ace99x2002

I have a 2003 Lancer oz rally edition.
well just started having this issue today. well when i cranked my car i noticed my rpms rose to about 2000 rpm and stopped instantly and went back to 600 or so like it had reached a cap and when i tried to take off my rpms did the same its started like it wanted to take off and go but nothing it just dropped down as if i didnt have the accelerator depressed. i have no clue what the issue is. i have changed coil packs, plugs, wires and ran a fuel system cleaner through it but still doing it.
Any advice would be great

Automatic 51

iTrader: (2)

Is the check engine light on? Is it thowing and error codes? Is it idling? If it is is it smooth or rough idle?

Did problems start after you replaced the plugs/packs/wires?

Could be anything from vacuum leak to a bad mass airflow sensor.

ace99x2002

yea the check engine light is on. the code is P0420 i think and its idling normal. no movement. smooth idle. and yea but it was a few weeks after the tune up

But update i added seafoam to my gas tank and problem has gone away.

hunter92

Just wondering you ever experienced this behavior again after using the seafoam?

Just adding my experience here. I have the exact same behavior. 2003 Mistubishi Lancer ES. I stomp on the gas and lose all power, as if I had let off the accelerator entirely. It's not just stuttering or losing one cylinder. The car literally begins to coast until I let off the accelerator about half way. I let off the throttle and ease back into it and the car goes, but I have to accelerate slowly. If I go to wide open throttle WOT too quickly, I begin to coast again. Started out as an intermittent problem. Happened once, then again about a month later and in between, I was stomping on the gas like normal. It just became more frequent over the last couple months. Now it is pretty much every time I go to WOT.

I have changed spark plugs, O2 sensors (upstream and downstream), cleaned air intake, force air sensor compartment, and throttle intake (where the air finally enters the head). I've tried techron fuel injector cleaner twice.

Guy at O'Reilly said it sounded like throttle position sensor. I checked the throttle position sensor with a multi-meter and it appears to be working properly. I tested by removing the sensor and attaching it to a solid surface, hooking up the multi-meter and simulating WOT with a flat screw-driver about 50 times. Each time the multi-meter reading went from near about 420 to 2410 ohms or vice versa if I switch terminals on the sensor. I also tried jiggling and tapping the sensor and there was never a single instance of failure.

I also swapped the horn and MFI relays and horn still works and problem persists.

Fuel filter is non-replaceable? Only thing left I know to try is the fuel pump, unless sea-foam works.

02modlanceroz

iTrader: (2)

Do you have any engine codes present? Could even be a plugged up cat.

hunter92

No Service Engine light. No codes.

Tried changing fuel pump. No change. I'll try looking at the cat.

02modlanceroz

iTrader: (2)

https://www.evolutionm.net/forums/la...-problems.html

Post 11 and 12 I describe how to properly test the TPS. You shouldn't need the Mitsubishi tool. Should just be able to put the car in auxiliary and check the wires I mention with a multimeter.

jakermeister

iTrader: (11)

Sounds like a MAF problem. Recently I had the same problem due to a piggyback. My wires on my piggyback had come loose and my car was going into "limp home mode". I pulled the piggy and soldered my wires back up and it fixed it. Try cleaning your MAF.