rb20 studdering in boost only

[Couped_up'd]

I can daily drive the car anywhere just fine...if I don't get on it. I can even push around 1/2 throttle with out it cutting out. I do not have a boost gauge yet. I put it in 4th gear and if pulls kinda better. In 1st to 3rd it will not even go AT ALL.

-I have tryed gaping my plugs down.

-I have tryed newish coil packs off another rb20 I got(not sure if they are good)

-Have checked for some boost leaks, but not very hard.


details:
Rb20det swap into s13. FMIC, Exhaust, and thats pretty much it.

Coilpacks right?

[Lozer]

Bov = fail (most likely)(is it routed back into the intake rubber in front of the turbo but behind the maf?)

you NEED a boost guage
are you using the stock wastegate actuator?
is there any play on the turbo shaft?

your discriptionleads me to belive its boost studdering which is VERY BAD for mr. turbo. your tubo is basically going from spool to stop really quick

[steve shadows]

What EMS are you using?

Also sounds like you need to check your ignition, grounds and timing as well

[eklips3]

im guessing it might be timing .

BUT i would agree with you on shitty coilpacks, i had a bad set of coils and the car would sputter somtimes if i had the boost turned up a little bit , got a brand new set , not one sputter , smooth sailing throughout my rpm range.

try swapping cam angle sensors with sombody and see what happens.

[dubtastic]

More detail! So many potential causes.. What kind of fuel setup are you exactly running?

Find out what the ignition curve, fuel pressure, and boost pressure actually is.. lol.

It could be a boost leak, it could be a small exhaust leak before your o2 sensor giving false signal to your ECM, it could be a wastegate issue. The list goes on.

Your kind of blindfolded without boost & A/F ratio gauges.

I don't believe a CAS can cause any driveability issues under boost pressure only.

[warauto]

It is a common problem with spark plugs....have you tried gapping and changing them ?

Vacuum leak and boost leak check. it could be your o2 sensor.

[DR NISSAN]

Try replacing your plugs & check the coils with an ohm meter, it's a spark issue!

[Couped_up'd]

Everyone agrees on it being a spark issue.

-I got new plugs when I gaped them down to .8 =/ It ran better, but not tha great still.

-I do not beleive it would be the cas either, thanks for your input though.

-I plan to do a boost leak test next.

-More details on the swap. (bought it like this)
1. 255 walbro
2. NO FPR
3. NO boost gauge
4. NO a/r readings
5. rb20det with 5speed rb20 tranny
6. Timming is dead on
7. changed plugs 3times (thinking lower gap)
8. tryed 2 sets of coil packs...
9. ignitor?
10. FMIC
11. Exhaust
12. Stock boost from what I know.
13. Stock maf.
-

[Couped_up'd]

Try replacing your plugs & check the coils with an ohm meter, it's a spark issue!


I look forward to doing this. I found a write up how to check the coils.

[warauto]

What heat ranged plugs are you using ?

My car stuttered using 7 but 8's worked fine.

[Couped_up'd]

I just got 300zx basic/cheapest ngk's. What heat range would those be?

[warauto]

I would think they are 5 or 6 man. Stock non-turbo cars usually run hotter plugs.

If its for a non turbo 300zx maybe its like 5's.

[warauto]

Pull them out and see It is written on them like BKR5E-11 or 6E-11 or 7E-11 and so on.

The higher in number you go the colder.....better for boosted cars, lower is hotter makes turbo vehicles stutter under boost.

[Couped_up'd]

I got a wideband now. Installing it soon.

I checked for codes today. Code 55 is thrown. Which means, "all ok". lol

[Couped_up'd]

The problem was the turbo intake, to valve cover, to valve cover HOSE! It had no clamp, and had a crack in it.

I installed GM coil packs, j30 ignitor, got a wide band, new maf, boost gauge, fixed all leaks....and it was a freakin hose. lol

My guess is that the turbo was sucking un-read air, before the maf, threw the hose, because it was cracked. When I boost leak tested it, air come out the hose hard core. =)

[Lozer]

yea i went through that when i first started with my rb20 i put new plugs, o2 sensor, cleaned the maf, tested the coolant temp sensor and wow it was a cracked hose causing me to run rich. RB's r fun huh

[blackrb20]

my rb20 has the same problem with the studdering under boost. the car runs fine out of boost. im running 16 psi and my afr is around 12.2-12.8. i changed my plugs and its still doing it. i was told that my fpr is around 60psi durning boost. i can hold 16psi but after a couple of seconds it start to studder. can anyone help me wit this?