Replaced head gasket - BLINKING Check Engine Light with Cylinder 2 misfire

[bearbalu]

a) Does a BLINKING CEL register on the on board computer?

 

I understand BLINKING CEL is worse than regular light. How bad it is to drive around with it?

 

c) Any suggestions on diagnosing – I am planning doing a compression test on cylinder 2?

 

The intriguing thing is that I had cylinder 2 misfire (stead light) a few months ago before I blew head gasket.

 

Here is sequence of events.

 

 

 

1. STEADY CEL with cylinder 2 misfire in June – I reset it, problem never occurred again. Since the same misfire with blinking was detected now, I am wondering if they linked.
   
2. Blew head gasket on way to LA over Grapevine steep grade
   
3. Yesterday I just finished replaced head gasket, clutch, timing belt, spark plugs. Cylinder 2 spark plug seemed fine when I replaced it. It was Bosch aftermarket before, I replaced with same
   
4. Car started first try, however had smoke coming from RIGHT side (Cylinder 1/3) exhaust manifold which reduced after around 10 minutes. I ripped out exhaust manifold to see if I left a paper rag in head or in manifold, none found. I am wondering if the blinking CEL is pointing to a problem here that is not registered on computer – hence the question a) above.
   
5. Took car for a spin – BLINKING CEL comes on
   
6. Today OBD II reads cylinder 2 misfire
   

[Cougar]

Have you made sure there is not a problem with the plug or the wire going to #2 cylinder? Also check the compressions of the cylinders.

 

Checking the exhaust by placing some flat paper near the end will help check the valves for a problem. If the paper gets sucked back to the exhaust pipe briefly then a valve is bad. This is called the dollar bill trick.

[bearbalu]

It seems to fail dollar bill test...I hear put-put sound coming from exhuast and it wants to suck in the bill - I compared it with another car. Do you know how reliable/conclusive this test is?

 

I just replaced the head gasket myself. I had new valve seals as part of overhaul gasket set and had the machine shop replace them - I guess they took the valves out to do it. Wonder if they could see valve problem if there was one or if they replaced the seals improperly.. While I did head gasket, I replaced shims to make valve clearance okay again - on cyclinder 2 it was .007/.008 on the two exhaust valves, I changed both shims to get it to .009 (spec being .01 +- .001).

 

I did compression test a few times on the cylinder - never done one. I disconnected fuel pump and spark plug connector and cranked the engine with starter motor. I saw two different patterns. In first pattern it rises as 60-140-150-150-180-200 with each crank. In the second pattern it rises as 120-140-150-150-180-200.

 

1. Can anyone throw light on what these compression numbers might mean ?

2. Would an accidental paper rag left in exhaust cause a failed dollar bill test (see #4 in my first post) ? Would such a rag burn off with exhaust heat or get stuck somewhere?

3. Any other suggestions welcome before resigning to another engine overhaul - that would make me sick!

[cookie]

It is a bit late to tell you to check the valves while the head is off but that is part of the job.

We used to put kerosene in the ports and if it did not leak we would just change the gasket. Any leakage and the valves got ground.

I hope somebody finds another reason for your problem.

[bearbalu]

I never tried the dollar bill test BEFORE doing the head gasket job, but I had no cylinder 2 misfire messages and no put-put sound. That lets me to conclude that it is unlikely I had leaky valves BEFORE.

 

I called the machine shop and the guy said he took the valves out and they seemed in great shape. He claims that I would get no compression if there was a valve leak - it would never go upto 200psi as it did.

 

Any thoughts...

[cookie]

are seating. A defective lifter can on rare occasion keep one open. I have never seen yours apart but I assume it is hydraulic? If it is not have you checked valve clearance?

[bearbalu]

How reliable is dollar bill test? Would put-put sound and dollar bill test mean ONLY a leaky valve? Could I get the same symptom if spark plug wasn't firing or injector wasn't putting in any fuel ? What does put-put sound mean?

 

 

As I edited my previous post, the machine shop guy thinks I would never get 200 psi if I had leaky valves

 

Valve lifters and shims - seems mechanical type. As I edited my post #3, I adjusted valve clearances to .009

[Nug]

Put-putting is misfiring.

 

Typically, you want to see 90 psi on the 1st revolution of a compression test. Did you use a screw-in compression tester? For the first-timer, they are a little more foolproof.

 

I would do a leakdown test on that cylinder, and pinpoint the (theoretical) leak. This is where leakdown testing really comes into its element.

 

I would take the car for a nice hard run, and see what it does afterward.

[bearbalu]

Is there a reason to believe that it is DEFINITELY a leaky valve? Couldn't it be some other ignition/fuel injection problem ? Put-putting could be for reasons other than a leaky valve...right?

 

The compression tester I used had a cable that screws into spark plug hole.

I also did a compression test on cylinder 1 to compare with cylinder 2. It is very similar in pattern.

 

For a blinking CEL, they recommend slowing down...why would I want to drive hard?

[cookie]

is to put a teaspoon of oil in the cyl and do another compression test. If the compression comes up it means you may have damaged your rings with the overheat.

[Cougar]

Hopefully the other cylinders read the same or close to it. The main thing is to have them within around 20 pounds of each other.

 

It sounds like the valves in #2 are ok but there could be a sticking one as was suggested. You could try replacing the Bosch plugs with NGK's. They seem to work better in Soobs than the Bosch do. If you haven't replaced the plug wires I would do that also with some good silicone ones.

