Twisties

I have searched multiple thread pertaining to misfires.

I am getting a misfire on the rear rotor only when I go past 5k. One on the times i slowly crept up to around 7.5k and noticed what seemed like fuel cut. If i drive normal shifting before 5k, I have no cel, no misfire.

I swapped the rear coils and plugs with the front ones to see if it would change it to a front rotor misfire. Still comes up with a rear misfire.

I've noticed some people in the threads i have read, that the ssv comes up often. This is the next thing on my list to check.

It goes in for a compression test on thursday 9/13/12

Specs 05 mt
new fuel pump
new starter
coils about 20k
plugs less then 7k
wires less then 7k
gutted cat


I have tested the coils using the DIY on the forum, all passed. Wires were replaced with the rebuild, so were the plugs.

The misfire still confuses me. I do not believe it is low compression as it would show up in lower rpm ranges am I correct?

Ign problems start at higher rpm and go lower the worse they get. So i'm assuming it is an ignition problem, although i am getting the compression test just to be safe. But if it was misfiring on the rear rotor, and i swapped all the parts to the front rotor wouldnt the misfire follow the ignition swap. I do not want to buy parts i do not need.

Since the coils passed, the wires are new, and the plugs dont looked fouled. What would be my next step. I am going to do more reasearch on the ssv, and other IM actuators and whatnot. Just if someone has had the same symptoms could someone chime in. Until then onto the search.

Nopstnz8

iTrader: (6)

Curious as well since I'm having similar problems

Mint87rx7

what are your fuel trims/o2 readings doing at time of misfire? any codes?

9krpmrx8

iTrader: (46)

Have you noticed any coolant loss?

Nopstnz8

iTrader: (6)

I'm having slow coolant loss. Does that mean the engine is failing, eventhough the engine still pulls at low rpm?

9krpmrx8

iTrader: (46)

I had the same symptoms when I had a bad coolant seal in my last motor and it drove me crazy because it drove fine most of the time. It was only at high RPM that I would get the misfire and bogging issues. I had my oil tested and it confirmed I had coolant in my oil. My guess is at high RPMS the coolant is entering the combustion chamber and causing misfires. I suggest getting an oil sample taken and having it tested. It's only $25.00 and an easy way to determine if that is the issue.

But of course you want to rule out other coolant system failure modes. Look for dried coolant at all the hose ends, water pump, reservoir, etc.

Twisties

i am not noticing any coolant loss. Although my ess is slightly off center because the bolt snapped off in the hole and the new threads are slightly off center. I'm thinking that could be a problem. now that i think about it more, the code for the ess being thrown at 7.3k makes sense the fuel cut would be because of the ess being off center. and maybe the misfire is due to the ess as well. I get no bogging no nothing, car seems to pull fine but it still throws a misfire at 5.5-5.7k but if i just keep on it, it still pulls and doesnt even seem like it is having a problem. So i'm thinking with the ess off center and not in the groove completely the computer thinks its misfiring when it really isnt, and it cuts fuel at 7k to save the motor even though it is fine. if that makes sense?

it goes in for a compression check tomorrow at 2. So i will know for sure if its compression loss or not. Although I am like 75% positive it isnt. If all is well, when i get my car back tom I am going to get the ess to sit centered relative to the plate. Hoping that solves the issue.

and as far as fuel trims this is what my code reader pulled on the last cel
p0336
tps 31.7
engine speed 7331 (when i exp fuel cut)
baro 99 kpa
calc load 52.1
maf 102.94 gr/sec
out temp 84
coolant 185
iat 86
ign advance 32
sec air atmos
short term 0.0
long term 8.5
veh speed 55mph

Mint87rx7

What I am seeing is your maf reading is high for 31% tps, if you are at full throttle here you should be way above 52% calculated load. can you watch live data when this happens and look at those 3 readings? im thinking possible maf failure

timmytriangles

i dont have cel but when i go up and over 7k it sputter a little. kind of hesitates. dont know why. plugs are new..

Twisties

Mint- unfortunately i can not do real time data logging. I will test the maf tonight.

9krpmrx8

iTrader: (46)

Dude, if your ESS is off in terms of placement that could definitely be a problem.

Twisties

Its only very very slightly off center, like id say a mm. It is something on this list to do when i get it back today. Check the maf sensor and fix the ess

Bladecutter

I'm guessing that you don't understand how truly important ESS placement is, then. Being off by 1 mm is enough to cause issues.

BC.

Twisties

why thank you for clearing that up...

Tested MAF, checks out.

