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Fast 102 LSXR Install Issue - Reduced Engine Power
I’m new to the C5 platform and just started installing some performance parts on my car. This past week I’ve installed a Fast 102 LSXR intake manifold, a 102mm throttle body w/ conversion harness and AFE intake. My issue is when I turned the key on before starting, I got a ‘Reduced Engine Power’ note on the dash and the check engine light came on. Checked for codes and got:
- P1125 Multiple Throttle/Position Sensor
- P1221 Throttle Position Sensor A/B Range Performance
- P1220 Throttle Position Sensor B Circuit
- P1120 Throttle Position Sensor A Circuit
- P1516 Command vs. Actual Throttle Position Correlation (TAC Module) Error
The car was able to start, it idled high for some minutes before coming down to about 1300 RPMs. Turned off the car, disconnected the LS2 TB conversion harness and plugged in the stock TB wire harness end to the stock TB and turned the car on and got no codes. Wondering if anyone else can point me in the right direction here?
I’m new to the C5 platform and just started installing some performance parts on my car. This past week I’ve installed a Fast 102 LSXR intake manifold, a 102mm throttle body w/ conversion harness and AFE intake. My issue is when I turned the key on before starting, I got a ‘Reduced Engine Power’ note on the dash and the check engine light came on. Checked for codes and got:
- P1125 Multiple Throttle/Position Sensor
- P1221 Throttle Position Sensor A/B Range Performance
- P1220 Throttle Position Sensor B Circuit
- P1120 Throttle Position Sensor A Circuit
- P1516 Command vs. Actual Throttle Position Correlation (TAC Module) Error
The car was able to start, it idled high for some minutes before coming down to about 1300 RPMs. Turned off the car, disconnected the LS2 TB conversion harness and plugged in the stock TB wire harness end to the stock TB and turned the car on and got no codes. Wondering if anyone else can point me in the right direction here?
LS6
Stock Intake System Removed
MAP Sensor Clamp
LS2 Fuel Rails
FAST LSXR 102 Intake Manifold
102mm TB w/ LS2 Style Conversion Harness
AFE Intake
DTC Trouble Codes
Has to do with the connection to the TB. might of damaged a wire. And don't forget bout a tune to utilize your upgrades or it means nothing.
If I remember I think the conversion harness is wired wrong,I remember swapping 2 wires,get a multimeter and check which wire is where at the end of the plugs
St. Jude Donor '14-'15-'16-'17-'18-'19-'20-'21-'22-'23
Originally Posted by DRIVER456
If I remember I think the conversion harness is wired wrong,I remember swapping 2 wires,get a multimeter and check which wire is where at the end of the plugs
I remember a thread about that. IIRC, you had to swap some wires around in the harness
If I remember I think the conversion harness is wired wrong,I remember swapping 2 wires,get a multimeter and check which wire is where at the end of the plugs
I wonder who posted that before but no one believed him cause he wasn't a vendor supporting member?????????????
When I finished my build I found my TB conversion harness was faulty. I replaced it with a Casper Electronics harness and all was good.
I ordered an LS1 to LS2 TB conversion harness from Racetronix just in case.
Originally Posted by DRIVER456
If I remember I think the conversion harness is wired wrong,I remember swapping 2 wires,get a multimeter and check which wire is where at the end of the plugs
Originally Posted by Smoken1
I remember a thread about that. IIRC, you had to swap some wires around in the harness
Originally Posted by bonesbrakr
I wonder who posted that before but no one believed him cause he wasn't a vendor supporting member?????????????
I was thinking about that, since the codes came back all cross with my TPS pins/circuits A and B. I was going to switch them in the conversion harness once I figure out which is which. Currently searching for a wiring diagram or switch reference so I can determine which is A and B.
I just saw you have a nick williams chinese knock off throttle body - dollars to donuts that is your issue. You should really consider getting a GM silver blade LS2 throttle body.
I just saw you have a nick williams chinese knock off throttle body - dollars to donuts that is your issue. You should really consider getting a GM silver blade LS2 throttle body.
Is silver blade a specific type of throttle body? I’m gonna do a search for one right now. The manifold, fuel rails and black TB in the pics above I bought in a kit for $800. I just had to piece together the mounting bolts, hardware and AN fittings
I just saw you have a nick williams chinese knock off throttle body - dollars to donuts that is your issue. You should really consider getting a GM silver blade LS2 throttle body.
You might be very lucky to find an OEM GM 92mm Silver Blade # GM 12570790...anything else will not function or will stop functioning...
Check eBay for a GM LS2 throttle body. Make sure you are buying a used GM / AC Delco TB, otherwise there are no guarantees. There are oem type replacements being made (also overseas) that may work and I bought one for $150 but I have yet to bolt it on to see if it works with our operating system.
and I feel the pain of piecing together the fittings for the fuel rails.
If you absolutely cannot find an OEM TB, this would be your next best choice “I think”. Like I said I haven’t bolted it up to verify it works but “it should”.
Sorry to keep blowing this thread up. Check on Facebook market place also - there are a few on there that are in my search radius, so there have to be options near you if not nationwide.
Check eBay for a GM LS2 throttle body. Make sure you are buying a used GM / AC Delco TB, otherwise there are no guarantees. There are oem type replacements being made (also overseas) that may work and I bought one for $150 but I have yet to bolt it on to see if it works with our operating system.
and I feel the pain of piecing together the fittings for the fuel rails.
Originally Posted by CinciZ06
If you absolutely cannot find an OEM TB, this would be your next best choice “I think”. Like I said I haven’t bolted it up to verify it works but “it should”.
Originally Posted by CinciZ06
Sorry to keep blowing this thread up. Check on Facebook market place also - there are a few on there that are in my search radius, so there have to be options near you if not nationwide.
If you do get to plug in that replacement, and it doesn’t throw any codes, I’d appreciate a link to the part and seller. I haven’t driven my car for a couple of weeks now, miss driving it. Having to crash course learning about AN fuel lines and fittings was not fun! Especially when the shop closes in an hour and they only had certain pieces available. I have all of my fittings in order now, just need to actually make the crossover line and fuel feed lines. No, do Lee blowing it up. I’m new to the LS platform. Don’t know anything about it yet other than it’s proving to be much easier to work on than I’m used to. I’ve had 3 C4 corvettes in the past, but my more recent years with a performance car was my 04 Mach1 5spd with DOHC. I appreciate the brutal simplicity the Vette has over my old Mach, I just need to learn it more.
Had a moment to run out and plug it in to see what happens.
GM LS2 TB sits at 19.something percent when it’s energized and the car isn’t idling. It will drop down to 6-7% open when the car is started and idling
I installed the knock off LS2 silverblade and this was the result.
The TB would flicker as it ran through its diagnostic process and then fault, showing 99% open and throwing codes.
Maybe be the same internals as the Soler Performance LS2 TB that won’t work with a C5’s OS?
So I’m super psyched about my $150 paperweight. Guess I’ll throw it on EBay, listed appropriately of course.
Dame sorry to hear that. Don't feel that bad, buddy bought the new NW102 boost TB because he keep getting 1514 1515. NW Said it would work for boost. 800buck. He says it looks good next to his bowling trophy 🏆 lol
Fast 102 LSXR Install Issue - Reduced Engine Power
