The P1188 is the code that seems to be most popular when the boost is raised with a boost controller. It is a Throttle Inlet Pressure error, as reported by the TIP sensor that is on the firewall just ahead of the speed control cable as it exits the speed control servo mounted with the solenoids on the passenger side strut tower.
The error indicates (from what I can gather from comments made about it) that there is pressure present when the PCM doesn't expect it to be - (throttle is closed, as an example). That should indicate that the system isn't venting pressure quick enough when the turbo starts to spool down...
When the turbo spools up, the MAP (Manifold Absolute Pressure) and TIP (Thottle Inlet Pressure) sensors report to the PCM (Power Control Module). Other info is also reported, but these seem to be the ones in the circuit that sends data to the PCM and in return, the PCM regulates boost pressure by using the wastegate and surge actuator solenoids to vent boost pressure and regulate exhaust pressure entering the turbo.
Apparently, the boost controller, by raising the low end boost pressure, slows the speed in which the PCM is updated, or sends data to the PCM that is not in agreement with what the PCM anticipates..
This seems to manifest itself as pressure measured at the throttle inlet when the PCM has already made it's attempt to vent it before it reaches that point. This is probably a result of the boost controller holding the low end of the boost curve that the PCM tries to maintain, (based on it's reports from various sensors), higher than the PCM anticipates (based on data sent back by the TIP). This is what seems to create the P1188 error code.
It is possible that the firmware for the TCM (Transmission Control Module) part of the autostick system to attempt to "de-link" itself from the drive system until the cause of the TIP error is eliminated, or verified to no longer exist at that given moment before re-engaging the transmission.
The ATX (auto trans) is controlled by CVI (Clutch Volume Index) readings. The CVI is a measure of pressure readings in the clutch portion of the transmission. I cannot fully explain the whole process, but according to what I have red in the service manual, the CVI data sent to the TCM/PCM controls the way the PCM/TCM tells the transmission to operate. There are different shift points based on temp and CVI, and various preventative measures taken when the PCM/TCM anticipate a problem, based on data that they receive.
It is a possibility that the p1188 error wasn't anticipated in the programming of the PCM/TCM, and it is causing them to tell the trans not to do anything rash at low speeds, when boost starts to raise quickly and the trans is in too high a gear to respond.
This seems to be the most prevalent situation in the 5 speed models, when the error occurs. In most cases, the 5 speed is in too high a gear and below 2500 RPM, (actually below the spool start speed of 2300 RPM), and the system senses something close to a WOT (wide open throttle) situatiuon. Until the engine builds speed above the 2300 RPM start of spool to the 3500 RPM inherit start of powerband, the engine "lugs". When this happens, it could be a combination of things such as O2 sensor(s) reporting too rich a mixture, Spark Misfire, and the pressure on the throttle inlet being too high for the current RPM/Gear Ratio/O2 readings being sent to the PCM/TCM.
Due to the way in which the Task Manager portion of the PCM records error conditions, then re-tests for integrity of the data, combined with monitoring other diagnostic data; the illumination of the MIL code p1188 doesn't occur at the precise point in time as the situation that caused the error. The error code may pop up minutes, hours or days from the time of the actual data being created.
During this time that the p1188 code is 'maturing" from the first data sent to the PCM indicating higher than anticipated Throttle Inlet Pressure, until the time that the Task Manager sees the error again within the cons
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