poor gas mileage

[mthinkley]

i bought a 1990 tracker, 8v, 3spd, auto, 2 door, soft top, etc..
it sat unused for 2 years before i purchaced due to a burnt exaust valve.
recently i replace the valve and head gaskets and other gaskets that were leaking from sitting. i also noticed that one other valve was changed in the past.
Anyway, with all the valves lapped and good compression, i only get 18-19 mpg. the tracker runs better that before but has the same bad mpg as with the burnt valve.
I set the valve lash and put the timing light on. everything checks out to be right.
Then i noticed that the CEL is burned out.
I am buying a new oxygen sensor today

What else should i check? What else could cause bad mpg?
Is there any special to do to set the timing on my 90 tracker?

[LongRod]

Originally Posted by mthinkley

i bought a 1990 tracker, 8v, 3spd, auto, 2 door, soft top, etc..
it sat unused for 2 years before i purchaced due to a burnt exaust valve.
recently i replace the valve and head gaskets and other gaskets that were leaking from sitting. i also noticed that one other valve was changed in the past.
Anyway, with all the valves lapped and good compression, i only get 18-19 mpg. the tracker runs better that before but has the same bad mpg as with the burnt valve.
I set the valve lash and put the timing light on. everything checks out to be right.
Then i noticed that the CEL is burned out.
I am buying a new oxygen sensor today

What else should i check? What else could cause bad mpg?
Is there any special to do to set the timing on my 90 tracker?

I'm rather slow witted when it comes to these things but you'll be able to tell more after you replace your CEL and can see what codes your OBD-I is sending out. I assume you have no exhaust manifold cracks. Possibilities could be, oxygen sensor, engine coolant temperature sensor, thermostat or your computer needs new capacitors.

[jtgh]

above , all. and... 90 8valve.
yes, you must jumper the DLC and freeze the timing before setting it.

there a huge list that can cause MPG drop as you say. 18mpg. < in the horrible cat.

1st, why not fix that bad CEL lamp.? then pull the codes. 12 = normal.

my short list: (in no order)
1: ECU bad, new cap.'s are needed , just replace them for $1
2: EGR leaking or bad.
3: more than one sensor bad causing ECU to drop ! to Failsafe or worse backup mode.
4: bad ECT, or IAT sensor . reading high all the time= richer.
5: bad o2 but yours is way worse than any o2 can correct, IMHO.
6: Fuel pressure reg. stuck closed.
7: cracked in exhaust from head to manifold gasket point to the end of Catcon.

is car stock? No mods no missing things , like cat cons and the like.?

ahhh,
huge list.
Bad-GAS-Mileage-Poor-MPG


keep in mind no CEL at key on , means, ECU malfunction. ( its way of saying, i failed my self tests)

[mthinkley]

i put a new o2 sensor on today and replaced the bulb for the cel
as for the timing the only information i can get is for a 1990 there is no need for a jumper. is this right? what and where do i freeze the timing advance?
i have replaced the spark plugs, cap and rotor, cleaned the egr (seems to be working properly), and replaced alot of gaskets.
the only modifications that i have done was put an electric fan in replace of the clutch fan and removed the catalatic converter.

[mthinkley]

how would i go about pulling codes for a 1990?

[jtgh]

you 90 is just like my 91 ,

89 is only weird year.
it don't have EGR fail codes in 90 ,i think,but it just quietly fails and gives bad MPG.

Check Engine Lamp stuck ON?

bad new on cat, as that will make the egr mod valve useless. (cause and effect)

that bottom tube, on the mod valve will detect NO exhaust back pressure. ( oops)
now this valve will stick open and flood exhaust into the intake and cause closed loop to never happen or worse , failsafe ,(rich mix and retarded timing.)
The mod valve , defaults to flood exhaust, and that is really a bummer.
YOu,see after starting car this back pressure, haults this flood and and then modulates the EGR based on engine load (sensed by back pressure) , the more the engine load ,the more back pressure.

see see my link above.
it is just a link off my sig . below.


click my sig; it has IGN timng, valve and all codes.

Ok you replaced CEL lamp.

now, turn the ign key on, do not start, does it glow?
next test
start car , does the glowing CEL above , go OUT?
now place the DTC jumper , it MUST flash out code 12, flash, pause flash flash, repeat for ever.
no codes is bad ecu
12 = good
other coming out 1 after the other is throwing DTC codes, read them, report them.

tell more, please.

cheers.

we dont get too many 90s, fun !

[mthinkley]

first off, thank you for all of your advice

i found the plug under the hood to place the jumper but it only has 3 wires in the 4 block (a,b,and c) there is a bigger gauge single wire(orange) close to it with a barrel style terminal.
i also flipped the switch for the mil or ses and the cel never went off.

i placed the jumper in terminals b and c anyway and the cel never flashed or blinked, it just glowed steady

now im confused.

mike

[mthinkley]

i noticed in comparison to jtgh's pictures that my distributer is different (it has a vacuum). also my 1990 tracker does not have a IAC and my rotor is shaped different.
another thing is that the tracker originaly had A/C but was removed before i purchaced it.

maybe this information can be useful
thanks
mike

[jtgh]

your IAC on the Throttle body is only rotated 90 degress ,nothing more than that.

or are you far from here (usa) and have a carb car?

vacuum implies carb.
EFI needs no vacuum on the dizzy. ecu runs it.

tells us what you really have.


the worlds a big place and there many a diff. 90 kick model.
what country you reside.?

[jtgh]

not usa/canada?
what your body tag say, fire wall center engine bay.
dont leave home with out it, ahahahahah


read body tag


see FAEnnnnn what's yours.?

the last 2 digits are the market code , with out it , nothing smart happens.

wrong parts, wrong diagnosis,etc.