Jump to content
SAU Community

Odd Miss @ Wot

KB240RB

By KB240RB,
in General Maintenance

 Share

Recommended Posts

KB240RB Contributor

KB240RB

Posted
Posted

First id like to say ive read the threads about the coilpack issues and i dont believe thats the problem. The problem is the car misses only when going WOT. At part throttle under boost its perfectly fine and pulls hard but once at 100% it misses and feels like it pulls timing. I dont understand whats causing it. I have timing set to 15*. Checked boost leaks to 20psi and found none. Fuel pressure is at 43psi w/o vacuum. New SS Performance Coilpacks. Ive tried BKR7EIX plugs and BCPR6ES-11 plugs both gapped at .030" and didnt make a difference. Just for the hell of it i disconnected the battery to try and reset the ecu. Everything is properly grounded. TPS is set to .45 volts closed. Anybody have any idea or suggestions what this WOT miss is caused from?

Link to comment
https://www.sau.com.au/forums/topic/286193-odd-miss-wot/
Share on other sites
nikr33turb Collaborator

nikr33turb

Posted
Posted
First id like to say ive read the threads about the coilpack issues and i dont believe thats the problem. The problem is the car misses only when going WOT. At part throttle under boost its perfectly fine and pulls hard but once at 100% it misses and feels like it pulls timing. I dont understand whats causing it. I have timing set to 15*. Checked boost leaks to 20psi and found none. Fuel pressure is at 43psi w/o vacuum. New SS Performance Coilpacks. Ive tried BKR7EIX plugs and BCPR6ES-11 plugs both gapped at .030" and didnt make a difference. Just for the hell of it i disconnected the battery to try and reset the ecu. Everything is properly grounded. TPS is set to .45 volts closed. Anybody have any idea or suggestions what this WOT miss is caused from?

Whats your boost set to bud?

Link to comment
https://www.sau.com.au/forums/topic/286193-odd-miss-wot/#findComment-4810119
Share on other sites
KB240RB Contributor

KB240RB

Posted
  • Author
Posted

It does it at stock 7psi, 10psi, or 13psi. What i found the other day is if i set the TPS to .45 volts with the engine off, the voltage drops to .35 volts when its running, and then voltage drops to .15 volts when the e-fans turn on. Its also not reading WOT. With throttle plate fully open, the ecu is only seeing 90% throttle at best using my AVCR. To get it to read 100% throttle, i have to turn the voltage up to .70 at idle and then when the e-fans turn on the voltage drops down to around .55 volts and then it wont go to 100% throttle. Im thinking the TPS is messed up. Has anyone else had this problem?

Link to comment
https://www.sau.com.au/forums/topic/286193-odd-miss-wot/#findComment-4810134
Share on other sites
DanShirts Collaborator

DanShirts

Posted
Posted
It does it at stock 7psi, 10psi, or 13psi. What i found the other day is if i set the TPS to .45 volts with the engine off, the voltage drops to .35 volts when its running, and then voltage drops to .15 volts when the e-fans turn on. Its also not reading WOT. With throttle plate fully open, the ecu is only seeing 90% throttle at best using my AVCR. To get it to read 100% throttle, i have to turn the voltage up to .70 at idle and then when the e-fans turn on the voltage drops down to around .55 volts and then it wont go to 100% throttle. Im thinking the TPS is messed up. Has anyone else had this problem?

I'm having the exact same problem. Runs perfectly at 95% throttle. But when I mash the pedal, it coughs and dies.

My TPS had the same readings as yours. I took my TPS apart and cleaned it. It isn't hard, but you can break it if your not extremely careful. I can adjust it correctly now (0.47 ~ 4.09), but I still have the miss.

I'm running BKR7E plugs gapped at 0.8 (0.030"). I've also run BCPR7ES plugs, they run the same. My coils are good.

I also have a bad turbo and a boost leak.. so that is likely my problem. Do you have a boost leak?

Link to comment
https://www.sau.com.au/forums/topic/286193-odd-miss-wot/#findComment-4810147
Share on other sites
mad082 Grand Master

mad082

Posted
Posted

the missfire is going to be either a spark or fuel issue. i see that you have a rb25 in a 240sx. do you happen to know what series motor it is (series 1 or 2)? there are a few ways to tell if you don't happen to know. the plug on the TPS and the presence/lack of an ignitor pack at the rear of the rocker cover. if the TPS is a black rectangle and there is an ignitor pack on the rocker cover then it is series 1. if the TPS is more rounded with 2 plugs on it and there is no ignitor then it is series 2 (they have the ignitor built into the coils).

back to the missfire, what is most likely happening (what happens with most missfire issues) is that the spark plug isn't able to ignite the fuel. the reason it happens at WOT and not lesser throttle is because the further you put your foot down the richer the air/fuel mixtures get as well as the more fuel that is in the combustion chamber. the cause of the missfire can be caused by a few things.

1: over fueling.

2: weak spark plugs.

3: weak coils.