Mazda recommended changing coils, rear o2, and cat.

o2 is on the list since the one in there is obviously aftermarket, the cat is not getting replaced.

coils will be replaced after i try fixing the ess


anyway. compression results

8.6, 8.9, 9.2 @ 333
9.1, 8.9, 9.3 @ 334

misfire code from mazda

p0302
load - 89.8
ect - 85* c
stftrm - 0%
ltft - 7.03%
rpm - 5601
vs - 131 kph
spark adv - 27*
iat - 29* c
MAF - 125 g/s
tp - 42.75%
baro - 101 kpa
cat temp - 948*c
vpwr - 14.12 v
alv - 85.88%
eq rat - 13.21:1
tr rel - 30.98%
aat - 28* c
tp_b - 53.73%
app-d - 50.2%
app_e - 39.22%
tac_pct - 46.28%

9krpmrx8

iTrader: (46)

Compression looks great. Replace all the maintenance items and you should be good to go.

Twisties

yea i did a quick fix using zip ties just to see if the ess being off a little bit made a difference. It did run good, made a few redline passes, no cel. Towards the end of my drive it started throwing misfire rotor 1 P0301. which could be the coils, since it was a spirited drive, after they warmed up they could have started failing. Or the zip tie could have moved a bit.

Either way, im bringing it into the shop tomorrow to fix that ess. My plan is to just grind the hole out a little bit and then use a bolt and lock nut to secure it in place.

Many thanks to everyone.

Nopstnz8

iTrader: (6)

^^Twisties can you explain in greater detail as to what you did to fix your issue? I'm having the same problems and have tried everything but what you just stated, and nothing worked so far. I still have two months left on the engine warranty, so I want to get my issue solved before it expires just in case. I'll probably get a compression test next week

Twisties

Well my ess sensor bolt broke out and the new hole was making the ess slight off center in relation to the plate. So i ended up enlarging the hole and using a bolt and locking nut got it to be center on the plate again. Then i used jb weld to bond the bolt to the front cover so it is now essentially a stud. To remove the ess you remove the nut and the ess follows leaving the bolt bonded to the engines front cover.

As far as trying to figure out the problem. Test your coils, and wires. Check your plugs. What codes are being thrown.

Twisties

And i would highly reccomend a compression test. 100 Bucks and they even tried to diagnose the problem for free. But for some reason didnt check the ess. But either way once you get that test done it takes a lot of guessing out.

Denztrasion

i have a problem too. first i got that misfire situation last month. until now im still figuring out what the hell wrong with my 8. i am still on limp mode, no power, cant rev up high only up to 3000. i changed my 4 coil brands were beck/arnley but i check those coils and saw some overheat marks so i order the real coils from the mazda dealer with new wires and brand new plugs from oreilly the ngk T & L. new catalytic converter and new o2 sensor. i'm still same camel power. on my obd2 tool monitor status showing is Flashing O, and C. every time i unplug the negative Batt and put it on like the next day or 5 hours, i warm up the car in cold start until i reaches 15 mins. i rev it soft and still no sign of quick rev power.

last month ago i start up the car and waited 15 mins and drive like a camel and shut of my engine then i check my hood touching my plug wires then engine on >> there i have a boost power. it happen twice after that, thats it. one more thing im driving with my wife and my kids all of a sadden RPM drops and stop at the red light then engine went off. i start the engine and a limp mode acceleration run. MAN!!! whats wrong with my 8. my hood is clean no oil leaks i check my OMP 4 brown wires i think thats the oil hose. my air pump is fine. what is causing the situation. need help here.... i only have a racing beat intake and my o2 sensor is bosch the universal the you have to splice the 4 wires. im thinking i want to replace my upstream front o2 sensor and downstream rear o2 sensor?? help help help... mileage 103xxx miles.....

Nopstnz8

iTrader: (6)

Yeah I'm planning to get a compression test done very soon since I'm still under the engine warranty till December, and if my engine is in fact going bad, they'll cover a replacement. I've noticed my coolant expansion tank has been low each month I've checked and refilled it over the last two months, but the car isn't smoking or leaking a puddle of coolant. My ESS sensor isn't broken like yours was, so that's not my problem. I removed and cleaned it a month ago and no change occurred. I'm not getting any CEL's, and my cat isn't clogged because I had the same issue when I unbolted it to test it. I already replaced coils, plugs, and wires as well.

Denztrasion

I had a problem on my 8. Man!!! Runs slow acceleration. I had that misfire code before. New OEM coils, plugs n wires. I been figuring out whats causing this Camel speed. I rebuild my clutch assembly and installed it. Plus new CAT n downstream o2sensor. I still hav the engine light on. My reader tool flashes O, and C. So im thinking my Upstream o2 is dead.