Updated! Rb25det Problem

[_MRR33]

Edit: I've now noticed it will do it when I'm sitting in park or even when taking off slowly seems like its missing

Hey,

I seem to be having a few problems with my RB25DET, it usually runs fine no problems at all but it seems to struggle on load.

What I mean by load is if I'm sitting in a low speed and give it a bit when it gets anywhere between 4000RPM and 5000RPM it sounds like it's hit rev limiter and struggles for a moment or two then push itself to 7000RPM-7500RPM which is rev limiter.

At higher speeds such as 100-110KM an hour and you give it a bit it's not as bad but it still has a very similar affect.

I'm not too sure what the problem could be, I've put the engine on a diagnostic program and it came up with no errors. I've had the car rebuilt within the last few months, I've done all the running in etc, I'm running good oil (Royal Purple), good spark plugs, I'm using 100RON with 5% Ethonal (V Power Racing) - however I haven't had it tuned since the rebuild - may this be the problem?

I've tighten everything that I think may have come loose. Any help would be greatly welcomed.

Engine Mods Include:

- K & N Pod Filter

- Cold Air Intake

- Forged Pistons

- Strengthen Conrods

- Blueprinted

- Balanced

- Port Polished

- Metal Head gasket

- Spitfire Coils

- High Performance Timing Belt

- High Performance Spark Plugs

- Greddy Turbo Timer

Edited December 24, 2006 by GTS793

[Syphon]

Standard or aftermarket engine management?

If it is standard ecu, sounds like knock sensor's could be detecting knock and pulling timing.....

[adikt]

what are your plugs gapped to?

i had a similar problem & once i regapped the plugs to, i think, about .7mm (recommend .9-.6) it went away.

apparently if the gap is too big, the boost blows the spark out.

[_MRR33]

Standard or aftermarket engine management?

If it is standard ecu, sounds like knock sensor's could be detecting knock and pulling timing.....

You could well be right there. I had the AFM and fuel pump both tested and they were fine. We bought it down to two problems - Coil Packs or ECU. I got new coils for them because they always break down in the S1 GTST. So, that does leave the ECU which is standard by the way.

If that is the case, how do I go about fixing it?

By the way, thank you very much for your help and Merry Christmas

what are your plugs gapped to?

i had a similar problem & once i regapped the plugs to, i think, about .7mm (recommend .9-.6) it went away.

apparently if the gap is too big, the boost blows the spark out.

I didn't gap the plugs at all I thought they would have been fine, you're the second person to tell me to check the gap on the plugs. I'll have to do that.

On the R33 GTST what should they be gapped to?

By the way, thank you very much for your help and Merry Christmas

[13thracer]

does it pop and fart around or just fall in a hole then pull itself out

if it pops and farts regap the plugs to .8mm see how it goes factory gap is 1mm way to big for anything other than stock, what plugs are you using by the way?

if it feels like it falls in a big hole then pulls itself, with the mods you have and the especially if your running more boost with stock ECU i would put money on rich and retard. time for aftermarket mangement or a piggyback like SAFC

do a search on thses there are heaps of old post with others having your problem....

[khunjeng]

Hey,

I seem to be having a few problems with my RB25DET, it usually runs fine no problems at all but it seems to struggle on load.

What I mean by load is if I'm sitting in a low speed and give it a bit when it gets anywhere between 4000RPM and 5000RPM it sounds like it's hit rev limiter and struggles for a moment or two then push itself to 7000RPM-7500RPM which is rev limiter.

At higher speeds such as 100-110KM an hour and you give it a bit it's not as bad but it still has a very similar affect.

I'm not too sure what the problem could be, I've put the engine on a diagnostic program and it came up with no errors. I've had the car rebuilt within the last few months, I've done all the running in etc, I'm running good oil (Royal Purple), good spark plugs, I'm using 100RON with 5% Ethonal (V Power Racing) - however I haven't had it tuned since the rebuild - may this be the problem?

I've tighten everything that I think may have come loose. Any help would be greatly welcomed.

Engine Mods Include:

- K & N Pod Filter

- Cold Air Intake

- Forged Pistons

- Strengthen Conrods

- Blueprinted

- Balanced

- Port Polished

- Metal Head gasket

- Spitfire Coils

- High Performance Timing Belt

- High Performance Spark Plugs

- Greddy Turbo Timer

all this and a std ECU....get one, tune it properly and see what happens.

