Rb25Det Turbo Sucking And Blowing At The Exhaust

[chris pohlman]

i have a 93 rb25det running on 10psi lately its been sucking in air through the engine and blowing from the exhaust, feels like hitting the rev limiter at 4000 rpm. anyone have any idea or a solution that could help me identify this problem. its running an rb34 turbo.

[89CAL]

i have a 93 rb25det running on 10psi lately its been sucking in air through the engine and blowing from the exhaust, feels like hitting the rev limiter at 4000 rpm. anyone have any idea or a solution that could help me identify this problem. its running an rb34 turbo.

huh? :S Thats how engines work.....

10psi + Stock ECU = Car runs like crap.

Wind it back to 7-8psi and it will run better

[leer34]

sucking in air through the engine and blowing from the exhaust

might have to try and be more specific if you can. hard to work out what could be wrong without more detail.

i thought it would run ok on 10 psi as long as everything else was working fine?

[cannabiscorpse]

Everyone is different, Some can take 12psi on factory ecu, although not many. Mine doesnt take anymore then 8-9psi without getting the shitty flat-spots courtesy of the factory ecu. (also flat spots are dead on 3000 & 4500rpm)

Definitely suggest winding it back down just to rule out the ecu.

Edited June 25, 2011 by cannabiscorpse

[Don Dada]

She's gone from suck to blow!....Do something!

[Room42]

Hmm never heard of an engine sucking in air through the turbo and blowing it out the exhaust before. I know how to fix the problem tho, you need to put your started motor in backwards so the motor will suck through the exhaust and blow through the turbo

[chris pohlman]

haha thanks for the comments

in a way, it feels like redlining at 4000prm and when i push it further, doesnt run as smooth, jumps and the car pulls back at 4500rpm if that makes more sense. i brought the car 2months ago and the guy installed the rb34 turbo on it. so unsure what happened to the one that was on it. never had a problem with it til now.

Ive never experienced this before and im all new to this. Never had this problem before in having the car, thought it might be something. ill run the car again and update the post.

[cannabiscorpse]

haha thanks for the comments

in a way, it feels like redlining at 4000prm and when i push it further, doesnt run as smooth, jumps and the car pulls back at 4500rpm if that makes more sense. i brought the car 2months ago and the guy installed the rb34 turbo on it. so unsure what happened to the one that was on it. never had a problem with it til now.

Ive never experienced this before and im all new to this. Never had this problem before in having the car, thought it might be something. ill run the car again and update the post.

Still pretty hard to get what you mean mate. Understandable though, considering you are new to it. If possible, can you take a video of the car while you are driving it? Should make things heaps easier. Does it have like a splutter/dead spot at 4000rpm, but pull well for the rest of the rev range?

[chris pohlman]

do believe its back firing from the dump pipes. probably need a new fuel filter. took it for a drive and its not doing what it did previously. its running smoother than before. running to 7000rpm without problems. I will try to post a video up. I did make a mistake in putting vortex 95 instead of 98. did let it run out today and filled it with 98. Dont know if that was the case.

[cannabiscorpse]

do believe its back firing from the dump pipes. probably need a new fuel filter. took it for a drive and its not doing what it did previously. its running smoother than before. running to 7000rpm without problems. I will try to post a video up. I did make a mistake in putting vortex 95 instead of 98. did let it run out today and filled it with 98. Dont know if that was the case.

That could be it, but probably not. If there is a popping and spluttering, take note if it is at the same rev range everytime. If it is, i would put my money on coil packs. Check out this thread for some tips with the coil packs, and a quick fix you can do to them. http://www.skylinesaustralia.com/forums/topic/32356-missfire-boost4500-5500-rpm-the-answer-for-me-at-least/

[Room42]

the guy installed the rb34 turbo

you mean r34 turbo right? There is no engine called an RB34. The closest thing to an rb34 is a 3.4 litre stroker kit for the rb30. Yup as stated already you will need to wind the boost down till it runs properly. Or get a power fc or the like.

