spits at hwy speeds uses gas

[kota77]

93 laser w/1.8 spits at hwy speeds. uses way too much gas. can smell it's running rich. tps?? really need some help as to what to look for. thanks.

 

[92AWDHX40]

Any cels, tune up, new plugs, could be anything, bad gas?

 

[kota77]

clutch went out last june. got around to replacing in oct. has run like this since. been driving truck til it died. need to drive this. can't see anything that i may have not put back together. am stumped.

ran good til then.

 

[Infamous33]

Have you tried anything yet? My first guess would be a plug wire arching out inside the tubes. No check engine light? Might start with plugs and wires for maint. if nothing else.

 

[tmaxx411]

Check the MAF. If it goes bad, it'll cause problems with running ridiculously rich.

 

[kota77]

had a guy check it out using some snap-on dianostic computor. came up with a coolant temp sensor. sound right?

 

[DSM1G90]

When a coolant temp sensor goes bad, the ECU tells the injectors that the system needs more fuel to get the thing hot to go into closed loop for a normal operation since, with a bad sensor, the ECU thinks that the coolant temp is at 177* which is too cold for a close loop normal operation. Temp has to be around 195 to 205* for a normal temp operation.

My 1.8 did the same thing. Ran the code and it came up with my sensor gone bad.

Bad T-stat that has stuck open can do the same thing where the temp sensor is reading coolant temp levels that are sub-par that will cause the ECU in going to do the same above.

 

[kota77]

very cool someone has this happen to them. was concerned that it wasn't right. got one on order. thanks. let you know in couple days if this works.

 

[kota77]

well. put sensor in and same thing. runs crappy and uses way too much gas. running way too rich. burns your eyes almost. no check engine lights on. any clues people? thanks

 

[DSM1G90]

..are plugs black from running rich?

Have you checked belt timing? The balance belt could have let go and it went into the timing belt causing it jump a tooth or two, or something else, and this would cause poor operation as well.

This motor is a non-interference motor.

 

[kota77]

dudes!! replaced the maf and runs way better.

 

[DSM1G90]

Good luck then ... congrats on your find! - DSM

 

[kota77]

now what happens is that i get a check engine light on at idle. goes away when reving or taking off. ??????

 

[nickk90]

Plugs are probably fouled from running soo rich. Id throw some new plugs in and get some fresh plug wires.

 

[DSM1G90]

Your idle RPM is just a bit too high with pulling in more air than fuel to match causing a lean mix and the 02 sensor is picking this up as it's sensing excess oxygen and the ECU isn't telling the injectors to compensate for the lean mix, thus the CEL comes on.

CEL goes out when the A/F mix hits the normal range during open throttle conditions since the 02 is sensing the proper oxygen levels in the exhaust.

What happens here is that your two stage idle settings aren't doing their thing correctly - which is the TPS settings and the Fast Idle settings.