Hesitation with any boost over stock

[DrifterProdigy85]

Well im out of ideas on whats wrong with my car. Ive tried new plugs (.030" gap), ignitor, coilpacks, checked timing multiple times, new tps, 43psi fuel pressure, checked boost leaks to 25psi and found none. Everything checks out pretty decent with my wideband. Runs around low 12's in the midrange and richens to mid to low 11's at high rpm. It runs beautiful at 7psi but has a slight hesitation through the entire rev band at 10psi and the hesitation gets worse with 13psi. Would a bad knock sensor cause this? Would a bad MAF be causing the engine to go rich like it is at high rpm? Does anyone have a log of there AFR on a stock RB25?

[Fibre guy]

I think a faulty water temp sensor can cause problems like this... It's a cheap part to replace and it's one more thing you won't have to replace down the road.I replaced mine because of idle issues.

[Cjmartz2k]

Faulty water temp CAN cause this, but it's because it'll send your s*** into warm up mode and make you run to rich. Look's like his a/f's are good though.

What did you replace the coils with? Is it just one cylinder dropping?

[DrifterProdigy85]

I run Super Spark Performance Coilpacks. Its not a miss. Its like its pulling timing causing the car to loose its power. There is no pop or misfire you can hear whatsoever. Ill check out the Coolant Temp Sensor and change it. Its worth a shot.

[Cjmartz2k]

Do you have an exhaust temp gage? If so, that would be helpful. Also, I know it might be a pain in the a**, but can you try somebody else's wideband?

[DrifterProdigy85]

I don't have an exhaust temp gauge. It has a new wideband o2 and it's an innovate lm1 meter. I may have a small leak at the exhaust manifold gasket. Would that cause something like this?

[Cjmartz2k]

Yeup, but you said before you fixed the leaks. An exhaust leak will throw a wideband off big time.

I'd still advise picking up a Ex temp gage on the cheap from glowshift or something like that. Tuning with out one isn't too great IMHO.

[DrifterProdigy85]

Nothing is being tuned. Everything is stock. Egt aside something is wrong?

[Cjmartz2k]

stock turbo and maf, right?

[DrifterProdigy85]

Yup.

[RustspecS13]

One thing to try is maybe moving your maf. If you have the stock soft rubber intake the maf might be in a bad position and at higher boost the turbo is creating a vortex and the maf wont read it right.

Ive read about it happening on higher HP engines with mafs but I don't see why it isn't possible on a stockish setup too.

~Alex

[DrifterProdigy85]

What your talking about is turbulance that's caused by too short of intake piping or not having the proper bend in the pipe. I ran into this issue on my old sr setup. It's not the case with my rb setup.

[mott6904]

It stops pulling when you boost higher then it is tuned for? sounds like you found your problem

[jaykeMURD]

I'm pretty sure the stock ECU is limited by the AFM...exceed the AFM voltage threshold and the ECU cuts both ignition and fuel to protect the engine.

BTW, your AFRs are about like mine...stock ECU and turbo.

[DrifterProdigy85]

It doesnt make sense though. So many people run 13psi on a stock ecu and turbo all the time without any issues. Whats so different about mine?

[jaykeMURD]

I've never been able to boost much over 12-13 psi without it cutting.

Stock ECU, full 3" exhaust from turbo back, 2.75" intake/intercooler piping, BIG intercooler, otherwise stock.

[DrifterProdigy85]

Guess I thought the stock rb setup was better than it is.

[Fibre guy]

And this is where the money pit begins...

[DrifterProdigy85]

lol yeah i know what you mean. Im not going crazy with this car though. Id really like to get 300whp with it but im not gonna spend over a grand to do so. Its only a daily driver for me.

[mott6904]

well you have to take in consideration it is only a 2.0. it is nothing crazy and i was pretty impressed from the performance from a small displacment engine. People think it is a skyline engine and it has to be fast. The ecu cannot sense a change in boost pressure. therefore, the fuel and ignition map doesnt not change. A leaner fuel map is faster to a certain extent. If this is a daily driver at the most i would go with a small turbo upgrade that would fit on the stock exhaust manifold. But a better tune with a little more boost would be a fun street car. I would spend more money on making the car reliable.

[DrifterProdigy85]

Mines the 2.5. What's a rb25 maf max at hp wise? I had a rb25 s13 and it pulled very hard at 13psi compared to this one I have now. It literally feels like timing is being pulled causing the tq to take a nosedive.

[TwoJayZee240]

Im having the exact same problem as you. I replaced my maf with a n60 from a maxima and checked my tps setting and for boost leaks. Im running my plugs gapped at .8mm also and still having the same problem. But i have a series 1 rb25 and im running a G8 ecu witch i think is a series 2 ecu. So i think my spark is weak from firing 2 ignitors before it reaches the plugs. Maybe thats your problem also.

[DrifterProdigy85]

My engine is a series 1 with a TJ ecu.

[DrifterProdigy85]

Got it all figured out. It was the electric fans. I removed them and put the clutch fan on and Problems solved. Must have been something with the fans drawing too much from the alternator weakening the electrical system. It drives so much smoother now and holds a more solid afr.

[RustspecS13]

Ah sounds like you need to upgrade your alt. I used the quest 125a and it fit really well. 14v solid at idle and 14.4v at any other rpm.

~Alex

[DrifterProdigy85]

I'll get the stock one rebuilt but I'm staying with the mechanical fan. There far more reliable.

[Fibre guy]

Dual Maxima fans FTW!

[DrifterProdigy85]

I'll stick with the mechanical fan. I've never had one fail. I've had 3 electric fans fail. 2 were flex a lites and the other was my stock Pontiac fans.

[Fibre guy]

That's funny because both my s13's original KA clutch fan and RB clutch fan ceased.... Not to mention my jeep had 2 clutch fans cease too.

[DrifterProdigy85]

Never had that problem