Possible R&r? Only 10Psi, Happens Randomly?

[hop1308]

Hey guys, I've had this problem for a very long time and i'm not too sure what it is, but it's pretty annoying.

I've got a R34 GT-T stockish, mods are:

- turbo back exhaust

- rb20 actuator, constant 10psi boost with no dual stage.

Anyways, the issue i have is, if i put my foot down completely on the throttle the car usually drives fast n fine, but sometimes it makes popping sounds from the exhaust region.

This problem is a lot more common when im on the highway at say 110km/h and i decide to put my foot down completely it'll pop and pop so much that any normal honda can get passed me.

I assumed it was R&R since its a stock ECU, but i've heard the stock ecu can take up to 1 bar of boost. this is only 10psi.

Any ideas on what it could be guys? and anyway to fix it?

[GTSBoy]

Could easily be R&R. The R34 ECU is no different to the R33 one in that regard (while being totally different in most other ways). 10 psi is enough to trigger R&R.

If you're loading it up in a high gear it will drag a lot of air in and if the AFM signal goes high enough the ECU will close you down.

One of the key differences between when cars do it and don't, and which cars do it and don't, appears to be the state of health of the AFM.

[Dose Pipe Sutututu]

R&R my shit box does it too when it's cold at 0.7bar

Solution: Standalone OR NIStune

[scotty nm35]

Can you elaborate on popping sounds?

It could be lean popping... Or simply coil packs breaking down too.

Try dropping the boost and see if it goes away.

[jiffo]

Really need a bit more info but doesn't sound like R & R to me, more like plugs or coil packs.

R & R, you'd know, jerking will put you in the windscreen.

As the cooler months approach we'll see heaps of these R & R threads.

[hop1308]

hmm im getting confused now because when it pops the car doesn't jerk at all. it simply reminds me of those heaps worked cars shootting flames or the sound of hitting rev limitter in some cars.

but yeah it doesnt jerk at all, just pretty much cuts off acceleration for that second. and doesnt shoot flames or hit limitter

when researching this I came across something like afm cuttoff or something, dunno though.

what could it be?

[GTSBoy]

"AFM cutoff" and R&R are almost the same thing. "AFM cutoff" is more properly known at "TP limit". "TP" is the Nissan ECU term for the load signal. It's calculated directly from the AFM signal. There is a table in the ECU called "TP limit" that makes the ECU cut when you exceed a given TP at a given RPM.

On the offchance that it is your coils (and it's a reasonable chance) you should try a known good set (preferably newish OEM coils or a set of Splitfires - rather than any of the other aftermarket ones or old original ones) to see if that helps. But realistically, you have a Nistunable ECU. I wouldn't own it for another week without getting it Nistuned and onto the dyno. No need to put up with Nissan ECU shenanigans unless you have an R33 (and then you deserve sympathy anyway).

cheers

Edited May 16, 2013 by GTSBoy

[Kinks]

R&R is not the same as a hard cut. It runs rich and retarded so the car just makes no power. I have done datalog runs on my R33 and it hits R&R around 10psi and the car just has no acceleration. The engine is running smoothly (no popping, no jerking) it just makes no power.

popping or jerking = coil packs, spark gap too wide, AFM cut. it would only be lean pop if your fuel pump is shot or you have clogged injectors. not as likely as the other scenarios (coil packs, spark gap, AFM)

[GTSBoy]

I didn't say they were the same. I said "almost the same". I didn't elaborate on the distinction because I was only interested in explaining what TP cut was. Everyone should already know what R&R feels like.

The "almost the same" line is simply that the ECU has built in "protection" at certain levels and they all ruin the fun.

[jay-rod]

It will be Coilpacks
Dirty Sparkplugs
To big gap Sparkplugs

Certain on that.

[Missileman]

is it throwing and fault codes?

[hop1308]

okay wow this is a bit of a worrying issue then I guess. always thought it was normal and no big deal and assumed it was r&r or that afm cut off.

so I really cant afford a new ecu or even a tune. what are the chances that this is:

- r&r?

-afm cutoff

-sparks

and what is the risk im taking by not getting it fixed. or maybe most cost effieient method to fix?

[GTSBoy]

2 of the 3 things in jay-rod's list are free to fix.

1 of them is the cost of a set of new coilpacks (I'm saying that's $500 for a set of Splitfires).

Nistune installed (into your existing ECU - it's not a comlpete new ECU) and tuned is just over a grand.

I tend to think if people don't have enough cash to support these type of costs, then they shouldn't try to operate 15 year old turbo cars. It's like buying a 928 Porsche because you can get it for $15k, but forgetting that every job on a 928 costs at least $3k.

[BLITZ-26]

Mine did the same tested on the dyno it was just going rich and not making power all I can run is 9psi it run smooth just makes no power it would go from 188kw to 100-120kw with 10psi so turn thr boost down and it will run fine

[hop1308]

well im just looking for advice on what to do from this point on. or better yet, the best method to determine exactly what's causing this problem.

is it worth changing my sparks? I was almost certain it wasn't spark related as it very rarely happens at low speeds whereas on high speeds it almost certainly happens

Edited May 17, 2013 by hop1308

[GTSBoy]

You do know under what circumstances coils and plugs find it easy to ignite mixture and under what circumstances they find it difficult to ignite? Don't you?

[jay-rod]

Its not hard to replace spark plus...Replace them with .8 gap and see what happens...

If that doesnt fix it, its the coilpacks

[Kane_R32]

well im just looking for advice on what to do from this point on. or better yet, the best method to determine exactly what's causing this problem.

is it worth changing my sparks? I was almost certain it wasn't spark related as it very rarely happens at low speeds whereas on high speeds it almost certainly happens

Problem: Running more then stock boost. Ecu thinks there is a overboost (aka rR&R)

Solution: Run stock boost, or buy a aftermarket ECU or install Nistune..

[hop1308]

gtsboy sadly im not sure what those mixtures are.

even worse, last night I was beaten by a gti r off the launch and even off second. and then I noticed that this problem occurs at all speeds now.

my best description is, that it isnt a loud pop but its half loud. and I lose all acceleration at that point.

ive come to realsie this must be fixed, so all legitness, is it ecu or spark plugs/ coils related? cause im getting all different answers here, and I can only afford to fix it once.

thanks heaps for all the help guys, id be lost without it

[AngryRB]

I think the fact of the matter is that with 10psi you at hitting around the 200kw mark and at this level its time for

- coilpack replacement ( highly likely)

- nistune or aftermarket computer

- tune

so 2 options

- restore to factory boost and get your butt kicked by gti r's

- open wallet and spend $$$ and kick some gti r's and smoke tires while doing it lol

most opt for the open wallet option