2.0L performance/power issue

[Revy]

Hi people!

I couldn't find exactly the same issue as mine on the forum so I'll post my question here.

I bought a little 2002 Protege ES2.0 (5-speed) here in Alberta about 4 months ago, after I wrote off my VW Golf TDI. So far I have 2000km put on it and little by little it's losing power...

I checked the car over when I purchased it and saw the air intake duct was cracked and falling apart. So I parked the car and ordered up an AEM aftermarket intake and installed it as soon as I got it. I had a look at the MAF, and it looks very clean. The engine itself is actually very clean, there are no rotted parts (besides for the air duct which was replaced) and everything is rust free.

I put the OBD-II reader on it and got this code:

P0421: Warm Up Catalyst Efficiency Below Threshold (Bank 1)

So the first thing I did was put my hand over the exhaust and there is fairly good pressure there. I have to leave my hand on it for about 5 seconds in order for it to start building pressure. Not sure if that means it's leaking from somewhere else?

My question I guess is would a bad catalyst converter create such a decline in power? And by decline in power I mean that it takes a long time to get to 100km/h, and in town it takes a long time to pick up speed.

Some other things worthwhile to note would be:
- It seems there is no more throttle after I press on the gas about 1/5th of the way. I don't think it's the cable or anything mechanical.
- When I have my ear close to the top cover of the engine and give it a short rev, when it's coming down from the highest rev it makes a feint ticking sound. I'm not sure if this is something to do with the valves or what. It doesn't make that noise when it's just idling.
- I didn't get much for history on the car, which oil it took, if it burned any, or anything else. So I did an oil change and put in some 10W-30 Quaker State Ultimate Durability Full Synthetic. Ever since I did that it seems to be consuming oil, but the exhaust is very clean so to me it can't be burning it, can it? I must check for oil leaks one dry day this week and update. Checked for leaks and replaced the drain plug. Small leak from the oil pressure switch.
- I've got 11/16th tank of gas left with 200 highway kilometers on it, so mileage is fairly decent.
- The car runs relatively smoothly. Sometimes though, if I'm in second just cruising, and let off the gas it will buck a little. It does not hesitate off the start and has quick throttle response in town and on highway.

Hopefully this is all the information anyone needs to help me with this issue...

All help is appreciated.

Thank you!

Mike


EDIT ( June 20, 2013 )
More than a week ago I took a one our trip on the highway. Half way there, the check engine light started blinking. I quickly shut off the engine, pulled over and hooked up my OBD-II reader and found the code P0300 (Random/Multiple Cylinder Misfire Detected). I reset the code inside the reader and kept going. There was no apparent misfiring and the engine was running smooth as normal. I kept driving it like it was.

Just over the last two days, the car started idling rough and stalling while I had the clutch in and at idle. I looked to see if any new codes appeared and none were flagged. So I did some research and found that the EGR valve could be the culprit.

So I disconnected the throttle body cables, hoses and throttle cable and the EGR valve cable and started loosening the bolts to the throttle body. When I finally got the throttle body off of the manifold, the gasket in between crumbled in my hands. So I took some thin cardboard and made a gasket as best as I could.

After that was done I started digging into the EGR valve. It was fairly seized. So I let Brakleen sit inside it for half an hour while I put the throttle body back on. I then cleaned the EGR valve the best I could and added some oil to the inside of the valve and to the spring on the outside.

I then put everything back together and reset the PCM. When I started the car for the first time it idled at 2100rpm for a little bit then dropped down and settled at 1100rpm. When it warmed up it sat at 700rpm and stayed there. No more rough idle or stalling.

This did not, although, fix any power problems.

 

[Revy]

Bump. Can anyone shoot some ideas to me?

My only code right now is P0421.

No power, but very smooth at higher RPMs.
Lower RPMs are sometimes a little jerky.

 

[tweety2300]

Sounds like a clogged cat.

P0421 means precat isn't doing its job. P0300 will come back eventually you may not always notice the miss fire though

 

[dskelly37]

Clogged exhaust will definitely sap power. Remove your front O2 sensor and see if that alleviates the problem.

 

[dskelly37]

Also the best way to tell if you're burning oil is to pull the spark plugs and look for deposits. Honestly though, a quart or two every 5000 miles really isn't that uncommon. At the dealership, 1 quart every 1250 miles is deemed acceptable (for new cars...)

