Radix Vaccum leak... still
03-02-2006, 08:36 PM
#1
Radix Vaccum leak... still
Okay, here's the story. Installed the radix back in last april or may.. Once I picked up EFI Live, I noticed a large difference in Trims but only in very low load situations. Bank 2 having 10-12% higher trim than Bank 1 in some cells. 
Pulled the unit off, check gaskets, re-installed. Same deal.
Installed Wideband and AutoTuned it, got VE nailed down (2 bar map), and had it running well in SD. Re-enabled the MAF to get that back, and all of a sudden running very lean at very low load again (decelerating), but only on the bank 2. As lean as 18.5:1. Leads me to believe that under low load, air is leaking in post-MAF, causing the reading to be off, and thus the PCM's fuel calculation.
Replaced vaccum lines, replaced throttle body gasket, and pulled the unit off AGAIN to check the gaskets and mounting surface. Remounted it, same thing.
Any thoughts??
Pulled the unit off, check gaskets, re-installed. Same deal.
Installed Wideband and AutoTuned it, got VE nailed down (2 bar map), and had it running well in SD. Re-enabled the MAF to get that back, and all of a sudden running very lean at very low load again (decelerating), but only on the bank 2. As lean as 18.5:1. Leads me to believe that under low load, air is leaking in post-MAF, causing the reading to be off, and thus the PCM's fuel calculation.
Replaced vaccum lines, replaced throttle body gasket, and pulled the unit off AGAIN to check the gaskets and mounting surface. Remounted it, same thing.
Any thoughts??
03-02-2006, 08:52 PM
#2
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Do you have headers? If so might want to check the gasket for leaks or see if they have any cracks. Heck, even if you have the stock manifolds still you might want to check them. They are post MAF, pre 02 and can cause a lean condition if there is a leak around them.
Also, check the exhaust pipe around your o2 sensor. A crack or gap close around it(on either side) could be getting fresh air to the sensor and causing the lean condition.
Also, check the exhaust pipe around your o2 sensor. A crack or gap close around it(on either side) could be getting fresh air to the sensor and causing the lean condition.
03-02-2006, 09:37 PM
#3
Originally Posted by XLR8NSS
Do you have headers? If so might want to check the gasket for leaks or see if they have any cracks. Heck, even if you have the stock manifolds still you might want to check them. They are post MAF, pre 02 and can cause a lean condition if there is a leak around them.
Also, check the exhaust pipe around your o2 sensor. A crack or gap close around it(on either side) could be getting fresh air to the sensor and causing the lean condition.
Also, check the exhaust pipe around your o2 sensor. A crack or gap close around it(on either side) could be getting fresh air to the sensor and causing the lean condition.
I'll try driving it again tomorrow with a closed loop speed density tune (something I haven't done!) and see if the difference is as noticable.
03-02-2006, 10:50 PM
#4
Hmmm... You know, I had some of the same symptoms before my last round of changes. At low throttle, my Ltrims would climb pretty high. I always had one side O2 that would read much higher than the other, maybe +10 higher. I thought it was possibly the placement of the O2 in the header collector because it would typically come back in line when under any load. When I buttoned everything back up last week, I swapped O2 sensors to see if the lean offset followed it. Guess what - my Ltrims are now equal again. So I think it was probably a leak somewhere that I fixed when I had everything apart.
Check your injectors. When taking mine out, I noticed on had a crimped O-ring which could have been a leak.
Check your injectors. When taking mine out, I noticed on had a crimped O-ring which could have been a leak.
03-02-2006, 11:03 PM
#5
Originally Posted by BigTex
Hmmm... You know, I had some of the same symptoms before my last round of changes. At low throttle, my Ltrims would climb pretty high. I always had one side O2 that would read much higher than the other, maybe +10 higher. I thought it was possibly the placement of the O2 in the header collector because it would typically come back in line when under any load. When I buttoned everything back up last week, I swapped O2 sensors to see if the lean offset followed it. Guess what - my Ltrims are now equal again. So I think it was probably a leak somewhere that I fixed when I had everything apart.
Check your injectors. When taking mine out, I noticed on had a crimped O-ring which could have been a leak.
Check your injectors. When taking mine out, I noticed on had a crimped O-ring which could have been a leak.
