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Discussion Starter · #1 ·
Hi all - this one has me baffled, and going to ask for suggestions.

Including this background in case it's relevant.

Last weekend, changed out the 3 lower motor mounts (the 2 donuts and the right side bottom) on the R, along with changing out the 4C struts for coilovers with resistors.

Had no codes, had no problems. Car ran fine. Drove it Sunday night for a little bit (10 miles) and Monday all day (about 20 miles total) and then Tuesday morning to work (less than 5 miles) - went to lunch, got about a mile from work, and suddenly no power, and then dies. Coasted to a safe spot and it cranks but sounds really odd, like a backpressure problem or some very large hose popped off the intake side, and won't start.

Towed it to the shop, started checking the intake side - note that this was removed the weekend before to get to the front donut motor mount - and when pulling it off again to check everything, I did notice that the IAT sensor boss that I used epoxy on last year was somewhat soft, and when I was messing with it out of the car, I got it to pop loose. So that got cut off, scraped, the tube scrapped, and properly welded onto a new tube - installed today. (Note: this had no effect on getting it to run - and I don't think it was leaking previous - however, wanted to full disclosure why I was checking it)

Put everything back together on the front end, even pulling the bumper off and checking the FMIC - all connections tight, clean and stable.

Pulled rear seat out again, checking for wires disconnected around the fuel pump area (thinking that it may be a fuel related issue) - this in spite of having fuel at the fuel rail, and when I crank it, after a bit it will backfire slightly. All connections inside the car are tight - I have NOT checked under the car yet, but hadn't taken any of it loose last weekend - was only checking stuff I disconnected/reconnected. Thinking that maybe the PEM died (and yes, I do believe it's outside on mine) but it doesn't add up quite because, as I say, I have fuel at the rail under pressure, and the fuel pump primes and runs when cranking.

Battery seemed to run down fairly fast when cranking - but when I pulled it out, charged it, and tested it with my old pile tester, it tests ok. That said, I still suspect slightly that it's a low voltage problem and the battery is 5 years old - so it's possible it's just low enough to cause a problem. I give this about 5%.

I had about 6 codes when I ran Vida/Dice unit on it - most of which I point to being when it died, not before -

ECM-3300, 3320, 3330 Ignition coils
I've had recurring ever since I got aftermarket non-Bosch coils - I replaced because I had 2 dead/dying ones with the originals a couple years ago - and since replaced 2 of the new ones - so I get an error on the 3 remaining with Vida/Dice - and have been.

ECM-3000 Intake Cam Sensor signal missing
ECM-3010 Exhaust Cam Sensor Signal Missing
These I think were when it died, not prior.

ECM-982A and ECM-984A ECM faulty signal - these I think are again when it died, but they may point to cause. One of these in VIDA/DICE is described as potentially being caused by blockage in exhaust . And honestly, that's what this sounds like (even though I feel exhaust moving when having the engine cranked and putting my hand over the exhaust pipe)

BCM-A031 Communications between Control Units Tolerance Control for SAS not run - the snapshot on this one reads like it was after it died and was coasting down.

So - I'm going to lift it up and put it on stands, and look at the exhaust system to see if I can see damage to the cat or something of that nature. Perhaps jacking and lowering the engine etc last weekend to get the mounts in caused the cat to fail by having the monolith break up and slide across the exhaust outlet.

Also, just for my peace of mind, I'm going to run a compression check on all 5 to see if I didn't have a timing belt issue - it's only got about 30k since the last change - but if the intake side jumped a peg, it could crash the piston, and cause all the problem, and still let me have a good exhaust pop like I have... and also explain the really odd sound it makes when starting (no, it's not smashing noise of interference fit, just more I don't even know how to describe it)

I'll take any suggestions for things to look at at this point. It's not often I'm stumped, but I'll admit I am this time...
 

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Check all of the grounds.... All of the codes point toward a communication issue. And definitely check the timing belt...

There's a basically zero probability any of these have to do with an exhaust blockage...
 

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Discussion Starter · #3 ·
Check all of the grounds.... All of the codes point toward a communication issue. And definitely check the timing belt...

There's a basically zero probability any of these have to do with an exhaust blockage...
Grounds are the first thing. I had the engine lifted up to change out the motor mounts, and so definitely a possibility.

