Im well-tooled & knowledgeable enough to deal with LOTS of different events but magic shouldn't
09-04-2008, 08:30 AM
#1
AudiWorld Super User
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Im well-tooled & knowledgeable enough to deal with LOTS of different events but magic shouldn't
be counted among them. And "magic" is certainly the culprit I'm dealing with related to my latest intake manifold installation.
First a little background:
After porting/polishing and CCing 2 identically perpared IMs during the IM workshop I installed one on the engine and have driven it every day since without issue. Got it right the first time and never looked back. End of story on IM #1.
Last Thursday I decide to CC my cylinder head intake runners. I also decide to use IM #2 when I bolt it all back together. It's a long weekend and I have no plans so it's a good time to do this before winter sets in. After CCing I pull IM #2 off the shelf where it's been sitting for years. Before storing I had assembled IM #2 EXACTLY the same way I had done on IM #1. It got a new gasket and was torqued to spec, ie; 7ft lbs on all the 5mm upper/lower IM attaching screws. After assembly it was duct-taped to seal out spiders, critters and dust. All intake runner ports were duct taped as well as throttle body flange and brake booster vac inlet as well as rear vac nipple below the FPR. ISV flange was duct-taped as well as were EGR inlet and EGR threaded sensor port. Intake manifold was at that point totally sealed from ANYTHING getting into it.
On Saturday, 2 days after starting the project I pull IM #1 off the shelf and set about prepping it for intallation on the newly CC'd heads. That involved duct tape removal and cleaning any/all duct tape residue of all flanges and using brake cleaner and a clean rag prepping all gasket/mating flanges for installation. I also did a "once-over" on ALL manifold mounting bolts to make sure they were still at torque-spec tightness. Every one caused the torque wrench to hit it's "click release" before the screws would turn which they ALL did without a single exception. Then installion continued.
Fast-forward to Sunday:
Everything went together perfectly. Manifold to head screws were installed and torqued to spec. Engine bay was picked up of all tools and blown out with compressed air due to cylinder head grinding. Car is started and after a few seconds to re-prime the fuels lines starts right up. Runs/idles fine for 10 minutes or so then engine starts to shake and there's an intermittant miss. I figure it's fuel related and I need to crank up my FPR a little. That helps some but it's acting a like it's got an unmetered air leak... similar to a vac leak on steroids. In fact after taking the car out for a 60 mile test ride. Car runs fine, great in fact except at idle where it still presents a lopey/uneven idle that cause the entire car when stopped at a redlight to shake side-to-side. I get home and install the vacuum gauge... just as I expected, car is only holding 10InHg of vacuum when it should be 18 or so. Thats when I know I'm sucking unmetered air in from somewhere as idle is where highest vac readings are reached and once to 2000/2200 RPMs there's no longer much need for vacuum. But this makes it extremely hard to get away from a stop tho once at 2k it runs like a raped ape. This kinda crap makes me crazy!
So I spend ALL day Monday poring over the intake system with a fine tooth comb and nothing, nada, zero, zilch, bupkus. I cant hear any vac leak and I can find NOTHING that would cause or contribute to this. That's when I decide it's time to go to Champagne and "smoke" the intake system the next day (yesterday).
Get there and carry the smoke machine out to the parking lot. Neat thing about the machine is it's 12V (that's 12Volts) instead of 110AC. Hook it up to the rear vac stem after plugging my 3" silicone hose aft of the MAF with a PVC pipe cap to seal & charge the system and prevent the smoke from just taking the path of least resistance out the airbox inlet. Aha, first thing I see is smoke coming from the EGR/IM gasket. Tighten it down and no change. Hmmm that was a brand new gasket I put in there during reassembly with a high-temp aviation sealer. Weird! So I go into Champagne and pick up another. Install it with the same aviation sealer and this one seals the system right up (that's "magic" event #1). Inspect the removed gasket and it's visually perfect! No flaws whatsoever but it would not seal (this is REALLY weird).
