higher rpm fuelling up + missing

my HR31 GTS-X with RB20DET running 10psi fuels up really bad after 4000rpm or so and u can even see black smoke pouring out the exhaust! When it does it u can certainly feel it, runs like a bag of crap!

Anyone with the same problem or any solutions would be greatly appreciated.

Also put flat to floor (in any gear, it's auto) and it revs the guts out of it and wont change gears until i back off???????

When was the last time you changed the fluids in your auto?

"RB20DET running 10psi fuels up really bad after 4000rpm or so and u can even see black smoke pouring out the exhaust!"

I do not really understand? My Stang runs 40psi at idle, and about 90-100 under boost. Sounds like your fuel pump is going, your psi is not there at the higher rpm range.

Black smoke sounds like your turbo might be going as well. Just a guess, all your problems seem to be unrealated, meaning you got some work to do;) Good luck.

Originally posted by SkylineUSA

Black smoke sounds like your turbo might be going as well. Just a guess, all your problems seem to be unrealated, meaning you got some work to do;) Good luck.

I was under the impression that white smoke ment bad turbo :confused:

And what friggin supercharger are you using Tony?

Black smoke? Maybe your right. Black is normally based from an oil problem, at least that is what I remember. I could be mistaken. Do a little research, its getting late for me.

I am running a S-trim, 13lbs now.

sorry i meant 10psi boost up from factory. It's not white (indicating head gasket problem or blue indicating burning oil) it's black excess fuel being burnt. It just chokes up really bad and runs really rich. I've run carbon cleans through it, had the injectors checked + cleaned. I've even tryed heaps of fuel additives + cleaners. I've replaced just about every electrical conector on the injectors, TPS, coolant temp etc.

It's gotta be an engine management problem or maybe o2 sensor or AFM????

You are absolutely right Black is Fuel, Blue is oil.

If your at WOT, o2 do not play. Have you cleaned your MAF?

It's gotta be an engine management problem. I totally agree

Yes sky, engine managment for sure.

Try resetting your ECU for the hell of it too.

I doubt it would be the factory ECU as they are pretty primitave in the R30 and R31's.
If the car idles fine and is fine under normal driving conditions other than at WOT then the AFM will be ok.

Assuming your car is fairly standard here, what sort of spark plugs are you running? In the RB20DET you should be using NGK platinums part number PFR6A-11. Set the gap to .9 mm or .035 inch.
While your there check the carbon tips on the coil packs. Depending on which style you have there should be a spring with a carbon tip. If the spring is weak then the carbon tip will not make good contact with the plug. You can gentely shave it down to make it square again and good contact with the top of the plug. Which brings me to another thing. Be very careful removing them as the wires and coil packs themselves will be brittle.

Another thing to check is for any splits in your induction hoses or loose clamps. What could be happening is a boost leak, a small one will cause you grief. The AFM will be seeing more air than what will actually reach the engine causing an over fueling situation.

it had a very fast idle, but i fixed that by pulling my idle speed control motor out and where the little piston runs in the sleeve inside was worn and really sloppy hence letting too much air through. i fixed that by wrapping it with electrical tape, no just runs at base idle of around 600rpm and idles fine and doesn't stall.

Just recently it has a bit of a miss at idle every now & then, i've reset the ECU a few times now, but nothing every seems to help let alone the fuelling up

I have put new NGK platinum plugs in it but i didn't adjust the gap

Did you check the gap, normally their in the ballpark, but you never know.

no, didn't check the gaps but the missing and fuelling up was there before replacing the plugs, the didn't make it any better or any worse :confused:

It is sound more and more like a leak in your pluming or i/c. Spend some time and pull it all appart checking for cracks or splits.

I guess using WD-40 will not show anything, looking for the leaks?

It would if he could put the car on a dyno and do the checks, then so would soapy water but not sudzzy.

Never mind, it was mentioned under boost, Oops.

heheh no worries.

Now if I can keep mine from blowing the bloody outlet line of the power steering pump off I would be stoked.

What about an under drive pulley for P/S pump? Do you think that would help?

no it needs the high revs to work properly. For some reason the banjo bolt is working itself free. I think it is the copper washers are work hardend so will replace them this week.

"it needs the high revs to work properly"

Can you explain? That is very interesting. I have never ran across any information like that concerning the steering and I truely would like some more first hand information. Thanks

I understand about the banjo fitting.

Tony

Because the Skyline is a high reving engine most pumps will cavitate. I know this as one of our club's sponsors drag GTR removed the hicas as it was unsafe and not wanted. by doing so they had to change the pump. the Primera and Skyline pumps are identical except one is for a 4wd car the other for a 2wd. the problem came in under revs it cavitated and they lost steering.

so they built a high bryed using a primera pump and a GTR pump. they used the primera pulley as it was already on. It did not give proper steering since it was too big. They had to switch to the GTR pully for it to opperate properly. That would indicate the pump needs higher revs to opperate properly.

Now another thing I noticed is the slightly heavier steering on my GTR at lower rpm levels. Once the rpms increased the steering got lighter. it did not matter the road speed. I have confirmed this numorous times in three different GTR's. The actually steering is much more repsonsive from about 4,000 rpm and higher than at say 2,000. It is very noticable.

I find that very strange. Cavitate? Cavitation should only happen at higher rpms, not lower. At least from the knowledge I have from studies I have read about submarines. Normally cause by the prop turning too fast, causing bubbles. If the prop is turning slower, it should not cavitate.

I can see why the pump would cause this at low rpms. :confused:

That is correct and as I re-read my post I can see how it would have been confusing.
I thought about binning the 4wd steer system as honestly I have no need for it and going to a primera pump, but since it would begin to cavitate at revs above 7,500 rpm that is not such a good choice. Merely changing the pully to a larger size to avoid this is not such a good option as I would have to fabricate a new braket system in order to get a belt that would fit it properly.