Wht to do.....

P

protegeforsale

Member
Hello all, i have been reading this forum like a bible for past 2 weeks,
I have a 2002 Protege5....beautiful condition!!
problem.....had for 3 weeks now, was trouble free 1st two tanks of fuel.
CEL popped on....PO300 & PO421.
I have replaced : plugs, coils, cleaned a egr that looked pretty new,
air cleaner, cleaned maf.
CEL stayed off after EGR cleaning for 70 miles.....light popped back on last nite. but it did not change performance. in the past it had a stumble in rpm than light would come on.
Started it 10 mins ago, light on, ran fine.....pulled it in garage, turned it off.
restarted .......flashing light wants to die, 200 rpm.
I'm about over this POS........
anyone have any ideas? Besides leaving it at walmart with keys in it for rest of weekend?
This friggin thing is possessed.
 
P0421 usually means that your first catalytic converter is shot. If you have p0300 which is random cylinder misfire, that's probably the reason. The misfire melted the cat. When you changed the plugs, did you gap them right? Did you replace the wires along with the plugs? Maybe your MAF just s*** the bed and broke. Those things are very sensitive. Sorry if any of this sounds elementary, but just trying to find all the possible sources to the problem.
 
just pulled codes....PO300 & PO421 again.............
wires are the only thing not replaced.
I cleared the codes again......parked it!
It runs so swiss watch like...then the occasional misfire and that happens
at any speed anytime.
So 1st cat is shot......is that causing the PO300?
Never had a car with so many problems!!!!!
Dude i bought it from swore up and down no probs ever!
Well i may just park this protege on top of his new mustang!
 
p0421 does not cause the random cylinder misfire. The misfire causes the p0421. I'd say get new wires as well. When you pulled your plugs were any of them fouled?
 
if you did plugs and wires already, it can either be injectors or a coil pack.... pull your plugs and find the odd one out, if you have a singled out plug start playing with switching injectors, plugs etc and see if you can narrow it down to a cause.
 
phoenix323 said:
if you did plugs and wires already, it can either be injectors or a coil pack.... pull your plugs and find the odd one out, if you have a singled out plug start playing with switching injectors, plugs etc and see if you can narrow it down to a cause.
Click to expand...

He said he replaced the coils already, and a bad injector would only cause a misfire in one specific cylinder (now, a bad fuel pressure regulator or something that affects all injectors is possible).

Like the above poster said, the P0300 ruined your cat, hence the P0421 code. Replace your spark plug wires, and the problem should go away.
 
Okay thanks guys.....I went and bought new wires, noticed that everyone says the NGK plugs are best so i bought a set, and replaced the brand new autolites.
Will the smoked Cat keep causing codes? I actually like the car........
protege52.jpg
 
Went and started it.......idle climbed to 2000 dropped down, in 300 rpm increments down to stall. restart....same thing lite starts flashing again. Turn it off...re start.....flashing light gone. Its runs smooth lite stays on!

I am lost.....dont want to replace cat until PO300 is fixed.

HELP!!!!!!
 
(uhm) mine has an issue on the idle, but its my idle control....it also burns oil like a mutha' trucka'




good luck with it.....im learning p5's have many problems -_-
 
protegeforsale said:
Went and started it.......idle climbed to 2000 dropped down, in 300 rpm increments down to stall. restart....same thing lite starts flashing again. Turn it off...re start.....flashing light gone. Its runs smooth lite stays on!

I am lost.....dont want to replace cat until PO300 is fixed.

HELP!!!!!!
Click to expand...

This is after your replaced your wires? Take your car to autozone or some other parts place and they can clear the light for free, and you can see if it comes back on.

It might also be a fuel issue - do the above and come back with an update.
 
You don't want to replace a KNOWN problem until you fix an UNKNOWN problem?
Take it to a shop, you obviously shouldn't be working on it yourself.
 
Not sure how much advice I can give as I am still going through the same thing. You already replaced wires, coils and plugs, I would try a new egr next. You may think its clean, but its hard to get down in there to get it real clean.

I don't think that it is an injector thing, like slavrenz said it would be a specific cylinder, like my P0303 code I had. Also try cleaning the IAC solenoid, maybe try that before you buy an egr valve.

Other than that it is a step at a time, much like what I am doing.
 
Thanks all for the help.....
I've made up my mind that these cars are just poorly designed and have no reliabilty at all. I just put this POS up for sale. This Forum really made me see the light.....They are very reliant on a mans wallet!
Thanks anyways guys.................
 
PO300 - is generally caused by 1 of 3 things.... gennerally its plugs, wires, or coil packs. What did you gap your plugs at? (I may of missed that)

Also have you checked your intake piping for any cracks of any sort? If you can get access to a vac or a boost/vac gauge let us know what your vac is at idle. It should be around -20 with ac off and around -16 with ac on.


Edit:

So make a long story short you have replaced the below for codes PO421 & P0300

1) plugs(GAP?), coil packs(both I hope), wires
2) air filter
3) cleaned MAF
4) Clean EGR.
5)


High idle on start up is normal! I fail to see how that cost 200 bucks but maybe if you paid someone to do it.

1) Anyways again check your intake for any cracks and what not.
2) Do you have any mods done on the car?
3) Do you know a local forum member that can help you out? Maybe swap parts temporarily for testing.
 
Last edited:
BoostedPR5 said:
You don't want to replace a KNOWN problem until you fix an UNKNOWN problem?
Take it to a shop, you obviously shouldn't be working on it yourself.[/QUOTE

That is right....if i fix the cat before the misfire problem is fixed, i risk smoking another cat! What part of that does not make sense?

Maybe you should think before you speak....better yet do not speak at all!
These cars are just pieces of s***....that does not take a shop to figure out!
All ya gotta do is read this forum.....theres more unhappy people than happy ones! Should have done that before I bought it.
Click to expand...
 
protegeforsale said:
Maybe you should think before you speak....better yet do not speak at all!
These cars are just pieces of s***....that does not take a shop to figure out!
All ya gotta do is read this forum.....theres more unhappy people than happy ones! Should have done that before I bought it.
Click to expand...

Did you replace the parts that go under the coil packs as well? They should of came with new packs. I assume or hope you replaced both packs.

Edit: Where are you located?
 
Last edited:
Thanks for helping in the middle of being pissed off at this thing.......
The car has no mods whatsoever.....air cleaner is new also.
NGK's gapped at .044
coilpacks came with new plugboots it thats the underneath items you are referring to.
I already know cat must be bad....that is KNOWN!
The UNKNOWN that i feel should be addressed 1st is the misfire
thats causing the bad cats. Thats just common sense...cats are not cheap!
 
protegeforsale said:
Thanks for helping in the middle of being pissed off at this thing.......
The car has no mods whatsoever.....air cleaner is new also.
NGK's gapped at .044
coilpacks came with new plugboots it thats the underneath items you are referring to.
I already know cat must be bad....that is KNOWN!
The UNKNOWN that i feel should be addressed 1st is the misfire
thats causing the bad cats. Thats just common sense...cats are not cheap!
Click to expand...
ok I updated the re-cap list for anyone else woundering. Also you never answerd how many miles and where you are located.


So make a long story short you have replaced the below for codes PO421 & P0300

1) plugs(GAP .44), coil packs(both), wires
2) air filter
3) cleaned MAF
4) Cleaned EGR (seemed to help for 70ish miles)
 
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