Jump to content
SAU Community

R32 Gtst Coughing Under Boost And Revving Up On Its Own

Aidan32

By Aidan32,
in General Maintenance

 Share

Recommended Posts

Aidan32 Rookie

Aidan32

Posted
Posted

Okay had a quick look over the forum and google searched and can't really find anyone else with this same problem,

Last night I picked up my very first Nissan,

It's a r32 GTST type M

Car apparently hadn't run in 3 years

Had a quick check over the car when inspecting. Compression is a bit lower than normal but even across all 6, when we were cranking it over when first inspecting I could hear a few cylinders fire so it gave me hope and I got the car and bought it home,

So the first thing I did was plugs, pulled them out and inspected, cleaned them up and slapped them back in, checked if it was getting fuel, just pulled the line off and cranked and kept cranking until the fresh fuel I chucked in started coming through. Tried starting car and it was very very close to starting, rechecked plugs and when watching for spark noticed it was weak and arcing between the threads of plugs,

Found some brand new ford falcon plugs in garage that were same thread so just chucked them in to test it, bam the car fired up straight away, was stoked that it started up after just a few little basic checks,

BUT as you'd expect the car was running smooth exactly, would barley idle, was running richer than bill gates, fuel was pouring out the exhaust, and if you accelerated it would just sit hunting around 2500rpm, even when foot flat,

straight away I thought it would be afm, but the car has a brand new genuine Nissan afm installed just before I bought the car, came with receipt for it,

Later on a friend came over and plugged his laptop in and used some program that reads all the sensors readings, start the car up, CAS was a little out, but when warmed up was sitting on 15 (got told this is where it should be)

TPS sensor was a little bit out so we set that, still no change,

Then we noticed afm wasn't getting a reading at all, checked it was all plugged in, checked the wires around close to turbo and stuff, looked all okay, checked inside around ecu as previous owner had been messing around with something and left trim off, found a single

Black wire with a male and female end which wasn't plugged in, plugged them together and started it up and BAM the car idles and revs up fine, but it had a misfire. Went and bought the standard plugs for the car and then it idled perfectly :) was super happy ,

After all this the computer said we had code 55 from memory ,which said (no sensor faults)

So all was good,

But then I went to go take it for a drive, started it up, was fine, tapped the accelerator pedal and all of a sudden it revved up on its own to 7500rpm and then dropped back down to idle , I reversed out and went up street putting around, was running smooth just driving normal, got it up to temp and went to go boost it, as it goes to come on boost it goes no where and coughs and splutters and blows out black smoke, and then when I back off after trying and press clutch in it all of a sudden revs up to 7500 again all buy itself, stock boost guage reads it is boosting but you don't feel it because it sits coughs and spluttering.

And that's where I'm up to, I know a lot of you guys will jump and say coil packs, but I don't wanna jump to conclusions, because of the fact it revs all buy itself that high,

I still need to gap the plugs, got told to gap between 0.6-0.8

At the moment I think they are at 1.1

Need to change fuel filter

Dump all fluids and filters and put all new fresh ones in

Need to check for any leaks (vacuum and turbo piping)

If anyone's got any other ideas I could check let me know please, thank you

Aidan32 Rookie

Aidan32

Posted
  • Author
Posted

I'd start by putting the correct plugs in there for sure. At least one boost leak is probable. As for the free-revving, not entirely sure.

It has the correct spark plugs in it now, no change

Went over and pulled off and reinstalled all turbo pipes, shouldn't be any leakage

GH05T Grand Master

GH05T

Posted
Posted (edited)

my fuel pump died on me slowly, caused missfiring.
new pump and filters can solve so many little issues.

7500rpm sounds like something just got stuck. throttle body cleaner would be my first purchase, clean the idle controll valve ect

also after tapping the pedal and getting 7500rpm, your damn keen to put it into reverse. could have been interesting.

Edited by GH05T
Aidan32 Rookie

Aidan32

Posted
  • Author
Posted

my fuel pump died on me slowly, caused missfiring.

new pump and filters can solve so many little issues.

7500rpm sounds like something just got stuck. throttle body cleaner would be my first purchase, clean the idle controll valve ect

also after tapping the pedal and getting 7500rpm, your damn keen to put it into reverse. could have been interesting.

Yeah a friend of mine told me to clean the idle control valve and shit aswell so I'll make sure I do that,

And the way I saw it, if it starts reving buy it's self I just clutch in and it won't go anywhere lol

Ben C34 Grand Master

Ben C34

Posted
Posted

Revving like that isnt caused by the IAC. Its more than likely the throttle got stuck. Which seriously needs to be addressed before you go much further.

And looking for leaks isnt the same as pressure testing for leaks. I strongly recommend you pressure test to find leaks. You will be surprised.

Aidan32 Rookie

Aidan32

Posted
  • Author
Posted

Revving like that isnt caused by the IAC. Its more than likely the throttle got stuck. Which seriously needs to be addressed before you go much further.And looking for leaks isnt the same as pressure testing for leaks. I strongly recommend you pressure test to find leaks. You will be surprised.

