Fast lsxrt drivability problems
08-19-2012, 11:44 PM
#1
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Fast lsxrt drivability problems
well remember when i said i liked my FAST LSXRT well i take that back its been the biggest PITA
but anyways heres the story.
as you all know i put this intake on my heads cam LQ4 nothing to crazy when i was finished installing it finally got the truck running it ran pretty good power wise but lacked good drivability aka stalling at red lights idles very irratic.
so i figured just needs to be retuned no biggie i kinda figured that anyways even before install. so i get the truck to my local tuner very well known for
lsx vehicles not stating any names. well the truck was there three weeks and he couldnt get the truck to idle very good def better then when i dropped it off must i add but still not like it should be. he tells me its most likely the intake leaking probably not sealing around were the two halves bolt together or a ripped o-ring on a runner. also he tried tuning it in speed density and said it didnt help any.
so i picked up the truck yesterday and checked the most common stuff as far as the the electronic stuff AKA MAP SENSOR-TPS-IAC and so on everything seems to check out id did most of this with my fathers SNAP-ON SOLUS PRO scanner. BTW the tuner also checked this stuff i just wanted to verify that it was all working just for my own piece of mind.
i then did the brake clean test to see if there was any vacuum leaks couldnt find anything.
i know BGARY had these issues with his anyone else run into problems with theres.
but anyways heres the story. as you all know i put this intake on my heads cam LQ4 nothing to crazy when i was finished installing it finally got the truck running it ran pretty good power wise but lacked good drivability aka stalling at red lights idles very irratic.
so i figured just needs to be retuned no biggie i kinda figured that anyways even before install. so i get the truck to my local tuner very well known for
lsx vehicles not stating any names. well the truck was there three weeks and he couldnt get the truck to idle very good def better then when i dropped it off must i add but still not like it should be. he tells me its most likely the intake leaking probably not sealing around were the two halves bolt together or a ripped o-ring on a runner. also he tried tuning it in speed density and said it didnt help any.
so i picked up the truck yesterday and checked the most common stuff as far as the the electronic stuff AKA MAP SENSOR-TPS-IAC and so on everything seems to check out id did most of this with my fathers SNAP-ON SOLUS PRO scanner. BTW the tuner also checked this stuff i just wanted to verify that it was all working just for my own piece of mind.
i then did the brake clean test to see if there was any vacuum leaks couldnt find anything.
i know BGARY had these issues with his anyone else run into problems with theres.
08-20-2012, 03:48 AM
#4
Hmmm only thing I could think of is you have a leak or your idle air control is messing up or a hose coming off the intake is leaking. When I put mine on my tuner adjusted a little bit but not because of any problems truck ran and idled great no issues at all.
08-20-2012, 05:26 PM
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im guessing it idles up to about 1500-2000 RPM then starts to stumble and finally just dies out?
if so thats what mine was doing be fore my tuner messed with the tune it def runs idles better now but not like it should.
i will im going to pull the intake off the truck tonight and see if i can find any problems inside the plenum were the runners are
08-20-2012, 08:41 PM
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I dont know too much about these trucks yet but I am a and have been a VW/Audi tech for 10 years. I have seen ect sensors cause this and bad o2 sensors as well on vw's especially on cold starts. You already stated the obvious, vacuum leaks, iac, map, tps. I like to start by looking at short and long term fuel trims. Check fuel pressure and the regulator. Maybe when its off load the regulator is bleeding down. maybe even couple the maf directly to the t-body without a filter to observe the t-body and while watching the tps on your snap-on scanner. Hope this helps a bit
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08-20-2012, 08:51 PM
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well i pulled the intake off tonight and found some stuff i dont like i took some pictures with my IPHONE
first thing was the lower part of the intake were it meets the cylinder heads i have ARP bolts and the washers stick out some enough to contact the intake and make small indents
second thing was a ripped o-ring on one of the lower runners no pic.
third was theres a nasty little ridge on the intake ports were the runners slide in im guessing thats why the o-ring was cut.
first thing was the lower part of the intake were it meets the cylinder heads i have ARP bolts and the washers stick out some enough to contact the intake and make small indents
second thing was a ripped o-ring on one of the lower runners no pic.
third was theres a nasty little ridge on the intake ports were the runners slide in im guessing thats why the o-ring was cut.
08-20-2012, 09:09 PM
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and yes i plan on notching out where the bolts hit on the lower manifold
also goin to order all new o-rings for both the runners and lower manifold meets the cylinder heads and one for were the upper half meets the lower manifold