Ok, back to smoking:
The EGR gasket is no longer leaking but now there's smoke pouring out of the rear IM upper half on its rear, where it mates to the IM lower half and just above the throttle body flange. Uhoh... this could be the warp I suspected. I go inside and borrow one of the tech's Snap-On digital torque wrench and throw it on the calibrator then go back outside and find the bolts across the rear to only be between 2.1 and 6ft lbs (7ft lbs is the spec). And I know what 7ft lbs feel like and my personal Snap-On torque wrench simply cannot be that far off. So I go around all the IM upper half bolts and they're all off by dramatic amounts ranging from almost 5ft lbs to .5 ft lbs. Now here's some more "magic"; ALL of the manifold intake flanges to cylinder head are perfectly torqued and holding their 15ft lb spec while ALL the upper/lower half manifold specs have somehow loosened. Hold on... it gets even weirder. So I dash home to get my torque wrench then drive back and throw it on the calibrator and it's only .1ft lb off from 5 ft lb to 32ft lb and .17ft lb off from 35ft lbs to 75ft lbs. Now how does that translate to an error of near 6ft lbs on a 7ft lb fastener yet retain perfect 15ft lbs on the 15ft lb fasteners with a torque wrench that was only .1ft lb off from 5ft lbs to 32ft lbs!?! That is simply "magic" no matter who ya talk to!
Car is 90% better now and holding 16InHg tho his morning I still have to take a traditional "L-shaped" allen wrench to the 4 IM front screws that hold the upper/lower manifold halves together and no way to get a torque wrench in there but I can get very close by hand... certainly closer than 6ft lbs off on a 7ft lb screw! Theses screws are installed from the underside upwards so no way to get a torque wrench in there. Once that's done I'll tweak my fuel pressure and hopefully find out what, if anything this week-long cluster-fu*k has netted me.
I've given up trying to understand the "why/how" in ANY of this and it totally escapes me. Sometimes ya just have to write things off as magic due to no other possible explanation.
First a little background:
After porting/polishing and CCing 2 identically perpared IMs during the IM workshop I installed one on the engine and have driven it every day since without issue. Got it right the first time and never looked back. End of story on IM #1.
Last Thursday I decide to CC my cylinder head intake runners. I also decide to use IM #2 when I bolt it all back together. It's a long weekend and I have no plans so it's a good time to do this before winter sets in. After CCing I pull IM #2 off the shelf where it's been sitting for years. Before storing I had assembled IM #2 EXACTLY the same way I had done on IM #1. It got a new gasket and was torqued to spec, ie; 7ft lbs on all the 5mm upper/lower IM attaching screws. After assembly it was duct-taped to seal out spiders, critters and dust. All intake runner ports were duct taped as well as throttle body flange and brake booster vac inlet as well as rear vac nipple below the FPR. ISV flange was duct-taped as well as were EGR inlet and EGR threaded sensor port. Intake manifold was at that point totally sealed from ANYTHING getting into it.
On Saturday, 2 days after starting the project I pull IM #1 off the shelf and set about prepping it for intallation on the newly CC'd heads. That involved duct tape removal and cleaning any/all duct tape residue of all flanges and using brake cleaner and a clean rag prepping all gasket/mating flanges for installation. I also did a "once-over" on ALL manifold mounting bolts to make sure they were still at torque-spec tightness. Every one caused the torque wrench to hit it's "click release" before the screws would turn which they ALL did without a single exception. Then installion continued.
Fast-forward to Sunday:
Everything went together perfectly. Manifold to head screws were installed and torqued to spec. Engine bay was picked up of all tools and blown out with compressed air due to cylinder head grinding. Car is started and after a few seconds to re-prime the fuels lines starts right up. Runs/idles fine for 10 minutes or so then engine starts to shake and there's an intermittant miss. I figure it's fuel related and I need to crank up my FPR a little. That helps some but it's acting a like it's got an unmetered air leak... similar to a vac leak on steroids. In fact after taking the car out for a 60 mile test ride. Car runs fine, great in fact except at idle where it still presents a lopey/uneven idle that cause the entire car when stopped at a redlight to shake side-to-side. I get home and install the vacuum gauge... just as I expected, car is only holding 10InHg of vacuum when it should be 18 or so. Thats when I know I'm sucking unmetered air in from somewhere as idle is where highest vac readings are reached and once to 2000/2200 RPMs there's no longer much need for vacuum. But this makes it extremely hard to get away from a stop tho once at 2k it runs like a raped ape. This kinda crap makes me crazy!
