Engine Problem? Maybe Nothing Major
 

Hey guys,

So I dont frequent the boards to often just for the shear lack of time. So my apologizes up front for not contributing more. But none the less wanted to see if I could get some much need help.

So for the past 2-3 months, occasionally my 04 will be sluggish when starting, taking around 5-6 seconds to start. Doesnt happen all the time but maybe once or twice a week. Keep in mind that I drive quite a bit. Probably 200 miles/week.

Fast forward to today.

My wife and I decide were going to take a trip down Natchez Trace (Scenic Highway from Nashville, TN to Tupelo, MS). Car was running great all day, no problems at all.

We head back home and as im getting off Natchez Trace and onto the interstate, I downshift to 3rd to merge into traffic. I get on the gas pretty heavy to get up to speed. Right as I hit 5k -6k the car bogs completely down. Felt like it just all of the sudden wasnt getting any gas, no power, or like a huge vacuum leak. (trying to be descriptive) Well at that point, I couldnt accelerate at all (no power) until I let up off the gas and back on it.

Backtrack maybe 6 months ago, I had the extact same thing happen ONCE when I was pulling out of my driveway. Was on the gas hard in first and it bogged down, almost like the car was getting no power. Again had to lift and reapply to get going.

So I'm a tad worried at this point and I'm curious to see if it ill do it again. I downshift and get on the throttle and it does it again. Almost like a its missing, and then the harder I press on the pedal it does that whole bogging down thing, until I life off the pedal. Continues to stutter/bog if I go over half throttle, for the next 50 miles.

So we continue to drive home, me being extra cautious.

We get off the interstate and hit a red light. Shift to first and take off, pedal maybe halfway down. Car studders, bogs and then as I lift off the gas, the car dies.

So I pull over thinking the motor is dead. Try to start the car and BAM, starts right up. Stutters a few seconds and then smoothly idles out. Its at this point where im thoroughly confused.

Start driving for home, get on the last stretch of interstate. At that point I noticed that it didnt seem to stutter or bog as I was getting on the interstate.....

So now im even more confused....

So I want to see if it will do it again. Downshift to 4th at 65mph and put the pedal down, take it to 8k....no stutter/bog....shift to 5th.....take it to 7k (108mph).....still no stutter/bog....I lift off....

HUH? WHAT? So now im just completely lost? 15 minutes ago I thought the thing was blown......

So yeah, sorry for the long post but I reid to include as much as possible...

Thanks in advance guys!

Please give us all the info on your car,miles,service done,mods,etc. You need to get the code read to see the problem... you are getting a cel aren't you?. Has it been flooded ever? It could be cat or fuel pump...we need to know...how many miles on your plugs,coils..etc.

Sorry, Its an 04 6-speed. 115k miles. Just had the oil changed yesterday. Oil changed every 3 -4k miles. Borla stainless steel catback. I bought the car a year ago this month from a local Mzda dealer and the car was taken very good care of. Didnt receive any service records.

Yes, I am getting a CEL. Matter of fact, CEL has been on for about 2 months. Had the codes pulled the day it came on and it pulled a P0037 (rear o2). From doing some research, I didnt replace it because most everyone said it did not effect performance. To my knowledge it has never been flooded.

As far as milage on plugs, coils, etc....I dont know. I cant remember if the dealer said they had been changed when I bought it or not. But I do know I have not replaced anything on the car, minus changing the oil.

Also, meant to add that for the last couple months I have been noticing a slight burning smell when I stop, after driving for a bit. Coming from the engine bay. No smoke, nothing noticably burnt, just a slight burning smell.

Did you read that here?? That code is a good indicator of a failed catalytic converter which needs to be fixed. I would first change the rear o2 sensor.

Ya this ....

The Rear O2 doesn't impact anything if you've removed the catalytic converter.
Thus the Rear O2 will report a cat efficiency problem.
But damn if you have a catalytic installed .... and the Rear O2 is reporting a problem then something is wrong somewhere.

I've had to replace my Rear O2 btw as an fyi.

I might suspect coils .....
Wow especially with that mileage ... if they haven't been change ..
I think you're the high mile winner for coils.

Ok, yeah that makes sense about the rear o2. Thanks for the clarification....
So I guess my steps would be replacing the rear 02 and coils? Are these DIY-able?

And also, anyway to check if its a clogged cat? Could that be a cause?

Yes coils and the Rear O2 are completely DIY-able.

For the Rear O2 and to check the catalytic you'll need a jack and jack stands.
IIRC you'll need a 22mm wrench to remove the O2 sensor.

The only way I know how to check the catalytic is to look at it or go for a Etest.
If it looks broken or clogged ... you need a new one.

If your going to replace coils .. you should consider coils from BHR (www.blackhaloracing.com)

Edit: Oh if you are going to do work on the exhaust ..... Buy some Liquid wrench and spray any bolt/nut and rear O2 well in advance (like over night!)

another indication if your cat is going bad is that it will be glowing red after a hard drive.