Rough Performance

[alansrs]

Hi, have been having troubles lately with my 2003 Celica GT.
It all started with the check engine coming on but the car was running good so just to make sure I took it to a mechanic and on the computer test there were engine misfire in cylinders 1, 2 & 4. The mechanic told me that the coil packs were bad and probably needed to clean the injectors and I did it, the check engine light came back the next day. My next try was to change the the oil (20-50w), sparks plugs (double spark) and air filter, the light came back again in one day. The car was running ok but I notice the mpg was going down and in some rare ocations the car takes around 10 seconds to start but everything got worst this week when I was going to work the car hesitates when I accelerate it seems too loose power, a little bit jerky the acceleration and the check engine light started to blink so I decided to stop and the light stop blinking so I continue but that has been the case all week when i give it too much gas the car doesn't response and the light starts blinking so I have to drive very carefully these days. BTW I clean de mass air flow sensor and that didn't work also.

What could it be? O2 sensor? Fuel pump? Fuel filter(located with the pump)? some valve? Do I need a new car?

Thanks,

[Jasonhughes2009]

hows the wiring harness and connectors going to the injectors and coil packs? damages,corroded,missing insulation?

[alansrs]

The wiriring? I have only visual inspect them and they look ok too me but is there another method to check how's the wiriring working?

[Jasonhughes2009]

visually inspect the connectors and terminals too
wiggle test
go get a dmm and check voltages going to the coils

[alansrs]

Ok I'll check those cables but the revs are ok when the care is Idle, could it possibly be the Fuel Pump?

[Jasonhughes2009]

less you have an oscope to do a current ramp test on it just do a fuel pressure gauge and report back.

[tauntline]

why would you use 20 w 50 on a small engine? im just wondering because i know a small engine i usually used 10 w 30 so the engine might be struggling with using such a thick oil

[Hitz]

Hi I'm a new guy here
my celica surges when i turn the a/c on but when i turn it off it idles fine.
does anyone know what can be the cause?

[Jasonhughes2009]

Originally Posted by Hitz

Hi I'm a new guy here
my celica surges when i turn the a/c on but when i turn it off it idles fine.
does anyone know what can be the cause?

seized/dragging compressor clutch. probably paired with a failing alternator.

if its just at idle then that's normal. the AC clutch kicks in putting a load on the engine and the pcm sees the AC clutch request and bumps up idle speed due to the extra load

[Jasonhughes2009]

Originally Posted by tauntline

why would you use 20 w 50 on a small engine? im just wondering because i know a small engine i usually used 10 w 30 so the engine might be struggling with using such a thick oil

a **** ton of miles is why you'd use it. but that still seems excessive for a small gasoline engine.