Random misfire occurs @ 6000 rpms, need help.
Nov 7, 2007, 06:07 PM
#63
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I have been researching on this issue and have come up with several possibilities.
Fuel pump....there are 3 relays for the fuel pump. The "high" voltage relay, if inoperative, will cause an issue with WOT situations because the fuel pump will not receive the higher voltage, thus there won't be a full supply of fuel to the injectors.
Cam Position Sensor...If the sensor is bad it won't tell the ECU the exact valve location which will certainly cause issues
Throttle Position Sensor...if this sensor is bad the ECU won't have proper calibration of the incoming air, thus causing issues.
Bad Ground....good luck at finding this. The Evo has TONS of ground locations.
Electrical Short....There is a strong possibility of this causing the problem.
I have tried 3 different batterys and all had the same issue. I don't feel this is the problem. (Oddesey, Stock, Optima)
Fuel pump....there are 3 relays for the fuel pump. The "high" voltage relay, if inoperative, will cause an issue with WOT situations because the fuel pump will not receive the higher voltage, thus there won't be a full supply of fuel to the injectors.
Cam Position Sensor...If the sensor is bad it won't tell the ECU the exact valve location which will certainly cause issues
Throttle Position Sensor...if this sensor is bad the ECU won't have proper calibration of the incoming air, thus causing issues.
Bad Ground....good luck at finding this. The Evo has TONS of ground locations.
Electrical Short....There is a strong possibility of this causing the problem.
I have tried 3 different batterys and all had the same issue. I don't feel this is the problem. (Oddesey, Stock, Optima)
Nov 7, 2007, 06:55 PM
#64
Well didn't get to much time to log the "issue" the map that was on the car was running dangerously lean since it is now very cold (no good air temp correction graph) and it ran rather lean to start with. Also the microset bit was rather large for the 1000cc injectors, it was dialed to a max of 28lbs on breakpoints, and a few other things that I wanted to change so I worked a new map based off my own calibration and started getting everything dialed in. Car idles so much better now (JUN 272's really turn heads 
), off boost cruising its very smooth, and accel fuel is much more dialed in and the car doesn't have any hesitation when modulating the throttle now.
The battery volts started at 13.5 volts and ended at 13.19 volts during the runs. The car still misfires around 7000 to 8000rpms which boost then falls off and the injector duty cycle was getting into the 90+ % (but intake temperatures were in the 40's and 23lbs of boost with a pt6776 on pump gas I kind of expected that to happen).
I am really leaning toward the CPS being the issue. Hope to get one to test in the next few days.
Below is a screen shot of the 4th gear log (external). The car started to misfire at about 7100rpm and we let out right after that. Anyone have an insight? Hopefully tomorrow now that we got a decent map i want to get some internal logs as they obviously show more detail.
), off boost cruising its very smooth, and accel fuel is much more dialed in and the car doesn't have any hesitation when modulating the throttle now.The battery volts started at 13.5 volts and ended at 13.19 volts during the runs. The car still misfires around 7000 to 8000rpms which boost then falls off and the injector duty cycle was getting into the 90+ % (but intake temperatures were in the 40's and 23lbs of boost with a pt6776 on pump gas I kind of expected that to happen).
I am really leaning toward the CPS being the issue. Hope to get one to test in the next few days.
Below is a screen shot of the 4th gear log (external). The car started to misfire at about 7100rpm and we let out right after that. Anyone have an insight? Hopefully tomorrow now that we got a decent map i want to get some internal logs as they obviously show more detail.
Nov 7, 2007, 08:25 PM
#65
If you do not know what code you are getting, then how are you going to trouble shoot this properly?
Please give the code that your ECU is spewing, unless you have AEM and it does not issue a code.
There is a whole section in the FSM about misfire codes and how to trouble shoot them. I had a Evo 9 with P0300 code and I followed the exact instructions in the FSM and was able to solve the problem. It turned out to be a weak spark plug. We installed new OEM spark plugs and the problem was gone.
Please follow the FSM when trouble shooting these problems. It is really helpful.
Please give the code that your ECU is spewing, unless you have AEM and it does not issue a code.
There is a whole section in the FSM about misfire codes and how to trouble shoot them. I had a Evo 9 with P0300 code and I followed the exact instructions in the FSM and was able to solve the problem. It turned out to be a weak spark plug. We installed new OEM spark plugs and the problem was gone.
Please follow the FSM when trouble shooting these problems. It is really helpful.
Nov 7, 2007, 09:34 PM
#66
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I'll be trying the CPS this weekend. My car's been running great lately, then all of a sudden, 1 mis in 1st , a few in 2nd, some more in 3rd then 4t is fine. Come to a yield, rip 1st up to 7600, no problem, 2nd 3-4 little misfires, 3rd is good up till 6000, then 2-3 misfires & she clears, 4th is fine. come to a light, I decide to nail it as fast as I can shift it w/ out grinding (bad synchros, tranny gets R&R'ed this weekend), 1st is fine to 7800, 2nd good to 7500, 3rd has a few mis's, but still strong and 4th is clean all the way to 6300. I went a ways further where it was clear again & did the same, except this time it doesnt mis a lick once, near perfect! I cruised around a little more after a stop and it would be fine for a while, then several little misfires. strange thing is, it hadn't had a mis in the past day or two, and the car feels really strong too.