4: weak ignitor.

now you have changed the plugs, so that rules that out. the overfueling can be caused by a few things. can be fouled injectors not shutting properly, dirty/damaged AFM or a boost leak (you have also ruled that out). you could try taping up the coils with electrical tape to reduce the chance of them arcing out. if your car has the ignitor pack then they can also strat to fail at higher load due to the fact that they are getting old now and don't perform like they used to.

Link to comment
https://www.sau.com.au/forums/topic/286193-odd-miss-wot/#findComment-4812029
Share on other sites
KB240RB Contributor

KB240RB

Posted
  • Author
Posted

Its a series 1. Have already put brand new coilpacks in it. I pulled the plugs and they do appear to be more on the darker side of a caramel/tanish color. Im gonna get a new set of bcpr6es-11 plugs and gap them down to .030" and try them. Ill see what i can do about getting another ignitor to try and ill clean my MAF as well.

Link to comment
https://www.sau.com.au/forums/topic/286193-odd-miss-wot/#findComment-4813068
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Duncan
      7 Speed Auto transmission fluid change (Skyline, Q50, Q60, Fuga, Q70, A62 Titan and probably heaps of others including Navara...)

      By Duncan · Posted

      OK, Step 3, if you need to remove the valve body, either to replace it, the TCM, or to do a more complete drain.  First, you need to disconnect the TCM input wires, they are about half way up the transmission on the drivers side. One plug and the wires are out of the way, but there is also a spring clip that stops the socket from sliding back into the transmission. On my car the spring clip was easy to get, but the socket was really stuck in the o-ring of the transmission housing and took some.....persuasion. You can see both the plug to remove (first) and the spring clip (second) in this pic Incidentally, right next to the plug, you can see where the casting has allowance for a dispstick/filler which Nissan decided not to provide. there is a cap held on with a 6mm head bolt that you can remove to overfill it (AMS recommend a 1.5l overfill). Final step before the big mess, remove the speed sensor that is clipped to the valve body at the rear of the box.  Then removal of the Valve Body. For this the USDM Q50 workshop manual has a critical diagram: There are a billion bolts visible. Almost all of them do not need to be removed, just the 14 shown on the diagram. Even so, I both removed one extra, and didn't check which length bolt came from which location (more on that later....). Again it is worth undoing the 4 corners first, but leaving them a couple of turns in to hold the unit up....gravity is not your friend here and trans oil will be going everywhere. Once the corners are loose but still in remove all the other 10 bolts, then hold the valve body up with 1 hand while removing the final 4. Then, everything just comes free easily, or like in my case you start swearing because that plug is stuck in the casing. Done, the valve body and TCM are out
    • Duncan
      7 Speed Auto transmission fluid change (Skyline, Q50, Q60, Fuga, Q70, A62 Titan and probably heaps of others including Navara...)

      By Duncan · Posted

      OK, so if you are either going for the bigger fluid change or are changing the valve body which includes the Transmission Control Module (TCM), first you should have both a new gasket 31397-1XJ0A and a torque wrench that can work down to 8Nm (very low, probably a 1/4 drive one). You can probably get by without either, but I really didn't want to pull it all apart together due to a leak. First, you now need that big oil pan. The transmission pan is 450 long x 350 wide, and it will probably leak on all sides, so get ready for a mess. There are 24x 6mm headed bolts holding the pan on. I undid the 2 rear corners, then screwed those bolts back in a couple of turns to let the pan go low at that end, then removed all the middle bolts on each side. Then, undo the front corner bolts slowly while holding the pan up, and 80% of the fluid will head out the rear. From there, remove the remaining bolts and the pan is off. You can see it is still dripping oil absolutely everywhere...it dripped all night.... I got another couple of litres when I removed the pan, and then another few when I removed the valve body - all up another 4l on top of the 3 already dropped in step 1.
    • Black_CSR
      Wheel Sizes & Offsets For Skylines

      By Black_CSR · Posted

      Yeh I think i'll message an old contact i had for ages that manages his own tyre shop now.. n tell him what i want n work with him before ordering..  Got this 17x9 +30 Driftteks on 245/45/17 PSR Drag Radials on the rear.. They fit well - for your reference in future - Rear guards  have been lipped in & minimal to non flaring of the rear Gaurds.    
    • Kinkstaah
      Wheel Sizes & Offsets For Skylines

      By Kinkstaah · Posted

      If only it were that easy! I also needed to remove seats, shocks, brake calipers, send my car through a fence, and use measuring and ended up guessing because I didn't remove seats, shocks and brake calipers. It can be hard sometimes Can be a little more complex than 'just measure' if you want to truly measure the entire wheel through all of it's suspension travel. But if you aren't going for every last mm then yeah, you can check the space you currently have and guesstimate.
    • GTSBoy
      Wheel Sizes & Offsets For Skylines

      By GTSBoy · Posted

      If you own a car, and it has wheels on it, and you know the offset of those wheels, and you have a measuring device, you have everything you need to work out if other wheels will fit.
×
×
  • Create New...