S2 Rb25det Breaking Right Down Under Load

[FordyR31]

Hey guys,

Got another big long question for you, I'll try to give all the details I can to get the best answer.

INTRO:

I was driving my car last wednesday (really hot day) and I only had to go about 10km. Car had been driving perfectly fine for about 5 or 6, temp was half way on the guage. It has a stock S2 RB25DET with stock turbo from an R34 NEO25 on 10psi using an RB20 actuator so no extra control unit or tap controls the boost, a FMIC, run by a power fc and new 2 month old JJR coilpacks. I have always used NGK BKR6E plugs in the engine. This setup minus the coilpacks has been in my car for about 15 months without a hitch.

WHAT HAPPENED:

I took off relatively easy from a set of lights. The boost probably hit 3psi at maybe 3000ish rpm before i changed gears. Gave it a bit more in 3rd probably up to 7psi and all of a sudden it lost power and started to miss, it sounded just like an EJ20 with a big exhaust. I got it back to my mates place. On idle it sounded like an EJ but not wanting to stall, giving it little revs up to about 2500rpm it sounded like an EJ. I didnt rev it past that.

WHAT WE DID:

We left the car overnight to cool down and tried it again, same rough idle and revving. We unplugged each coilpack individually, the 1st 4 we unplugged starting at the firewall and working forward dropped the idle and the idle returned when plugged back in. The 2 coilpacks at the front did not change the idle at all. I called justjap and they told me to bring those 2 in for exchange under warranty. They did this no worries and handed me 2 new ones. I got home and changed them over along with brand new spark plugs. Same thing. The old spark plugs when taken out were a mix of a tan colour whish is supposed to be normal and a carbon build up, they were at this stage about 2-3000km old. We turned it off and left it.

The next day I took the coilpack loom off and unwrapped the tape to check all the connections and to see if any of the wires were bent at sharp angles and it looked really good, felt around the wiring and couldn't feel anything out of the ordinary. No buildup or corrossion of any kind on any of the connections.

Last night I plugged it all back up and started it to get it on the trailer to take to another mates house. Idled perfectly, revved perfectly, so it all sounded. I took it for a little drive up the road about 200m in total and turned around. Same happend as before at the lights, taking off easy in 1st and 2nd, no boost, drove beautifully. Gave it a little bit of poke in 3rd and as soon as boost came on it made a noise constantly until i backed off which i did very quickly as soon as I heard the noise.. The only way I came can describe the noise is like someone 'rolling an R' really quickly lol.. RRRRRRRRRRRR. This is a different noise to when i described it as an EJ20. After I backed off it went away and the car sounded normal again. all revs r fine off load, as soon as it hits into boost even in neutral it makes this noise and doesnt want to go anywhere.

A mechanic mate looked at it today and I took him for a little drive, approx 100m all up after I warmed it up and it did exactly the same. He ruled out anything mechanical, going on how it idled and drove off boost. He took the plugs out and most of the flat part of the hook was white. He said that means its running lean. Tomorrow i'm going to put in some BCPR6ES (reccomended to use by someone who has proffessionally worked on skylines for years and owns 3) plugs to try and plug back in the standard ecu. The fuel pump is getting voltage and it seems the engine is getting the right fuel and spark off load.

THE QUESTION:

Has this happened to anyone else and what was wrong with your car? At the moment the things suggested are the power fc for some reason is running it really lean, the afm could be stuffed, wiring issue where the coilpacks or fuel pump aren't getting voltage under load. Could it also be a stuffed fuel pressure regulator? Any suggestions would be helpful so we know what else there is to try and what else has failed/broken in other peoples cars doing the same thing.

Thanks in advance

Edited January 13, 2009 by FordyR31

[NizR33]

Have you checked that all the intercooler plumbing is OK. I had a similar issue a few years ago with the car running OK off boost but when boosting (could only get ~3psig) car ran like a dog and smoked heaps(black)... Found a hole in the piping that was causing loss of boost and making a funny sound when attempting to make boost.

cheers

[The Dan]

Yeah that's where I would look first. If you come up trumps there, try doing a fuel flow test to see what your pump is doing and also don't rule out an injector problem. If you've got shit in two of the injectors, it could be causing mayhem when the engine actually needs the fuel.

