Misfires and flashing CEL

[blue62]

Originally Posted by ecp

They said the pistons looked good. hoping for busted valve spring or a stuck lifter but i’ve already got a used head and cams priced out. just gotta get the car back and tear into it on a weekend

Maybe it is a broken cam or something in the valve train.
Keep us posted.

[Stl-986]

Dont forget to lock the cams!

[ecp]

I almost have all the bolts off the cam cover. it’s a bit of a squeeze. i pulled off the scavenge pump and so far things are looking neat and clean inside, but the real telling part is yet to come

[ecp]

I got the cam cover off and i’m not going to lie, it looks perfect in there. it’s got 124k so there’s a little bit of wear marks on the cams and lifters but nothing catastrophic. no metal in the oil. from what i can see of the lifters everything looks okay.

What are your thoughts? I’m leaning towards a broken spring at this point. Just as a recap the dealership said they could see one valve stuck open on what i’m assuming is cyl two, since that’s the one with zero compression. When i took the header off though it was very obvious cylinder one wasn’t firing either.

[Stl-986]

did you have plastic bits in the oil pan?

Leak down test would have helped before as that will show a valve issue usually.

snap some pictures of the head, maybe it will be obvious if it's a spring.

You did lock the cams right? Both of them?

[ecp]

Originally Posted by Stl-986

did you have plastic bits in the oil pan?

Leak down test would have helped before as that will show a valve issue usually.

snap some pictures of the head, maybe it will be obvious if it's a spring.

You did lock the cams right? Both of them?

Yes the dealership did a leak down test and borescope. I’ll try and attach photos if i can figure it out, i have an iphone. and yes i have both cams locked

There’s always been some plastic bits in the oil. I’m pretty sure it’s the chain guides. i replaced the IMS last july

[ecp]

i pulled the exhaust cam, a definitive broken valve spring broken on cylinder two, need to pull the intake cam to look at the intake springs on cylinder two or one.

Do you guys think i need to pull the head? i’d definitely like to avoid that if i could. I’ll probably end up replacing all the valve springs if two simultaneously broke to be safe.

also any tips on reassembling? i marked the chain and sprocket with a marker and have the lock tool from my Ims kit. it’s a variocam 3 chain motor

[blue62]

Originally Posted by ecp

i pulled the exhaust cam, a definitive broken valve spring broken on cylinder two, need to pull the intake cam to look at the intake springs on cylinder two or one.

Do you guys think i need to pull the head? i’d definitely like to avoid that if i could. I’ll probably end up replacing all the valve springs if two simultaneously broke to be safe.

also any tips on reassembling? i marked the chain and sprocket with a marker and have the lock tool from my Ims kit. it’s a variocam 3 chain motor

These are interference engines.

If you have broken valve springs then there is a very good chance that the pistons have contacted those valves.
So the valve stems on those valves could be bent or there could be damage to the valve guides, and or damage to the valve seats.
Or other damage.

The only way you are going to know if there is damage is to remove the head and have it checked out by a good machine shop.

You may have dodged a bullet and can save that engine.
Pull the head and have a automotive machine shop examine the head and check the specs.
That is the prudent thing to do.
Anything else would be foolish in my opinion.

[ecp]

Originally Posted by blue62

These are interference engines.

If you have broken valve springs then there is a very good chance that the piston has contacted those valves.
So the valve stems on those valves could be bent or there could be damage to the valve guides, and or damage to the valve seats.

The only way you are going to know if there is damage is to remove the head and have it checked out by a good machine shop.

You may have dodged a bullet and can save that engine.
Pull the head and have a automotive machine shop examine the head and check specs.
That is the prudent thing to do.

I did another borescope (at home). no contact with the piston, no seat damage. i was able to wiggle it around just enough to get a good look at the seat and it looked good.

Honestly at 124k miles, i’d rather start saving for a new or upgraded motor. I thought about pulling the head, but the borescope answered questions i had. The spring broke in such a way that it wouldn’t return fully, but it wouldn’t go in far enough to hit anything either. No damage to any piston.

I think that cylinder one was “dead” because the ecu went into some kind of mode or just couldn’t compensate for the one cylinder with zero compression.

I’m trying to decide now if i should replace all 24 springs, just the springs on bank one, or just the one spring. they look okay, but if one broke, others might soon follow. replacing all the springs and getting it back on the road is worth it to me. Any thoughts on that or good while you’re in there’s are welcome

I do love this car so spending the money for a new engine down the road doesn’t bother me. i just don’t have that kind of cash right now

[Stl-986]

Usually there is a reason why it broke. I wouldn't do them all right now if it were me, I would just do bank 1.

