Loosing power while driving around an hour, comes and goes

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2003 mazda protege 5
Hello everyone im new to the forum and would greatly appreciate it if some can help me solve a prolem So ive had my 03 mazda p5 for about 3 months, and now it does this thing when i drive in the freeway at a constant speed for about an hour or so it accelerates like its strugling and wont let me speed up wont let me pass 4000 rpm for about 20 seconds then it goes back to normal and accelerates normal and then i can actually speed up . It comes and gooes so i have to stop and wait for it to cool down after that i can start driving But it will keep doing it. It seems the problem happens after 45-60 mins of driving so i think i has to be either a censor or throttle body iacv, map, etc Im going to replace the coils and spark plug wires next, ive already changed the oil, spark plus, and coil boots. can some one please HELP before i sell it and buy a civic
 
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pcb

The Diagram Dude
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2002 MP5
Coils sound like a good idea.
Sometimes they only fail once the car is hot.
 
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Mazda, Protege5
I had an issue that was much, much worse than yours, but it started out by losing power while cruising down the interstate. At the beginning it felt like the car was losing power and I had to floor the pedal just to keep it from dropping too much. Then it would just fix itself.

It got a lot worse, and to the point of stalling, and not starting back up. I never got any CELs with the issue and couldn't figure it out.

It ended up being the wire of the crankshaft positioning sensor rubbing on a pulley and getting damaged. I found it by accident while checking out something else.

I'm not saying that is your problem, but it is an easy and quick thing to check.

I would go with what pcb is recommending and checking out the coils. Coils are super cheap and is a common cause of issues for the P5.

Judging from what you said, it could potentially be many other things.

Other things to check out, plugs, plug wires, fuel pump/filter, fuel regulator, camshaft positioning sensor, airflow meter, a lot of other sensors....

Do you have any CELs?
 

Natey

Moderator
Contributor
Patron
I'd put a new 02 sensor in. Cheap, pretty easy to replace and they are a wear item so even if it's not the issue it definitely wont hurt to slap a new one in. (thumb)
 

pcb

The Diagram Dude
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2002 MP5
I'd put a new 02 sensor in. Cheap, pretty easy to replace and they are a wear item so even if it's not the issue it definitely wont hurt to slap a new one in. (thumb)
I question that..
O2 sensors aren't listed as a possible cause for his issue and there is a whole bunch of codes covering the O2 sensors which he should throw if he has a problem with them.



I've not replaced an O2 sensor in the nine years I've had my car.
I'm waiting till I get a code to replace them.

(although there's nothing wrong with new O2 sensors... Apparently they get old and slow down reducing efficiency.
It might take quite a while for the efficiency to drop far enough to throw a code.)

If an O2 sensor is old, it should throw a slow response code followed by a no response code when it dies.

 
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Natey

Moderator
Contributor
Patron
Well damn. Do you question that they're cheap, easy to replace or that they're a wear item?

Whatever you do, don't put a new oxygen sensor in when you get intermittent power loss. (shrug)
 
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pcb

The Diagram Dude
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2002 MP5
The price.
If they were $10~$20 I'd replace mine too.

It would cost me $72 CAD for the two cheapest oxygen sensors with tax and shipping.





Remember, my car is worth ~$250 as scrap metal (it won't pass safety without ~ $2,000 worth of welding in new metal)

So I'm financially biased with my opinions.
 
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pcb

The Diagram Dude
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2002 MP5
I remember PM'ing a guy from Oklahoma a bunch of year ago, trying to help him figure out his engine misfire issue.
He replaced his coils but it would still misfire after a complete heat soak.
He even brought an oscilloscope home from work and we went through the service manual trying to figure it out.

He finally decided to throw his old coils back on just to see and the misfiring stopped.
His brand new coils right out of the box were bad and started shorting to the valve cover when they got hot.

Coils are the source of all kinds of problems with our car and might be the only part that I would spend the money on for OEM.
(although I went with Beck-Arnley from Rockauto and they have been fine.)

The part that sucks is that when you go through the list and replace the coils with new ones, you figure they're not the problem because they're new.
Apparently Hitachi are a reliable brand as well as Polish coils.

The bench test for the coils is useless too because they're sure to behave properly on the bench then screw up when you put them back on the car.
 
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2014 Mazda3 S GT auto, 2008 MX5 6-speed
Throwing parts at the problem can cost you much more than it needs to. Unless you are well-experienced with troubleshooting, it may be better to have a reasonably-priced-work mechanic check it out.
 

Halfbaked

The F*** Up King
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Depths of Hell
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'03 Protege5
Is it just my phone browser (latest android os) or does most of these threads just abruptly end with no resolution to the original problem? Yes, I see the next/previous page buttons under many threads but almost everyone where they are very similar to my car's issues they just end...

Anyways, I'm new to this forum and new to Mazdas, what's good erryone?

Any fix for this issue? Thanks
 

pcb

The Diagram Dude
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2002 MP5
A lot of times people end up getting their car fixed and don't post about what they did to fix it.
People are more inclined to repost when the problem persists.

It would really help if people would post about how they resolved their problem so we could learn from it.
 

pcb

The Diagram Dude
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2002 MP5
If you are considering new coils, don't buy cheap ones.
Go with OEM or the Hitachi brand at RockAuto.
Hitachi is the most expensive but they are considered quality coils.
 

Halfbaked

The F*** Up King
:
Depths of Hell
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'03 Protege5
Yep, I've been a moderator on a few different big atv forums before and I've always been the type to finish through with threads for the next person coming along.

My 327 reader will be delivered tomorrow so I'll get to the bottom of it eventually lol.

Just curious if anyone has had this same exact issue as this car has, when I unplug the maf and start the car and let it run for 30 seconds without it plugged in then shut it off and plug it back in then fire it up again it runs like a champ for around 15 to 30 minutes and then the symptoms come right back
 
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