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Discussion Starter · #1 ·
Hello all! Not new to Subaru's or this forum, but it's been a while. My son bought a 2011 WRX last December and was lucky enough to develop a knock a few weeks ago. So, being the enterprising wrench turner that I am, and to get him some experience (he's actually a big truck/diesel mechanic), we went for a shortblock replacement (stock from dealer 2.5L pre-assembled short block). We went with a full engine gasket kit and all new timing kit components. Disassembly and reassembly were underwhelming, with the only problems having been a ruined passenger exhaust cam sprocket bolt (I know I'm not the only one to do that...) and a stripped thread on the timing tensioner bracket. 3rd or 4th time I've dealt with Subaru boxer timing systems, I've done an engine pull on an older model for a clutch, but have a lot of experience with tons of other vehicle types and didn't find anything to be too terribly new.

Once we got everything re-assembled and in the car, fluids topped off, everything double-checked, she fired right up immediately. Idled/ran beautifully, just above to just below 100psi oil pressure immediately, came down to 30ish after it was warmed up. Spent about an hour idling in front of the shop, making sure we got all the bubbles out of the coolant system and nothing was leaking. Went for the first shakedown run, it drove/ran/idled/shifted perfectly... for 1.25 miles. Then it shutdown (it just seemed to "stall") as I pulled in to turn back towards home, and would not restart. It will crank, and *occasionally* makes a very weak attempt to fire.

The car:
2011 WRX Limited Sedan turbo (non-STi). Mods: Invidia catless TBE, AFE CAI (don't think it's the SRI, it goes into the fender well), and Cobb AP w/several tunes (current tune file name matches mods), run 91 octane (usually best you can get around here), have a vacuum/boost gauge and an oil pressure gauge installed.

Elaborated current status:
Car "cranks" in that the starter engages and the engine turns over. Scanner shows RPM going to approximately 160rpm (seems "slow" to me). Usually doesn't even attempt to actually "fire" and RUN, just turns over steadily. I have pulled the timing covers all the way off and verified no movement of the belt (new belt was marked and teeth counted, everything lines up EXACTLY as before). I have not tried to push start it due to living on gravel roads, but it's on my list of things to attempt at some point. Have also not tried to jumpstart, but the battery voltage seems strong and the starting sounds are consistent. I'm currently looking at a crankshaft/camshaft position sensor replacement - the old crankshaft sensor was checked for resistance, and the first time it showed a short (4 ohms), but a subsequent check showed 1960 ohms (online info said 1k-4k was good). I attempted to simulated the inductive pickup by passing a metal/ferrous object in front the sensor at speed, and the resistance noted maybe an 8 ohm difference, and DC voltage showed as high as .1V (online info suggested -7 to +7 was required). The crank sensor DID have sludge/metal particles on it when pulled (it transferred with the front cover assembly so wasn't specifically looked at during the rebuild), but after cleaning and installation no change to the car's symptoms.

I've done a good deal of research on this forum and "that other forum", unfortunately most of the threads that sounded line mine had no resolution (I found a few with the aforementioned sensors fixing it, and a few more with random wiring/grounds issues so those are on the list as well).

The only other piece of information, and it may be nothing, but I'm noticing that when I try and crank it, afterwards I hear the turbo spin down with a little bit of a whistle, which seems odd - but I can't say I heard it before after cranking and it not starting, so that may be normal. One last thing being when I did the swap, almost the entire intake manifold and everything connected to it was left intact. I took apart the bare minimum necessary to change it over from one engine to the next, so the only set of gaskets that was replaced on it was the TGV to head gaskets. I say this so that everyone knows most of the plugs that are on the intake were not touched in any way.

Any other ideas or thoughts appreciated. I'm not much for throwing random parts at things, so if you have a test procedure I'd love to hear it for whatever malfunction you might suggest.

Thanks,
Jon
 

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Crank no start is a hard one. It can be anything from a sensor, to a leak in the intake.

I would start with the electrical system. You said it was fine then went to crap after a short drive. I would check your grounds make sure nothing came loose. After that I would verify spark then fuel.

Also verify that the tune you are using supports the intake you have. They are not one size fits all. I believe Cobb's notes for the GR supported Cobb and perhaps aem if i recall.
 

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Discussion Starter · #3 ·
IIRC, the only grounds that I took off were the large one on the starter mounting bolt, and the 2 small ones that connected to each valve cover on either side. I know I've had eyes on the valve cover ones, I'll check the main one, but don't see how it could have come off. I'll also look for a larger ground diagram somewhere to check others.

I do know the tune is ok, it does specifically list the items that are on the car by brand and type. I did plan on putting it back to stock, but decided I might as well leave it and just trust he stayed out of it for the most part during the break in.
 

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Dogging a brand new engine is bad news.

Yeah if you are feeling it's slow to crank start there.
 

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Discussion Starter · #5 · (Edited)
Update:
No LOOSE grounds, tomorrow I will be taking them off and cleaning all of them and where they connect to.

Today I verified spark (pulled a coil, put another plug in it, grounded, and got spark). I verified that the FPR is working and there are no leaks... BUT, it took about 5 to 6 cycles of the key to get to the pressure it should be at.

Having verified spark and fuel, I determined I should check the timing one more time. The previous check I only took of what I had to to see the belt, so I didn't get a good look at a lot of it. This time I stripped out the cooling system and everything in the way so I had a clear view. Everything checked out EXCEPT the driver's intake cam was 1 tooth off (I remember feeling like there was too much slack between driver's cams before). Everything was still tight.

Tried to fire it up, and this time it would run, but very very rough. It smells of plenty of fuel. I don't see how it can be in the realm of possible that 1 tooth on 1 cam could cause valve damage, but if I had to put money on a guess right this second that would be it. Desperately hoping a ground loop is contaminated and making sensors lose their minds.
 

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Discussion Starter · #6 ·
Update (for anyone in a similar situation to help):
Driver's intake cam apparently spun on the end of the camshaft. Apparently it can seat in an oil hole if it turns. New sprocket and seals and car is back in business. Getting the break-in miles on it now.

New (sort of) issue is that occasionally coming off throttle it fails to catch itself on idle. Not all the time, maybe 1 in every 50. First day it had a Crank sensor to Cam sensor mismatch, but that was cleared and hasn't come back in.
 
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