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90 4.0 Idle

JT_Law

NAXJA Forum User
Location
Oregon City, OR
Hi
Got the ol 90 I'm trail rigging, when it was the wifes' it had major heating issues due to a clogged radiator, so I rerigged the electric fan so it stays off unless in defrost or ac, then is full time on, and put a 160 thermostat in.

It had had a tuneup, but after I dropped the temp it started getting 90miles to a tank :mad:

Got a new radiator in it, and today I put a 195 thermostat back in, came up to temp just fine, but now if I don't let off the gas real slow it dies, when it stays running it is about 250rpm at idle on the tach, was about 500rpm with the 160 thermo.

Any thoughts on what may be causing this?

I know to search, but frankly, we have dial up at shop, and this pc is on a 33.6 modem, lol

Thought I'd post this now and get a head start for when I get back on cable tonight in about 5 hrs, lol.

Thanks ya'll
 
I use factory wires/cap/rotor (you can get a kit from the dealer which is cheaper than buying it all seperately) and either Champion or NGK plugs gapped to .035". It could be staying in open loop due to a bad O2 sensor.


Mike R
 
my best guess is a bad o2 sensor, with the 160 thermo in it would stay in closed loop operations and never take readings from the o2 now that you are allowing the system to get to temp it starts to read the o2 sensor and that is when it begins to run bad. before ya go buy a new o2 try cleaning the one ya have with carb/brake cleaner.
 
yup in chiltons but it is located in the down pipe just after the exhaust manifold. it's the only thing in yoru exhaust with wires coming out of it
 
bj-666 said:
my best guess is a bad o2 sensor, with the 160 thermo in it would stay in closed loop operations and never take readings from the o2 now that you are allowing the system to get to temp it starts to read the o2 sensor and that is when it begins to run bad. before ya go buy a new o2 try cleaning the one ya have with carb/brake cleaner.

Open loop.


Mike R
 
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