Post 120K Engine Failure

rubydist

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That is not the noise of a too-tight timing belt.
That is the noise of a significant vacuum leak. You will need to chase that down to make things work. I am not liking the look of the clamps you have on the new silicone hoses connecting the outer and inner intake manifold. I suspect that type of clamp will result in leaks due to misalignment between the 2 aluminum parts that the hoses connect to.
 

myotis1134

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3425BDEE D444 4ECD 8814 431D80A18BBE Sprayed down this area with carb cleaner, and the whine hiccuped then disappeared until the engine died. It was back when I started it up again, so I’m thinking it’s gotta be a gasket leak at the heads.

Just picked up a lot of beer, so I’m gonna drain coolant and pull the intake to evaluate the gaskets and mating surfaces.
 

myotis1134

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@rubydist - those couplings and clamps have been on the vehicle for the past 10 years. I had a chance to see how well they seal when I cleaned up the intake, and they appear to squish down into the gaps very well.

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This is before I cleaned them up, but you can see that protrusion in the center where they are sealing.

However, I agree that there is way less flex between the two parts with this setup.
 

zoomlater

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Try some starting fluid that mist when you spray it and see if and where it affect the idle. The second video of the idle sounded much better than the first video. You can adjust the timing belt tensioner without taking the front apart. There is a little door on timing cover that you can access the tensioner.

When I had the 60K done on my 92 (its silver as well), I had a belt whine that I thought the belt was tensioned too much. I had Mike at Shosource look at it and recheck the tension through that little door. It ended up being the type of belt (Gates) had a whine for about 1000 miles or so. You car has a much higher pitch whine.
 

myotis1134

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Do you think that my forgetting to torque this last bolt on the intake could cause a leak that would whine like in the video?

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I’m so f*****g glad I got beer now...
 

luigisho

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Maybe. Did you fire it back up? Those multilayer steel gaskets are incredibly reusable. Especially with a little tack spray.
 

myotis1134

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I’m not a *******! Or at least in this case...

Went ahead and pulled the intake - just to cover my ass, and the intake bolt that I forgot to torque appears to have stripped the threads in the pocket.

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Luckily, I still have the EZ-Lok thread repair kit from the valve cover job, so... here I go.
 

myotis1134

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I’m scared to do this free-hand, so I’m currently attempting to build a jig.

CB857A93 9318 4DDF 9A05 69D2FDCBB5A6

Trace of intake ****** gave me basic dimensions. Used studs in the head for more specific measurements.

Image

Did the math, and came up with this design, but it felt too flimsy.

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So I drank a few beers, gave it some thought and ended up with this.

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If I wasn’t in a hurry I’d cad it out and have someone in town 3D print it. As I am in a hurry, it’s going to be wood - which sucks, but should still be slightly more accurate than trying to eyeball everything.
 

myotis1134

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Intake manifold thread is repaired, and I got 17 lb/ft at all 12 bolts.

Engine is re-assembled, and now I'm back in the same boat minus the intake leak - the engine starts, runs for a few seconds then dies. If I give it gas it shudders then bogs down and dies when I let off the gas.

I'll get a video of the engine behavior tomorrow. I'm a little too fed up with all of this to do it tonight.
 

myotis1134

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Post intake manifold leak idle video HERE

Afterwards I pulled these codes:

123 - Throttle position sensor voltage above maximum voltage.

542 - Fuel pump secondary circuit fault.

I'm going to pull the new TPS and stick the old one back on - just to see what happens.
I'm going to have to research the 542 code to see how to investigate it.

p.s. I'm reading on another post that code 542 pops up every time the car dies without being turned off. This leaves the TPS code, and I'm wondering now - when installing the sensor, does it just butt right up and get fastened, or does it need to be rotated 90 degrees when mated with the throttle body tab - then rotated back to line up with the fastener holes?
 
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myotis1134

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The idle issue appears to have been the new TPS. Slapped the old on back on and the engine is not dying, but actually sounds ok.

VID

Tentatively think I'm done here. Thank you guys for all the help.
 

myotis1134

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Well it was a nice thought... Still idling rough, and I understand it should smooth itself out eventually, but it’s spitting out what seems like a lot of fluid from the exhaust.

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Should I be idling the car to see if this fluid and the idle clear up?
 

rubydist

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542 is a meaningless code on these cars and should just be ignored. It gets set any time the engine stalls.

The crap out the exhaust could be unimportant if its been idling a lot and running badly and just washing some of the carbon off the inside of the exhaust system. Or it could be a sign that something serious is wrong. You will need to do a little more investigation - see if a 10 minute drive eliminates it or makes it worse.
 

myotis1134

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Just checked fuel pressure.

1st - Initial prime 0 psi - without clearing second prime pushed it up to 10 psi.

(after the first reading of 10 psi, I zeroed the gauge after each measurement)

2nd - 18 psi

3rd - 26 psi

4th - 26 psi

5th - 27 psi

6th - 28 psi

According to the '89 SHO engine book, the standard prime pressure range should be 31-41 psi. Not counting the pre-primed gauge readings (0 & 10), I'm seeing an average pressure of 25 psi which is considerably lower than the manual's lower range number of 31 psi.

If I've suddenly developed a faulty fuel pump or clogged line/filter, could it be causing the current symptoms of rough idle and stalling? Could a bad pressure regulator cause these numbers?

- @rubydist - At this point the vehicle won't stay running long enough for me to drive it. Should I go ahead and attempt to keep it running as long as possible to see if any of this crap resolves itself?
 

myotis1134

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It just occurred to me that I replaced the standard injectors with the 48 lb ones from sho source.

Before ordering them, I searched to see if any supporting components like a different pressure regulator were required, but didn't find anything that suggested it. The sho source website talks about the accel 48 pounders as if they're a drop-in replacement. Could these larger injectors be degrading my rail pressure when the engine is running?
 

luigisho

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Aren't normal injectors around 24#? I'm not sure they are plug and play. 48# in a v6 is for over 400hp. You still have the original injectors?
 
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rubydist

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Wait - you replaced the standard injectors with 48# injectors but did not do any tune? It will never run right. No wonder there is all that soot in the exhaust. You need the correct injectors in there.
 

myotis1134

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OK guys, you were right. I swapped out the 48# with some 26#, and now it runs. I had some high engine temps when I took it out for a test, but I'm dealing with that now.

What I'm observing that's bugging me is a whine from the belt area, and I can't really tell if it's the water pump getting starved because all the air isn't out of the coolant system yet, a pulley, or the timing belt.

I'll continue to work out the air bubbles and add coolant, but I don't think there can be much more capacity in there at this point. A best guess would help me out a lot.

Engine whine vid HERE.
 
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