X-Link w/ 90mm TB, Reduced Engine Power
08-31-2013, 09:35 PM
#23
boost happens when there is a difference in pressure between the atmosphere and the cylinder head, so anywhere between the compressor and the cylinder head there is boost. Boost only exists if there is a restriction so generally, the more boost you are running the less percentage of air in relation to compressor discharge you are using. Hence why 5 lbs of boost on a 370 has much more power than a 350 with 5 lbs of boost. So the boost can effectively shut the blade closed, due to the weak blade motor, especially on an ls2 style throttlebody.
09-01-2013, 07:53 AM
#24
boost happens when there is a difference in pressure between the atmosphere and the cylinder head, so anywhere between the compressor and the cylinder head there is boost. Boost only exists if there is a restriction so generally, the more boost you are running the less percentage of air in relation to compressor discharge you are using. Hence why 5 lbs of boost on a 370 has much more power than a 350 with 5 lbs of boost. So the boost can effectively shut the blade closed, due to the weak blade motor, especially on an ls2 style throttlebody.
Airflow and vacuum are the two main variables, more importantly air stability. I would bet in a scan you can see the TB % fluctuating prior to this happening. I bet it gets worse of you remove the air filter due to the increased turbulence. Do you have a CAI laying around that you can use the conicle filter from?
09-01-2013, 08:41 AM
#25
Dealing with turbos all the time, I had a complete brain fart on that one, never crossed my mind!
I am just stumped with this X-link and P1515 code. It seems to not be consistent, sometimes it will throw it instantly at WOT in any gear. Other times the truck will rip and it will throw it at the top of second. All wiring to the TB and X-link shows to have zero issues, TB is not getting stuck or hung up on anything, and TB stays consistent without anything weak making it fluctuate.
I am just stumped with this X-link and P1515 code. It seems to not be consistent, sometimes it will throw it instantly at WOT in any gear. Other times the truck will rip and it will throw it at the top of second. All wiring to the TB and X-link shows to have zero issues, TB is not getting stuck or hung up on anything, and TB stays consistent without anything weak making it fluctuate.
09-01-2013, 09:42 AM
#27
When I had this problem I was running the supercharger. Now that I have had my turbo engine that is moving way more air and under pressure it is not happening. I switched to a turbo so I coudl eliminate this problem. I feel that it has something to do with vacuum and a weak motor on the TB.
09-01-2013, 10:25 AM
#28
What is significant is that this only occurs when the engine is running. For a 1515 to set the TPS signals must be good.
I am curious as to what code will set if you manually push the blade closed when it is active. 1515 or 1516? According to 03 DTC descriptions, it should be 1515. For newer trucks it should be 1516, both are commanded vs actual. For 03 1516 is described as predicted vs actual.
I am curious as to what code will set if you manually push the blade closed when it is active. 1515 or 1516? According to 03 DTC descriptions, it should be 1515. For newer trucks it should be 1516, both are commanded vs actual. For 03 1516 is described as predicted vs actual.
09-01-2013, 10:53 AM
#29
setting such limits will mess up any tps reliant tables, you would have to decrease every tps table for the relationship 98=100, so the tables would have to be multiplied by .98, the zero tables would remain constant as 0 times .98 =0 so they are unaffected, but you may fall into further problems where 100% tps is required and the only availability would be 98, falling 2% short and not satisfying such tps requirements. Stock TB would be safer, more reliable, and to be honest would yield similar power output ~10whp less at low boost.
09-01-2013, 11:22 AM
#30
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I had the same exact problem with a 87MM truck throttle body. Sometimes it would trip just idling and sometimes it would trip at the top of second and had the fluctuations in TP% at WOT. Tried 2 diff 87mm TB and the second one only did it at the top of second... So I bought a LS3 style 90mm TB and haven't had a problem since.