[_MRR33]

does it pop and fart around or just fall in a hole then pull itself out

if it pops and farts regap the plugs to .8mm see how it goes factory gap is 1mm way to big for anything other than stock, what plugs are you using by the way?

if it feels like it falls in a big hole then pulls itself, with the mods you have and the especially if your running more boost with stock ECU i would put money on rich and retard. time for aftermarket mangement or a piggyback like SAFC

do a search on thses there are heaps of old post with others having your problem....

Sometimes I feels like it's poping and farting then like you said just pulls itself out and revs out to 7000RPM-7500RPM.

I'll regap the plus when I can, prob next day or two and see if that will fix the problem. I'm using Irrudium plugs, they were around $25ea.

Well, what I'll prob do is check these plugs and see if that fixes it, if not may be the ECU. I'm running stock boost, I have no other mods at all besides what I listed in the first post.

I just went for a run and I noticed it kind of struggles at lower speeds also?

[khunjeng]

Apart from paying to much for Irrudium plugs (IXs I assume) they should be at least gapped to 0.8...IXs are 0.8 already.

I'm now running copper plugs gapped to 0.8 and replace them more often...cheaper...and they seem to run fine. I replace them at each oil change now...still cheaper than the Irrudiums..but a bit more hassel...

[_MRR33]

Apart from paying to much for Irrudium plugs (IXs I assume) they should be at least gapped to 0.8...IXs are 0.8 already.

I haven't gapped them at all so they should be 0.8mm then - however is it possible one or two may be slightly out?

[13thracer]

the stock ecus on 33's are very tempremental things they dont like being taken outside much past stock without causing some sort of issues sort out your plugs first see what happens may wanna check the ignitor module to make sure it dont have dirty connections and such. failing that if it doesnt feel like a missfire look into ecus and piggybacks to tune it out..

cheap way to check if it is plugs is buy the copper ones as a test set they are about $3 each quick easy way to eliminate any plug issues

BCPR7ES gapped to .8 is what i use no probs so far.

[_MRR33]

I've now noticed the car sort of misses when it is parked or even when taking of slowly.

Not as bad, but its there.

Any other ideas?

[13thracer]

are you still running the stock fuel pump they can cause all sorts of trouble when there on the way out may want to check fuel pressure particulary when its idling funny see if the pressure is jumping all over the place.... either way an ungraded fuel pump is a smart mod to do as well.

[_MRR33]

are you still running the stock fuel pump they can cause all sorts of trouble when there on the way out may want to check fuel pressure particulary when its idling funny see if the pressure is jumping all over the place.... either way an ungraded fuel pump is a smart mod to do as well.

Thanks heaps for you help I'll let you know how I get on.

[philta]

had the same prob on a recent track day when i was running .8bar of boost (12.3ish psi) however, my car is fine anyother time.

after letting it cool alil it was hitting .8bar just fine.

some of the guess here are pretty much covered.

stock ecu

fuel pump

and spark plugs

i think mine were due to spark plugs, i got irdiums gapped at 1.1 at high boost and temp i think it had a hard time firing or maybe my injectors were maxed out since the avcr was returning 90-almost 100% injector duty.

[_MRR33]

PRONLEM FOUND:

Seems as though the 6th spark plug had a piece missing.

The part circled is where it broke

Bad picture I know, sorry guys! The last one on the right however is the one that was stuffed.

One on the right is the one that is stuffed.

Edited December 25, 2006 by GTS793

[_MRR33]

Thanks to everyone who helped, and gave me ideas on what to look for SAU People rock!

Merry Christmas and have a great new year!

[_MRR33]

Can a mod lock this please? Please revert to http://www.skylinesaustralia.com/forums/in...howtopic=148652 - Thanks!

[13thracer]

now its time for the fun part were did that little piece go i would be having a good look for it internally that little piece can cause some seriuos damage if it hasnt allready.

[_MRR33]

now its time for the fun part were did that little piece go i would be having a good look for it internally that little piece can cause some seriuos damage if it hasnt allready.

What can I do to try and locate it? Looks like it has melted away from the looks on the Spark Plug.

[13thracer]

id be having a good look inside the cylinder wind the engine over with out the plug in and get the piston towards the top of the bore and if you have a magnet that will fit down there and go fishing for a little bit just to be safe (be care full not to drop anything else in there while your looking), if it has melted away which by the looks of it has so its probably worked its way through the system and you got lucky if there are no other problems at the moment, you may want to find out why though, it may have been a defective plug but the best idea is to wack it on a dyno and check the air fuel ratios and if possible knock levels to make sure everything is ok.