Just a side note: I bolted up a set of lightweight Kosei wheels w/ some Toyo RA1's, I shaved 7 lbs per tire & wheel for a total of 28 lbs. strange thing is, they're 235/40/17's, but they're almost an inch shorter than my RE01R's in the same size. It's amazing how much faster the car accelerates! Dropping weight and effectively raising my gear ratio makes a huge difference t say the least, I don't want to swap back!
Just a side note: I bolted up a set of lightweight Kosei wheels w/ some Toyo RA1's, I shaved 7 lbs per tire & wheel for a total of 28 lbs. strange thing is, they're 235/40/17's, but they're almost an inch shorter than my RE01R's in the same size. It's amazing how much faster the car accelerates! Dropping weight and effectively raising my gear ratio makes a huge difference t say the least, I don't want to swap back!
Nov 7, 2007, 11:27 PM
#67
Here is a list of possible reasons of P0300:
1. Bad CPS. Replace it and see if the misfire goes away
2. Check the voltage supply to the CPS from the CPS harness and from the ECU
3. Check your fuel trims. The STFT should be within +/- 20 and LTFT should be between +/- 12.5. Test them @ 2500 rpm.
4. Check the spark plugs and make sure that you have a strong spark. Better yet replace them with new plugs.
5. Check the resistence on the plug wires. Make sure they are below 19 ohms. Better yet replace them with new ones.
6. Disconnect the injector connectors and make sure that the resistence is between 2-3 ohms.
7. Check the harness connection from the injectors to the ECU. Make sure that there are no loose wires or connectors.
9. Check the timing belts for a skipped tooth
10. Check the EGR and see if it is working properly
11. Check the compression and make sure it is up to spec.
12. Replace your injectors if they are bad.
13. Finally, if all else fails replace your ECU.
I suspect that the reason Blamo is getting the misfire is the AEM EMS. Go back to the stokc ECU and it might solve your problem. The ECU can handle the power levels that you are running with ease.
1. Bad CPS. Replace it and see if the misfire goes away
2. Check the voltage supply to the CPS from the CPS harness and from the ECU
3. Check your fuel trims. The STFT should be within +/- 20 and LTFT should be between +/- 12.5. Test them @ 2500 rpm.
4. Check the spark plugs and make sure that you have a strong spark. Better yet replace them with new plugs.
5. Check the resistence on the plug wires. Make sure they are below 19 ohms. Better yet replace them with new ones.
6. Disconnect the injector connectors and make sure that the resistence is between 2-3 ohms.
7. Check the harness connection from the injectors to the ECU. Make sure that there are no loose wires or connectors.
9. Check the timing belts for a skipped tooth
10. Check the EGR and see if it is working properly
11. Check the compression and make sure it is up to spec.
12. Replace your injectors if they are bad.
13. Finally, if all else fails replace your ECU.
I suspect that the reason Blamo is getting the misfire is the AEM EMS. Go back to the stokc ECU and it might solve your problem. The ECU can handle the power levels that you are running with ease.
Nov 8, 2007, 09:33 AM
#68
Here is a list of possible reasons of P0300:
1. Bad CPS. Replace it and see if the misfire goes away
2. Check the voltage supply to the CPS from the CPS harness and from the ECU
3. Check your fuel trims. The STFT should be within +/- 20 and LTFT should be between +/- 12.5. Test them @ 2500 rpm.
4. Check the spark plugs and make sure that you have a strong spark. Better yet replace them with new plugs.
5. Check the resistence on the plug wires. Make sure they are below 19 ohms. Better yet replace them with new ones.
6. Disconnect the injector connectors and make sure that the resistence is between 2-3 ohms.
7. Check the harness connection from the injectors to the ECU. Make sure that there are no loose wires or connectors.
9. Check the timing belts for a skipped tooth
10. Check the EGR and see if it is working properly
11. Check the compression and make sure it is up to spec.
12. Replace your injectors if they are bad.
13. Finally, if all else fails replace your ECU.
I suspect that the reason Blamo is getting the misfire is the AEM EMS. Go back to the stokc ECU and it might solve your problem. The ECU can handle the power levels that you are running with ease.
1. Bad CPS. Replace it and see if the misfire goes away
2. Check the voltage supply to the CPS from the CPS harness and from the ECU
3. Check your fuel trims. The STFT should be within +/- 20 and LTFT should be between +/- 12.5. Test them @ 2500 rpm.
4. Check the spark plugs and make sure that you have a strong spark. Better yet replace them with new plugs.
5. Check the resistence on the plug wires. Make sure they are below 19 ohms. Better yet replace them with new ones.
6. Disconnect the injector connectors and make sure that the resistence is between 2-3 ohms.
7. Check the harness connection from the injectors to the ECU. Make sure that there are no loose wires or connectors.
9. Check the timing belts for a skipped tooth
10. Check the EGR and see if it is working properly
11. Check the compression and make sure it is up to spec.
12. Replace your injectors if they are bad.
13. Finally, if all else fails replace your ECU.
I suspect that the reason Blamo is getting the misfire is the AEM EMS. Go back to the stokc ECU and it might solve your problem. The ECU can handle the power levels that you are running with ease.
