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l28et s30 swap bad sputtering


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Since I sort of piggy-backed on 240z7273's thread, just wanted to follow up and found my issue was caused by loose pins in the ECM connection -- have gone through all the pins and fixed as needed and solved my issues. Even though we had similar symptoms, dont know that we had the same problem.

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No we dident have the same problem. I went over the ecu connections many times..i will never know what my issue was. The car was sold and motor was tore out. Aparrently the motor blew shortly after i sold it. One problem was too much aftermarket stuff on stock ecu. I will never buy a bad running swap again thinking well shoot i can fix that haha.

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  • 4 months later...

This is most likely not the cause but worth a shot, I have a L28ET as well and was having real bad sputtering that progressed to the point where it would die. After looking all over I found that the gasket that is under the spring in the pop off valve had shifted enough to make it remain open all the time. This threw off the AFR so much the car ran horribly. Simply put it back in place and the car ran great.

 

I cannot for the life of me find any info on the location of the pop off valve. Where is it? Im having a similar problem. car wont even start and if it does it will run absolutely terribly at 500 rpm and 10 in vacuum

 
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The "Emergency Relief Valve" on the stock intake manifold is on TOP just aft of the A.A.C..  (that drawing above does NOT show stock components in their actual location!  It's a representation of the ECCS system and it's component parts laid out so you can easily see function)

 

You can't miss the "pop-off", it's sorta big and round - looks like it has a lid on top (well, it does have a lid on top...).  If you keep going aft, there's the vacuum fitting for the brake booster and then the EGR...  It's built to relieve pressure over ~9 pounds or so.  So if your wastegate gets stuck or there's some sort of failure that would cause excessive boost, it opens and let's the air out...  Under normal operation, this will never happen.  If you put a manual boost controller on your turbo, set it to 10 pounds and stick your foot in it, you'll eventually hear the "pop", and rattling wheeze of the emergency relief valve.  This safety valve is in addition to the internal "blow off valve" (not actually called that by Nissan) built into the manifold.

 

You can remove and test it - it just unscrews.  Note the large HEX pattern near the bottom of the device.  It you're unsure, go to Home Depot, buy a 1" black (galvanized, brass) pipe plug and screw it in the emergency relief valve hole (teflon tape or a little paste on the threads of the plug - NOT on the threads of the hole (female threads) - please don't drop / get anything down IN the manifold...).

 

In the '82 FSM, EF & EC-74 show the operation of the E.R.V.  but I couldn't find a drawing that shows it's position on the manifold clearly.

Edited by cgsheen
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In that case, mines been removed and blocked off, so im wondering what i heard a couple months back when i spiked at 12 psi and heard a screeching/pop noise.

 

Cant for the life of me figure out this no start problem...

 

Barely starts if at all. Usually just cranks. If it starts itll barely idle at 500 rpm,  and 10"  vacuum. Misses terribly.  Grounding plugs one at a time on the strut tower they get spark.  Theyre getting soaked w fuel.  Compression is solid all cyls.  

 

Seems like a huge vac leak.  The only thing i swapped out were afms, swpped back.  Thought i destroyed the crank angle sensor so i jus wired up my optical cas in the dist today and it didnt change.

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  • 2 weeks later...

You guys are mistaking SCHEMATIC DIAGRAMS meant to convey functional understanding of a system to DRAWINGS OR PHOTOS which actually show the location of the actual components. If you look in the Turbo Supplement for an 81, or the ECCS COMPONENT LOCATION DRAWING at the front of the ECCS System Section of the FSM, you will see the components circled and arrows showing EXACTLY where the things are on the actual ENGINE.

 

One thing you learn early on with schematics in electrical circuits: wiring diagrams may bear no resemblance to what you see on a schematic, but it works just the way the schematic says it will.

 

Same for the mechanical components.

 

It's likely the screech and pop you heard was a surge event in the turbo.

Edited by Tony D
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Nissan forgot to put the relief valve in the Component Parts drawing, or didn't think it belonged (they left the PCV valve out also), so the schematics were the next best place to look.  Good engineering practice is to make any illustration as descriptive as possible.  The drawing is misleading and could be improved.  At least they showed it's general shape on EF-30.

post-8864-0-20125800-1360947380_thumb.jpg

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The PCV is clearly defined elsewhere, and if you take a look again: there it is, emergency relief valve, the only COMPONENT not clearly identified! By looking at the other drawings defining the Emergency Blow Off Valve, you can easily see the same outline right there on the manifold, at the rear in front of the EGR, behind the A.A.C. Valve...

 

To be fair it's a turbocharger safety component and shouldn't be on that List. The blow off valve is not really well defined either, but it's got one.

 

But for a reference point for a guy who has no clue what he's looking at...EF30 CLEARLY shows the Emergency Relief Valve and it could have been circled with FAR better recognition than the prior examples (which were SCHEMATIC in function, not diagrammatic!)

 

Had it been circled on EF30 (or the ECCS and EFI versions compared "what looks different between these two drawing's un identified components?") I think location confusion would have been over after that post.

 

No?

Edited by Tony D
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