'90 gt-s hatchback problem - Toyota Nation Forum : Toyota Car and Truck Forums

GTSR5Corolla · 12-27-2004, 04:14 PM

Seems like I'm having a gas issue with my celica.. 5sfe.. 5spd.

WHen the needle is around 1/4 I'm only at like a 180miles.. and that's on a completely full over-filled gas tank lol..

Also every couple of days it'll start to run sloppy.. get like real jerky.. It ain't my driving either.. cuz I pull the intake tubing off the throttle body and spray a SHITLOAD of carb cleaner in there.. let it sit for a little bit and then start the car up.. go out and whip it around hard around the block and then it'll run fine.. purrrrr for a few days.. no jerkin or anything when lettin the clutch out.. etc it's real smooth.. I don't know what's up.. I gotta pull spark plugs.. I know the old ones looked ok though.. a tannish/white color.. so it isn't running rich.. causing bad gas mileage.. Does the tank needle just fall far below where the tank is really at?

I put a new T-stat in.. new NGK spark plugs.. air filter is clean... everything on it is factory i haven't modified anything. I checked the vacuum at warm idle and I got a healthy 21-22" of vacuum.. so the valve seals appear to be good.. the oil smells like oil.. so no gas in there.. I changed the oil with 10W30 Valvoline Durablend.. been in there for a little while now.. so oil is fine.. no coolant leaks.. nothin.. I can't explain the bad gas mileage.. I thought maybe it is the O2.. yet I put multi-meter on the O2 and I get a reading.. usually around 400-600mV .. so I mean the O2 sensor seems to be working unless it's goin out intermittenly or something..

Any suggestions would be appreciated!

Deep · 12-28-2004, 02:04 PM

Condensation in the tank? Stick Idle Air Control Valve? Clogged fuel filter? Heavy right foot?

GTSR5Corolla · 12-29-2004, 04:06 AM

No heavy right foot.. I rarely speed or jump on the peddle.. condensation in the tank? Clogged fuel filter.. I'm not positive how this would cause bad gas mileage though as if anything it would cause their to be less fuel getting to the injectors... and the idle is fine.. so the IACV isn't stuck...

I'm more interested in this rough driving problem though.. I think that is causing my bad mileage and I'm thinking it might be the PCV Valve or something letting oil into the manifold.. clogging shit up.. maybe it's a clogged up EGR valve.. I'm not positive just yet.

WHere the heck is the PCV Valve on this engine anyway? I can't fricken find it!! LOL

Pineapple · 12-29-2004, 09:42 AM

No PCV on 5S-FE

How old is the O2? A slow respond O2 will cause bad milage. Slow respond -> take long time to get heat up or won't heat up at idle. Use a bottle of injection cleaner, clean the intake manifold and throttle body. Also check ignition coil. Take it out to see if its rusted to hell.

GTSR5Corolla · 12-29-2004, 02:21 PM

I pulled the distro cap and it looked fine inside.. Like I said above.. I have to spray the intake manifold down with carb cleaner.. like mad crazy and then start the car up .. and go whip it around.. then it'll drive like a dream for a few days

It's a single wire O2 sensor.. so no heater.. can I replace the O2 sensor with one from my old 4AF (which was a single wire sensor as well)?

It's either that or one off my 7afe.

Pineapple · 12-29-2004, 02:31 PM

Heater or not, O2 sensor need to get heat up first to work. No heater O2 need exhaust gas to heat it up. Old sensor will take longer to get hot enough and sometime won't. An old sensor will looks like it works with a hot engine. Unless you got a A/F gauge to see if its working or not, its kinda hard to check. You can idle a cold engine and see how long it take for the sensor to give you voltage.
Its never a good idea to use old O2 unless you tested it and know its not a slow respond.

GTSR5Corolla · 12-29-2004, 03:33 PM

Well all I was asking is if basically all O2 sensors are the same.. I know they need to heat up and stay hot.

I mean if basically all "universal" O2 sensors are the same I will just get a heated sensor and wire it in.

Pineapple · 12-29-2004, 03:40 PM

Yes, they're all the same. As long as you can bolt it on and you know how to rewire it.

speedyts49 · 12-29-2004, 11:08 PM

Quote:

Originally Posted by GTSR5Corolla

Seems like I'm having a gas issue with my celica.. 5sfe.. 5spd.

WHen the needle is around 1/4 I'm only at like a 180miles.. and that's on a completely full over-filled gas tank lol..

Lucky! Last tank I only got 14 mpg city driving and at a 1/4 I was at 150 miles on the odo.
Got 20 on a highway only run. I recently changed plugs to the correct ones but I think its mostly a lead foot on my car.
Sorry about borrowing the thread.

GTSR5Corolla · 12-30-2004, 12:20 AM

Well good news.. got a 152K on the car.. pulled O2 sensor.. it is the original toyota one still!.. it's shot.. i bench tested it.. it either read or it didn't read.. wasn't able to get a steady reading at all.. so i grabbed my old (yet very good) 4AF o2 sensor.. has the same fricken plug on it as the 5sfe!... so I found an old flange.. screwed the o2 sensor into the flange and slapped it on the 5sfe manifold..

i read O2 voltage with it disconnected.. the O2 was reading 600-700mV at idle!!! explains bad gas mileage.. lol

I noticed on the engine harness side of the o2 wire that right at the elec. fitting the wire was cracked open and the copper was corroded.. so i reconnected the o2 and tried reading the voltage there.. i could only read 200 to 300mV.. so apparently the ECU is seeing a lean condition from the O2 sensor.. so it is pumpin more gas in tryin to correct it.. yet because of the wire corrosion it doesn't know what the fuck is goin on that it is really running rich.. so since the cracked wire is right on the connector i have no choice but the cut the connector off.. i can't re-solder it or anything.. so i gotta cut both ends of the wire and use quick connect terminals.

GTSR5Corolla · 12-31-2004, 03:40 AM

as it turns out i may have an oil leak.. which would explain my oil loss. As for the performance issue.. I don't know. I'm gonna run sea foam through the intake manifold, gas tank and crankcase.. The car probably sat a long time before I bought it so it very well may explain all the build up in the intake manifold.

The new O2 sensor works.. I tested TPS and coolant temp sensor.. they both check out fine.. I tested the EGR system...
I very well may have a LOT of shit built up in the EGR system.. hopefully I can sea foam it all good.