help needed with 1990 t-bird

35thT-Bird

Registered User
hi, i recently did the heads on my 1990 supercoupe and it hasn't been running right. It sounds like a vacuum leak, but i double checked the vacuum lines and they seemed to be good, so i scanned it and came up with the following codes:

41) EGO(H025)NOT SWITCHING RICH +LEAN

91) LEFT EGO SENSOR LEAN OR NOT SWITCHING

72) NO MAP/MAF CHANGE ON THROOTLE SNAP

73) NO TPS CHANGE ON THROTTLE SNAP

25) NO KNOCK SIGNAL DURING SELF TEST

do you think there are many problems or one root problem thats causing all of these errors?

if you have any suggestions or possible solutions, they are EXTREMELY appreciated! thank you,
-Jeff
 
when i replaced the supercharger on my 90' tbird i for to to connect part of the main wiring harness located behind the right front shock tower. before i found out that to be the cause my car was running really bad and settng the check engine light just like it had a huge vacuum leak. its just one of those connectors that can be easily over looked.
 
35thT-Bird said:
hi, i recently did the heads on my 1990 supercoupe and it hasn't been running right. It sounds like a vacuum leak, but i double checked the vacuum lines and they seemed to be good, so i scanned it and came up with the following codes:

41) EGO(H025)NOT SWITCHING RICH +LEAN

91) LEFT EGO SENSOR LEAN OR NOT SWITCHING

72) NO MAP/MAF CHANGE ON THROOTLE SNAP

73) NO TPS CHANGE ON THROTTLE SNAP

25) NO KNOCK SIGNAL DURING SELF TEST

do you think there are many problems or one root problem thats causing all of these errors?

if you have any suggestions or possible solutions, they are EXTREMELY appreciated! thank you,
-Jeff

did you "rev" the gas during the test when it asked you to?, if you did maybe a loose or unconnected harness
 
35thT-Bird said:
hi, i recently did the heads on my 1990 supercoupe and it hasn't been running right. It sounds like a vacuum leak,

41) EGO(H025)NOT SWITCHING RICH +LEAN

91) LEFT EGO SENSOR LEAN OR NOT SWITCHING

thank you,
-Jeff
41 is no switching detected on right HEGO
91 is the same on the opposite side.

I'd say that you might not have the oxy sensor connected properly or at all. Check the wires to make sure they are intact and connected fully.

i'd also clear the codes and run for a day and check again. All other codes you got were related to you not performing the tasks that were part of the test process.

And if you are hearing a vacuum leak, check to make sure the connections at the SC top, IC, and manifold are all sealed tight.
 
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