Intermitted Power Loss, Please Help!

Do note that if you clean the IAC and throttle body it is best to disconnect the battery and reset the ECU. That way the ECU can relearn everything when it's clean because it does adjust to compensate for the dirty components that don't open/close all the way. This is a MUST for cars with an electronic throttle body but also makes a difference in cable operated TB as well.
 
Do note that if you clean the IAC and throttle body it is best to disconnect the battery and reset the ECU. That way the ECU can relearn everything when it's clean because it does adjust to compensate for the dirty components that don't open/close all the way. This is a MUST for cars with an electronic throttle body but also makes a difference in cable operated TB as well.

Thanks for the tip.

As a habit, I tend to reset the ECU after a lot of minor maintenance (not stuff like fluid changes), doing mods, part cleanings, and part removal and replacing such as sensors or electronic parts.

I usually do it after changing ignition components like the spark plugs, but as mentioned in the above post, I was trying not to reset the ECU after my latest plug change due to me having my MD emission test due.

If the ECU is recently reset, there isn't data for them to read, and they will automatically fail it and make you come back.

So, I was trying to not reset the ECU, but the car wouldn't run at all with the new plugs, so I ended up just resetting it.

I still have not done a second long test drive, I am waiting for a cold night to do it, but hopefully the plugs were the issue.
 
Yea,... My car runs like crap after I disconnect the battery especially right after I start the car for the first time,.. It almost stalls then gets progressively better with each idle attempt.
It apparently takes about 100 miles to get a smooth idle back.

I notice this too. Sometimes after a ECU reset, I notice stalls, hard starts, rough idles, and sometimes other things.

Actually, on the original USD motor I had on my P5, when first replacing the spark plugs with the long JDM ones, there was a screeching sound coming from the motor when first starting after resetting the ECU. It lasted like a half of a second, not sure why...

It does not do it with the JDM motor, but I never had the USD recommended plugs in the motor, so maybe that's why.
 
Do note that if you clean the IAC and throttle body it is best to disconnect the battery and reset the ECU. That way the ECU can relearn everything when it's clean because it does adjust to compensate for the dirty components that don't open/close all the way. This is a MUST for cars with an electronic throttle body but also makes a difference in cable operated TB as well.

Thats a very good point. A modern ECU will be able to adjust quickly and smoothly, but an older one will need more time for adjustment so thats definitely not a bad idea.

However... you are taking a bit of a risk by disconnecting your battery. Its definitely not good to do for your car, especially often.
 
Thats a very good point. A modern ECU will be able to adjust quickly and smoothly, but an older one will need more time for adjustment so thats definitely not a bad idea.

However... you are taking a bit of a risk by disconnecting your battery. Its definitely not good to do for your car, especially often.

it's not about new ECU or old ECU or adjustment time. Newer cars are drive by wire meaning there is no cable running from the gas pedal to the throttle body. The gas pedal is just a resistive sensor that gets translated by the ECU and a signal sent to a motor in the throttle body to open or close it respective to the gas pedal sensor. What happens in the newer cars is when you get a lot of carbon build up, the plate won't close all the way anymore, so the computer learns this new point as "zero". Then you clean all the crap out of it, it has a new zero and they can have trouble idling unless you reset the ECU. Older cars compensate differently. They change fuel trims and IAC compensation for the gunk. When you clean it out and the TB closes/opens fully, it helps to reset the ECU from these "learned compensations" so zero point calibration will be with the new cleaned throttle plate/vacuum ports/etc. since they all flow freely now.

The only problem with disconnecting your battery is having to reset your radio presets and clock. You could disconnect your battery every night when you park the car and it's not going to damage anything.
 
The interesting thing for me is,.. the worse your car runs after a reset, the further your car has drifted from original factory specs.

I'm pretty sure that all of our cars started up and idled perfectly on the docks in Japan back in 2001 so they could drive them on to the boat without stumbling or stalling out.

If your car is completely stock and stumbles or stalls after a reset and start, it's probably a sign of something off kilter.

In my case specifically, my car is probably stumbling because I live in Canada and it's -40 and we live in igloos.
 
Last edited:
Minor update:

As of yesterday I drove about 80 miles since the ECU reset. @ about 65 miles, the P5 started fine, idled fine during warming up with no stalls, and drove fine for about 15 more miles.

My confidence in the P5 has increased enough for me to drive in it solo, but I won't put my children in the car yet. I definitely won't commute in the car, due to me taking my baby to daycare during my commute.

I need to test it a few more times, preferably in colder weather, which looks like will coming back to where I live.

So I will update the thread again if the problem was solved, or if I will move on to other potential solutions.
 
Last edited:
BTW, I wanted to thank everyone for their input.

If the source of the problem ends up being a bad spark plug, I will be very, very happy, as it was a cheap, quick, and easy fix, as it takes literally less than ten minutes to change the plugs on the P5.

But, I if it is just a spark plug, I am probably going to be a little embarrassed, as I probably should have ruled them out before even making a thread. It is just that the plugs in there only had a few thousand miles on em, and I wasn't getting any CEL code that I usually get for ignition related stuff.

Either way, I am sure that if someone else if having similar symptoms to what my P5 was having, this thread could be a good guide on what to check to solve their issue.

Anyways, thanks!
 
It still seems weird to me that your plugs would misbehave only when it's cold out ??

One other guy mentioned that he removed and cleaned his ECT and that fixed his problem (I forget what the problem was,.. I think stalling ? I forget where his post was)

Now you might have to wait till next winter to see if you've really fixed the problem.
 
It still seems weird to me that your plugs would misbehave only when it's cold out ??

One other guy mentioned that he removed and cleaned his ECT and that fixed his problem (I forget what the problem was,.. I think stalling ? I forget where his post was)

Now you might have to wait till next winter to see if you've really fixed the problem.