Good things to check
Didn't someone in a previous post mention that they swapped out to a brand new AEM and it didn't solve the problem
Maybe there is something to this as all the cars w/ the hi rpm mis-fire are running AEM'sThe only car that doesn't do it yet it mine w/an AEM and only 3000 miles on the ignition system and only 500-1000 on the shortblock.
Nov 8, 2007, 11:26 AM
#69
Good things to check
Didn't someone in a previous post mention that they swapped out to a brand new AEM and it didn't solve the problem Maybe there is something to this as all the cars w/ the hi rpm mis-fire are running AEM's
The only car that doesn't do it yet it mine w/an AEM and only 3000 miles on the ignition system and only 500-1000 on the shortblock.
Didn't someone in a previous post mention that they swapped out to a brand new AEM and it didn't solve the problem
Maybe there is something to this as all the cars w/ the hi rpm mis-fire are running AEM'sThe only car that doesn't do it yet it mine w/an AEM and only 3000 miles on the ignition system and only 500-1000 on the shortblock.
For informational purposes reguarding this my car has 76,000 miles on it with an AEM EMS tuned by me, AMS 2.3 stroker (only about 2000 miles on engine), AMS race head, AMS 37r, meth injection, JUN 272's, and 30lbs of boost and the ignition was always solid. Currently the engine is back at AMS and I look forward to getting it back, reinstalled, and still have a trouble free ignition system till I switch to COP.
On another note I picked up a CPS for the car I am working on that has this misfire issue so I hope it solves the problem tonight and I can continue tuning with the new map I made for the car yesterday.
Nov 12, 2007, 10:29 AM
#71
I'd like to hear what happened if any good news.
We on the other hand had good and bad news.
Our Evo had the prob fixed it seemed like w/ a diff battery and the owner/driver said he went to a TNT at Infenion Raceway and the whole day not 1 problem.
Then for the actual event the misfire reared it's ugly head again
Everytime he'd get into boost he said he had a large hiccup and misfire
That pretty much ended his day as the afr would sky rocket lean at that misfire so we'll see what happens when i get to the shop after my "real" work is done at noon.
We on the other hand had good and bad news.
Our Evo had the prob fixed it seemed like w/ a diff battery and the owner/driver said he went to a TNT at Infenion Raceway and the whole day not 1 problem.
Then for the actual event the misfire reared it's ugly head again
Everytime he'd get into boost he said he had a large hiccup and misfire
That pretty much ended his day as the afr would sky rocket lean at that misfire so we'll see what happens when i get to the shop after my "real" work is done at noon.
Nov 12, 2007, 11:52 AM
#72
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WOO HOO....I FIXED IT ! ! !
I replaced the plugs with new colder Iridiums.
I replaced the seals in the throttle body. (mine were leaking BAD)
I put dielectric grease on the plug wires (both ends)
I am not sure which one of these fixed it......but it is running like a champ! !
I replaced the plugs with new colder Iridiums.
I replaced the seals in the throttle body. (mine were leaking BAD)
I put dielectric grease on the plug wires (both ends)
I am not sure which one of these fixed it......but it is running like a champ! !
Nov 12, 2007, 03:05 PM
#74
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blowoffsilver,
Glad to hear you got it fixed! Are you planning on coming to the Dragon?
I should know the status tonight or tomorrow as my car is currently in the shop, they replaced the CPS but weren't able to test drive it today due to a clutch related issue(clutch pedal kept getting soft after adjusting it, like air was getting in the line, they replaced the OEM hose w/ a SS one, but same thing. they're swapping out the MS tonight). Once they test it I'll let post if it worked or not. They also said that my battery voltage was inconsistent and/or bouncing up & down, so they're swapping in another battery too after testing the CPS. Sad thing is, it's a new BUbby Club Racing mini battery.
Glad to hear you got it fixed! Are you planning on coming to the Dragon?
I should know the status tonight or tomorrow as my car is currently in the shop, they replaced the CPS but weren't able to test drive it today due to a clutch related issue(clutch pedal kept getting soft after adjusting it, like air was getting in the line, they replaced the OEM hose w/ a SS one, but same thing. they're swapping out the MS tonight). Once they test it I'll let post if it worked or not. They also said that my battery voltage was inconsistent and/or bouncing up & down, so they're swapping in another battery too after testing the CPS. Sad thing is, it's a new BUbby Club Racing mini battery.
Nov 12, 2007, 03:16 PM
#75
Unfortunately the CPS didn't fix the misfire on the car I am working on. We are now going to try the AEM EMS from my personal car and see if we can swap the battery for another one and see if that makes a difference. I'll report findings soon as I get a chance to work on the car, just been hit or miss between the car owner and myself.