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What's Exactly Wrong With My Car? Symptoms: Flatspots, Power Being Held-back. Please Help!

Andi

By Andi,
in Engines & Forced Induction

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Andi Experienced

Andi

Posted
Posted (edited)

Ok all, I've done ALOT of research and reading about this but as there are too many relating issues and thus being to vague, I think its time to open a thread asking specifically what seems to be wrong with my car. Heres whats currenty done to my car:

R34 GT-T

BATMBL SS Split Dump

Xforce SS Hiflow Cat

Trust 3.5" Catback

Apexi Pod (open - no enclosure/cai)

Profec B Spec II (10/12psi)

FMIC

Bosch 040 Pump

Ok this is what happens when I plant it (100% throttle) in second gear at approx 2000rpm. Power begins to build and then there seems to be flat spots all the way to redline. The most noticeable ones would be at ~3000rpm and 5000-5500rpm. When these flat spots occur it simply makes the car feel VERY slow as if the car is being held back and not being allowed to reach its full powerband. This happens at both 10psi and 12psi.

I've already replaced the plugs with 0.8 pre-gapped coppers, also just replaced the fuel filter. The coilpacks have been tapped up as well, and I'm not sure if its mis-fire because I can't hear any popping noises.

Apologies for the long post and I'm sorry if this sounds 'repetitive' to some but as my symptoms came up with so MANY results I'm not sure what exactly it is. I would just like to get rid of this problem as it feels as if I'm being robbed from my cars true potential. :)

Thanking those who are reading this in advance and any help will be greatly appreciated! :)

Cheers,

Andy

Edited by OnGsTa
Andi Experienced

Andi

Posted
  • Author
Posted

I've always assumed that Rich and Retard was a viscous jerk/sudden stop in power? I've actually experienced this already at ~80% throttle and though the stuttering/flatspots I get at 100% was different?

Skrags Rookie

Skrags

Posted
Posted
Anyone else?

Yeh my cars doin exact same think wen i boost it over 12 psi and i also tried a 0.8mm plug gap still does it tho... so at the moment i just run it on 10 psi :) i think it may just need to be tuned to it ???????

But i fairly wouldnt mind to know why it does it!

My Mods:

3 1/2 inch turbo back exhaust aka snail-to-tail

GFB B.O.V.

POD filter

Front mount

Boost control(manual) :D

AdamsR33 Mentor

AdamsR33

Posted
Posted

Skrags, if your running stock ECU it will not let your boost go any higher than 10psi, it sees too much air and thinks there is a problem and starts rich and retard. As stated Dale FZ1 its nissan's failsafe so you won't blow the motor. To run this much boost you will need to run a piggy back ECU or a full ECU like a PFC. Some owners have been able to get more than 10psi but not much more. And besides the stock turbo is nearing its limit at 12psi. If i were you i wouldn't go much past 10psi anyway.

Munna1 Proficient

Munna1

Posted
Posted

Sounds like rich and retard to me mate have a look at the tuning guide on my webpage it goes into more detail. Invest in a SAFC or Power FC and get it dyno tuned you will be amazed how much extra power this will add.

cheers

Abo Bob Grand Master

Abo Bob

Posted
Posted

It is certainly not R&R. Your coil packs are stuffed. Remove them and replace with new Splitfires. This will fix your problems - both of you.

The R34 will run 12psi ok on the stock ECU but you will get R&R which by the way in R34's is not rich and retard, it's just retard. All you will notice when this happens is the power seems to fall away at at 5000rpm then it picks up again.

What you have described in the first post is misfiring. Taping R34 coils doesn't seem to work.

Abo Bob Grand Master

Abo Bob

Posted
Posted

Have a look at my old dyno sheet here. This was full exahust + boost to 12psi. The bottom line is stock boost.

In the top power line you can see the power actually drop below the stock boost line. This is "R&R" however if you look at the corresponding AFR line down the bottom you will see that it actually gets slightly leaner at that point so obviously the Rich is not there but the power drops and it's this that indicates the drop in timing, ie retard.

post-7957-1162973032.jpg

Andi Experienced

Andi

Posted
  • Author
Posted
All you will notice when this happens is the power seems to fall away at at 5000rpm then it picks up again.

Hey Abo Bob, so are you describing with that statement? Is that the retarding, or the misfiring/coilpack problem?

I'm pretty sure R34's have R&R too because as I stated in the original post I had that massive power loss where the car would feel like it cut out and I would literally be flung foward because of sudden jerking.

Cubes Grand Master

Cubes

Posted
Posted
I've always assumed that Rich and Retard was a viscous jerk/sudden stop in power? I've actually experienced this already at ~80% throttle and though the stuttering/flatspots I get at 100% was different?

Nope thats fuel cut. :blink:

Cubes Grand Master

Cubes

Posted
Posted

Airflow vs RPM.

The old rb20det running 16psi on the stock turbo would see fuel cut at around 5500rpm on a cold night.

THe RB30DET on the stock ecu would see fuel cut on 6-7psi with the stock turbo at ~3000rpm.

Abo Bob Grand Master

Abo Bob

Posted
Posted
Hey Abo Bob, so are you describing with that statement? Is that the retarding, or the misfiring/coilpack problem?

I'm pretty sure R34's have R&R too because as I stated in the original post I had that massive power loss where the car would feel like it cut out and I would literally be flung foward because of sudden jerking.

The retarding.

I've never experienced fuel cut in my r34.

Andi Experienced

Andi

Posted
  • Author
Posted
The retarding.

I've never experienced fuel cut in my r34.

But what you described sounds exactly like the symptoms I'm asking about? Doesn't that mean I'm hitting Retarding and its not a coilpack problem?

Anyhow I think I might start a NSW thread to see if anyone who has an R34 and Splitfires is willing to let me take a run with the Splitfires to see my car runs better, allowing me to see if I need to buy a set or not.

Abo Bob Grand Master

Abo Bob

Posted
Posted
But what you described sounds exactly like the symptoms I'm asking about? Doesn't that mean I'm hitting Retarding and its not a coilpack problem?

Anyhow I think I might start a NSW thread to see if anyone who has an R34 and Splitfires is willing to let me take a run with the Splitfires to see my car runs better, allowing me to see if I need to buy a set or not.

If you drive over to my place in Sutherland you can take me for a spin and I will tell you 100% what it is.

Andi Experienced

Andi

Posted
  • Author
Posted
If you drive over to my place in Sutherland you can take me for a spin and I will tell you 100% what it is.

I shall take you up on that offer. :( It'll have to be at the end of the month (27-29th onwards) when I get my car back and finish my exams though. Will this be an inconvience?

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