03-02-2006, 11:11 PM
#6
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Originally Posted by dc_justin
Stock manifolds. I've thought of a post-combustion chamber leak as causing the problem, but the fact that it is just fine when in speed density kind of rules that out...
03-03-2006, 07:10 AM
#7
Originally Posted by dc_justin
Injectors have been a thought of mine to check as well. But with Bank 2 being under the J tube on the radix, that sounds nasty to pull them. Any advice on getting under there easily? Also, when I also take into account that my NBO2 values typically sit 10-15mv lower on that bank, makes injectors seem likely, as I really don't know what else it could possibly be.
BTW I am all ears on hearing an easy way to get to those injectors on Bank 2. Need to pull mine anyway.
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03-03-2006, 08:30 AM
#8
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Easy Vacuum Leak Test
To check for injector o-ring vacuum leak(s) use a small plastic (squeeze type)
squirt bottle filled with tap water. Start the engine and let it idle. Use the squirt bottle to liberally apply a stream of water under the J-Tube and onto each injector base/seal. If you feel you need to be more precise in the delivery of the water then attach a piece of 5/32" vacuum hose (approx. 2 feet long) to the tip of the squeeze bottle so you can better direct the stream of water. If you have a small vacuum leak you will hear/feel the engine stumble when you hit the leaking o-ring. If you have a large vacuum leak you will also hear a sucking sound when the water hits it.
Put ALOT of water on one intake runner/injector at a time.
squirt bottle filled with tap water. Start the engine and let it idle. Use the squirt bottle to liberally apply a stream of water under the J-Tube and onto each injector base/seal. If you feel you need to be more precise in the delivery of the water then attach a piece of 5/32" vacuum hose (approx. 2 feet long) to the tip of the squeeze bottle so you can better direct the stream of water. If you have a small vacuum leak you will hear/feel the engine stumble when you hit the leaking o-ring. If you have a large vacuum leak you will also hear a sucking sound when the water hits it.
Put ALOT of water on one intake runner/injector at a time.
03-03-2006, 09:09 AM
#9
Originally Posted by FARM-TRUCK
To check for injector o-ring vacuum leak(s) use a small plastic (squeeze type)
squirt bottle filled with tap water. Start the engine and let it idle. Use the squirt bottle to liberally apply a stream of water under the J-Tube and onto each injector base/seal. If you feel you need to be more precise in the delivery of the water then attach a piece of 5/32" vacuum hose (approx. 2 feet long) to the tip of the squeeze bottle so you can better direct the stream of water. If you have a small vacuum leak you will hear/feel the engine stumble when you hit the leaking o-ring. If you have a large vacuum leak you will also hear a sucking sound when the water hits it.
Put ALOT of water on one intake runner/injector at a time.
squirt bottle filled with tap water. Start the engine and let it idle. Use the squirt bottle to liberally apply a stream of water under the J-Tube and onto each injector base/seal. If you feel you need to be more precise in the delivery of the water then attach a piece of 5/32" vacuum hose (approx. 2 feet long) to the tip of the squeeze bottle so you can better direct the stream of water. If you have a small vacuum leak you will hear/feel the engine stumble when you hit the leaking o-ring. If you have a large vacuum leak you will also hear a sucking sound when the water hits it.
Put ALOT of water on one intake runner/injector at a time.
03-03-2006, 09:14 AM
#10
Originally Posted by dewmanshu
but wouldn't it still have problems in SD if the injector had a leak. SD is bypassing the info of the NB's right? Gotta be a leak pre-o2. I guess one Wide Band wouldn't notice the difference of one cylinder being lean and the pcm would care either since your telling it ignore it. Nevermind, just talking/typing out loud.
BTW I am all ears on hearing an easy way to get to those injectors on Bank 2. Need to pull mine anyway.
BTW I am all ears on hearing an easy way to get to those injectors on Bank 2. Need to pull mine anyway.
I'm thinking that since I hooked the WB up to the leaner bank, that it possibly wasn't noticably as I just took the leak into account with the tune... And like you said, if only one cylinder is leaking, the average difference in the WBO2 reading is small enough to be missed. Stock MAF calibration does not have that extra fuel cushion that I tuned into the VE table...
