So it was 3 years ago when I first posted a thread about my car losing power on the road. Since then I have taken it to 3 different mechanics (one of them a master tech at my local Mazda dealer) and have left it at shops several times for several weeks at a time. To this day I still have no solution and I want badly to keep my car but it is starting to become unmanageable.
ANY help would be greatly appreciated!
I have a 2001 Miata LS with about 193,000 miles.
So here are the symptoms: randomly, sometimes 1, 2 or 3 times a day or sometimes not for days, my car loses power and the CEL starts to blink. Actually, right when I feel the misfiring, if I take my foot off the accelerator and give it about 3-5 secs, the car will return to normal with no CEL, blinking or not. However, if I continue to give the car gas when I first feel it, I will lose power and it will take longer for my car to return back to normal.
This happens regardless of the temperature, the driving conditions, humidity, time of day, beginning or end of commute, etc.
When I first started getting these symptoms, I got a P0300 code which reads as follows:
Random multiple cylinder misfire detected
Mechanical condition of engine. Faulty wiring and connections. Faulty oxygen sensors.
At the suggestion of folks on this forum and my mechanic, I changed my spark plugs, wires and fuel filter but with no change.
Not too long after, I started to get the P0420 code which reads as follows:
Catalyst operating efficiency below threshold-Bank1
Mechanical condition of engine. Faulty wiring and connections. Faulty oxygen sensors.
Also, about the same time I had a peculiar problem arise that I didn't think was related at all. One time I tried to start my car and the engine would crank but not start. After multiple tries several minutes apart, it started up. I took it to a mechanic who said he couldn't find anything wrong with it. Over the next couple of years I would get it only occasionally.
I'm not sure if I experienced that problem before, after or concurrent with the P0420 code for the cat.
The problem the techs had was reproducing the problem so that they could diagnosis it. Because it happens randomly, the just gave me theories and told me what to replace next.
Btw, I also had the recall work for the ECU done after I started getting the symptoms. That did not change anything with the car.
So after the plugs, wires and fuel filter, I then changed the cam sensor, which seemed to make the symptoms milder. So mild that I couldn't feel when the random misfire was happening and I would continue to give the car gas, causing my car to lose power and not recover for several seconds.
Next, I cleaned out the mass air flow sensor and that also seemed to make the symptoms slightly milder (but I could be imagining that).
I stopped the driving the car regularly for a period of a couple of months, but now I am driving it again and I noticed that I am getting the problem with the cranking/not starting much more frequently. It seemed, in the beginning, to happen when it was hot during the day but would start fine in the evenings.
I changed the crank sensor and that did absolutely nothing.
I had been driving on 87 octane for some time, but have switched to 91 octane as of the past couple of years.
Mechanics say my fuel pressure is fine.
Recently, I witnessed my car going through the power loss while in idle. I was behind the car and could see liquid (fuel?) spitting out of the exhaust.
I have not changed the cat because I figured that if I don't fixed whatever caused it to go bad, the new one would just go bad too.
For some reason, none of the mechanics have suggested it could be one or both of the O2 sensors.
The Mazda mechanic thinks I should change the mass airflow sensor.
Another mechanic thinks it could be a problem with the coils themselves.
I hope all the above data helps narrow down the possible causes. I've searched through the forum but haven't found any satisfactory solutions in them.
Your help would be greatly appreciated by this Miata lover. Unfortunately, I don't like to take out my girlfriend and not be sure that the car is going to start. If I can't fix this, the Miata will have to go.
Please help!
from hearing what you said sounds like a problem with the coils, because I have exprienced something like this before too and replaces coils at the same time as my pluggs and wires and everything was cured. if it is missfireing and you see and smell gas that most likeley means that your not getting sparks to burn the gas. and you said fuel presure is ok.
What brad said. Swap coils with someone or buy a used set somewhere. I feel for ya. I hate problems like this.
You do not hear of many people that have problems with 2001 coils. It might be the prob. In reading your post , did you ever replace o2 sensor?
no never replaced the o2 sensors. for some reason none of the mechanics mentioned them.
any reason you guys think it's the coils and not the mass air flow sensor or the o2 sensors?
thanks so much for the replies!
