Problems around 5k at wot.

[Thanielson]

so it started happening about a month back when im driveing i can free rev it to 7k rpm + but if i pedal to the metal so to speck it sputters out and doesn't want to do a dam thing. I've got the blazt cable and a laptop i data logged it when i get to the point were it happens the injectors and the duty cycle fall on there face to what would be idle outputs. i gaped the plugs to 30 some one told be i could be blowing out the spark the are ngk ird plugs BKR6EIX-11. changed the fuel filter thinking maybe it is clogged i don't have a fuel pressure reg so i cant watch the pressure. the mods on the car are neo rb25, apexi gt spec exhaust, dele cat, k&n air filter, hybrid front mount, walbro fuel pump, @ 11psi boost. there was no mod that was done anytime Pryor to this happening i did get a tps code 46 come up about 2 weeks ago it is a neo only code about the voltage being off for the tps.
Modified by Thanielson at 5:41 PM 3/23/2008

[omgsky]

I have the same problem with my R33 RB25 . Acts like it wants to go like hell...then BLAH.

[Thanielson]

ya pisses me off i wanna go to the track but dont wanna chance anything your in northern wa you ganna go to the nwn gg meet?

[omgsky]

If I can get the damn thing running right.

[bmadd2402]

I had that problem too, and after doing some research, found that it is most likely the "rich and retard" function of the RB25det's ECU. Suprisingly enough, the GTS-t is not a real performer. better than average, but still a somewhat economical commuter. the tune is notoriously rich, and has a protection feature built in, which many called rich and retard. you have increased your mass air flow through your engine by adding all your mods. you may not have changed boost pressure, but air flows easier. the rb25det ECU's MAF senses the increased mass air, and dumps fuel and pulls timing, hence Rich and retard. many people call this overboost protection, which it kind of is. if this is the case, the only thing that will fix it is tuning. Good luck, and if I'm way off, sorry.

[Thanielson]

did tuning fix the problem for you?

[bmadd2402]

didn't experiance this problem until after my rebuild where i did some head work trying to get the motor to flow better. finished right before i deployed, so havent yet tried to tune it. will let you know here in a month when i go home tho!

Get on SAU and search "rich and retard" and i think you will find many threads with your same symptoms. through troubleshooting, i have eliminated everything else.

[quikdime]

I had a similar problem on my rb25det . I installed a fuel pressure gauge and oh my god!!!The pressure was set at 100psi. I turned it down to 37 psi w/vacuum. The motor puls hard to 7,000 rpm. When I purchased the motor the factory fpr was cracked. So I installed a Nismo. Thinking it was pre-set form Nismo,I just installed it. Boy was I an idiot!Good luck!

[Thanielson]

thx bmadd that deff seems to be my prob after reading some r&r post on sau im ganna get a power fc in a month or so to fix the problem.

[bmadd2402]

Keep us posted!

[daveh93s13]

so it seems the engine puts itself in rich and retard on its own, but how do you pull it out of that mode? i just dont understand if this is a factory function, there must be a way to repair without spending a ton of money on a pfc, or other aftermarket control management. would a rough run throughout the rpm range, from idle on up with popping and bucking be a symptom of the rich and retard? im thinking its more coil/ignition related but would like some input from more knowledgable nissan ppl.thanks

[Thanielson]

when it happens it isnt a constint thing it cuts it for a second and if you let off the gas it comes out of it but if you try to keep you \r foot to the floor it will keep doing it. also i know it is the R&R cus i have nissan data scan and a blatz cable to watch it take the timing from 50+ to 0 in a heart beat and the inj just drop off the map it isnt a simple miss fire or something like that it happens at the same point everytime and only happens when im at 3\4 to wot throttle and hey was ganna get a pfc anyway so no biggie.

[bmadd2402]

No, it is not rough thru the rpm range. It is almost like a switch. You are driving along, about 2000 rpm, some civic rolls by, you drop it in second and mash it. it pulls hard up until about 5500, then sputters like it hit fuel cut. you let a little off the throttle, and it's pulling again, then mash it again, and sputter. It is really quite embarassing. it does make sense, to protect the motor. But it becomes a problem when you are trying to get everything you can out of your motor.

i guess the cheapest route you could go would be some kind of piggyback controller to trick the MAF sensor's output voltage, and at the same time adding fuel. Something like the S-AFC.