Now, with that said....the plastic you have been getting in your oil and that you have noticed....is a problem. Should have addressed that when you saw it the 1st time. I suspect this was the 1st problem and then started to get worse. Shouldn't cause a broken spring, but, if there is something in in the oil that shouldn't be there, it is only a matter of time before that plastic gets somewhere that will cause bigger issues.

[blue62]

Originally Posted by ecp

I did another borescope (at home). no contact with the piston, no seat damage. i was able to wiggle it around just enough to get a good look at the seat and it looked good.

Honestly at 124k miles, i’d rather start saving for a new or upgraded motor. I thought about pulling the head, but the borescope answered questions i had. The spring broke in such a way that it wouldn’t return fully, but it wouldn’t go in far enough to hit anything either. No damage to any piston.

I think that cylinder one was “dead” because the ecu went into some kind of mode or just couldn’t compensate for the one cylinder with zero compression.

I’m trying to decide now if i should replace all 24 springs, just the springs on bank one, or just the one spring. they look okay, but if one broke, others might soon follow. replacing all the springs and getting it back on the road is worth it to me. Any thoughts on that or good while you’re in there’s are welcome

I do love this car so spending the money for a new engine down the road doesn’t bother me. i just don’t have that kind of cash right now

You can do what ever you like it's your car.
I gave you my opinion and I stand by it.
Keep us posted.

[ecp]

Originally Posted by Stl-986

Usually there is a reason why it broke. I wouldn't do them all right now if it were me, I would just do bank 1.

Now, with that said....the plastic you have been getting in your oil and that you have noticed....is a problem. Should have addressed that when you saw it the 1st time. I suspect this was the 1st problem and then started to get worse. Shouldn't cause a broken spring, but, if there is something in in the oil that shouldn't be there, it is only a matter of time before that plastic gets somewhere that will cause bigger issues.

I’m leaning towards just bank one right now. It’s a bit of a hassle to get everything apart engine in the car.

The plastic is pretty minimal. I always assumed it was the chain ramps since there’s an occasional chatter on startup. But looking at them they don’t look too worn, on bank one at least.

Now that i think about it though, theres always been a slight noise coming from bank one, which i now think was the spring getting ready to go. it failed at 6k rpm, maybe it was over revved by the previous owner and it got weak. just glad the motor is repairable for revatively cheap

[ecp]

Originally Posted by blue62

You can do what ever you like it's your car.
I gave you my opinion and I stand by it.
Keep us posted.

I do appreciate your opinion. if i had the cash and lots of time i’d definitely take that route. unfortunately i only have time to work on it during the weekends, if it’s not raining of course

[ike84]

Not to derail this victory (good job finding the broken spring!) But what is going on with cylinder 1? There's no "limp mode" that will cause total loss of compression.

You said the dealer did a leak down test - what did they find on cylinder 1?

If you have no compression in cylinder 1 and a leak down supports that finding, I think you still have more trouble ahead.

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[ecp]

Originally Posted by ike84

Not to derail this victory (good job finding the broken spring!) But what is going on with cylinder 1? There's no "limp mode" that will cause total loss of compression.

You said the dealer did a leak down test - what did they find on cylinder 1?

If you have no compression in cylinder 1 and a leak down supports that finding, I think you still have more trouble ahead.

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I’ll have to ask them. all they mentioned was a valve was stuck open. I had assumed it had no compression like cylinder 2 because it was also not firing, but i never checked with the gauge. so if there’s nothing wrong that i can see right now, i was just wondering if it could just be the ecu not keeping up due to the dead cylinder and not a mechanical problem

[ecp]

I did my own sort of test. i modified my compression test hose so it can put air into the cylinders, and then when i unplugged the compressor line, i’d feel for air coming back out of the hose that’s screwed into the head. cylinders two and three had good pressure when i undid the line, but cylinder one had nothing. keep in mind all valves are closed, but cylinder one is at TDC.

My question is:
Is the reason that i felt no air coming back out of cylinder one because there’s no space for it to go (TDC, very small space vs the other two pistons which are further inward etc)
or because there’s also a problem with cylinder one and the broken valve spring on cyl two isn’t all that went wrong.
Cylinder one was not firing, i’d like to think it’s just the ecu not being able to compensate for cylinder two which had zero compression, but this is having me re think my approach. I don’t want to pull the head, but if i have to, i have to.

i only put in about 25 psi. Should i try closer to 100 like what people do when they perform leakdown tests?

[ike84]

Originally Posted by ecp

I did my own sort of test. i modified my compression test hose so it can put air into the cylinders, and then when i unplugged the compressor line, i’d feel for air coming back out of the hose that’s screwed into the head. cylinders two and three had good pressure when i undid the line, but cylinder one had nothing. keep in mind all valves are closed, but cylinder one is at TDC.



My question is:

Is the reason that i felt no air coming back out of cylinder one because there’s no space for it to go (TDC, very small space vs the other two pistons which are further inward etc)

or because there’s also a problem with cylinder one and the broken valve spring on cyl two isn’t all that went wrong.