The camshaft sensor is suspect. Recommend replacing to cure intermittent no start hard start problem. (No fail codes, intermittent, rough start, no start)
Camshaft sensor
Coil pack is suspect.
Front O2 sensor
Crank Sensor may need adjustment. (or replacement)'Also, about the same time I had a peculiar problem arise that I didn't think was related at all. One time I tried to start my car and the engine would crank but not start. After multiple tries several minutes apart, it started up. I took it to a mechanic who said he couldn't find anything wrong with it. Over the next couple of years I would get it only occasionally.'
Eugene, I first saw your post yesterday, and have been thinking about your problem ever since, yes it's been bugging me. Let's look at the symptoms, cat code, random misfire, unexplained and strange temporary power loss, intermittent starting problems, liquid coming out of the tail pipe (fuel?). And then, the attempted fixes. Seems to me, it's a fuel related problem. If you had an injector that was leaking, it could possibly explain all your symptoms. Excessive fuel will take out the cat, foul a plug, or multiple plugs if the fuel was puddling in the intake, causing your random misfire, also causing a power loss by running excessively rich, and can certainly explain your starting problems, and fuel coming out of the tail pipe. While it's extremely difficult to long distance diagnose, your symptoms are very familiar to me. Now, as to what could have possibly caused the leaky fuel injector, put the blame on Mazda's non-return fuel system, and it preponderance to accumulate contaminates in the tank. It is possible to send out the injectors to be cleaned, and if you have a bad one they will tell you, or you can simply replace all four with new, which is what I did. But don't make the same mistake I did, install new heat insulators on the injectors, or you'll end up with a blown head gasket. Happy driving, Bob
Three different cars, all three the same symptom(s). One solution for all three: New coil packs.
The Miata's is ridiculously priced; the other two were a 1/4 of the Miata's price.
Went through the plug changes and fuel injectors' cleanings with the first occurrence.
Second car/time also, but but didn't dilly-dally with it so long.
Third time just checked the the plugs if OK, and got the new coil.
I think your mechanics are not very competent (but I'm hope I'm wrong for your sake).
You can screw up your cat with consistent misfires in the Miata.
I've just read Popstoy's response (above); that's very good advice; in one of the cases I also almost bought a new injector, suspecting fuel delivery issue, as the misfire was identified in the CEL (was #1 cyl). For some reason I eventually ruled that out, but I no longer remember why, and just went with the new coil pack.
Please provide a feedback as to the solution; if Popstoy is right, that would be instructional for all of us.
thanks chuck75, popstoy, netuddki!
cam sensor and crank sensors have already been replaced with no results.
all of the above had been mentioned as possible problems by those mechanics, but they all told me to start with the above 2 sensors and the mass airflow sensor (which i cleaned but did not replace).
they all thought the fuel injection system was least suspect because they all found that the fuel pressure was good. but maybe we're missing something here.
the last time i saw a mechanic, he mentioned that it could be the o2 sensors.
any and all insight/information is helpful, everybody! it looks like i have a list of possible causes but i'd like to narrow it down as much as possible so i don't have to waste any more money replacing things that didn't need replacing.
any ideas on how to test or diagnose to see which part it is?
also, i remember one of the mechanics telling me that the misfiring was not in any particular cylinder, and that the 2001 doesn't have the coil pack that the 99-00's had.
thanks! i hope i'm getting closer to a solution!
Fluid spitting out the exhaust pipe is probably condensation. Water. It would take a lot of gasoline to make it all the way back there without evaporating.
Just out of curiosity: where's the fuel pressure regulator?