[BEST1TUNING.COM]

You guys are absolutely right about the rich and retard, any small amount of airflow above stock will retard timing as low as 5 degrees and richen the mixture as a result. There is a way around it using the stock ecu and chipping it with a remap eliminating the feature. It is $650 if its worth it to you, also allows for full tuning of the ECU jsut like any other ROM tune.

[IronMonkey]

zerothread?id=309275i had the same problem...ended up being a bad maf....switched out the maf and everything was good...

[catch221134]

I have had the same problem, and it has stumped just about every one. I also posted up on nico several months back.

I have the usual mods': intake manifold, gt spec exhaust, aeromotive fpr, syoko outlet elbow, no cat, apexi neo and avc-r.

My car does the same thing, since i have switched to the intake. So I would advise all people to not go with one, unless you want to go all the rest of the way and upgrade turbo, waste gate, and so on.

The only other thing is that, my car has some weird boost creep problem. In first it will almost act like a boost spike, but in 2-5 it will hold at .55 bar and then creep to what every it wants to. Stock turbo, second one because of this issue. Any suggestions?

As for the others, I feel you pain, and it is quite embarrasing. You can't even drive the car, and if you are like me, have quite a bit sunk into something you cant even mob out in, or take to the track...a pity...

I think that tuning is the answer and the R&R is also the reason. So get it tuned. I was on the way to get mine tuned and this boost creep issue came up and the turbo blew up before I could get it tuned. But I did mess around and lean the fuel out in my neo at 5.5 to 6.5 (mine seemed to snap out of the R&R at 6.5 to redline) and it ran amazing...

If anyone has suggestions of the boost creep, please let me know. And I have switched everything on the engine, maf, plugs, all that stuff that fixes everyone elses. And have ran a boost leak on it, and it was fine.

[bmadd2402]

There is also loads of info on the boost creep problem on SAU. I'm was having the same problem. wire it full open , and see if it still creep, if not, it is the actuator. If it creeps, I guess you are flowing too much air. I also heard tuning can help this too. GL!

[catch221134]

Alright boyz and grrls, I went and got a buddy's Wideband, and did a street tune on it, and its a completely different car, so I fully believe in the R&R. And the boost creep issue did simmer down a lil, to about .75 or .81 bar. But last nite, I hammered on it, and it went to .95 which makes me really nervous.

But bmadd2402 what do you mean by, wire it full open? I have switched two turbos, and two actuators, and they both still do the creep/spike issue. So With tuning it did help it out alot, and hope to get it on the dyno on Thursday, to see if that helps it out completely with the creep/spike. I will keep you guys informed.

And if the tuning doesn't work I will just get a hks actuator, and call it a day.

[catch221134]

Ahh I found something on the wire open thing, but I already think i know the problem.

I have a apexi gt spec, no cat, custom 3" downpipe, and a syko outlet elbow... I guess my exhaust is too big, so I should just port the waste gate, but I just put that turbo on, so I really don't wanna pull it off. But it spikes pretty heavily. I am going to try and put that pos factory restrictor in the back of the exhaust, and see if its a bandaid for now.

Here is a good article explaining big exhaust=boost creep, and fixing it via porting.

http://forums.nasioc.com/forum...00296

And here is something that everyone should be aware of dealing with R&R and coil problems.. its a lengthy article but quite helpful.

http://www.skylinesaustralia.c...+plug

[bmadd2402]

And here is something that everyone should be aware of dealing with R&R and coil problems.. its a lengthy article but quite helpful.

http://www.skylinesaustralia.c...+plug

There seems to be 2 major problems which can be confused: R&R, and coils. Only after all ignition and spark problems, along with checking all sensor voltages, can you really be sure its the R&R. I pretty much ruled everything else out. I'm going Standalone this month, so I'll let you all know what happens.

[catch221134]

Well long and short, if its an RB25det, and you have full exhaust, and an outlet elbow, and an intake, you will have Rich and Retard.

And if you have rich and retard there is a good chance that you are going to have some kind of boost spike.

So lesson learned, port your waste gate if you think you are going to do any of the above things, I wish I would have read this before I did everything to my car, upgrades and replace stock turbo....

I put the silencer back in, and it automatically made my car hold at .58, dead nutz. So in one way its fixed, but in another its less peppy and sounds no bueno... so I will proabaly pull the turbo off and port the wastegate myself, then take the silencer out, and get a tune.

[bmadd2402]

well said.

[catch221134]

You and Coolwhip are the one that gave me the ideas, so Well played sir, well played