Gt-r Engine Problem

[DSF]

G'Day Skyline Guru's,

I am calling upon your collective expertise to help in a problem I have with my car. Firstly I would like to apologise for the long winded post, but want to make sure I include as much information as possible to aid in the fault finding. Secondly I will admit that my mechanical knowledge is very limited and my own resources after the same (i.e. basic tools with limited spare in my garage). To start with I will give details of what I know of my car and when this problem first started, its a 1989 R32 GT-R imported by Autoworx that is in standard condition except the following;

* Nismo 240km/hr speedo

* Cat back exhaust

* Pod filters

* Twin plate clutch

* Aftermarket suspension

* Greddy boost and temperature gauge and a Delphi head up display unit.

I was heading home when I was about to turn onto a 100km zone stretch of road. I thought to myself that giving the car a bit of stick up to the speed limit won't hurt, so I gassed the pedal in 2nd gear. The revs were at roughly 5500rpm when I heard a backfire and the engine started to stall. I managed to coast the car most of the way home with the engine not wanting to exceed 2000rpm at any stage. Luckily I lived not to far from when this incident happened (1km max distance) so once I parked the car I pondered on the extent of damage I had done. The next day I cruised the car to the local servo mechanic (again only 250 metres away) were he tested the car to the best of his abilities. His limited findings were that compression in all cylinders were good and the engine oil and coolant were not fouled (meaning no blown gaskets). He said that the battery needed changing so I got that replaced straight away but other than that he had no idea about these types of cars. A certain import store with a so called GT-R specialist (which I will not defame) was recommended to me for the repair of my car, so I organised for the car to be trucked to them with details of what had happened. Anyway to make a long story short I received my car back after 9 days with the GT-R specialist saying that he doesn't know how to fix it (this is after paying a considerable amount of money for his expertise). So the car has been parked in my garage ever since awaiting repairs.

These are the known symptoms;

Engine idles smoothly but if you try to free rev it will climb to 4500rpm than just after that it will stall back to a rough idle for a few seconds before regaining a smooth idle. It is hard to tell if the turbo's are boosting but there is needle deflection from the boost gauge.

Trying to drive the car it will not exceed 2500rpm and the engine wants to stall and stutter continuously. If the battery is disconnected and all power is drained, upon reconnection the car drives as normal for a period of no more than 30 seconds.

The engine appears to be over fuelling as there is copious amounts of black soot/unburnt fuel than there was before this problem. Again there are no unusual sounds coming from the engine and the temperature remains normal.

Before all of this the car was a dream to drive with the only hiccup being a very infrequent engine stall during low speed cruising.

Here is a list of all the things that have been carried out to try and fault find the source of the problem:

* ECU code checked with nil faults found (I used the guide on this forum).

* Removed than replaced boost gauge and Head up display with nil change in performance.

* Swapped and replaced AFM's with nil change.

* Replaced and gapped spark plugs (another guide located on this forum).

* Replaced fuel pump with a new item and carried out the earth wire and positive wire mod including installing a relay (again I used a guide on this forum).

* Replaced all vacuum hoses were possible.

* Checked timing, it advances during revving until the 4000-4500rpm mark were it goes all over the place than retards itself.

* Checked all wiring at the ECU and in the engine compartment, including rearrangement of the ground wiring kit.

* Removed majority of inlet pipe work then cleaned and refitted securely.

* Removed coil packs and mega-ohm the casings to check for current leakage.

* Fiddled with the TBC to see if that was a contributing factor, as yet I am undecided due to the limited rev range.

* Disconnected exhaust at turbo's to check for no blockages in cat converter (this was done buy the GT-R specialist so I doubt its authenticity)

* Disconnected O2 sensors to confirm operation (again it was supposedly done by the GT-R expert)

* Swapped over ECU and AFM's were known serviceable items (you guessed it, done by the GT-R specialist so I have no idea if it was really carried out).

* I have even tried praying to God All Mighty, Allah, Vishnu and Buddha (not necessarily in that order) to see if any of them are just jerking my chain, but alas to no avail.

I have conversed with a member of this forum and he has suggested that it is a turbo failure. I believe that this is more then likely the end scenario but am hoping that it might be something simple I can fix (coil packs, leaking pipes or wiring that I have missed). Or if possible is there anyone in the Newcastle area willing to help in further diagnosis/repair, I would be much appreciative (i.e. offering alcohol, money or eternal praise). As the time has come when my wife is totally annoyed with the car sitting in the garage and she wants it gone. I hope to repair the car before I sell it just to take it for that last drive, but if not I will be forced to sell the car as is.

[paulr33]

youve blown one of the intercooler pipes off - check all of the clamps, and at a last resort, undo each of them and re-do them one by one

[Swiper the Fox]

youve blown one of the intercooler pipes off - check all of the clamps, and at a last resort, undo each of them and re-do them one by one

yes...what he said

[raver1987]

not a gtr expert here but i would also have ur injectors checked

[Swiper the Fox]

not a gtr expert here but i would also have ur injectors checked

for what ?

[DSF]

youve blown one of the intercooler pipes off - check all of the clamps, and at a last resort, undo each of them and re-do them one by one

Thanks for that idea, it's probably the only thing I have not checked especially the pipes and clamps at the blow-off valves and intercooler.