That said, one of those 2 ECM codes states that a blocked exhaust system can set this code, and further the VERY odd sound the engine now makes when cranking puts that into the realm of possible - since, again, banged around the bottom of the engine pretty hard to get those mounts changed. That is the further 'why' of looking at the cat.

Like I said, I'm fishing for ideas at this point, and definitely thank you for the suggestion.


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All coils have same mileage? Unless i read it wrong, you mentioned you had replaced 2 from the aftermarket set which have given you codes. What condition is the wiring harness in? Perhaps there is some exposed wiring that lead to a short, popping a fuse or two (speaking from experience).
I too would be concerned about the timing belt. Best of luck resolving the issue!
 

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Discussion Starter · #5 ·
All coils have same mileage? Unless i read it wrong, you mentioned you had replaced 2 from the aftermarket set which have given you codes. What condition is the wiring harness in? Perhaps there is some exposed wiring that lead to a short, popping a fuse or two (speaking from experience).
I too would be concerned about the timing belt. Best of luck resolving the issue!
2 coils are back to original, 3 are 2 years old.
Wiring harness is solid (or was last fall the last time I had the coil cover off) the only problem was 1 broken retaining clip on 1 coil plug, which I used a zip tie to go around to hold it in place until I can find a harness or part number for the plug replacement. Low priority on the plug.
The coils/plugs however, I think should be checked / replaced just to get everything back where I'm comfortable with it.
I will be checking that over as I pull that off to do a compression test.
Thanks!

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Discussion Starter · #6 ·
Spent a couple of evenings, part of last weekend, and all of yesterday in the shop:

I checked every place I was at with the previous work - and in fact have taken it further down in case I pulled a wire loose on the "far end" of what I was moving around. Everything is tight and fairly clean (understand this is a 249k daily driver... well maintained, but certainly some "ain't broke don't fix it" points around the car. Like under the rear seats - that haven't been out since I don't remember when)

The battery is at 12.2 and seems to be holding a good charge with my old school battery tester. That said, it is 5 years old, and may be not allowing enough juice through or drops off quickly - I did notice when cranking I dropped to just under 10v which makes me suspect it may be the ultimate culprit. This is after 3+ hours of slow charging.

Rattled the exhaust and have some rattling inside the exhaust system - still not very confident that I had a catastrophic catalytic converter (try and say that 3 times fast) but I am not confident that it was root cause, either. Am definitely thinking of using this as the excuse to put a new downpipe on, however. Just if it runs first. Since I was right there when I was under it, and was prying around to get the new motor mount in, yes this is legitimately a concern, if my banging around caused the last bit of whatever was holding on to let go... I just want to be clear that this thought didn't come completely from the VIDA Dice codes.

Checked fuel pressure - and had 50psi on the fuel rail when the key is turned on - it drops and then recovers as cranking - it did drop to zero once and immediately recovered (within 1 second) which is really odd to me - PEM, maybe? I pulled it off and looked it over (did not open it up) Connection had a little bit of fine sand in it when I took it off, but everything was clean and the wire connections looked good. Is there some test bench info on this in case it could be it???

Pulled the airbox and when cranking it over, I had only minimal movement in the MAP. THIS CONCERNS ME. I should have enough air volume to allow the cylinders to fire, granted, not the Hoover these things are when running, but SOMETHING. I had to actually use a tissue paper to see some movement, as I wasn't sure I was feeling it with my hand. Barely there. Tailpipe, there is enough you can feel it moving, but only barely, again, not expecting same as when running, but more than intake??? Now I am concerned about an air leak on intake side.

Pulled the top cover and cam cover. Checked cam gears and (BIG SIGH) the cam alignment points and the crank shaft alignment point all line up. No jumping of cams.... that said, when I was feeling everything over, the exhaust cam felt slightly loose like it could have had a bit of wobble... don't know if that was a function of the vvt, or if it was just my imagination, as I checked it again after rotating the engine a bunch, and no wobble or movement.

I pulled the coils and plugs - plugs are a bit grungy for only 30k on them, I've seen a lot worse not work - but I am definitely on the path for new coils and new plugs just because.

