1993 Pontiac Firebird Rough idle, bad gas milage, engine co

Tiny
PATMX31995
  • MEMBER
  • 1993 PONTIAC FIREBIRD
Engine Performance problem
1993 Pontiac Firebird 3.4l 6 cyl Two Wheel Drive Manual

I have bad gas milage (12MPG) and a rough idle. My engine light isnt on but I did put a scan tool on it and I got codes. Lots of them
24, 22, 21, 15, 14, 13, 35, 33, 32, 31, 55, 45, 36, 46
Bad O2 sensor?
ECM problem?
TPS poblem?
Coolant temp sensor?


Please help!
Do you
have the same problem?
Yes
No
Monday, January 11th, 2010 AT 6:21 PM

4 Replies

Tiny
PEAR69
  • MEMBER
That is too many codes to be accurate. Erase the codes and drive around for one or two complete heat cycles, or a day or two. Then post back and lets see what codes come back.
Was this
answer
helpful?
Yes
No
Tuesday, January 12th, 2010 AT 12:53 AM
Tiny
PATMX31995
  • MEMBER
Otday I went over some sensors and checked them acording to the manaul.
TPS, IAC, ATS, and MAP sensor all seem to be working and getting power.
I also checked the grounds going to the ECM and they are good
The weird thing is I cant clear the codes and the engine light isnt on.
Bad ECM?
Was this
answer
helpful?
Yes
No
Tuesday, January 12th, 2010 AT 1:56 PM
Tiny
PEAR69
  • MEMBER
Check EVERY ground. Make sure they are good and clean -- also, measure the resistance to ground. It seems that many of the sensors that the trouble codes indicate, share the same ground. Also, Make sure that the battery ground (negitive wire) is clean and terminated to the chassy good and clean. Your check engine light may be burned out. Test to see of there is voltage to it -- if there is then check the ground to the ECM again. Your ECM applies a ground to the check engine light to trigger it. If the ground to the ECM is bad then it has no way to illuminate the light. Just because a sensor has voltage does not mean that the sensor is working properly. Many sensors rely on a good ground termination to operate correctly. Your manual should have a ground distribution diagram that informs you on where to look for the terminations. If you are sure that all the grounds are good, then try removing power to the ECM for 5 minutes. Then try to erase the codes and see what comes back. If this fails then have the ECM reflashed at a dealer. If this fails then it could be the ECM. But it is rare that an ECM of this year fails.
Keep us posted
Was this
answer
helpful?
Yes
No
Tuesday, January 12th, 2010 AT 2:48 PM
Tiny
PATMX31995
  • MEMBER
I checked main ground right off and cleaned it all up good. I cant see the where teh ground is for the ECM, Any ideas?

I know the engine light works because it comes on when my key is on but not started.
It also came on when my coolant temp sensor was unplugged but turned off when I plugged it back in.
I checked the sensors according to the reapir manual and they all seem fine.
Was this
answer
helpful?
Yes
No
Tuesday, January 12th, 2010 AT 3:03 PM

Please login or register to post a reply.

Recommended Guides