 

[Revy]

Clogged exhaust will definitely sap power. Remove your front O2 sensor and see if that alleviates the problem.

Remove it completely? I'm not 100% sure how fuel injected engines work, but wouldn't doing that make the thing run lean? I recall removing the baffle from my old 230cc dirtbike did that exactly and burnt the piston.

Also, it never burned oil before changing it. I'll have to pull those plugs some night this week, take some pictures and put them up.


I have another concern. I'm looking around for a throttle body gasket, but cannot find mine.
Here's a picture that shows the gasket they provide me and my throttle body...you can see how it's different. My car was manufactured in Japan. Does that make the throttle body different?

 

[tweety2300]

Unhook it and the Ecu will see that it's not reading it and run rich, won't hurt it at all. Ecu doesn't read the o2 sensor under wot anyway it only reads the maf and iat and dumps fuel

Was your dirt bike 2stroke? My brother built a 250cc 4stroke scooter and ran it straight piped for awhile. 2strokes however have to have back pressure

Can you post a picture of your engine bay? Sounds like you may have the fsze which will be a bit different diagnosing due to the differences. If I'm right you will have a black plastic piece on your intake manifold and may possibly have a 4-2-1 header. The major differences are the cams high compression pistons and the intake manifold which may be why your gasket is wrong and it will be obd1 iirc

 

[Revy]

Here is the picture of my engine bay. I noticed on the right side of the engine block that there is "FS9". I did some research and most people relate the FS9 to the FS-DE engine, with 130hp and 135 lb-ft of torque.

About the dirt bike, it's a 4-stroke Honda. I was told that removing the baffle caused it (an already lean running engine) to run lean, causing internal damage, unless you put bigger jets in the carb.


EDIT1: Just removed the heat plate and O2 sensor and took a drive around (with some snarls pointed at me for the loud noise of course) and the problem is still there. Still no power. Would the O2 sensors themselves cause a problem? and if so, how do I diagnose them?


EDIT2: I just thought about what you meant by removing the O2 sensor and now I'm thinking you didn't mean actually remove it from the exhaust header like I did...
So, I unplugged and tested the output. It was floating around 40-45mV at idle and shoot upwards of 700mV, but it was not consistent with the idle... During revs it would jump around everywhere from 40-750mV. Does this mean bad O2 sensor?
I drove around while unplugged, seems to alleviate some of the problem, but it still seems to be lacking a bit of power and still jerky around the low revs in 2nd. Actually, seemed to be even more jerky all around with the O2 sensor unplugged.

 

[tweety2300]

Is the check engine light on? If its not on with the car not runing turn the switch to the on position but don't start it and make sure it comes on

 

[Revy]

The check engine light is on. I checked the code and got P0421 (see OP).

Might be worth telling that when I reset the PCM, that the exact code comes back after about 90KM.

 

[Installshield 2]

the code you are seeing is related to the primary catalyst...which could be damaged, especially if the car ever went through a series of p0300's like what you experienced...if the engine is actively misfiring, the first thing to get tossed is the primary cat...raw fuel is thrown into its mesh, and ignites in there instead of the cylinders...and its life is over...

so since you're not the original owner, you don't really have a real way of knowing what kind of shape its in...a clogged catalyst very much will hurt power, as well...

I'm not saying that is the exact problem, just a possibility...the code is coming from the 2nd o2 sensor, which reads the condition of the first catalyst...the sensor itself may simply be damaged or worn out, but something else is causing the power problem...but i would first recommend removing the primary cat, looking for cracks or leaks on any of the exhaust components around there, and trying to get a good idea of what kind of shape everything is in...then let us know, and we'll go from there...

 

[tweety2300]

^ what he said, even with it sensing that it will run rich and lose more power

You can replace, gut, or delete the precat via an aftermarket header

 

[dskelly37]

Yeah, I meant physically removing the O2 sensor and driving around. I probably should have explained a little better lol. By removing the O2 sensor, you're giving the exhaust gases a place to escape if the exhaust is clogged. So if it runs better/noticeably different you are probably on the right track. Unplugging the front O2 sensor will also cause the PCM to enter open loop, so it'll run richer but it wont hurt your engine.