Ran compression test. This is inconclusive as I am not certain that my tester is seating down tightly to get a good reading (last time we used a friends unit which was an extended reach "push in" type, where mine is a double step threaded with o-ring type that has a very shallow smaller dia before the step... not sure it's long enough to reach in tight enough to seal correctly. My readings prove that out - I got a very consistent reading... but only 24-26psi compression - no where near what I've had before. SO, I am going to the store today to see about a longer reach tester to see if that answers the question - engine or tool. If it's tool, great - if it's engine - now I am perplexed as to the suddenness and consistency of the failure. Remembering that I ran a 14.5 "street" (deserted country back road, and not racing anything except the clock) quarter with it as recently as 4 weeks (less than 100 miles) ago. It wasn't pulling weakly at all (not great, but not weak) . Doesn't make sense, except if I'm missing something.

Which leads back to the coil question as to how they could be root cause - and why I don't hold a lot of confidence in that thought - it was an immediate shutdown situation, no misfires, no nothing - just a serious drop in power, and then shut down. And they've been running ok up until this.



FOR THE tl:dr crowd, checked a bunch of stuff, have a couple of question marks, but overall nothing that really makes much sense. Battery, Fuel module(?), or IDK what else...
 

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2 coils are back to original, 3 are 2 years old.
Wiring harness is solid (or was last fall the last time I had the coil cover off) the only problem was 1 broken retaining clip on 1 coil plug, which I used a zip tie to go around to hold it in place until I can find a harness or part number for the plug replacement. Low priority on the plug.
The coils/plugs however, I think should be checked / replaced just to get everything back where I'm comfortable with it.
I will be checking that over as I pull that off to do a compression test.
Thanks!

https://www.autoguysland.com/best-pex-crimp-tool/
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Hello!

I had a somewhat similar situation once.
It would oncasionally crank and would not start. But very sporadically.
There would be no releveant codes.
It ended up to be a loose fuel pump connector.

Not saying this is your case, but it's worth mentioning.
 

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Discussion Starter · #8 · (Edited)
Thanks for the thought on that! I really was questioning this as well, since I was moving those wires around and had that cover off when I was doing the 4C delete. That said, I checked it, and that is all tight.

I pulled the PEM apart today and an amazing amount of crud came out - determined that it was sacrificial corrosion off the aluminum heat sink. Unit is actually working properly (or is now that I blew it out with Electro-Motive cleaner)

I ran compression with new unit - still at 25psi - very even - weird but....

I have codes still in the ECM over intake and exhaust cam readings - which would drive the lack of running and also not allowing it to build good compression

So codes I have are Intake Cam Sensor, Exhaust Cam Sensor, ECM-91C7 (Throttle Valve, Faulty Signal) I am still not discounting that it may just be the battery - but all of this was with the R connected via GOOD jumper cables to the Subaru that was left running. So, MAYBE still a ground wire issue - even though I've been over them at least 4 times, and all are clean, tight and in good condition.

Down to the ECM or I'm missing a plug somewhere or another ground. I did note that the ECM was very warm when I felt it after doing the tests this afternoon... the other option would be a bad ECM, but I question that.

Thanks again (and in advance) for any thoughts of stuff to check.

Added a couple of pix. White on the tire is the crud out of the unit.
 

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Discussion Starter · #9 ·
Spent a further day plus in the shop (thank goodness for airconditioned shop in Kansas in the Summer!)

Replaced Battery - it was iffy but at 5 years on an R - I'm ok with replacement.
Compression is still at only 25psi on each of all 5 cylinders.
Timing alignment marks are exactly where they are supposed to be.

I am back to the 3 codes I consider relevant -
ECM-3000 Intake Cam Sensor signal missing
ECM-3010 Exhaust Cam Sensor Signal Missing
ECM-91C7 (Throttle Valve, Faulty Signal)

I got an ECM puller tool, removed it, and took measurements down the relevant wires - everything tested out ok on the wiring end - no shorts, approx 950 ohms resistance on each sensor (within a couple of ohms on each) and the throttle valve wiring also tested ok.

When looking at each of them in VIDA - they all communicated but I keep having an ECM not ready state.

Any other thoughts before I send the ECM off for a replacement? I'm at a loss at where else it could even be at this point - and as always, willing to listen to suggestions.
 

