Sensor in front A/C coils on LS1 99 corvette?????

[GS963]

Hi All! I'm new on here and looking forward to being schooled on the LS1. Bought a 99 LS1 corvette with headers and full exhaust. Problem is car has no real power. It has the MAF sensor on it. But I noticed there is a plug coming off the MAF sensor harness that plugs into a sensor mounted in front of the A/C coils. My 02 has no such plug or sensor. I'm trying to figure out what is killing the power. Anyone have any idea what this sensor is for?

[pajeff02]

Welcome to the site!

If a sensor is unplugged you are generally going to see the SES light on in the dash. Have you scanned the PCM for DTC's? Other connections in that general area are going to be the Intake Air Temp (IAT) sender and Throttle Position Sensor (TPS).

[GS963]

No sensor was unplugged. The car had several H codes. 10-pcm p1431H
40BCM B0502H
B0507H
B2482H
58-SDM B1001H
U1000H
U1016H
U1040H
U1096H
U1064H
AO-LDCM B2282H
B2284
B2262H
U1255H
U1065H
U1016H
U1096
A1-RDCM B2283H
B2285H
B2265H
U1255H
U1064H
U1016H
U1096H
B0-RFA U1255H

I have no idea how long these codes have been logged. I have since cleared them to see if new one come back or it repeats some. I'm not too good with the meaning of all these codes. I did figure out that the AIT sensor was moved to in front of the A/C coils. There is a kit for this. I guess to read cooler air. I'm not sure if it was working. But there were no lights on. I'm going to move it back to the original location and install a new sensor. Do you see any codes that would kill performance?

[GS963]

I did figure out that someone put the kit to move the Air intake Temp to in front of the A/C coils. I assume to get cooler air. I'm going to put it back original and put in new sensor in case the other one was not working right or something.

[pajeff02]

P1431 appears to be a fuel level sensor issue. The rest of that stuff... some body codes and no clue what a "U" code is.

[GS963]

Yes My gas gauge did stop the other day. Turn key off and on it it cured it for now. After I get new AIT sensor I'm going to focus on MAF sensor if the car still runs lousy. I cleand air filter and it helped maybe a little but car still wants to flatten out around 3500 when taking off and even stumbles and pops sometimes.

[pajeff02]

Best test for a faulty MAF is to unplug it. If the engine starts to immediately run better that is a good sign that the MAF is probably the culprit. Unplugging it forces the PCM into speed density mode, and will trigger the SES light, but will not harm anything.

[LHanded Lead Foot]

I am re-reading this post several times to get enough info to reply with help. You mentioned the "AIT" sensor...are you talking about the "Intake Air Temp" sensor? If so, moving it to a cooler area will trick the PCM to believe that air is cold and will increase the air/fuel ratio making it more rich. I would put it back where it belongs. The MAF sensor should be a hot-wire type but they are still able to get dirty. Special cleaner's are sold and some use tools like a tooth pick or cotton swab to clean. NOTE: Be careful, the wire is delicate and can be easily damaged. As posted, if the MAF is not matching the PCM v RPM v Coolant temp v throttle position...will set a code.
Many codes can be set with the engine running and a person is testing or unplugging something. The PCM is very busy checking each circuit that effects emissions, for integrity. This means it is there and working as design. When unplugged, not only will it set a code. turn on the SES light, but may take a minute as the PCM has to follow a program that goes around to each sensor continuously while in service, before it get back to...say the MAF. The PCM, BCM and other modules contain software for backup mode to keep running. With many codes, clearing them as posted is a decent place to start, but be patient. Each test the PCM makes, on each device has to meet enable criteria. Battery voltage, below 14k feet altitude, RPM above 550, coolant temp above 172 degrees F, etc. So it take a few minutes to run most all. Other require the vehicle to be moving at road speed, while others yet, run on a timer like EVAP system testing or EGR (If equipped), etc.

The "U" codes are serial data failures. Since the Vette was the first to use "CAN" bus in 2004, yours uses cavity #2 at the DLC, using class 2 serial data. While running, some during cranking, if a device was disconnected or not responding because it had no power (or ground), but did not respond, it will set a "U" code". Modules on the serial data bus talk to each other, state-of-health, etc. Some of the code you listed are as follows;
U1000 = Loss of communication.
U1016 = " " " PCM
U1040 = " " " TCS
U1064 = " " " BCM
U1255 = Serial Data Line Malfunction (Note: As for the "H", I don't get that on a TECH2)

So, clear codes. Check battery condition and connections, Fuses, use dielectric grease on connectors and plug in...then go for a drive. See what codes come back. Understand, code that effect emissions turn on the check engine light when fault is detected. This type "A" codes. If it does not effect emissions, type "B" codes, require two times driving the vehicle from a cold start (IAT & ECT are within 10 degrees F of each other at start), fails a second test, then it turns on the light. Go from there and let us not what you get.

Make sure the fuel filter is not rusty, air filter clean and no bananas in the tail pipes. There is no excuse for good maintenance before diagnosing a problem. Remember, Loud radios sell a lot of car parts.
U1096 = " " " IPC