gas mileage problem 98 ram

[vancamp]

I have a tech question that im kinda lost on, my daughters 98 ram 360 engine 2 wheel drive all of a sudden started dropping in fuel mileage almost half of what it normally gets, i found that the throttlr body to  air cleaner gasket was died out and broke and thought maybe it was sucking to much air making the computer dump more fuel fixed that and the same problem, the air cleaner is new, plugs and wires are good. i put a new idle air sensor on it a few months ago if it carboned up again would it cause the fuel mileage problem?

[firefighter3931]

I bet the o2 sensor needs replacing 


Ron

[Cooter]

Without looking at Data on a scanner, ther's no way we can diagnose this here....It COULD be anything from an O2 sensor to a clogged air filter, to a vaccum leak....

[vancamp]

Without looking at Data on a scanner, ther's no way we can diagnose this here....It COULD be anything from an O2 sensor to a clogged air filter, to a vaccum leak....

air filter is new and clean, i will check 02 sensor this weekend she is supoosed to bring it home and leave it with me.

[62dodge]

check for a clogged catalytic converter that was my problem went from 17 to 9 mpg

[vancamp]

ok if it is the catalytic converter and i remove it will it cause the check engine light to stay on???

[Charger RT]

if it has an o2 sensor after the cat the light will stay on.
Tim

[62dodge]

 I am not say'n that this could happen to you but when we cut the cat off for inspection and all the innards fell out (wink wink) then we welded it back in, problem solved. But then we don't have smog checks in this area.

[vancamp]

I am not say'n that this could happen to you but when we cut the cat off for inspection and all the innards fell out (wink wink) then we welded it back in, problem solved. But then we don't have smog checks in this area.

we dont have smog or inspections here, i have had several people say that it would cause the check engine to  stay on even if the 02 sensor was upstream in the exhaust due to lack of back pressure, i will have the truck this weekend so i guess i will find out.

[hemihead nc]

...if the motor PINGS constantly and uses more oil than usual, you probably have a problem with the intake gasket. We had that issue with my brothers 98 Ram and MA Mopar must have changed out 3 or 4 gasket sets over a 2 year period, with the same defective gaskets. Fel Pro has a vastly improved version, and I would imagine that Mopar caught up too. After the Fel Pro change no more problems. Good Luck.....

[John_Kunkel]

  but I think the Hughes setup is the best fix for the intake gasket.

[BrianShaughnessy]

if it has an o2 sensor after the cat the light will stay on.
Tim

If there's 2 O2's... one before the cat, and the other after...    the 2nd o2 checks for a difference from the 1st o2 to sense that the cat is working.   Sometimes people have problems with this when the exhaust is too free flowing.
I put a magnaflow 3"/3" cat on my 5.9 GC.   No codes.

but I think the Hughes setup is the best fix for the intake gasket.

Yes. Hughes has a new bottom plate deal for the kegger or the FI manifold but the price is steep.      I got a single plane 2 bbl M1 for my 5.9 and haven't really noticed losing any mileage but I gained some usable rpm over 5K.     

[FLG]

Too obvious, but have you checked for fuel leaks? 

[vancamp]

Too obvious, but have you checked for fuel leaks? 

yeah did that not so much as a drip that i could find.