[Nismo_God]

im having similar issues....noticed only on hot days.....ive concluded that jjr coils arnt matching clips perfectly and heat causes it to expand and pushes the clips apart and breaks connection....

[FordyR31]

All the spark plugs are the same when taken out, BP Ultimate fuel is the only fuel I use so no shit goes in or at least i try to keep it to as little as possible and the fuel filter is changed with the plugs and oil every 5000km. ALL 6 were white after the last run meaning all 6 cylindrs were lean.

I did check the cooler piping and clamps and joins etc and all seem to be fine. We have had the car revving with the bonnet open and we cannot hear a leak as such. Also I would have thought that would make it run rich. If the afm has already accounted for the air and it isnt getting to the engine then wouldnt't it run rich??

As for the JJR coilpacks I have noticed the stock clips from the loom dont 'clip' on. They do come close but not quite. They have endured other hot days without a worry tho. I am trying to start cheap hence the change of plugs. But having said that the BKR6E plugs had been in for 2 months and were new when the coilpacks were new without a hassel but its cheap and worth trying.

I dont know if my mates workshop at his place has a place we can test the fuel pump but then again I dont know how to do it. It starts on ignition and primes, runs fine on idle and off boost but obviously cant account for what its doing when the problem arises. I am obviously not ruling anything out until its been tested and proven to work fine but it was getting enough voltage at idle.

BTW I'll edit this into my 1st post, the car is not blowing any smoke at any time but does smell a tad fuely.

[The Dan]

All the spark plugs are the same when taken out, BP Ultimate fuel is the only fuel I use so no shit goes in or at least i try to keep it to as little as possible and the fuel filter is changed with the plugs and oil every 5000km. ALL 6 were white after the last run meaning all 6 cylindrs were lean.

I did check the cooler piping and clamps and joins etc and all seem to be fine. We have had the car revving with the bonnet open and we cannot hear a leak as such. Also I would have thought that would make it run rich. If the afm has already accounted for the air and it isnt getting to the engine then wouldnt't it run rich??

As for the JJR coilpacks I have noticed the stock clips from the loom dont 'clip' on. They do come close but not quite. They have endured other hot days without a worry tho. I am trying to start cheap hence the change of plugs. But having said that the BKR6E plugs had been in for 2 months and were new when the coilpacks were new without a hassel but its cheap and worth trying.

I dont know if my mates workshop at his place has a place we can test the fuel pump but then again I dont know how to do it. It starts on ignition and primes, runs fine on idle and off boost but obviously cant account for what its doing when the problem arises. I am obviously not ruling anything out until its been tested and proven to work fine but it was getting enough voltage at idle.

BTW I'll edit this into my 1st post, the car is not blowing any smoke at any time but does smell a tad fuely.

Then if you have a new filter on it I would be putting my money on the fuel pump.

It's easy to do a flow test. Just take the fuel feed line off after the filter and place it into a container of approx 1L or whatever...something that you can use to measure.

Then apply 12V constant to the pump. You can either bridge the relay or just hotwire the feed direct to the pump. Just do it for 15second by stopwatch and multiply your result by 4. You need to see at least 3L/min but 4 would be better. That's a free flow test so it will tell you it's free flow capacity, if it is low then the pump is dying. It will explain the lean mixtures and the shit running condition, even the noise you described.

[FordyR31]

Is the 3-4L/min the same i should expect for a bosch 040 pump? Sorry out of all that shit i mentioned i still 4got stuff.... Do u know how much that pump should flow? Its about 2 or 3 years old.

[The Dan]

Is the 3-4L/min the same i should expect for a bosch 040 pump? Sorry out of all that shit i mentioned i still 4got stuff.... Do u know how much that pump should flow? Its about 2 or 3 years old.

Then forget 3L, it needs to be 4L...if you get 3L/min from that pump, it is dying.

That pump will free flow 4-4.5L/min easily

[FordyR31]

ok thanks for the info i'll mention it to my mate who is checking it all out and get him to do a flow test.