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Discussion Starter · #10 ·
I got asked a few questions so I'll throw this all out there for consumption/suggestions:

the low compression appears to be caused by fuel in the oil (apparently something triggered the fuel to dump) I have almost a pint over full in the oil. Good for cleaning out gunk in a 67 GMC, but not so good on a motor that really is pretty clean inside. Oil Change immediately. (and to think I thought it wasn't getting fuel at all...)

Timing marks are spot on. I was asked if that could have been a problem, so I verified by stripping it all down and checking - cam marks were good and still are - but pulled the bottom out, even took the serp belt off to get enough visual in there to spot the teeny tiny mark on the engine - and it is aligned up. So that isn't it.
 

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Discussion Starter · #11 · (Edited)
Went through a lot of other checks - ended up sending the ECU off to Xemodex after a bunch of back and forth and some questioning they threw at me - it tested OK on their bench, but I went ahead and got it replaced - got the new one back - and... same codes.

I did fix the coils with new Bosch coils - no longer have those codes.

So, doing some other reading, I am back to my original question that I said off the seat of my pants - and watching some other videos and asking other technicians... if I had a high vacuum on crank I would look to the intake side, but with no vacuum at all and still having a very low compression - I'm thinking extreme exhaust blockage is a possible issure.

From the old days with naturally aspirated cars - a blocked intake side would cause low compression with very high vacuum during compression test. A blocked exhaust side would cause low compression with a zero vacuum during compression test. Hence I am now back to looking at it.

I will say, I tried to spin the turbo by blowing air through the intake side, and I get air moving through it, but I don't hear it spooling at all, and get a weird sound out of it - could be that the turbo itself grenaded and is blocking the exhaust - or it could be that there is so much backpressure from the cat that it can't move any air through...

Thoughts on my thinking on it? Anything else I could be missing?
 

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The car will not start with these codes:
"ECM-3000 Intake Cam Sensor signal missing
ECM-3010 Exhaust Cam Sensor Signal Missing"

Clear and see if they reappear?
 

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Discussion Starter · #13 ·
Cleared, but still has the odd starting sound - still had the compression at 25-26 psi on all 5 cylinders. Out of sheer frustration, I dropped the cat off and sure enough it definitely has something loose inside at the front end. I can blow air through it now, but how much and how long? Unknown. With all restrictions off the turbo, it spins freely - so another point towards a blockage in the exhaust side of the turbo - but I squirted about 6-8 squirts of oil down the cylinders, and will compression test them again tomorrow night when I get off work, because the only other component that is on the same ground as those cam sensors is the intake throttle body - and it could ? cause an issue - so I want to check my compression again with everything else off and with special attention to it.

After that, it's into the motor to see why the compression is suddenly so low.
 

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have you checked your timing marks? The fact that your low on all cylinders seems like it might be something timing related.
 

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Sounds like you're approaching this from a "young mechanic" kinda angle. Did you verify spark? Lack of spark would explain the fuel in your oil --- lots of cranking with injectors firing will spit gas in your cylinders, then leak down into the crankcase. Not sure if that's the way this system works, but i sure as heck seems plausible.
As for compression, the gauge is essentially a one way valve on a tire gauge. It measures how much pressure your sealed cylinder can make. I think 91shelby is on to something. Maybe you're valves are opening/closing at the wrong time, thus not generating significant compression. Time to check your timing marks.
Do you have any blown fuses???
 

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Discussion Starter · #16 ·
"Young mechanic" - bless your heart! I'm only 54, and grew up in a mechanics shop, had as many as 4 ASE certs (including the old school driveability - now broken into 2 or 3 different ones - others were suspension, brakes, and paint)
More like old and set and wtf am I missing?

Spark, verified off car with ground wire to coil method. Replaced coils anyway. Plugs show the 20k since replacement.

Timing marks have been verified 4 times. Keep going back to that, as it's a logical jumping off point.

Gas in oil was suspected because of 2 things - always on 'noid light on injector and also 6-8oz over full on crankcase. I really suspect any washdown is just supplemental to the root cause. It was making odd compression noise from the time it died.

No fuses blown. All relays test good.

Right now, with what codes are set and how it was going, I plan to check compression with only the turbo (exhaust is off, and cat had lot of rattle in it, but the substrate looks ok at the outlet side) and the intake throttle plate in place.

I can't get everything to clear properly, ecm will not test ready. My concern is that the ecm swap from xemodex may be a bad ecm (junkyard)

Really not used to being stumped like this.