[chris pohlman]

That could be it, but probably not. If there is a popping and spluttering, take note if it is at the same rev range everytime. If it is, i would put my money on coil packs. Check out this thread for some tips with the coil packs, and a quick fix you can do to them. http://www.skylinesa...or-me-at-least/

I will keep in mind of what happend. I have splitfire coil packs so ill check out the thread. They are about 3months old. Thanks heaps

[cannabiscorpse]

I will keep in mind of what happend. I have splitfire coil packs so ill check out the thread. They are about 3months old. Thanks heaps

Very highly doubt it is the coil packs then mate.. Usually a problem reserved for the old oem coils

[89CAL]

Wind the boost back to stock (as this is the cheapest option, just connect the boost feed straight to the wastegate actuator if you dont have an adjustable boost controller)

if the car drives like normal then to much boost on stock ECU is your problem

Fix = Get an aftermarket tunable ECU and get a tune to run 12psi on the stock turbo, this is the more expensive option

or

Keep your boost at 8psi or below as most RB25's will handle this easily. Cheaper option

If the coilpacks are new and only 3 months old then it shouldnt be anything to do with them unless you got a faulty coilpack

[JonnoHR31]

new bcpr6es plugs, if it still does it gap them down to .6-.7

[HR32GTS 4DOOR]

She's gone from suck to blow!....Do something!

+1

Hahaha spaceballs

[ARTZ]

i have a 93 rb25det running on 10psi lately its been sucking in air through the engine and blowing from the exhaust, feels like hitting the rev limiter at 4000 rpm. anyone have any idea or a solution that could help me identify this problem. its running an rb34 turbo.

I have no idea what your talking about let alone whats wrong with your car..

[Rolls]

haha thanks for the comments

in a way, it feels like redlining at 4000prm and when i push it further, doesnt run as smooth, jumps and the car pulls back at 4500rpm if that makes more sense. i brought the car 2months ago and the guy installed the rb34 turbo on it. so unsure what happened to the one that was on it. never had a problem with it til now.

Ive never experienced this before and im all new to this. Never had this problem before in having the car, thought it might be something. ill run the car again and update the post.

Could be a combination of these common issues or just one of them, I am certain it is one of them though as your symptoms are incredibly common.

The R&R part of the map in the ECU is being used, the rich and retarded bit, this is due to the extra airflow from your rb25 turbo and running ~10psi is putting A LOT more air through the engine, the R&R part of the map usually drops the AFR down to 10:1 or even lower, went down to 9:1 on my old engine. This can cause a rich misfire and really really sucks the power.

Now the other thing is old coil packs with cracks in them, skylines are getting on now and most of the coil packs are on the verge of shitting them selves, now on standard boost they are often fine but when you get a really rich mixture like you are almost certainly getting now with the weak spark these old coils provide the spark could be getting blown out also causing a misfire.

The last problem is old spark plugs or spark plugs with a greater than 0.8mm gap, these have more of a tendency to have a weaker spark due to the larger gap, coupled with the above issues could compound the problem.

How to resolve this? First thing is check the coilpacks for cracks, there are lots of guides how to tape and glue them up, this might fix your issue, is is basically free to try anyway. If not splitfires are a drop in replacement and should solve part of the problem. The next step is an ECU remap via a nistune (cheapest) this will allow the tuner to tune out the R&R section of the map and this alone might fix the issue allowing you to use even your old stuffed coils still.

I recommend doing all 3, more power from the tune, better economy and a smoother motor, better spark is always a good thing as well, so replace the plugs and coils if they are old.

edit:

Cheap fix? turn the boost down to stock level ~8psi with a free flowing exhaust, this will almost certainly fix it, but if you want the higher boost do the above. If using an rb20 actuator you can get 10-12psi with no boost controller just via a free flowing exhaust, if this is the case then you really have to do the above.

Edited June 26, 2011 by Rolls

[mad082]

normally i wouldn't say R&R at 10psi, but since it is running a r34 turbo then i'd say that it is most likely a contributing factor. it is probably on the limit, but on the colder days lately that is probably putting it over the edge.

if winding down the boost by a little bit (best to do it in small increments rather than just dropping it back to stock boost, or drop it back to stock boost and then slowly start increasing the boost to see at what point the problem occurs) doesn't fix it, then i'd start looking at spark plugs and the ignitor module.

[bluey33]

Do as above!!! The last owner said he fit a r34 turbo, could even be a VG30 high flow which will almost definitely cause R&R at those boost levels.