Originally Posted by eugene87
thanks chuck75, popstoy, netuddki!
cam sensor and crank sensors have already been replaced with no results.
all of the above had been mentioned as possible problems by those mechanics, but they all told me to start with the above 2 sensors and the mass airflow sensor (which i cleaned but did not replace).
they all thought the fuel injection system was least suspect because they all found that the fuel pressure was good. but maybe we're missing something here.
the last time i saw a mechanic, he mentioned that it could be the o2 sensors.
any and all insight/information is helpful, everybody! it looks like i have a list of possible causes but i'd like to narrow it down as much as possible so i don't have to waste any more money replacing things that didn't need replacing.
any ideas on how to test or diagnose to see which part it is?
also, i remember one of the mechanics telling me that the misfiring was not in any particular cylinder, and that the 2001 doesn't have the coil pack that the 99-00's had.
thanks! i hope i'm getting closer to a solution!
only the first o2 sensor has any effect on the car running right. It sets the fuel, the 2nd only tells if cat is good. You already know your cat is bad, no need to replace both.
New here, I had the exact same problem on my 99. Ended up taking it to a friend who has a shop, the problem was that one side of the coil pack was breaking down when it got hot and causing the misfire. Got a new coil pak through mazmart at about half the price of anyone else and have not had a problem since.
The fuel pressure regulator is mounted just above the fuel pump, in the tank. In 01, Mazda did redesign the fpr, because the 99-00 fpr was too easily fouled from contaminates that could effect the pressure. But since you're fuel pressure was checked, and found to be normal (53 to 61 psi), I doubt that's the problem. I would have jumped all over the coils, as suspect myself, except for the fact it's not a 99-00 model. There has been a few 01-newer coils that have failed, but they're much more reliable than the earlier models, and you have other symptoms that aren't indicative of the ignition system. Liquid coming out of the tail pipe could be condensation, but that would only occur at warm up, or if you had a blown head gasket, and then the coolant level would indicate that, along with a cloud of steam following you around. Looking at the spark plugs would be a good indication of what's going on, darkly colored plugs would indicate too much fuel, clean or strangely colored (greenish) plugs would indicate a coolant leak, but aren't indicative of the intermitten nature of the problem. 02 sensors are easily checked, with a scanner, but they don't cause an intermitten problems either. The crank angle sensor can be heat sensitive as well as the cam angle sensor, the crank sensor being responible for timing the spark as well as monitoring for misfires, the cam sensor timing the injector pulses and used as a reference for which cyclinders to send the spark too, but since they have previously been changed, with no effect to the problem, they're no longer suspect. The VVT system can cause hard starting, and a slight loss of midrange power, but not to the extreme as described, and there'd be a cel indicating it. Could it be a combination of faults causing the problem, sure, but I can't assume there's a conspiracy going on. All of which, leads me back to a fuel injector. Bob
The reason I asked, Bob is that I once had P0300 (random misfires) on my old 97 which were first traced to the Fuel Pressure regulator (in an NA off the end of the fuel rail) which had been sticking and then to the fuel pump. I thought the FPR on 01+ cars was in a different location, though.
Originally Posted by POPSTOY
The fuel pressure regulator is mounted just above the fuel pump, in the tank. In 01, Mazda did redesign the fpr, because the 99-00 fpr was too easily fouled from contaminates that could effect the pressure. But since you're fuel pressure was checked, and found to be normal (53 to 61 psi), I doubt that's the problem. I would have jumped all over the coils, as suspect myself, except for the fact it's not a 99-00 model. There has been a few 01-newer coils that have failed, but they're much more reliable than the earlier models, and you have other symptoms that aren't indicative of the ignition system. Liquid coming out of the tail pipe could be condensation, but that would only occur at warm up, or if you had a blown head gasket, and then the coolant level would indicate that, along with a cloud of steam following you around. Looking at the spark plugs would be a good indication of what's going on, darkly colored plugs would indicate too much fuel, clean or strangely colored (greenish) plugs would indicate a coolant leak, but aren't indicative of the intermitten nature of the problem. 02 sensors are easily checked, with a scanner, but they don't cause an intermitten problems either. The crank angle sensor can be heat sensitive as well as the cam angle sensor, the crank sensor being responible for timing the spark as well as monitoring for misfires, the cam sensor timing the injector pulses and used as a reference for which cyclinders to send the spark too, but since they have previously been changed, with no effect to the problem, they're no longer suspect. The VVT system can cause hard starting, and a slight loss of midrange power, but not to the extreme as described, and there'd be a cel indicating it. Could it be a combination of faults causing the problem, sure, but I can't assume there's a conspiracy going on. All of which, leads me back to a fuel injector. Bob
When I bought my '01 it had an intermittent misfire that would set off a flashing CEL. It had been taken to Mazda who claimed it was due to moisture in the plug wells as the previous owner had washed it. It of course wasn't. I changed the CPS and it seemed to improve some, but still misfired. I swapped the coils with new ones and haven't had another problem in 30K miles. My guess is you are misfiring and the raw fuel is damaging your cat. Swap the coils and run it for a while. It may clear the cat code. My wife’s Millenia S did the same thing with a bad COP, and if you think the '01's 2 COP are expensive look up the price on 6 COP's for the Millenia S!
