1991 Oldsmobile Cutlass Supreme 3.1 V6, I can unplug the EGR valve and the MAP sensor and the OBD will not send a troublecode AT ALL? Is my ECM bad or might it be the wire harness?
2006-11-25 05:09:39 · 4 answers · asked by bionicstarfairy 1 in Cars & Transportation ➔ Maintenance & Repairs
1991 Oldsmobile Cutlass Supreme 3.1 V6, I can unplug the EGR valve and the and the OBD will not send a troublecode AT ALL? Is my ECM bad or might it be the wire harness? Do not have scanner, this sensor IS needed but it runs better when it isnt plugged in... but the computer isnt reading it as being there or not... Any suggestions
2006-11-25 05:38:21 · update #1
Try another code scanner first :)
2006-11-25 05:20:05 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Once the car is running, if you disconnect SOME G.M. maps, it will run differently but may not set a code, because it is using a "programmed" value to keep the engine running.
unplugging the EGR valve won't set a code until the PCM expects to see a signal. The digital EGR you have is controlled by the PCM, not the other way around. If the EGR is requested, the PCM looks to the fuel trim values to see if the command was executed and uses those values for further control. You cannot see this information without a scanner.
Does the "Check Engine" light come on while cranking? If not, repair that first. (probably a bulb.)
When the "Check Engine" light works, go here------>
http://autorepair.about.com/library/ts/obd-i/bl-dtcs-96.htm
...for a discussion of the procedure for drawing the codes without a scanner, using a paperclip.
When you nave the codes in hand, refer to a repair manual for the proper diagnostic and repair procedures.
NOTE:----> Do the DIAGNOSTICS first, before the repair. Remember that the codes refer to a fault or failure in a circuit or system, and not NECESSARILY a component.
Good Luck
2006-11-25 09:28:21 · answer #2 · answered by Ironhand 6 · 0⤊ 0⤋
We're opening up quite a large can of worms here. #1 Not all OBDII scan tools (snap-on, mac etc) will report the same information. We have that happen all the time where one will give you the codes and another wont. #2 Yours is an OBDI system that may not have a response for exhaust gas return or manifold absolute pressure. #3 Is the dash light burned out? #4 A bad ECM computer will 'cause' problems, not hide them.
Ask your mechanic to use several different scan tools, borrow them from other mechanics if necessary and see what happens.
2006-11-25 05:35:07 · answer #3 · answered by Fosteroak 1 · 0⤊ 0⤋
It may not need those sensors at an idle, did you drive this car after you unplugged those sensors????
2006-11-25 05:28:20 · answer #4 · answered by wilbur_v2 2 · 0⤊ 0⤋