2002 P5 Acceleration Problem

[limate]

I drove my car back from work to home on local roads, and everything was good at the beginning. But during the driving suddenly I noticed my car stuck at 25mph, no matter how I pressed my acceleration pedal: the engine speed rose from 1k rpm to 3k rpm, but the car speed was kept below 30mph. It seemed the car did not get any power delivered. At the same time I could hear exhaust pipe made larger noise. After several minutes like this, I had to pull it over. Then I switched the gear to parking, and noticed engine speed dropped suddenly to 500 rpm for a few second, but it returned to 800 rpm. I also got out of the car and checked the exhaust pipe; observed it was shaking, but smell was not too bad. At this moment I decided to turn off the engine ( no CEL on during the incidence).

After one minute, I turned on the engine, and the car was back to normal with all the symptoms I mentioned above disappeared. I finished the rest 5-mile ride with 40mph, no more problems.

My car is 02 P5 with auto transmission and a 50k mileage. The EGR valve was changed 10-day ago according to a dealer's diagnosis based on my CEL issue.
Here is my last thread with details:
http://www.msprotege.com/forum/showthread.php?t=123731998

I am concerned the EGR valve was not the root cause of my previous problem. Would you please share your comments and suggestions on how to deal with this issue? Thank you very much for the inputs.

 

[echofall]

This is exactly what happened to me before I replaced my ignition coils. Just like you, i had to pull over and turn the car off, turn it back on and it was back to normal. But the odd thing is that you didnt get a CEL, when it happened to me I got the misfire code P0300.

 

[limate]

echofall,

Thank you for the reply. Actually my previous CEL code was P0300 but without today's symptom, that was why I changed EGR valve based on Mazda dealer's diagnosis.

Would you please share where to buy the ignition coils? Did you change spark plugs and plug wires at the same time? How many times the problems happened before you made the change?

Regards,

limate

 

[echofall]

The misfiring happened to me at least once everytime i drove the car, probably about 15 occurrences. The cheapest ($35 each) I found was at www.RockAuto.com which surprisingly is located in the city i live in. I suggest changing plugs and wires also, misfire tends to corrupt plugs and my rule if thumb is replace wires with new coils. Replacing the EGR was a good move as Ive read that the original EGRs have issues.

I should mention before you go spending money, you should check to see if your fuel pump screen isnt clogged. This is also a culprit to random misfires. I say this because it is very cheap to check if you are handy with simple tools, and a new screen is only like $10. You can get a detailed how-to with pictures in the how-to section for removing the pump.

I hope this helps, good luck

 

[limate]

Finalized the parts for change today, but ignition coils would not be available till two days later. However, got a CEL with code P0421 on the way home, and light was on without flashing.

Definition: Catalyst efficiency low-bank 1
Possible causes:
1. Catalytic Converter defective (Failure possibly due to #2,3,4)
2. Engine misfire or running condition
3. Large vacuum leak
4. Engine oil leakage into exhaust-valve guide seals, piston rings.

Would it be ok to keep driving the car for two more days while waiting for the parts? I do not know if the catalytic converter will be damaged by this.

Thank you so much for any replies.

 

[echofall]

I had the same code come up twice during my ordeal. Im sure it had something to do with the misfiring. I did drive my car in this condition knowing that I was going to replace my cat with a header, so it didnt matter to me weather or not I ruined my cat, which at the time i thought i had melted it but wasnt the case. I believe most people on this forum would advise not driving it until you get the parts, but I believe you should be fine if you take it easy while driving, and pull over immediately if it starts to misfire.

 

[limate]

Hi all,

Replaced spark plugs, wires, and coil packs today, also reset the CEL code. Drove home without further issues yet, and tested one of the old coils to find out huge resistance. Hope this is the root cause!

It turned out that the damn stealership was so bad in doing the diagnosis while charging so much for the useless inspection.

Will watch carefully in the following days and cross my fingers.

Special thanks to echofall and flash75 for the warm-hearted help.

 

[limate]

Bad luck came back this morning with same code repeating.