O2
I'd agree on changing the coil packs at this point. Either buy a new set or give Tom@The Parts Group a call.
I had the same problem on my 99. Replaced all the things you mentioned but no joy. Finally found the haromic balancer pullies at the front bottom of my engine were loose enough to have broken the key which allowed the timing to slip causing the problems.
Good luck.
thanks for all the help!
so the culprit or culprits, it seems, could be the fuel injectors or the coils or the haromic balancer(never heard of that one).
does it matter that the problem is intermittent? if my coils were bad would the car always misfire or would they misfire randomly like they do?
Many of the electrical components (coils included) short out over time, leading to less and less intermittent problems. In other words, look at replacing them.
The definition of a P0300 is: a random misfire detected. One of the possible causes is a coil malfunction. Age and heat tend to do them in. With the miles you have on your vehicle, if it has not been replaced, I'd be thinking of replacing it.
I had the random misfire code (0300) starting in February followed by the cat code (0420) that persists to this day. In March, I went to a wrecker's that had coils form an '05, so I bought both for $150 + tax (~$169 as I recall) and it solved the problem. But I did not have a hard starting problem other than what would be caused by two plugs misfiring (and each coil operates two plugs). Mine is an '01 and even if it did not have as many instances of trouble as the 99-00 models, they still fail.
Fortunately, I have a Geniscan that I use to clear the 0420 code, but I have to do this every few days. I still have a spare coil but I don't want to swap out the catalyst yet until I am satisfied that it will not happen again.
hi amptramp! did you have the same experience of intermittent power loss?
the power loss i experience is almost always when i am in 6th gear and traveling on the freeway at 70-80mph. occasionally, i experience it when my car is idle and the car feels like it's going to stall. i can't ever recall a time it happened when i was driving locally at 40mph.
Eugene, That random loss of power, while cruising is why I by passed the coils as a possibility. Certainly running on two cyclinders would be a loss of power, but every coil pack failure I've seen has always occured at start-up, typically at warm startup, and would clear up with the rpm going up, or fail completely. But if it failed completely, then it would be intermitten.
Originally Posted by eugene87
thanks for all the help!does it matter that the problem is intermittent? if my coils were bad would the car always misfire or would they misfire randomly like they do?
Originally Posted by POPSTOY
Eugene, That random loss of power, while cruising is why I by passed the coils as a possibility. Certainly running on two cyclinders would be a loss of power, but every coil pack failure I've seen has always occured at start-up, typically at warm startup, and would clear up with the rpm going up, or fail completely. But if it failed completely, then it would be intermitten.
My missfire was intermittent, often at cruising speed. It was explained to me that as one coil drops it tends to some how short out the second one so you get a momentary loss of both. Can't say it's your problem, but changing the coils solved mine.
POPSTOY: IIRC the OP has a '01 which does not have a coil pack but has two COP coils. My COP coil failure never acted at start up and was usually at cruise in 6th gear.
Response to my original post on this issue long ago (vb/showthread.php?t=295716):
Originally Posted by POPSTOY
It indeed could be one of your coils. If one of the ignitors, temporarly shorts out, you will lose quot;ALLquot; the signal voltage triggering both coils, dumping raw gas into the cat, followed shortly by a cat cel. It's not common on the 01-newer, but does happen, and was quite common on the 99-00 models. Bob
Yep from POPSTOY
O2 |
Post at 2-7 04:31 AM
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