Throttle cable deffinatly dosnt get stuck, I've already checked that,

And okay I'll do a pressure check

scotty nm35 Grand Master

scotty nm35

Posted
Posted

Well I was going off something online, how are you meant to check them, they should be good anyway, cause it doesn't misfire at all

I was going to say with your tongue, but I don't want someone to actually try it on my suggestion. :P

If it's revving to 7.5k there is a large air leak somewhere after the throttle, and the car is running way too rich. Sounds like it may have been modified at some point. I would be replacing the AFM with a known good one and perhaps checking the injectors aren't highflowed.

Aidan32 Rookie

Aidan32

Posted
  • Author
Posted

I was going to say with your tongue, but I don't want someone to actually try it on my suggestion. :P

If it's revving to 7.5k there is a large air leak somewhere after the throttle, and the car is running way too rich. Sounds like it may have been modified at some point. I would be replacing the AFM with a known good one and perhaps checking the injectors aren't highflowed.

If you read the information I've supplied,

AFM has been replaced with a genuine BRAND NEW nissan one

And is reading correctly (checked with plugging in consult cable)

There's no air leaks ANYWHERE

And it just revs up buy it self only sometimes when I start it and touch throttle now,

Sometimes is rich when I first start it but clears up quickly and runs fine

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • MissMintyR33
      R33 persistent issues. P/steering and lag/misfire

      By MissMintyR33 · Posted

      I thought that might be the case, thats what I'll start saving for. Thanks for the info 
    • jtha7
      Strange issue RB25DET wont start

      By jtha7 · Posted

      Ps i found the below forum and it seems to be the same scenario Im dealing with. Going to check my ECU coolant temp wire tomorrow    From NICOclub forum: s1 RB25det flooding at start up Thu Apr 11, 2013 7:23 am I am completely lost on this. Car ran perfectly fine when I parked it at the end of the year. I took the engine out and painted the engine bay, and put a fuel cell with an inline walbro 255 instead of the in tank unit I had last year. After reinstalling everything, the engine floods when the fuel pump primes. if i pull the fuel pump fuse it'll start, and as soon as I put the fuse back in it starts running ridiculously rich. I checked the tps voltage, and its fine. Cleaned the maf as it had some dust from sitting on a shelf all winter, fuel pressure is correct while running, but wont fire until there is less than 5psi in the lines. The fuel lines are run correctly. I have found a few threads with the same problem but no actual explanation of what fixed it, the threads just ended. Any help would be appreciated. Rb25det s1 walbro255 fuel pump nismo fpr holset hx35 turbo fmic 3" exhaust freddy intake manifold q45tb q45 maf   Re: s1 RB25det flooding at start up Fri Apr 12, 2013 5:07 am No, I didn't. I found the problem though. There was a break in one of the ecu coolant temp sensor wires. Once it was repaired it fired right up with no problems. I would have never thought a non working coolant temp sensor would have caused such an issue.
    • jtha7
      Strange issue RB25DET wont start

      By jtha7 · Posted

      Hi sorry late reply I didnt get a chance to take any pics (my mechanics on the other side of the city) but the plugs were fouled from being too rich. I noticed the MAF wasn't genuine, so I replaced it with a genuine green label unit. I also swapped in a different ignitor, but the issue remains. I've narrowed it down a bit now: - If I unplug and reconnect the fuel lines and install fresh spark plugs, the car starts right up and runs perfectly. Took it around the block with no issues - As soon as I shut it off and try to restart, it won't start again - Fuel pressure while cranking is steady around 40 psi, injectors have good spray, return line is clear, and the FPR vacuum is working. It just seems like it's getting flooded after the first start I unplugged coolant sensors to see if its related to ECU flooding but that didnt make a difference. Im thinking its related to this because this issue only started happening after fixing coolant leaks and replacing the bottom part of the stock manifolds coolant pipe. My mechanic took off the inlet to get to get to do these repairs. My mechanics actually just an old mate who's retired now so ill be taking it to a different mechanic who i know has exp with RBs to see if they find anything. If you have any ideas please send em lll give it a try. Ive tried other things like swapping the injectors, fuel rail, different fuel pressure regs, different ignitor, spark plugs, comp test and MAF but the same issue persists.
    • GTSBoy
      Freddy Plenum vs Genuine options RB25

      By GTSBoy · Posted

      My return flow is custom and puts the return behind the reo, instead of at the bottom. All my core is in the air flow, rather than losing some of it up behind the reo. I realise that the core really acts more as a spiky heatsink than as a constant rate heat exchanger, and that therefore size is important.... but mine fits everything I needed and wanted without having to cut anything, and that's worth something too. And there won't be a hot patch of core up behind the reo after every hit, releasing heat back into the intake air.
    • Murray_Calavera
      R33 persistent issues. P/steering and lag/misfire

      By Murray_Calavera · Posted

      There is a really fun solution to this problem, buy a Haltech (or ECU of your choice) and put the MAF in the bin.  I'm assuming your going to want more power in future, so you'll need to get the ECU at some stage. I'd put the new MAF money towards the new ECU. 
×
×
  • Create New...