Cylinder one was not firing, i’d like to think it’s just the ecu not being able to compensate for cylinder two which had zero compression, but this is having me re think my approach. I don’t want to pull the head, but if i have to, i have to.



i only put in about 25 psi. Should i try closer to 100 like what people do when they perform leakdown tests?

So you pressurized the cylinders (with the head cover off I'm assuming?) And cyls 2-3 returned pressure when the supply line was vented but cyl 1 returned nothing?

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[ecp]

Originally Posted by ike84

So you pressurized the cylinders (with the head cover off I'm assuming?) And cyls 2-3 returned pressure when the supply line was vented but cyl 1 returned nothing?

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yup i have the head cover off, and removed the broken spring. was just trying to get my parts list together and wanted to make sure i didn’t need to add a bunch of things to it. Cyl one returned very little after doing the test again with more pressure put into it. I think it’s due to the fact that there’s a much smaller space for air to go since the piston is at tdc. starting at zero and firing up the compressor it builds pressure nearly as quickly as when an air tool is attached to the line.
there’s a slight hiss coming from back near the crankshaft area which i assume is just air seeping past the rings. it did it on all cylinders

after putting more pressure in and confirming air returned on cylinder one numerous times i think it’s worth a shot putting new springs in and trying to fire it up, and maybe it was just an ecu error causing cylinder one to not fire. I could be wrong, but i could be right. Only one way to find out.

The fact that the dealership only mentioned a valve being stuck open on one cylinder also leaves me to believe that they didn’t really find any other issues, but i’m gonna give them a call tomorrow and ask just to double check.

[ike84]

Originally Posted by ecp

yup i have the head cover off, and removed the broken spring. was just trying to get my parts list together and wanted to make sure i didn’t need to add a bunch of things to it. Cyl one returned very little after doing the test again with more pressure put into it. I think it’s due to the fact that there’s a much smaller space for air to go since the piston is at tdc. starting at zero and firing up the compressor it builds pressure nearly as quickly as when an air tool is attached to the line.

there’s a slight hiss coming from back near the crankshaft area which i assume is just air seeping past the rings. it did it on all cylinders



after putting more pressure in and confirming air returned on cylinder one numerous times i think it’s worth a shot putting new springs in and trying to fire it up, and maybe it was just an ecu error causing cylinder one to not fire. I could be wrong, but i could be right. Only one way to find out.



The fact that the dealership only mentioned a valve being stuck open on one cylinder also leaves me to believe that they didn’t really find any other issues, but i’m gonna give them a call tomorrow and ask just to double check.

At tdc, both intake and exhaust valves should be closed. Hence, whatever pressure you put in should stay there. Even in a small space, 25psi is a lot of air. If you aren't getting it back there is a problem. You are effectively doing a poor man's leak down test, but I don't think you're gonna get any kind of good diagnostic data with the way you're doing it. You said the dealership did a leak down - what did it show?

The bottom line here is that if a cylinder won't pressurize, or won't hold pressure, you have a serious problem.

One caveat there - we have low pressure piston rings. So, in the absence of a crank case vacuum, expect some leak down. Not complete loss though.



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[ecp]

Originally Posted by ike84

At tdc, both intake and exhaust valves should be closed. Hence, whatever pressure you put in should stay there. Even in a small space, 25psi is a lot of air. If you aren't getting it back there is a problem. You are effectively doing a poor man's leak down test, but I don't think you're gonna get any kind of good diagnostic data with the way you're doing it. You said the dealership did a leak down - what did it show?

The bottom line here is that if a cylinder won't pressurize, or won't hold pressure, you have a serious problem.

One caveat there - we have low pressure piston rings. So, in the absence of a crank case vacuum, expect some leak down. Not complete loss though.



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Poor mans leakdown yes. I have the cams out on bank one so all the valves are closed. The boxes of suspension parts sitting in my house drained me dry, and then this happened. I know it’s not the best or anywhere near precise, but it would give me a yes/no answer if wether there was pressure building or not.
I’m gonna give them a call tomorrow. They did perform a leak down and borescope but only mentioned the one valve that was open, which i was able to diagnose as the busted spring. I know the motor isn’t perfect. It sat for about two years and given the state it was in when i bought it, definitely neglected. that’s why i don’t want to put major money into a repair of a neglected engine with 124k miles. would rather put in a new or nice used one in the future.

I did have my buddy with a good borescope come by, we didn’t see anything. in cyl one it was hard to see with it being at tdc, but i didn’t want to rotate the engine with the cams out. But it’s not like we saw glitter or a big hole in the piston, just normal carbon buildup on it. Just wishing i put the compression tester on cyl one when i did cyl two....