[FordyR31]

Ok we r really stuck with this.

It still isnt running right, the guy working on it has owned and worked on a lot of RB20's and 25's over the years and still cant work it out.

The fuel pump has been tested for voltage and flow and is fine, compression was tested and was pretty high and very even across all 6. The fuel pressure regulator has been replaced. Coilpacks have been changed back to standard to check... ecu changed, afm and o2 sensors changed, all earths checked and made sure to be earthing properly. A few broken wires in the loom have been repaired, plugs changed yet again and gapped perfectly..... I dont know what else it could be. It is still running rediculously lean under any sort of load but can just be driven on a flat if u take it really easy, idles ok. Its worse in hot weather.... I dont know what else to list.

Any1 have any ideas?

Thanks

Liam

[The Dan]

Ok we r really stuck with this.

It still isnt running right, the guy working on it has owned and worked on a lot of RB20's and 25's over the years and still cant work it out.

The fuel pump has been tested for voltage and flow and is fine, compression was tested and was pretty high and very even across all 6. The fuel pressure regulator has been replaced. Coilpacks have been changed back to standard to check... ecu changed, afm and o2 sensors changed, all earths checked and made sure to be earthing properly. A few broken wires in the loom have been repaired, plugs changed yet again and gapped perfectly..... I dont know what else it could be. It is still running rediculously lean under any sort of load but can just be driven on a flat if u take it really easy, idles ok. Its worse in hot weather.... I dont know what else to list.

Any1 have any ideas?

Thanks

Liam

Were you sure the original missfire was due to coilpacks or were you just guessing. What about the injectors or even the plugs for the injectors.

PTU maybe?

There are still many things it could be. If your friend knows his way around a skyline it should be fairly easy to locate the problem.

Swapping parts out is a last resort.

[FordyR31]

As posted in my 1st epic is how it happened. I did unplug the coilpacks individually and the idle didnt change at all when 2 of the coilpacks were unplugged, the other 4 dropped the idle when unplugged... It actually sounded when it very 1st happened like it was down on a cylinder or 2, both on idle and any sort of revving. Now it seems to idle ok and rev ok under no load at all but put any sort of load into it and it will missfire and run really lean. Is it possible to have a fuel pump flow freely at its normal rate yet when any sort of back pressure is put on it from the fuel reg it will not push the fuel to make any pressure? Its becoming expensive to find even at mates rates.

[The Dan]

As posted in my 1st epic is how it happened. I did unplug the coilpacks individually and the idle didnt change at all when 2 of the coilpacks were unplugged, the other 4 dropped the idle when unplugged... It actually sounded when it very 1st happened like it was down on a cylinder or 2, both on idle and any sort of revving. Now it seems to idle ok and rev ok under no load at all but put any sort of load into it and it will missfire and run really lean. Is it possible to have a fuel pump flow freely at its normal rate yet when any sort of back pressure is put on it from the fuel reg it will not push the fuel to make any pressure? Its becoming expensive to find even at mates rates.

Even if you have a non-firing injector and you unplug a coil pack, it will still not change anything when you unplug it. That doesn't mean the coil pack is stuffed, it just means that cylinder is not making power. You have located the responsible cylinders which is the first step. Now you just need to find out what is causing the problem.

It is possible to have a fuel pump do that, you would need to do a pressure test while driving to see what happens when you put the power down.

I would start by checking to make sure you have power to ALL injectors. When they are plugged in you will get battery V on both wires. When unplugged, you will get battery V on only one wire. The other wire is the trigger from the ECU.

If you have power at all injectors (with IGN on of course) then you should plug in a NOID light to determine if the injector is firing. If the injector is firing then it will have power but you still need to do the first test to make sure the injector is not open circuit or whatever.

If the injectors are all ok and firing, then you can look at the coil packs again. Once again, they need to have power going to them. Find the wire and check it. It will be the same wire on all coil packs.

You can plug a HEI tester into the coil end and see if there is spark.

If you don't have NOID lights or HEI testers then take it to a mechanic as you don't have the equipment to do proper testing.

Or you can buy the equipment or use other things like a 12V test light and a spark plug with the outer electrode bent out to give a large gap ~1cm or so should do.