[SLIPPERY]

Yeah i was also going to say that one of the pipes has come loose.

If failing that, i had a similar problem that was finally diagnosed as being a dodgy AFM connected. Changing AFMs wouldnt fix it obviously so i bought a brand new plug and rewired the AFM plug. No more intermittent problems in my case.

[bnr#@]

Yep, almost certainly a hose poped of, done it so many times on so many cars its just not funy any more...

[DSF]

Yep, almost certainly a hose poped of, done it so many times on so many cars its just not funy any more...

YOU GUYS ROCK.

Sorry for shouting but I have to say thanks to all the guys that suggested a popped piping. I managed to find the culprit and re-seat the piping and started the car and gave a few revs all up to 6000rpm with nil hesitation. Thinking that I had fixed the problem I proceeded to take the car for a drive but a hundred metres down the road the car started popping and revs dying above 2000rpm. Coasting back to the drive way it sounded like the BOVs were continuously venting and while in neutral giving a few revs, I noticed the boost gauge going from -700mmHG rising rapidly to above +500mmHG (the Greddy boost gauge was deflecting -0.5bar to almost +0.5bar). Now I am thinking its an over boosting problem and checking the search forum I have a few ideas on what it might be. I have almost ruled out the AFMs as disconnection each one makes the engine idle rough and almost stalls when revving. I will endeavor to find the problem and am still wishing for help from any Skyline gurus close by.

Main thing is that you all have been a big help and I feel as though this overall problem is almost fixed.

Thanks again guys

[nitestalkr]

I would give this 'GTR specialist' a miss from now on.. He sounds like he is failing at life if he hasn't checked any piping.. haha

Glad to hear things are much better now!.

[DSF]

Well I wouldn't say much better, but I think there is only one problem left to find and fix. That was what was so hard in the first place, the fact that the symptoms did not lead to just one fault but possibly two. Slowly getting there but I have to confess that I'm a noob and a GT-R twin turbo set up is baffling me at the best of times.

Cheers.

[Syphon]

2000rpm and over breaking down, still sounds like either AFM Fault, or another blown hose . Re-check every hose between the afm and throttle body. If you have to remove them and check for splits on the hoses etc.

It's gotta be a pretty serious intake leak to be causing this issue, so you should be able to spot it.

Sounds too low down to be a spark related issue, but certainly can't rule that out. Either that or as you suggested already, over-boosting, but I doubt that at 2000rpm either. Not sure where an RB26 with std turbos obtains full boost....

[GTR-32U]

quick question.....are all of the pipes standard or have they been changed ? Reason why

I ask is that sometimes you get some boob who installs his own pipes and said pipes sometimes dont have the flange on the ends and continually blow off. also are you using rubber or silicon hose in the connections of the IC piping ?

[DSF]

quick question.....are all of the pipes standard or have they been changed ? Reason why

I ask is that sometimes you get some boob who installs his own pipes and said pipes sometimes dont have the flange on the ends and continually blow off. also are you using rubber or silicon hose in the connections of the IC piping ?

All the piping from what I can see is HKS branded with silicon hoses.

I will take it for a drive tomorrow to hopefully better explain the symptoms when in motion, I'm just a bit scared as I thought that it should not make full boost (almost 1 bar) when revving out of gear. Though I am more than likely wrong in that theory. Securing the loose piping had fixed the problems I first had while just revving the engine, it seems as if I still have the same problems while trying to drive it.

[nitestalkr]

U make full boost when revving out of gear? What revs are we talkin here? I have a feeling your second issue may be piping related as well..

[DSF]

U make full boost when revving out of gear? What revs are we talkin here? I have a feeling your second issue may be piping related as well..

Okay finally got around to looking at the car, when out of gear it makes full boost at 3500rpm. Now I have been searching these forums for solutions and if I understand correctly this over boost is either caused by a blockage to the actuators, or a wastegate is not opening. I managed to disconnect one of the actuator vacuum hoses but the other is almost impossible without pulling half the intake apart (remember I am a numpty at this). With just one actuator disconnected made no difference to the boosting. Tried to drive the car but it sure does not want to exceed 2000rpm with the needle moving up and down (is this fuel cut due to the over boosting??) and the blowoff valves are chattering and hissing continuously. I have found a schematic of the induction system and I will try to find a common point that may be effecting both actuators, other than that I am pulling out what little hair I have left diagnosing this issue.

[Adriano]

About the only thing that will make the car make boost in neutral like that is a skipped timing belt, retarding the cam and ignition timing.

[kevind]

This might not be quite the same but i had 246awkw, then i got a decent front pipe, cut out the cat to 3 and a half inch exhaust.. From the exhaust place

i took it up the road, put my foot down & it was misfiring over 5000rpm.. Took it to my tuner, he eventually found it was my boost pipes.. He tried a couple of

new clamps on my std pipes but they weren't holding so then i had to get a new set of boost pipes..

[kevind]

Ive got 303awkw now :

[DSF]

About the only thing that will make the car make boost in neutral like that is a skipped timing belt, retarding the cam and ignition timing.

Thanks Adriano as I will look at this as I am not having much luck in locating a possible vacuum blockage. I can only hope this is the problem then all will be fixed