Have an ‘06 with all flashes and TSBs up to date. 60K miles. I’m the original owner. 5W20 oil changed regularly, no pre-mix, burn 93 octane Chevron only, spirited driving habits with rev to 8K multiple times daily, all new plugs @ 51K miles. Engine coolant is bypassed around the throttle body. Air box has one of the screens removed. Air filter is clean.

My problems occur after 1-2 hours at 80+ mph on highway. Acceleration to pass is noticeably reduced. When I get off the highway, engine idle is not smooth. Power is diminished and engine is much more noisy (more “throaty” sounding), some pinging can be heard (marbles in a can), engine seems to be laboring. After engine cools for several hours, problems disappear.

Anyone have any guesses?

 

CAT getting hot and clogged up?

 

Get an add on OBD2 gauge/reader, check the temp...

 

First of all THANK YOU! excellent information to start. really appreciate you taking the time int he first post to do that.


i would lean towards cat or fuel pump. take a look under when the symptoms appear and see if the cat is glowing.

do a lot of highway driving?

 

Will check for glowing. May be awhile before I can get away. Yes, I do a fair amount of highway driving.

 

Thanks for the reply. OBD2 guage/reader? Plz explain. Read temp of what?

 

If you have the original ignition coils, chances are that they are weak and have begun to destroy the catalyst. You will also want to clean the MAF sensor, reset the e-shaft profile, and clean the e-shaft sensor. If you can spring for it, now is also the time to have a competent compression test performed.

 

Indeed have original ignition coils. I clean the MAF sensor when I replace the air filter. Resetting eccentric shaft profile: given that I have not had any major repairs, what causes it to need resetting? I've been suspecting the cat.

 

Ordered an Ultragauge OBD2 guage today. Looks like a way cool toy...er...tool.

 

disconnected battery.

 

The e-shaft sensor profile will, on ocassion, fall out of calibration (or the battery has been disconnected, as Zoom mentioned) and the "20 Brake Pedal Stomp" procedure needs to be performed to reset it. Dealer techs, for example, often forget to do this after engine swaps or any time the front pulleys are removed from the engine and they will usually end up with a blinking CEL (misfires). I had an East Coast turbo shop contact me a few months ago with the same problem and their customer was quite upset. After the reset was performed, everyone was happy.

You may wanna do a search on the 20 Brake Pedal Stomp, otherwise you may get flamed.

 

I get the car back tomorrow. I'll do "the 20 stomp" this weekend. Thanks.

 

Update:

Took my 8 to the dealer for the normal 60K mile PM stuff and asked him to solve the “loss of power after highway driving” problem I described at the beginning of this thread. He said there were no codes indicating a problem (no surprise there) and that the car was running great (no surprise there either). I asked if the CAT could be deteriorating slowly and he admitted that could be possible and that my CAT was still under warranty.

So, is there a definitive test(s) that can pinpoint whether the CAT is dying?

 

Yes, and it is performed at the dealer.

 

And your warranty for your CAT is 80k miles so you have nothing to worry about. Might as well get a new one if you can.

 

Agree on gett ing a new CAT. However, the dealer is being somewhat evasive about what testing they have done. They say there are no codes indicating the CAT. I asked, so, what tests have you done with external equipment and got some words about testing the exhaust. I don't think they are accustomed to dealing with people that can understand the technical aspects.

 

Rattles under the car I thougth might be clutch issue = I had dealer check it out during oil change. He opened up the exhaust and took out a few melted parts of the honeycomb looked like stones. New cat FREE at 60k in my 04!! No problem anymore. $1152 for the cat otherwise. Had to wait 3 days over the holidays to get a new one but worth the wait. He told me not to drive it as might plug up and blow out intake gaskets. I obeyed. Car is faster now.

 

Where on East Coast of Florida? What County if nothing else.
Seems like I have read of quite a few 06's with what I would term "early CAT issues"...........I'm just saying.

 

Brevard County, Palm Bay.

 

Well, If your new toy(tool) doesn't show any codes, then I would probably drop the CAT at the front and peer in with a flashlight and see if the honeycomb is still looking okay.
You might want to take it for a good spirited drive at dusk and when you get home, look to see if it is glowing first.

I work basically at the corner of Robert Conlan Blvd and Palm Bay road.

Just for grins......when was the last time you changed you coils if ever?

 

Original coils. I've noticed no misfires so far (there was one transient code for misfire at 40MPH). I'm thinking it's time. I went out to do that drive last night but got preempted. I'll try this weekend.

Friday I have to go to West Palm. I told the dealer I was returning directly to his doorstep and making him drive the car. That will be 2+ hours at high speed.

I'm in Bldg Ren (53).

 

Oh! You threw me a little with the "Bldg Ren" still not sure what that means?
Possibly same campus then(sort of....I suppose) I'm in 62!


So.........we know who the dealer is if you are talking in Melbourne..............and I'll be honest........they are pretty good overall.

It's time to do those coils for sure, and you might wanna take a good hard look at the wires, but probably okay.
I'm actually shying away from the CAT now with the info you have given. It could just be weak or going coil(s) that are really hot after a long extended run. If it is the coils and they are getting weak..........CAT failure will eventually occur. Keep an eye out for a flashing CEL while on the way to WP this weekend.
I don't have stock coils, but if I did.............I would be changing them about every 25k miles. Seriously.......I would be.

 

I was thinking coils and wires. Can you recco a good brand?

 

If going with OEM(Mazda coils), then just hunt around on the vendors section of this site and look for the best price. Will be way cheaper than the dealer for sure!

Check back in ten minutes and I'll give ya a few inks.

 

BHR is the best although stock replacements are good too, especially if you are not FI. I was reading the other day that you can get stock coils from AutoZone for about $30 a piece.