The spark needs to be bright. You can test this by removing the CAS and with the IGN on, turn the end around to simulate the engine running.

If you can confirm all these basic things are ok, then we can begin to test other things.

[The Dan]

Where are you located?

[FordyR31]

Im in western sydney. I'll try and pass this info onto the guy who is trying to fix it atm. I had narrowed it down to the front 2 cylinders at 1st but then when I tried to load it onto the trailer it ran perfectly fine without any load put on it. All 6 plugs came out with white tips after the 1st drive with my mate in the car.

I'll pass this all on to my mate fixing it anyways, he does have all the necessary tools to test everything so i'll c how we go from there. He did do a pressure test on the fuel pump and it wasnt holding any pressure but flowing freely at the rate it should. We r going to start by replacing the fuel pump because of this and if it doesnt work I'll ask him to check the injectors like u suggested.

Thanks for all your advice.

Liam

[The Dan]

Im in western sydney. I'll try and pass this info onto the guy who is trying to fix it atm. I had narrowed it down to the front 2 cylinders at 1st but then when I tried to load it onto the trailer it ran perfectly fine without any load put on it. All 6 plugs came out with white tips after the 1st drive with my mate in the car.

I'll pass this all on to my mate fixing it anyways, he does have all the necessary tools to test everything so i'll c how we go from there. He did do a pressure test on the fuel pump and it wasnt holding any pressure but flowing freely at the rate it should. We r going to start by replacing the fuel pump because of this and if it doesnt work I'll ask him to check the injectors like u suggested.

Thanks for all your advice.

Liam

If the pump makes no pressure then there's your problem. How long have you known the pump had no pressure? Surely your mate could have told you that is your cause.

[FordyR31]

My mate did tell me last night it wasn't holding pressure after he tested it. Im hoping this is the only problem tho. Been a bloody expensive fuel pump fix.

[DrewII]

hmmmm i have R33 gts-t series 2

not exactly the same problem but a very similar problem

however i made an extra fix to your issue. when i was thrashing my car hard in 3rd gear bang had this wrx sound. loss of power etc etc.

my AAC valve wasnt working (broken couldnt adjust idle, idle didnt change when air con on) so i got a second hand one from a spare parts shop and the idle is now fixed. also one of my coil packs went so i replaced that and i also replaced spark plugs. got number 7 plugs slightly colder than standard in case i wish to race my car in the near future. however after doing all this my car was still extremely unsettled. shaking, virbating bad idle etc. replaced the standard bov. found out the bov wasnt working at all. went to autobahn bought a cheap Drift brand bov. had it installed. straight away car ran smoother. now no more wrx, no more shaking clean idle.

however now i have not as much power as before and car is out of tune. its much moree noticeable on high boost (12psi) than it is on low boost however leaking boost is noticeable everywhere. i had a toshi remap before and the car was running quick and afr's were perfect. after inspecting the new blow off valve further my mechanic found the new bov is faulty. leaking boost. we tried the bov in "atmospheric" mode and it was sucking in air. it can't be good for an engine to be sucking dirt and dust particles straight into the intake. my mechanic concluded diaphram problem and the spring isnt hard enough too which is most likely contributing to the afrs being out and the obvious boost leak. i rang Drift people down in melbourne they say the bov is good for well over 24 psi. well mine definetely is not.

the entire issue could be fixed by me spending 400 on a turbosmart or gfb plumb back valve which are much better quality. so this weekend i will replace this Drift bov and get back to you with my results. fingers crossed.

[FordyR31]

Good luck with ur car. My car already has a GFB BOV and the problem is under load, not necessarily boost. Just cruising uphill will make it break down.... I'm not sure when the fuel pump is going to be replaced, hopefully tomorrow and will post if it fixes my problem or not.

[FordyR31]

Ok just to end this. The 1st issues that prevented the car from running were shagged fuel pump, shagged fuel pressure reg and blocked injectors. There were quite a few other problems also which may have contributed but now its back its running better than ever b4... Its going to WSID next wed if its not raining just to celabrate.

Thanks to everyone who had suggestions and helped out.

Liam