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Didnt catch it in all the writing...Have ya pulled the cam sensor housings off and checked the trigger wheels? IF it won't start and you keep on trying to crank it fuel will wash the cylinders down and create a low compression issue. Tablespoon of oil in each cylinder will restore this if thats the case. Be sure to change oil once you get it figured out.

Secondly, have someone else turn the engine over and listen for where that noise is coming from. IF its in the starter flywheel area, pull the crank sensor our and check it for metal shavings. Crank sensor is magnetic and picks up its signal from the flexplate/Flywheel. It's not uncommon to have a a starter/flywheel problem and create metal shavings that end up on the crank sensor. Does the tach jump around when you try to start the engine?

Also..and we've seen this too - When turning the engine over, if the starter is failing and drawing too much current it will cause a very hard to start issue as it interferes with the ignition signal. The tach signal jumping around is another indicator of this.

**Can you graph the Cam sensors and Crank sensor wave form via vida under cranking speed?
 

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Sorry, didn't mean to insult.

Something to noodle on... Just for giggles, ya might consider taking the gauge off of your compression tester and rotating the motor to TDC, then squirt some compressed air into the cylinder through the compression tester hose. AKA, a poor man's leak down test w/o gauge. Maybe start from making sure your cylinders are actually sealing, then if not listen for where you hear compressed air going. Just a thought for a starting point... Obviously not the end all solution..
 

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Discussion Starter · #19 ·
No insults taken - really been very frustrated.

So updates... did an oil change just to make sure I had not washed down cylinders (a definite possibililty - and as was beaten in to me at an early age - oil is cheap, an engine isn't...) Put about a dozen squirts down each hole and disabled fuel pump - cranked it again (oh, btw, dc clamp ampmeter shows it's pulling about 35-40 amps with no compression load on it, so within reason on the starter loading, good thought on that, though!) and checked compression - still 25-26psi... so - thought about a few other issues that could drive it - one of the other codes was throttle body - if it were totally slammed shut, that may not allow enough air in. If the exhaust were plugged (bad converter) it wouldn't allow enough air to move out - so I dropped the exhaust and used a pair of needle nose vise grips to hold open the throttle plate - a lot of work involved to find out that no, still 25-26... very even, very consistent.

So, checked yet again on the timing marks - all marks are on time... got a cam locking set - locked down the cams - and yes, they are within spec on top. Crank gear is centered on the timing mark on the oil pump... so I got to thinking what could have moved? Belt showed no damage, no signs of it jumping... just 20-30k of wear from when I'd replaced it last.

I went further back into the basics (and I will upload videos so you all can see I'm not hallucinating on this) - put my 12" long 3/8" extension down the tube of number 1 cylinder (plug out, of course) and with the cams locked, and the timing belt off, started rotating the crank by hand - it was dropped off and falling away... rotated it back 20 degrees before I got the piston up on top dead center... the timing marks are way and the heck away from the crank mark point, but it's centered... put the timing belt back on - cranked it over, the car sounds like it should, and I am getting 135#+/- on each cylinder now... which I think is acceptable for a 250k motor... (what do you all think?)

I started putting everything back together on it, but don't have it all together to fire it yet, but will have later this week - so hopefully she'll start and I can be back on the road...

My thoughts on root cause on this - timing belt gear on the crank was installed incorrectly at factory when new - and the first time I did the timing belt (at 110k) I had the cams locked up tight on the cams themselves - I used my Lisle cam lock that goes between the gears, not the back of the engine cam locks) this last time I did, but I honestly thought then I had a cam gear rotate on me, but I checked it for marks, it all lined up, and (obviously) the car ran for 20-30k with the gears as set... but finally, it got far enough out of spec that it gave up trying to soak up that difference between the crank position and the cam position, and said, "Eff it, I'm out..." and threw codes and caused everything to drop off. This is a guess, but it seems the only likely thing to make what happened happen.

Again, I've got video of this last bit and i'll probably end up sticking it up in the next little while on Youtube to show my shame/frustration on this one... but has anyone else ever run into a crank gear misinstalled from factory?
 

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did you check the back of the cams (drivers side of the engine) and lock them that way? Could be an issue with the VVT solenoids or hubs as well since you are getting some compression.
 
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