TCCoA Forums banner
1 - 8 of 8 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter · #1 ·
I am attempting to help my brother who owns a 1990 T-bird with the 3.8L and about 150,000 miles. On his way home from work (about a 10 mile trip) the engine began to idle higher and higher. Now following start-up it settles down to an idle of 2,500 rpm. We pulled the idle bypass valve and it looked exceptionally clean. The car is in good shape and has been returning 28 mpg. I am unsure of the age of the oxygen sensors and we could detect no vacuum leak. Hopefully this type of problem has not been beaten to death, I did a search and found nohing that matched these symptoms. Any help would be greatly appreciated.

Thanks
 

·
Registered
Joined
·
16 Posts
You have a vacume leak

You have a vacume leak some where, start tracing vacume hoses in the engine compartment. Check your PCV valve has it come out of the passenger side rocker cover? Take a pair of pliers and pinch the soft rubber lines and see what happens to your idle, for the solid vacume lines disconnect them and plug with your thumb or finger. Is black smoke coming out the exhaust?

Chris.................

Sutter said:
I am attempting to help my brother who owns a 1990 T-bird with the 3.8L and about 150,000 miles. On his way home from work (about a 10 mile trip) the engine began to idle higher and higher. Now following start-up it settles down to an idle of 2,500 rpm. We pulled the idle bypass valve and it looked exceptionally clean. The car is in good shape and has been returning 28 mpg. I am unsure of the age of the oxygen sensors and we could detect no vacuum leak. Hopefully this type of problem has not been beaten to death, I did a search and found nohing that matched these symptoms. Any help would be greatly appreciated.

Thanks
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #4 ·
gentlemen

I will advise my brother to check the above listed potiential sources. Thanks for your assistance.

Sutter
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #5 ·
Chris

I did not notice any smoke or unusual discharge from the exhaust.

I will reply with an update assuming we locate the problem.

Thanks
 

·
Administrator
1997 Thunderbird LX
Joined
·
8,785 Posts
Do the these cars (90) have a TPS (throttle positioning sensor)? If it does, this is something else that you can look into.

Joe
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #7 ·
Joe

I am certain that they do have a throttle position sensor. I think all injected engines have a TPS. I will add that to the list. With the change occuring over the duration of his drive home from work, the problem developed quickly.

Thanks
 
1 - 8 of 8 Posts
Top