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RB20DET Issues

Deli Rep

By Deli Rep,
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Deli Rep Enthusiast

Deli Rep

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Hey all,

I'm a new user, straight outta NS.com.

I've got an 89 R32 RB20DET, had the car for a few months, and have a problem that is becoming REALLY difficult to source.

I've been told you guys are pretty good with tech stuff so I'm hoping someone can shed some light on it.

The car has the following bits:

HKS 2510

Exhaust (turbo back)

FMIC

stock ECU (with martin Donnon tune)

Walbro fuel pump

HKS Fuel Cut Defender

bleed valve 1-1.2bar boost

Adjustable fuel pressure regulator 40psi @ idle

Stock injectors, Air flow meter etc

Now my problem is that as it ramps on boost and spikes 1.2bar (ish) it is leaning right out, and I mean like 14+ A/F ratio. When this happens it misses, pops, farts and complains in general. It's making only 150rwkw, but with everything it has it should make anywhere from 200-220rwkw quite happily (this figure has been confirmed by many tuners/workshops).

Since I have had the car (only about 3 months) I've changed the following bits to try source numerous issues:

ECU several times (originally had a Tomei chipped ecu)

Air Flow Meter

all 6 injectors

Actuator

crank angle sensor

timing belt

water pump

all coil packs replaced for better RB25 type

complete exhaust changed (eliminate cat conv issues)

fuel filter

adj fuel reg (added)

HKS FCD (added)

original GTR fuel pump changed for brand new walbro pump (same as what runs trents 180SX) now swapped back to a different GTR pump and then again to my old Bosch pump that I can guarantee is fine.

Throttle position sensor

cooling temp sensor changed

external fuel pump earth added

none of this seems to have made any difference, it's not making more power, it's still leaning out, it's still not as responsive as it should be etc etc.

I've had the car looked at by Jazmac (my usual workshop) and also tilbrooks.

On the Dyno 2 days before the anzac day hol it ran 140kw with A/F ratios in the mid 10's.... VERY RICH. then just last week it made similar power with A/F peaking over 14 on tilbrooks dyno... VERY LEAN!

Nothing has been changed it the mean time and the car feels exactly the same to drive.

What I am asking for is any ideas, any experiences that may help me. I will entertain even the stupidest theories as I'm running out of ideas fast,

Cheers for any help anyone can offer.

P.S The weirdest bit is that even with such little power, and running so rough it will still happily hold 3rd gear slides on the track?

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Deli Rep Enthusiast

Deli Rep

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what ecu is it running now, if it has a standard one on then that could quite possibly be a problem, also bleed valves arn't the most reliable of things

It is still running the stock ecu remapped by Martin (out of the Viva Garage drift R32)... have tried several others, from dead stock to jap modified, no difference. The stock ecu I have in my possession actually runs it much worse than the one in it now?

If I had the $$ for elec Boost control, it would be on it.

I hate bleed valves and understand their problems as much as the next person...

Tho I don't think it's the problem in this case...

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Deli Rep Enthusiast

Deli Rep

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Id say there's your problem....

ditch it, get a power fc, and get it tuned properly by Shaun at BoostWorx.

A total of around 7 different ecu's have been tried, none make any difference....

Some people say certain tuners, other people say other tuners....

I can only go by what I know, and several of SA's top drifters (good friends of mine) find Donnons tune to be safest and most power productive.

If someone wants to throw a Power FC my way I'd be more than happy to plug it in :rofl:

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Deli Rep Enthusiast

Deli Rep

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I think we all know the answer to that :P

 

Can i ask if you have done a compression test on the engine?....

Compression test today, showed 125 on all 6, that not the issue :D

going to check voltage to all necessary bits next, lack of could create lazy pump? or something similar?

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paulr33 Grand Master

paulr33

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agreed i'd try a full aftermarket ecu and see how that goes, would certainly take off a lot of the restrictions, give best power gain and allow full control of the setup. also the wallbro wont run at full capacity if its used with the stock skyline wiring as it only gets 12 volts instead of 15volts that it needs to run at normal rated capacity

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Deli Rep Enthusiast

Deli Rep

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agreed i'd try a full aftermarket ecu and see how that goes, would certainly take off a lot of the restrictions, give best power gain and allow full control of the setup. also the wallbro wont run at full capacity if its used with the stock skyline wiring as it only gets 12 volts instead of 15volts that it needs to run at normal rated capacity

Interesting info on the walbro volts, will check that out (although it is running Bosch pump currently).

I think some people may be missing the issue a little, unfortunately....

with the mild setup I'm running and the few modifications done, a dead stock ecu with a simple FCD and some boost would happily control the potential 200kw with no reason for lag, or leanning out, or missing or anything else....

My car is very Lean, feels as if it's towing a house and is very down on power.

Even a simple exhaust, FMIC, pump and bar of boost combination would make better power with response and everything else as it should be?

There is some other problem!!

I don't quite understand why aftermarket ecu is needed?

don't think I'm having a go at anyone, just trying to clear up any confusion.

cheers for all help and ideas regardless.

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Bl4cK32 Grand Master

Bl4cK32

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Well the way i look at it you need to go back to basics to eliminate stupid stuff....

Its lean? And was all 3 dyno runs above on the same dyno?

Have you looked at an inlet manifold leak? You know that trick where you spray around the inlet manifold and listen if the revs change?

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sky30 Mentor

sky30

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Have you tried running without the FCD, or tried adjusting it??

Is the fuel pressure regulator working correctly (check with gauge under load), or is the a blockage in the fuel system, maybe fuel filter.

Id also go back to a stock ECU in working order, and start form scratch( stock boost) untill you can get the correct tune, then start changing your ECU and turning up the boost so you can see how each modification affects it.

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Deli Rep Enthusiast

Deli Rep

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There has been two different dynos used. But the outcomes are very similar and all the recent stuff has been from just the one.

EVERYTHING on fuel delivery has been checked, except voltage which I am getting onto next. Pump has been changed several times, filter changed, lines checked, pressure checked, Adj Reg is brand new etc.

Out of the seven or so ECU's tried, a few have been stock.... they are no better.

I've had the FCD checked (wiring is ok) and adjusted too.. no improvement..

I understand your point of gettin back to basics, but believe me, we've been there sometimes repeatedly, everything seems to be fine, it's driving me insane :P

A shitty little 2$ sensor that would normally mean f**k all, sending the wrong signal and causing Air/fuel delivery to be wrong is a strong bet? yes?

something so stupid... it has to be...

Whatever it is, when I find it, I'm gonna get it, put it in a vice, get a forklift, a hammer (or 9) some friends.... and go to town on the f**ker!

;)

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BHDave Grand Master

BHDave

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I'd be inclined to remove the FCD, the r32 doesn't need one and the remapped ecu would have removed the cut anyway (hopefully). Also at 150rwkw you will not be hitting a cut anyway.

Next would be to remove the adjustable reg. Is the new reg inline with the stock reg or have you removed the stocker? Fairly stupid question but is it a 1:1 reg or rising rate? With the A/M reg removed and a stock reg in place plug in a stocker ecu and it should run properly.

Check the AFM is in fact a stock rb20 unit and check that it is giving an output proportional to the load on the engine.

But after all that, i reckon your FCD is clamping the AFM signal at around 4.5V and it isn't putting enough top end fuel in Once you are flowing enough air to make 150rwkw it should be reading close to 4.9V. Thats why it'd be the first thing i turf.

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