Jackal's 20g to 18g e85 Soap Opera

The more I think about this, the more a bad or burned exhaust valve seems to fit (unless valve lash really is something we can and should be adjusting on these engines). Low power, poor fuel economy, and I have noticed the occasional 'pop' when I release the accelerator and depress the clutch while shifting if under medium or higher load.

 

Not to get too far ahead until the leakdown results are in, but any ballpark guesses on what it might run to have the exhaust valves replaced? I suppose it's probably a good time to do the timing belt as well?

Edited November 20, 2015 by jackal8788

Do these heads have rockers or shims and buckets?

They are shim and bucket. Although I believe Cosworth makes some "graded" buckets that get rid of the shim altogether.

Good to know thanks! I will be cleaning and putting new stem seals on my 98 dohc motor so I was curious how similar it is to ours. Doesn't look difficult but very time consuming I am sure. It has been a long long time since I broke down a cylinder head. But they are straight and in good condition save for the gunk built up in the intake ports.

When I just did the head studs my heads were 450 to have the valve job done and the valves adjusted. There should not be any extra cost to do new exhaust valves besides the cost of the valves. That was the cost from the machine shop. All the labor on the engine I did myself so I can not comment on what that would cost.

Valve lapping compound is only $4, valve spring compressor $30 or so, feeler gauges ( you should already have a set) $10.

I prefer toothpaste to lapping compound TBH.

 

 

Sent from a device using some software.

I prefer toothpaste to lapping compound TBH.

 

 

Sent from a device using some software.

 

Minty fresh valves! Very interesting! Maybe even grease mixed with baking soda?

When I was a kid all we could buy at retail was a lapping paste that came in a double-ended can. Every shop had a can. One end had a grit that was really too coarse and the other a finishing paste that took forever to get anything done. Toothpaste was right in the middle and the difference in price was a couple of beers.

If you can buy smoker's tooth powder that's even better, mix it with a little water. Slightly coarser than toothpaste.

Edited November 22, 2015 by fahr_side

I love the dialogues that have evolved in this thread. It almost makes the inevitably high repair bill worthwhile

 

In seriousness though, I've learned some pretty interesting stuff along the way here and I appreciate everyone's contributions and ideas. I'll post up the results from the leakdown test tomorrow night, provided it can be completed by then.

The mystery continues....

 

Leakdown percentages were no higher than 2% at 100 PSI for all cylinders. The guy who did the test said it was about the best he's seen and that 5-8% is much more typical. He had a hard time keeping the car from moving when pressure was applied.

 

Sooooooo.....what now?? :confused:

It would only take 15 minutes to put the car on a lift or jackstands and do some ruling-out. Seems like a small time investment compared with the work you've already done under the hood!

 

Ever get it on the lift?

Completely talking out of my butt here since I don't know these type of specifics, but since it hasn't been mentioned. Any chance it could have anything to do with the turbo itself?

Ever get it on the lift?

 

We did. Everything is in proper working order and no abnormal drag. Parts moved pretty easily.

 

Completely talking out of my butt here since I don't know these type of specifics, but since it hasn't been mentioned. Any chance it could have anything to do with the turbo itself?

 

I'm certainly not an expert but it does still hit boost targets (actually slightly quicker than it did after my dyno tune) and the IATs seem to be on par with what they should be based on ambient. Other's with more knowledge can (and are encouraged to) step in here, but I would think if the turbo was at fault, I would either see a lack of boost or some very high IATs due to the lost efficiency heating up the charge. We did visually inspect the compressor wheel and it appears to be find. There is no radial or lateral play to speak of either.

 

Again, no expert me so if others have thoughts, please share or correct my erroneous train of thought above.

 

We will find out soon enough as we are taking the valve covers off to look around, but I wonder if a valve spring could be broken?

^^^Interesting theory on the valve spring. You would think you would hear it, but at this point who knows. Could be anything.

You would have valve float and attendant misfires.

 

 

Sent from a device using some software.

I kind of figured something more obvious would present, but at this point, I am even more lost than I was a week ago. For so much power to be gone, it just seems like the cause would be easier to diagnose.

 

 

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Dead cat in the intake, maybe?

I kind of figured something more obvious would present, but at this point, I am even more lost than I was a week ago. For so much power to be gone, it just seems like the cause would be easier to diagnose.

 

This. After taking every inch of the motor apart, and doing every test, it's passed with flying colors. Nothing to diagnose in the engine bay!

 

Do your MAF readings still show you are moving good air? IE, the motor is still making power, it's just not making it to the ground... there's gotta be a more methodical way to check the drivetrain, anybody?

Probably slower because of all the 4thgens you're pulling around

Or maybe a ton of tears weighing him down because no real 6MT?

 

Actually, that's probably the best move going forward... full STi drivetrain swap. You know, just in case.

I'm certainly not an expert but it does still hit boost targets (actually slightly quicker than it did after my dyno tune) and the IATs seem to be on par with what they should be based on ambient.

 

Can you verify the boost pressure is actually what the engine (ECM) is seeing. If the boost pressure was actually lower than what is being used by the ECM, it seems you would experience lower performance, as you are now... ?

 

Throwing out ideas.

^^ Good thought. Jackal, do you have a standalone boost gauge or are you relying on boost reading from the stock MAP sensor thru the ECU?

Thanks Gents. I do have a standalone gauge (it resides next to my wideband) that is confirming what my Accessport is recording. So yeah.....

Didn't this all start from a 15 WRX that was supposedly stock pulling on you like you were standing still?

 

Since you've gone over nearly everything on your car I think it's safe to say that the WRX owner was playing the sleeper role. It's likely a 500whp car.

 

Just throwing some humor/smartassness into the mix here...seems outrageous that you've found anything yet! Good luck in your search jackal8788!

Edited November 24, 2015 by ebo03