Disconnecting the battery will remove any stored codes. If the problem still exists with the battery hooked back up you will go thru this again.

Limp home: Default running program that won't pass emissions. Gets you home as the PCM cycles thru default/normal/default/normal seeing if the problem has been fixed [closed/open loop control]

Check engine light on: engine runs 'okay'; PCM in limp home mode; not relying on feedback/closed loop control. PCM then returns to normal running closed loop mode, Check Engine light goes out, and the car runs like crap - and it continues operating in this mode until the problem is fixed or gets worse OR the computer returns to limp home mode where it runs halfway decent again with the CEL illuminated.

This understandable? [edit: the reason for the cycling is to see if the problem has gone away or has been fixed; and I'm sure there are failure modes where the PCM will stay in limp home mode and will not cycle based on what failed. I'll hope that someone with more knowledge of specifics here will chime in]

doug

[ 02-08-2007, 05:52 AM: Message edited by: wood95ss ]

 

Has CEL come on?
If so, there is/are DTC(Diagnostic Trouble Code/s) stored in your PCM.

Get to a shop that has the appropriate OBD1 Scanner, inorder to retrieve stored code/s, which may help diagnose this issue.

*______________*_____________*______________*____________*
Btw, NEVER disconnect a Battery Cable(BC) while engine is running!! You could get a voltage surge from Alternator, causing PCM damage.

But you can disconnect[leave it off 10 minutes] BC w/engine OFF, inorder to clear CEL,
but as Doug has intimated, if a problem still exists, CEL will return.

 

Under some conditions, your transmission can go into a 'limp' mode where you only have third & reverse gears (or maybe second, third, & reverse). The car runs smooth, but seems to have no power, because you're starting out in high gear! Count the upshifts from a stop.

 

A simlified explanation of Limp Mode,
is when the PCM is NOT relying on information from all the different engine Sensors, especially the Oxygen Sensors,
but instead, operates in a default mode using a set Fuel Trim/Timing Program.

This results in engine running on the rich side, and very lazy performance.

Off top of me head, these are just two things that will cause default:
* ECT connector damaged, or disconnected> www.shbox.com/1/temp_sensor1.jpg
* MAF connector D or D > www.shbox.com/1/maf.jpg

[ 02-08-2007, 03:57 PM: Message edited by: LarryCigar ]

 

Originally posted by Jimbeau:
Under some conditions, your transmission can go into a 'limp' mode where you only have third & reverse gears (or maybe second, third, & reverse). The car runs smooth, but seems to have no power, because you're starting out in high gear! Count the upshifts from a stop.

I had this problem and it turned out that the 1-2 Shift Solenoids were shot and was a cheap fix.

 

I have had experience with limp-home mode and 7 cylinder performance. Limp-home performs completely different. Starting off in 2nd gear, no performance. Do not run it too long like this. With 7 cylinders, the engine has a noticeable miss. Mine was a fouled #8 plug.

 

You only have 3rd gear and no converter lockup in limp mode. Fans will be running all the time.

 

i think my tranny is going into limp mode.but its only at the track on WOT useing slicks.when i stop im stuck in 3rd gear.i shut the car off and restart..everything is fine.should i change that solenoid too?

 

Originally posted by impalassdude:
i think my tranny is going into limp mode.but its only at the track on WOT useing slicks.when i stop im stuck in 3rd gear.i shut the car off and restart..everything is fine.should i change that solenoid too?

No, I had the same problem at the track. It started happening all the time once I got drag radials. Assuming you have an 2800 plus stall. My programmer told me it was called the OBD1 shift fix. Search that in the drivetrain section.

 

There is a temperature sensor inside the trans. If it senses too much heat, it will force a 'third gear only' condition.

 

i do have a 2800 TC and it only happens when i use the slicks.runs great till i hit 3rd gear then its like you removed your foot from the pedal.my programer dosent think its programing issue but most folks tell me it is.really puzzled.

 

Your trans could be overheating, or the internal temp sensor could be fubar(b)ed.