Savage Flat spots

[GunMetalR33]

I have read the thread talking about a small flat spot and I have a similar problem but on a larger scale!

When the engine is under any kind of load the car flat spots like crazy! The first thing i tried was to change the plugs but that did not work, so the next thing for me to do is check the coil packs...

I was wondering about the best way the single out faulty ones in the set? Or if any body else has any idea as to what this might be!

NOTE: I dont think it is the fuel maps ( Flats spots a way to big)

& I dont think it is the cam timming ( had someone have a look at it)

Any comments would be helpfull, thanks guys....

[Guest Robo's]

Are you running extra boost?

[GunMetalR33]

yep, i run about 11 psi!

Its probably worth mentioning that the problem is not as bad when running in low boost mode, ie 7 psi.

Also the car ran fine at 11 psi for about 3-4 months then one day it just started playing up!

[Guest Robo's]

Mate, this is true, i had exactly the same problem, its all fuel, when you turn the boost up, it dumps more fuel in, it needs to be leaned out. I had a slight miss on 7psi, (checked everything) then went to 10psi and it was useless. Everytime i booted it, and as it revved, it coughed , farted, backfired. You should see my dyno graph.

Put an SAFC in and it has done wonders, and so much more power.

[GunMetalR33]

I thought that originally,

but the car was running at 11 psi very well for months then one day the problem started! & I have not changed or modified the ecu.

ALSO, its not just one flat spot its constant flatting as soon as i put my foot down!

[predator]

Fuelling issue.. could be your fuel pump is dying. Get that checked out.. or at least the pressure in your fuel system is at the correct pressure under load.

Apparently to test the fuel pump squeeze the fuel line before it enters the rail. If the engine cuts out with only a little finger pressure its on its way out.

[GunMetalR33]

Ahhh, ok i will give that a go! I also had an idea that it could be the fuel filter! because this problem started soon after I put a full tank in!

thanks for the help!

[rb25]

I just put an HKS EVC4 in at 0.85bar and the fuelling is still all good and no flat spots at all.

[Guest Robo's]

Definately something to do with fuel i think.

Maybe get a dyno run and check your A/F ratios, then you will see if it dieing or not

[46n2]

this happened to me when my 32 came back from the 'mechanics'...

Check your intake plumbing. Make sure a hose hasn't come loose at all, and that all the clamps are doing their job. Basically as my 32 hit 7+lb it would overfuel like a bitch and drown the engine. the more boost, the slower it went.

Just my 2c but good luck...

[GunMetalR33]

Thanks for the 2c's I will give it a go!

[ix9]

I have yet to get my AFCII properly tuned, i had a flat spot plus misfiring around 4500rpm

just by taking out 2% of fuel out at 4500rpm it's made the misfire a lot less!

All in the fuel!

[GunMetalR33]

All though fuel is a problem in r33's because of the fuel dump at 4500 rpm due to the ecu ajusting for the duel stage stock boost controller, I dont think this is the source of the multiple flatting...

I say this because my car ran fine ( with a small flat at 4500) for about 3.5 months. Then all of a sudden the super flatting started!

This leads me to think that the problem is one of the following:

(thanks to all the posts above!)

1)AFM

2)coil pack

3)ignition pack

4)spark plugs & gap ( not the case because i have changed them over twise)

5)fuel pump and or filter

6)timming (long shot!!!)

Thanks again to all who helped with suggestions!!!

Any other suggestions will allways be helpfull.

[Sime]

I had the same problem with multiple flatting at higher than standard boost. Mine was fixed by putting colder plugs in. I know you've checked the plugs and assuming you put the same plugs in as the original ones you had, then this probably won't help. But I do know how frustrating it is trying to track the problem so I thought I'd mention it.

[GunMetalR33]

Yea, its very frustrating and I think everybody who tunes there skyline past stock probably goes through the same thing!

I was running shit sparkies which led me to think that they were the weak spot. But I now run NGK Iridium's and i was under the impression that these are quiet good, am i on the right track here?

[Sime]

I'll start by letting you know I'm an accountant, not a mechanic, but Iridiums are supposed to be very good.

I had platinums put in mine when I bought the car and had this flat spotting problem when I increased the boost. It would get worse if I gave the car a hard time (engine gets hotter).

Plugs have a heat rating and I think spark at a different temperature depending on their rating. When I replaced the plugs with colder ones, the flat spotting went away.

Perhaps get a second opinion though as I don't want to give you the bum steer. Plugs aren't cheap.

[GunMetalR33]

thanks for the info mate!

[Guest Robo's]

Its not spark, me think its still fuel, i changed plugs and it didnt do anything. As soon as i upped the boost, it got worse so i would to run stock boost, even then it wasnt good as it got warmer.

Get an SAFC, lean the fuel out. When you increase boost more fuel is dumped in, simple.

[Guest RedLineGTR]

thanks for that pred

[adam 32]

fuel is the easy one to check - get a $40 power run done at ur local dyno and check the AF curve.

its spark which can be a prick to find, and you never know it could just be a dodgey connection somewhere in the ignition wiring, these cars are getting on 10 years old now and with intense heat its easy for connections to corrode