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Mystery Leak? Lean condition


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#81 wstefan20

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Posted 16 February 2018 - 12:42 AM

Right; I know it was tuned to have the rear o2 removed...I was there lol. The trick is null in void whenever the converter diagnostics still run and need to read the sensor. You spacing it is still preventing it from reading the sensor, fully. It'll show passed with your scantool because it's set to not report. That's why Brian said you needed the rear o2 back in it without modification ;) Also; with the coolant leak, I'm half temped to think that either the elbows are leaking only under pressure/load, or the coolant port you opened up under the throttle body is opened too much and the plate isn't sealing around it 100%. Just my thought.

Lol ok, so you're saying that I want to set the trouble code?? If the test is passing, doesn't that mean everything's running correct? Idk. You're probably going to have to enlighten me on a kindergarten level as I'm pretty unfamiliar in this aspect. Yeah. I did find some seepage around the coolant port on the side, but put some rtv and there's no new seepage even under load. I think I'm going to have to get an inspection camera since I can't see the rear elbow under load. It passed the coolant pressure test oddly at 15psi.

#82 wstefan20

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Posted 16 February 2018 - 04:44 AM

Well, on a side note, I did a compression test and I'm pretty stoked with the results. Now, to preface, I used a cheap harbor freight compression tester and I had to remove the o-ring just to get enough threads to even hold. There were only two maybe three threads that actually threaded, so the numbers are lower than they would be with a decent tester. That being said, they all tested within two or three psi of each other and were around 120psi. 

 

Spark plugs were all still gapped correctly and looked like new. Tested for spark and all is good. For sh*ts and giggles, I just bought a fuel injector tester pulse tester, so we'll see how that goes. 

 

One thought I have. My fuel pressure regulator came with a screw in the top and the stock one didn't. I had to install the screw as it had come out and I'm wondering if it might have something to do with the fuel pressure? Everyone is saying the fuel pressure should be around 50psi jumping to 60psi with vacuum removed. Mine is 62psi and jumps to 70psi. That seems really high to me. Here's a picture of the regulator:

 

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#83 wstefan20

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Posted 16 February 2018 - 06:08 AM

Not sure if this is also a potential issue, but I noticed that it seems the fuel pressure drops off kind of fast with the key removed. I thought maybe leaking fuel injector so I pulled the rail and tested with the rail out, and absolutely no leakage at the rail. No leak under car, and no gas smell. Strange... See what you guys think:  



#84 55trucker

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Posted 16 February 2018 - 01:01 PM

Hmmmmmm.....pinch off the return line to the fuel tank & do your test again......


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#85 wstefan20

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Posted 16 February 2018 - 02:28 PM

Hmmmmmm.....pinch off the return line to the fuel tank & do your test again......

That's what I was thinking, but won't pinching the plastic lines break them? Can't see a way to isolate the fuel system. Maybe removing the fuel line and "capping" it temporarily? Would that hurt anything?

#86 wstefan20

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Posted 16 February 2018 - 04:15 PM

Well, blue, you were right about the leak. It's very very slow, but it's leaking out the bottom of the side coolant cover. Strange thing is that I checked both surfaces with a machinist's straight edge before installing the cover. I even used the felpro improved gasket and cleaned the surfaces with acetone. At this point I'm contemplating going with copper rtv and then using jb weld all over the outside. Any other suggestions on this? Really not looking forward to draining the coolant again....



#87 wstefan20

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Posted 17 February 2018 - 04:16 AM

Well, the plot thickens... turns out I have a vacuum leak again! lol didn't think that could happen with negative fuel trims.... anyways, figured I'd post a really quick video of me doing the smoke test and where it's leaking from. I'll definitely be going with a new throttle body. This one is just too warped. Definitely just using rtv and no gasket this time though. 

 

Good news is I used the same method on my exhaust and there are no leaks! (finally)

 

Still have to take out the o2 spacer. Still not sure how that works, but maybe it'll help. Looks like I have my weekend cut out for me...

 

 



#88 bluegtp91

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Posted 17 February 2018 - 02:39 PM

Like I said; because in the 01+ cars, it does have to read the rear o2 throughout the converter diagnostic parameters when the car fires up.  If half the sensor is blocked via the fouler it's skewing your pre-closed loop trims.

 

It's pretty basic. 


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2004 Chevrolet Corvette MRM A4 - AFE S2 Intake/TSP Catless LT's/3" ORX/C6 ZR1 Wheels/Exhaust Tips
2012 Buick Regal T - Intake/HID's/Tint
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#89 wstefan20

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Posted 17 February 2018 - 02:41 PM

Like I said; because in the 01+ cars, it does have to read the rear o2 throughout the converter diagnostic parameters when the car fires up. If half the sensor is blocked via the fouler it's skewing your pre-closed loop trims. It's pretty basic.

Lol thanks again blue. Definitely didn't quite understand that at first. I'll give it a shot and see what the trims look like!

#90 bluegtp91

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Posted 17 February 2018 - 02:47 PM

Lol thanks again blue. Definitely didn't quite understand that at first. I'll give it a shot and see what the trims look like!

 

Wouldn't even worry about it until the TB leak is fixed.  Along with the coolant leak.  I'd be more worried about those than the o2; honestly.


  • wstefan20 likes this
1999 Chevrolet Silverado K1500 Classic Z71 - Intake/Gibson Exhaust/HID's/Tint  
2004 Chevrolet Corvette MRM A4 - AFE S2 Intake/TSP Catless LT's/3" ORX/C6 ZR1 Wheels/Exhaust Tips
2012 Buick Regal T - Intake/HID's/Tint
Previous W-Body's: '98 SM GT Coupe, '98 TDGM GTP Coupe, '03 BBM GTP Sedan, '05 DCM GXP
 

#91 wstefan20

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Posted 19 February 2018 - 12:47 AM

Well, gasket didn't seal, but just straight rtv sealed fine. Was still concerned about the fuel pressure, so I grabbed one from the junkyard. Fuel pressure dropped to 48 key on engine off and 57 with regulator vacuum removed on idle. Now fuel trims are perfect. Fml. Just say no to any other sensors than acdelco.




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