My buddy just installed his P1SC Procharger on his '99 T/A. It came with the programmer and everthing so it's pretty much plug and play. The car feels real strong except that every 10 seconds WITHOUT FAIL the rpms will drop and almost die. This happens whether he is accelerating hard or normally or at idle or crusing at a constant speed. When this happens, the temperature guage pegs out and then resets back to normal.
It's throwing P1635 and P1639 codes.
Anyone got any ideas?

 

DTC P1635
5 Volt Reference 1 Circuit

DTC P1639
5 Volt Reference 2 Circuit

Be sure and check the MAP sensor, TPS and FTP sensor. These run off a 5v reference. Not sure which circuit goes to which thogh.

 

I'd say something is unplugged, check all the connections that could of produced the codes. Bob

 

Or a wire got pinched somewhere, or a PCM ground is off somewhere.

 

The MAF has been replaced but the problem persists. The surging isn't nearly as bad but every ten seconds on the button it does it. I'll have him double check all the connections to make sure everything is secure. Thanks for the help and if anyone else has any suggestions...I'm all ears!

 

It sure doesn't sound like a "ProCharger" problem, but more of an intstall or tuning/tuner problem. Your title is VERY misleading!

 

Sorry. Didn't realize it.

 

Similar thing happened to me. Under hard accelaration the car would shut off, or would stumble. Turned out it was a PCM ground.

 

Okay, it is my car with the problems-- it does not appear to be the Procharger causing the problems. The engine has a 500 rpm drop at ALL times; idle to WOT -- at about ten second intervals -- EVERY ten seconds -- like clockwork! There is no loss of fuel pressure. Diablo program has been taken out and re-installed several times. Replaced the MAF, codes were erased, now they have returned- P1635 & P1639. Other than that, the car runs great! LOL

Any ideas or suggestions would be great....


Also, were exactly is the ground for the PCM? I do not see any wires near it that are grounded.

 

Get a scantool, a real one and look for the incremented runtime timer. I think your car is "rebooting". It really sounds to me as if you have a short to ground from the 5v supply circuit to the sensors.

 

I have the Diablo handheld that shows real time. What should I be looking for & which sensors should I check?

 

Circuit Description
The PCM uses a common 5.0 Volt Reference 1 circuit as a sensor feed. This circuit supplies 5 Volts to the following sensors:

The TP sensor
The MAP sensor
The EGR valve
The PCM monitors the voltage on the 5.0 Volt Reference 1 circuit. This DTC sets if the voltage is out of range.

Conditions for Running the DTC
The ignition switch is in the RUN position.

Conditions for Setting the DTC
The 5.0 volt reference circuit is out of range.
All above conditions are present for greater than 2 seconds.
Action Taken When the DTC Sets
The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Use a scan tool in order to clear the MIL and the DTC.
Diagnostic Aids

Important
Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.
For any test that requires probing the PCM or component harness connectors, use the Connector Test Adapter Kit J 35616-A . Using this kit prevents damage to the harness connector terminals. Refer to Using Connector Test Adapters in Wiring Systems.

Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed.
For an intermittent condition, refer to Symptoms .
Test Description
The numbers below refer to the step numbers on the diagnostic table.

The 5 volt reference circuits for the sensors are connected together inside the PCM. Both DTCs P1635 and P1639 set at the same time, indicates a 5 reference circuit is shorted to a voltage.

The 5 volt reference circuits for the sensors are connected together inside the PCM. When only P1635 is set, this indicates a short to ground on one of the 5 volt reference circuits.

This step isolates the 5 volt reference circuit from the sensor signal circuit.

This step determines if the 5 volt reference circuits or the fuel level sensor signal circuit are only shorted when the fuel pump is enabled. You may have to enable the fuel pump a couple of times to see if the voltages increase. Inspect the fuel pump harness thoroughly for being shorted to the fuel tank pressure sensor and/or the fuel level sensor.

The Data list can be changed while in output controls. Select the MORE soft key to select the next Data list. This procedure is necessary to view all parameters. Refer to scan tool users guide for detailed information.

The 5 volt reference circuits may be shorted to another PCM circuit. The shorted circuit may not be apparent when the PCM harness connector is disconnected. Testing continuity from each 5 volt reference circuit isolates the shorted circuit. For detailed circuit information, refer to appropriate full page schematics.

For detailed circuit information, refer to appropriate full page schematics.

This step is testing for a component failure. Disconnecting each component individually isolates which component might be causing this DTC to set.

Continued.....

 

This is from GMeSI...the formatting sucks on the web. I'll create a pdf and attach it so you can see the troubleshooting charts better....

This has got to earn a brother a beer.

 

Thank you soooo much, guess I have some reading to do.....

Oh YEAH, you deserve a beer...thanks again

 

Thanks, guys!

 

You're welcome. Please let us know what ended up fixing it....

 

If you are running the STOCK GM tune, does it still occur?? You can start the car and idle with it, but I wouldn't get on it at all...

 

More than one in my book.

 

It does this even with the factory tune. I think the best bet will be to take it down to South Texas and have the car custom tuned -- that is the plan. I believe I have uplugged, replugged, caressed, finessed about very connection on the car...LOL I think the PCM is surely involved in this conspiracy.....will keep everyone informed....more thoughts are greatly appreciated.....