keeping the engine in the speed range where the misfire occurs. It doesn't always work, but only takes 20-30 minutes to try.

Edited by Fairtax4me, 28 February 2013 - 11:09 AM.


#15 ivans imports

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Posted 28 February 2013 - 11:06 AM

the arrows on the ps uper cam indacates what #cly you are on arrow strait up addjust #1 strait right #3 strait down #2 and strait left is #4 i like them a bitt loose 0.020 mm intake and 0.025 mm exhaust factory is about 0.015 -0.020 mm the exhaust is the most important and is hard to get to i donot think it can be addjusted with cams in position. The one i did had to remove the head and grind down ends of valves to get the right clearance this was very involved and time consuming but it fixed it right up no more missfires and way smoother. for now just make shure it has enuff clearance and if it gives you a misfire code you know what cly to check first



#16 1 Lucky Texan

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Posted 28 February 2013 - 11:38 AM

does this car have the bucket shims or is it screw and locknut like my old 69 Datsun roadster?

 

I dunno, I barely could change spark plugs, getting valve covers off and on, well, that's gonna definitely be at the edge of my comfort zone.

 

still, I will try the above to set a code, and I am gonna inspect the crank sensor for 'debris' as suggested on a different forum. easy stuff first - though I understand the risk is a burnt valve if this contimues and IS a valve train problem.

 

I appreciate the support guys - thanx


Edited by 1 Lucky Texan, 28 February 2013 - 11:39 AM.


#17 Gloyale

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Posted 28 February 2013 - 12:23 PM

02 has shims on buckets. 03 has selectable thickness buckets instead of shims. Either way you have to measure then clearance, then remove cams and buckets and then buy shorter or taller ones where needed.

A compression test will tell you if one is really bad. Leak down will tell you wether it's intake or exhaust. You'll hear the air hissing out.

#18 1 Lucky Texan

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Posted 28 February 2013 - 02:03 PM

2006 WRX wagon



#19 1 Lucky Texan

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Posted 01 March 2013 - 09:01 AM

this is preliminary but, after cleaning the CA sensor yesterday, I detected no missing driving to work this morning. I'll feel better by Tuesday/Wednesday next week but, there were metallic particles stuck to the sensor.

if it proves out that the car is fixed, I will try to post some pics I took.



#20 1 Lucky Texan

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Posted 03 March 2013 - 08:38 PM

very odd, but, while friday's trip to and from work seemed trouble free and I was about to claim the problem solved by cleaning the CA sensor, the issue was back today.

If I were going to replace the CA sensor, what brand would you guys recommend? Or is there a preference? or a brand I should avoid?



#21 ivans imports

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Posted 04 March 2013 - 10:11 AM

I whould be more worryed about were the meatal came from coged idler ? tb pullys and mabee some is on the cam senser to



#22 1 Lucky Texan

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Posted 04 March 2013 - 10:52 AM

I whould be more worryed about were the meatal came from coged idler ? tb pullys and mabee some is on the cam senser to

 

 

I AM wondering about that. It wasn't a lot, and, evidently, may not have been a problem - though, for a day, it seemed to be working after I cleaned it.

 

But, could an idler bearing be failing? Is it because the car gets so few miles a little corrosion is forming on some pulley surfaces? (the debris is black, not rust-colored), The theory at a thread at NASIOC is, since the sensor has a magnet and coil inside, any magnetic particles that build up o the sensor could confuse the timing.

 

I wish I had a CEL. I may check again for pending codes, and try some longer 'pulls' like fairtax suggested. I tried a few but, it didn't seem to 'force' a miss.

 

I may pull the cam sensors for inspection next(but they are at the rear of the engine right?) - then put a new crank sensor in if they seem OK. Is Delphi a good brand, Beck/Arnley?

 

It's so random.


Edited by 1 Lucky Texan, 04 March 2013 - 10:53 AM.


#23 ivans imports

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Posted 05 March 2013 - 10:28 AM

Beck arnley have had good luck with there parts. Mabee you can force it to miss wash the motor while its runing see if it misses if it misses high tention curcit  it helps to narrow it down. Do you have a stocih gauge ? if not mabee put one in so you can watch the air feul ratios mabee is going lean and missfireing. On the race buggy had to put in 550 injectors before i got it to stop running lean. could also be a ring land broken have seen two wrxs 2.0s do thiss a comp test will tell you check for low hole the bad one i saw was 180 180 175 -85 the piston was broken between the comp rings. Also had fair amount of blowby out the oil cap when reved. In one race season i broke 4 pistons thiss way and is commen problem with wrx



#24 1 Lucky Texan

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Posted 05 March 2013 - 10:52 AM

Beck arnley have had good luck with there parts. Mabee you can force it to miss wash the motor while its runing see if it misses if it misses high tention curcit  it helps to narrow it down. Do you have a stocih gauge ? if not mabee put one in so you can watch the air feul ratios mabee is going lean and missfireing. On the race buggy had to put in 550 injectors before i got it to stop running lean. could also be a ring land broken have seen two wrxs 2.0s do thiss a comp test will tell you check for low hole the bad one i saw was 180 180 175 -85 the piston was broken between the comp rings. Also had fair amount of blowby out the oil cap when reved. In one race season i broke 4 pistons thiss way and is commen problem with wrx

 

 

thanx, I think a compression/leakdown test might be the step to go to after I try ;

 

refreshing more ground connections (they have all looked good - wonder where exactly the CPS is grounded?)

 

wiggling cable harnesses while idling

 

inspect cam sensors

 

replace crank sensor

 

double check for pending codes and read fuel trim data again

 

 

It still happens at 1800 to 3K or so (maybe above and below but perhaps not noticed?), stone cold engine or warmed-up. after a turn, during accel OR deceleration (in gear, like engine braking - this seems weird???) still goes 'chk' and bucks/jerks a little. If I really put my foot in it, it still pulls strong. (but I admit to driving more like a granny since this started) Just filled the tank - this is probably the 5th tank of gas since the problem started/was noticed. There has been no rain or other odd weather.



#25 1 Lucky Texan

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Posted 05 March 2013 - 12:01 PM

I have tried to 'force' some missing - no go. Even lugging it in high gear up a hill - it's just as random as 'regular' driving. @ days agao I tried to let the tank get really low and 'thought' , maybe turning with a low tank would cause it cause it happened a coupla times. Then, on a straight section, I tried some hard 'slalom' maneuvering - nothing. it seems completely random.

 

if I get to a point that I want to take it to a real mechanic, what should I ask, suggest is done? Would a borescope show any scoring from a cracked ring land? Then what, comp/leakdown, then check the valve lash clearances?

 

I just now ordered a beck/arnley CPS. cheap enough from rockauto to try. ($26)


Edited by 1 Lucky Texan, 05 March 2013 - 12:04 PM.






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