cant get rid of code 48 on 95RRCLWB

[deadboy1977]

I keep getting a code 48 for a stepper (even though I put a new one in, a genuine LUCAS). The stepper works I know for sure (left the spare in the plenum and plugged in the new one outside the plenum - it was hunting!).

After a ECU reset by disconnecting the battery to get rid of the 48 code, when I start the vehicle cold, idle goes to 1500RPMs or so then after 20 secs or so dips down below 500 and dies. I restart it, 1500 again, 500 then dies. The third time it usually goes 1500-2000 then 500-600RPMs but jumpy. I drive the car a 100 miles or so before I get the 48 code again, sometimes longer.

I did a base idle adjustment (many times!!) to no avail. All the usual suspects have been examined - MAF, TPS, T piece, breather hole in valve cover, injectors (they are new), fuel filter, fuel pump, etc. COmpression tested at 140 in all cylinders except 8 which get 125. I have 155000 miles on the truck.

Only items not checked are fuel P regulator and ECU.

Any ideas??

[daway]

http://www.robisonservice.com/servic...ouble.asp#1990

here is some info.
go down alittle and u will see what to check on code 48 and shows u how to clear a code.

also, this is what i do after cleaning my stepper motor. got it from a old lr tech.
"once you reinstall, start your truck, get to operating temp, unplug the stepper motor, turn engine off, wait 1 minute and reconnect. this will allow the onboard computer to calibrate it."

cheers

[Kevin88RRC]

Originally Posted by deadboy1977

I keep getting a code 48 for a stepper (even though I put a new one in, a genuine LUCAS). The stepper works I know for sure (left the spare in the plenum and plugged in the new one outside the plenum - it was hunting!).

Did you have the new one plugged in with the rover runnning & not installed??? I've always heard that was bad & could trash the stepper.
When you installed the new one, did you clean the plenum where it sits?

Like Daway said, try resetting the ECU. Don't know which way is better.
-Switch ignition ON – DO NOT START ENGINE.
-Disconnect Stepper Motor plug.
-Switch Ignition OFF.
-Listen for EFI Relay to click (it’s under passenger seat).
-Reconnect Stepper Motor.
-Switch Ignition ON – DO NOT START ENGINE.
-Disconnect Stepper Motor.
-Start ENGINE in neutral (without touch throttle).
-Reconnect Stepper Motor.
-Switch Ignition OFF.
-Listen for EFI Rely to click.
-Start ENGINE and Rev briefly to 2000 rpm.
-Idle should stabilize at 665-735 rpm.

[TerryS]

You shouldn't power up a stepper motor not installed in the valve body, because the motor can spin the plunger right off the end of the shaft. Since the plunger is keyed, so it can't turn, just move in and out, it is impossible to get it back onto the screw thread shaft, unless you know how to manually connect to the servo motor itself to power the plunger back on.
Getting a stepper servo motor code does not mean the motor is bad, it generally means that it's motion is not correcting a high or low idel condition. This can be from a dirty valve and plunger surface to crud on the servo shaft. Crud can slow or bind the plunger and while the ecu thinks the servo is in motion, nothing is changing, so it throws the code. Clean the shaft with carb cleaner, then lube it with CRC (not WD-40, since WD-40 dries and gets gummy).

[TerryS]

Dont mean to confuse anyone, I use the term 'stepper motor' and 'servo motor', but they are one and the same.

[daway]

Originally Posted by daway

http://www.robisonservice.com/servic...ouble.asp#1990

here is some info.
go down alittle and u will see what to check on code 48 and shows u how to clear a code.

also, this is what i do after cleaning my stepper motor. got it from a old lr tech.
"once you reinstall, start your truck, get to operating temp, unplug the stepper motor, turn engine off, wait 1 minute and reconnect. this will allow the onboard computer to calibrate it."

cheers

when i say unplug, i mean to unplug the wire connection on the stepper motor.
i spray the stepper motor w/ carb cleaner w/o pushing or rubbing it. then i take a long screw driver and rap a clean towel around it and then i spray carb cleaner on it. rub the towel around the hole were the stepper motor screws into the plenum to get that area clean.