The car is a 2003 Lancer OZ with ~197k miles.

This has been an on and off issue since Sept last year. I will go through periods where deeply mashing the accelerator or trying to get up to highway speeds will cause RPMs to drop out on my car. I will intermittently get codes for warmup cat. I had a code for the EGR which went away before I got to do anything on it. Today, I had a code for the tps, egr, and multimisfire that caused the cel to light.


This is what I've done so far since Sept:

• When the warmup code pops up or the issue starts, I throw in a bottle of injector cleaner and it resolves. I haven't yet this time due to other codes.
• There were new plugs, wires put on in Sept when I replaced the valve cover/boot gaskets.
• Took car to respected muffler shop. Mechanic didn't find a block/issue.
• Cleaned throttle body best I could with special cleaner.
• Cleaned MAP with map sensor cleaner.
• Swapped TPS, just today, with junkyard one from a 02 OZ (Made it run better, with less acceleration issues "in town" and cel hasn't came on)

I plan to get an oil change tomorrow at work, and they offer a fuel injector service for $10 right now with high mileage changes that has something thru vacuum lines and a gas additive, so I figure I'll try it for $2 more than Seafoam.


I'm not sure where to go from here. My gut is leaning injectors or Fuel pump at this point, but I'm learning as I go. I can get parts pretty cheap as long as its not the actual engine as the junkyard got a 02 lancer with snapped timing belt a week or so ago.

 

When you say wires, are you referring to the ignition coils (coil packs)? How is the car at idle? Sounds like either injectors or coils. I've had 2 pumps go out on me and have also helped friends with theirs. They usually give no warning.

 

The boots. The coils I haven't replaced, and I'm not sure when last they were.

One of the times I got codes read, Autozone/O'Reilley's couldn't connect, and the shop they sent me to said the electrical readings on the tablet-like unit they connected looked normal. It was when it just threw Warm-Up Cat.


edit: The idle was a little rough, but between cleanings and other things, it's very smooth and reads fairly low, even rpms.

 

CEL came back on. P0421 and p0300.

I don't have a day off till Monday but I'm gonna gap check the plugs.

 

I'm leaning towards coil packs. My 318i had the same acceleration symptoms you describe. Car has over 215k. Surprisingly the injectors are original with no problems. Knock on wood. If an injector(s) goes out, the car will start shaking like hell. When you give it throttle, it'll feel like half the motor is missing. I've had that happen to.

If you plan on keeping the car, I'd say start with that. Might clear both codes. Since you said you already changed the plugs.

 

I'm planning to change coils as I have other sources recommending it, since I probably should anyhow. I just have to wait for my day off on monday. Car seems to run fine if I drive a bit like a granny.

 

With that amount of miles, you should change them anyway. I've seen them go out as early as 50-60k on some cars. Especially bmw's. Same thing... slightly rough idle, slow acceleration, emissions and misfire codes...

Anyway be sure to post and let us know what you find.

 

I bought two cheap but well rated/high selling coils off amazon. They got here today and I put them on and used it as an excuse to drive ~10mi to next town to over for panda express to test.

Car DEFINITELY drives and idles better, but I'm still getting mugged down if I press the pedal hard/fast. Like I can do a faster accelleration to merge now, but its still not "normal" and it bucks and shakes.

A friend who's been helping is coming to look/listen at it.

 

You should change all 4 IMO. Why did you decide to only switch out 2? Did you test them?

 

It only has 2.

 

You're right. My mistake. Slipped my mind for a sec. I'm use to replacing 4 on other motors.

 

Buddy came and looked at it. He disconnected the MAF and the issue stopped. We reconnected it, went to the junkyard I got the throttle control from, and I bought the MAF off that 02 lancer they had. Car runs smooth now. Idle is a little bumpy for around 30 seconds, but otherwise the car runs MUCH MUCH MUCH better. Probably best in years.

Now I'm just trying to decide if I even need to get a rental to go ~350mi to San Antonio in a couple months or just take this one now that it's running so good :V