Issues that become more prevelant in cold typically hint at an ignition coil, possibly injector issue. When I had a faulty coil in my BMW it would misfire more often when the engine was cold.

OP, glad to hear your protege is running well again. I had a 1.6L protege that I bought back in the day - learned how to drive manual on it during the test drive. It was a great car - was still running when I sold it. It was one tough little son of a b*tch. the 1.6L is gutless... I drove the absolute s*** out of that thing and she never failed to start on me. Theyre very tough cars.

It was a slow car, but very impressive powerband for a 1.6L - very linear. I love mazdas engines. Smooth and it made a truly amazing sound when you got on the throttle.
 
It still seems weird to me that your plugs would misbehave only when it's cold out ??
Yea, I am unsure about this too. It is why I won't put my baby in the car yet. This morning would have been a perfect morning to test it, as it was below freezing, but I couldn't because I was taking my baby to the daycare.


One other guy mentioned that he removed and cleaned his ECT and that fixed his problem (I forget what the problem was,.. I think stalling ? I forget where his post was)

Now you might have to wait till next winter to see if you've really fixed the problem.
I am on my second EGR valve, as my first one kept get stuck and I got tired of cleaning it.

I ended up getting Canada's cold weather EGR with the water line on it.

I never had problems with the cold weather one until I had my motor swap done. It got stuck a few times, but I cleaned it in 2015 and I think it has been fine since then.

But, the symptoms I experience multiple times from a stuck EGR was just stalling related, almost always when coming to a stop, such as stop signs and red lights.

I don't think the power loss issue is related to the EGR, but I guess it wouldn't hurt cleaning it again.
 
OP, glad to hear your protege is running well again.
I hope the P5 issues are fixed, but I think it is too early to tell. I really need to test it a few more times.


Issues that become more prevelant in cold typically hint at an ignition coil, possibly injector issue. When I had a faulty coil in my BMW it would misfire more often when the engine was cold.

I replaced each coil twice in the past 1.5 years, so I doubt it is them. I guess it could be an injector, I just wish I knew which one.

Maybe I will remove and clean each one to be thorough.
 
Last edited:
I am on my second EGR valve, as my first one kept get stuck and I got tired of cleaning it.

I ended up getting Canada's cold weather EGR with the water line on it....

I'm talking about the ECT engine coolant temperature sensor....

He removed his sensor and it was covered in a layer of black crud... He sanded it off and that fixed his car.

His ECU was getting false or at least inaccurate data.
 
Last edited:
I'm talking about the ECT engine coolant temperature sensor....

He removed his sensor and it was covered in a layer of black crud... He sanded it off and that fixed his car.

His ECU was getting false or at least inaccurate data.

Sorry, I quickly scanned your post, and thought I saw EGR, probably because I see a lot of posts on the forum about the EGR issue, and I assumed that is what it was.


As for the ECT, I will check it out. I did consider this, as I had a problem on another car of mine, with some similar symptoms, that ended up being ECT sensor.

One day, my Turbo MR2 has stalling issues, CEL (I think it was code 22), and hard start after warm up. As soon as it cooled, it started fine.

It ended up being the ECT sensor, as the CEL code said. Easy and cheap fix.


I am not sure this is the issue on the P5, as not all the symptoms don't match up. One example, I had stalling issues when the motor was cold. Although, other than what I suspect was ECU reset issues, I haven't really had any stalling problems since I replaced my fuel filter and pump.


Anyways, thanks for the advice from you and everyone else. I really need to take it for a drive on a cold day, but I just haven't been able to yet. Hopefully I will soon.
 
We have three codes for our IAT...
Essentially a broken wire, a shorted wire and one for performance.

We only have two codes for our ECT...
The ECU can't detect bad data,... Just no data.

 
We have three codes for our IAT...
Essentially a broken wire, a shorted wire and one for performance.

We only have two codes for our ECT...
The ECU can't detect bad data,... Just no data.

Thanks,

I am not getting any codes, but like you said, there isn't a code for bad data, so I guess it still could be the sensor.

I was comparing symptoms of my Mazda and the Turbo MR2 with the bad ECT, and I think there are enough similarities to at least check it out. Maybe the ECT sensor on the P5 is just dirty and sending wrong data to the ECU.

I am pretty sure the one on my Toyota just totally went bad, considering I got a CEL. I was curious how many different ECT codes there was for the Toyota so I looked it up, and there was only the 22 code, "ECTS Signal". I guess that is combining the newer P0117 and P0118 codes together? Not sure...

Anyways, at a minimum, I will check the ECT sensor for dirt and build up.

I was going to do a drain and fill of the radiator and cooling system anyways. It has not been too long since I did it last Maybe 4 years at the most, but I have not done it since the motor swap. Might as well clean it then.
 
Remember,... The goal is to give your car to your baby in about 15 years when he/she gets a drivers licence.

Keep her going... (how is it for rust ??)
 
Remember,... The goal is to give your car to your baby in about 15 years when he/she gets a drivers licence.
Well, I wanted to give it to my son when he starts to drive, which should be less than a year, as he is going to be 15 in a few weeks, and then my two oldest daughters who are now 12 and 11, but.......

(how is it for rust ??)
This is pretty much the reason why my children will end up not using the P5.

On the outside, the rust is not bad at all, but the rust is out of control on the frame rail. If it was not for the frame rust, I would probably keep the P5 forever!.



I love my P5, it looked great, has been a mostly trouble-free, fun car to drive. I would have loved to give it to my children, but I think it is at the end of its life.

I would love to get another year, maybe two out of it, but at this point, it is only a matter of time before the rust takes it.
 
Back