[bearbalu]

I haven't done cylinder 3 and 4 compression, but cylinder 1 and 2 seem pretty close.

 

How would I unstick a valve without taking the engine apart again? Any easy tricks with lubes etc?

 

I replaced the #2 plug. Tried swapping spark plug wire 2 and 4 to see if misfire moved to cylinder 4 - didn't work - it is still on cylinder 2. It seems to take a little longer to get the light, but I suspect that is misleading.

 

I checked the resistance on ignition coil and plug wires - seem okay. I checked the resistance on fuel injector connector - seemed okay too...

 

BTW, would a bad injector give P0264(265)("Fuel injector number 2 circuit low(high) input") also? Or just a misfire - P0302.

 

Any other ideas ? I am getting desperate!!

[Cougar]

If the injector resistance was too low or too high I would think it would generate the appropriate code.

 

If you have MPFI you could try swapping the injector with another cylinder.

[bearbalu]

Is there anyway of reconciling the failed dollar bill test (which would point to leaky exhaust valve) with 200 psi on compression test ?(which would imply exhaust valve is not leaking)

[badrasta]

bearbalu: when you say "failed dollar bill test", do you mean the bill was sucked right inside from 1" out?

 

I did this same test on my MY99 2.5 RS with 178,000 kms and it didn't suck it in, however if I hold it close enough to the end of the pipe, the bill will flutter. Just wondering how bad your car failed the bill test to get an idea of how serious the exhaust valve problem is.

-badrasta

[frag]

Just trying to explain why a car could fail the «dollar bill test» and not necessarily have a bad exhaust valve. Pure theory...

1) The exhaust system is the theatre of a rapid succession of hot gases bursts. It's reasonnable to think that between those bursts, after a certain mass of hot gas has been rapidly expelled from the pipe,there is a small moment of vacuum during which time colder outside air is sucked in even a little bit (normal flutter). The hot gases exiting the system fast enough for a certain inertia to take place create a small amount of vacuum as they leave the pipe.

2) Imagine now that one cylinder miss for any other reason than a bad exhaust valve. This vac period will be longer and might be long enoug to have the bill sucked in.

Trying my best...

[cookie]

if the misfire moves? You do have the injector wire on the correct injector and all the coil wire correct don't you?

Since I don't know exactly how your engine is configured take this with a grain of salt. I understand some subie engines fire both sides of the coil together so the coil wireing would not matter. I am more familialiar with my BMW which has seperate coils and if you mix one up it is kind of like having the plug wire on the wrong clyinder.

Having the injector wire on the wrong cyl is another famous trick.

It is very possible for an injector to have been damaged on head removal and work also.

[bearbalu]

Update folks,

 

Here is the good news – the CEL problem seems to have vanished.

 

Here is the bad news – I have no clue why – I can’t take any credit for fixing it &*@&$@*&$@Q!#!%^#^#%!%#!*&%#!*%#! I hate it when things happen without explainations!!!!!

 

May be I am speaking too soon – I have seen too many posts where CEL seemed to have gone away only to bite back in the butt within days.

 

Here is what happened.

 

Till Dec 30, the light would come on within 2-3 miles of street driving (40 mph max). Put-put sound from exhuast was noticeable. Dollar bill test failed... I did hold it an inch or so away, and once in a while it would violently hit the exhaust pipe.

 

On December 31’st it didn’t come on within 2-3 miles, so I drove more, and more…till I logged 30+ miles including 25 miles on highway with speeds upypo 80mph . Later in the day my brother drove it another 50 miles. Seems to drive reasonably smooth. The dollar bill problem seems to have reduced, though I can’t be sure. The put-put sound coming from exhaust seems to have gone away.

 

My speculation - Not sure, but here a few things that could have fixed it in decreasing order of my guess

1. The valves were sticking due to some dirt – as I replaced the head gasket, I removed quite a bit of carbon from piston tops and tried cleaning the coolant/oil passages - may be some of was sticking. That would explain why $ bill test failed, while engine had good compression. Though the put-put sound wasn't erratic - it seemed pretty steady...what is steady to ear might not be steady at 1000 rpm.
   
2. Valve lifters were sticking due to some dirt on other side of the head – not sure what dirt made it there. I pulled out camshafts/valve lifters and changes some shims.I did put engine assembly lube on valve lifters.
   
3. Dec 31 AM, I removed camshaft position sensor connector to measure sensor resistance, resistance seemed okay, put it back ini. I don’t think there was a loose connection, but putting the connector back might have done something. Camshaft sensor is on cylinder 2 intake, not sure if that makes a difference.
   
4. I remove the crankshaft position sensor completely to measure resistance – hard to measure with it inside. Seemed okay, put it back.
   
5. Dec 30 was very rainy – Dec 31 was humid and showers… perhaps spark plug wires…but that seems unlikely, aftter swapping 2 and 4 spark plug wires, and the problem was still on 2 on Dec 30.
   
6. Does the ECM (computer) have to relearn everything since I disconnected battery and pulled out the engine for about a month – does it take time to do it ? So is what I went through normal when you start a car after disconnecting negative ? Not sure how Subaru's work - do they store data in an EPROM/flash? Even then I am not sure how long it remembers data - they must discharge over time. However, I still can't explain why it was mifiring so badly to make the put-put sound and have CEL come on within a day.
   

Cookie, I never swapped injector connectors - just spark plug wires! I did put a screwdriver on each injector and they all seemed to be clicking.