So I spend ALL day Monday poring over the intake system with a fine tooth comb and nothing, nada, zero, zilch, bupkus. I cant hear any vac leak and I can find NOTHING that would cause or contribute to this. That's when I decide it's time to go to Champagne and "smoke" the intake system the next day (yesterday).
Get there and carry the smoke machine out to the parking lot. Neat thing about the machine is it's 12V (that's 12Volts) instead of 110AC. Hook it up to the rear vac stem after plugging my 3" silicone hose aft of the MAF with a PVC pipe cap to seal & charge the system and prevent the smoke from just taking the path of least resistance out the airbox inlet. Aha, first thing I see is smoke coming from the EGR/IM gasket. Tighten it down and no change. Hmmm that was a brand new gasket I put in there during reassembly with a high-temp aviation sealer. Weird! So I go into Champagne and pick up another. Install it with the same aviation sealer and this one seals the system right up (that's "magic" event #1). Inspect the removed gasket and it's visually perfect! No flaws whatsoever but it would not seal (this is REALLY weird).
Ok, back to smoking:
The EGR gasket is no longer leaking but now there's smoke pouring out of the rear IM upper half on its rear, where it mates to the IM lower half and just above the throttle body flange. Uhoh... this could be the warp I suspected. I go inside and borrow one of the tech's Snap-On digital torque wrench and throw it on the calibrator then go back outside and find the bolts across the rear to only be between 2.1 and 6ft lbs (7ft lbs is the spec). And I know what 7ft lbs feel like and my personal Snap-On torque wrench simply cannot be that far off. So I go around all the IM upper half bolts and they're all off by dramatic amounts ranging from almost 5ft lbs to .5 ft lbs. Now here's some more "magic"; ALL of the manifold intake flanges to cylinder head are perfectly torqued and holding their 15ft lb spec while ALL the upper/lower half manifold specs have somehow loosened. Hold on... it gets even weirder. So I dash home to get my torque wrench then drive back and throw it on the calibrator and it's only .1ft lb off from 5 ft lb to 32ft lb and .17ft lb off from 35ft lbs to 75ft lbs. Now how does that translate to an error of near 6ft lbs on a 7ft lb fastener yet retain perfect 15ft lbs on the 15ft lb fasteners with a torque wrench that was only .1ft lb off from 5ft lbs to 32ft lbs!?! That is simply "magic" no matter who ya talk to!
Car is 90% better now and holding 16InHg tho his morning I still have to take a traditional "L-shaped" allen wrench to the 4 IM front screws that hold the upper/lower manifold halves together and no way to get a torque wrench in there but I can get very close by hand... certainly closer than 6ft lbs off on a 7ft lb screw! Theses screws are installed from the underside upwards so no way to get a torque wrench in there. Once that's done I'll tweak my fuel pressure and hopefully find out what, if anything this week-long cluster-fu*k has netted me.
I've given up trying to understand the "why/how" in ANY of this and it totally escapes me. Sometimes ya just have to write things off as magic due to no other possible explanation.
09-04-2008, 04:34 PM
#4
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fun fun fun....i got to play with 30yr old Techumsa Snowblower engines today....
i get $100 for each i get running (3 total, got one today)...lets just say i got sabotaged for 3 hours on a hole just barely the width of a staple that was clogged with junk. Ohh and yes old gas does smell like strawberries... strawberries that make you wanna toss your cookies
09-05-2008, 05:15 AM
#5
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sounds like fun :-X
possible thermodynamics to blame? lil heating/cooling tossing things all screwy?
That wouldn't explain why only half the bolts loosened though... so you might want a witchdoctor to go over the car once or twice before proceeding :-P
That wouldn't explain why only half the bolts loosened though... so you might want a witchdoctor to go over the car once or twice before proceeding :-P
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