My friend cleared the code before I tried to set up an appointment with the damn stealership since I was told the cat is still under warranty. But the car is running stably, so it would not be a bad idea to watch it carefully several more days to be sure the pre-cat was the problem, not the O2 sensors.

Driving 10 more miles w/o issues after today's code reset.

Is there any quick way to check O2 sensors?

Thanks!

 

[TheMAN]

forget the O2 sensor and stop clearing the codes... the problem you had before already damaged the cat more than likely because you kept driving the car after the "CEL" was blinking or turned on... P0300 or any misfires for that matter are terrible to cats

be glad your cat is still under warranty... get it replaced! it could possibly be melted which could also cause the lack of power issues

 

[limate]

Thank you for the inputs, THEMAN!

My only concern is the incapable local dealer since they gave me wrong diagnosis when my first P0300 showed up. They might point me another direction when I bring the car in by saying not the cat problem blah blah...

Is there any good way when I deal with them to get the pre-cat changed w/o any rip-off?

 

[TheMAN]

for the protege, P0300 misfires are often caused by a bad EGR valve... this has been numerously documented, especially in the official TSBs... like I said, continued driving with a misfire problem WILL damage the cat... the cause of your problems stems from the EGR valve, but it has caused a domino effect in which your cat is now bad also

as long as you know it is a P0421 code and nothing else, just go to the dealer and play dumb... they'll make you agree to their 1 hour diagnostic fee but if they happen to "find" it is the cat, then the diagnosis should be covered under warranty.... in otherwords, if they do replace you cat, do NOT in any circumstance let you pay for their diagnosis time

 

[limate]

TheMan,

I have made an appointment with the dealer for Monday since the CEL was back.

Please allow me for a follow-up question: why it is better to play dumb in approaching the dealer to do the warranty work? For example, if the dealer treats me as a dumb, and told me there is a P0421 code, but the problem comes from vacuum leak or oxygen sensor, what should I do?

What will be the bad side if I told them I know the CEL code?

A clarification from my last diagnosis experience with the dealer: it seemed that they did not follow the diagnosis procedure for P0300 (based on the service manual) in giving me the conclusion that EGR valve was bad. The ignition system should be checked before throwing doubt on the EGR. If they followed a right procedure, then the coil problem should be caught. I thought that they just looked at TSB after getting my CEL code without further real diagnosis. This gave me the concern that they might treat the P0421 code at will.

Thank you so much!

 

[TheMAN]

well then if it was that way then they ought to just give you a new cat just by looking at the code

you can either be very knowledgeable and it'll be hard for them to give you s***, or you can "know enough to be dangerous" and they will treat you like a hotshot and give you hassles... or you can play dumb and they can just do their job and then later on if they try to screw you, you know how to catch them if you're smart

yes, there's a way to check for a bad cat, but that involves time and know-how

 

[echofall]

yes, there's a way to check for a bad cat, but that involves time and know-how

ultrasound is a good way to check if a cat has been cracked or melted, but that involves cutting the metal away from the catalyst

 

[limate]

Hi all,

Playing dumb today worked, but it was not easy. I will be back next week to get the work done, so far nothing will be charged orally from the dealer (after a small fight). They are really not honest in the nature.

I will keep you posted till the story finishes.

Thanks a bunch for helpful comments from TheMan and winston3x.

 

[limate]

Hi All,

I got the warranty repair done on Monday, and did not get the paperwork (simple one page stating just changed pre-cat and gasket)until today. Good thing is to be rip-off free.

The service manager originally tried to take advantage of my playing dumb by quoting me parts and labor charges till I showed the evidence of warranty that he should have been clearly aware from the beginning.

Be careful when dealing any stealership.

 

[echofall]

Good for you. How is the car running now?

 

[limate]

It is running normal w/o issues now. Thank you all for the kind and helpful comments.

 

[bgibb68]

woot....p5's running strong....what i wanna hear

 

[idrift4wd]

sry to highjack but my first gear seems really heavy. like it doesnt pull like it use to. should i get it checked out?