RB20DET Issues

[The Dan]

Pressure doesn't mean anything. You need to do a flow test on the pump. Although doing a pressure test will sort of give you a fair indication it is still by no means an accurate fuel test.

If it has been on a dyno, they should be able to pinpoint the problem straight away. If not, then they are not doing their job properly. A dyno is there to finely tune vehicles. They should know exactly what your timing is doing, your fuel flow and pressure, your air flow and air temp, your injector duty cycle and injector timing plus all the rest.

I would agree with Bl4cK32 in saying that you have to start with basics. look at the fuel system and delivery, then move onto the ignition and plugs, then move onto your charge air. You should be able to look at the plugs and see what is going on in your engine. If not, pull them out, take a digital photo, post it up and I'll tell you what's going on in your engine.

I still can't believe you have had it to a dyno three times and no-one can tell you the problem.

[The Dan]

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.

I thought it went to 3.5-3.8V.

[BHDave]

I thought it went to 3.5-3.8V.

TPS at WOT reads around 3.6-3.8V, AFM is maxed at about 5V typically.

[Deli Rep]

OK Guys, now we're getting somewhere... finally some theories I haven't heard yet Goodwork!

I'm happy to remove the FCD and run it without, but isn't it basically a boost cut where if I were to run 18psi or so the stock ecu would cut it? (I can't be sure but I don't think the 're-map' did remove it) I realise I wouldn't hit the cut @ 150kw but the point is I should be @ 200kw

I have checked the AFM to be RB20, it is. As for the Volts.... will follow that up.

I have experienced faults with plugs, coils etc before... it's different, altho coils have been changed and plugs checked a few times.

Under load the fuel pressure is dropping off, but The pump itself is ruled out as 4 pumps all of which have good working history can not all be shite... 1 or 2 maybe... but not 4.

The volts to the pump will be checked 2morrow arvo, along with volts to everything else.

The Reg is rising rate (I think), but I will stick the stocky back on just to check it out.

There is also another stock ecu at the workshop which I will give a go.

There is a metal line that runs from the fuel tank, into the engine bay and to an emmisions/charcoal cannister up front next to radiator (passenger side). If that cannister were removed, would that line need to be pressurised/blocked off etc? Or can it vent to nowhere?... may only be a little thing, but a thing none the less.

Cheers for your input peoples, hopefully 2morrow will shed some new light on the situation.

Fingers crossed

[AD4M]

FUEL PUMP!

get it checked

if it still the stock pump thats your problem.....

i have a bosch 040 and not one problem

take it to a workshop and see what they say

cheers

Adam

[BHDave]

I never found a boost cut on my rb20 and was making about 175rwkw by the end, it's worth removing the FCD just as a trial. If you hit a mystery cut at some point then reinstall it.

The line to the charcoal canister is a vent for the fuel tank to let excess pressure/vapour out. If you remove the canister then let it vent to atmosphere but it will smell a bit.

[Bl4cK32]

LOL...i reckon the charcoal cannister is not letting the petrol tank vent properly, and not being able to suck petrol enough under boost

The pump may work, and so will the regualtor, but if the tank isnt breathing, it may just not be circulating air for petrol fast enough....

Did that make sense?

[The Dan]

TPS at WOT reads around 3.6-3.8V, AFM is maxed at about 5V typically.

I am pretty sure also that TPS will read somewhere near 10.5 V at WOT. I'll have to check the manual again, haven't got the time right now.

[BHDave]

Trust me, i have been logging these thing for the past few months in the hunt to get my emanage running properly (stupid emanage, i'm getting a pfc). TPS maxes at about 3.8V, afm is seeing the high side of 4V as i'm not maxing the Z32.

Previously, on my rb20 afm it would be seeing 4.9V plus from about 4500rpm.

[sky30]

3LIT3 FOR3:-"Fuel pressure means nothing"..... what the F**k?? SO if the fuel pressure doesnt rise under load how is it going to run the correct ratios?

[Deli Rep]

OK!

It's official..... my car is retarded... literally!

Tonight we did voltage checks to fuel pump, coils, etc.... all showed up fine power supply.

We tried another ecu, another afm and another crank angle sensor..... almost un-noticable differences.

Did another fuel return test, fuel returned fine.

Dyno's were all over the show, leaning out, then phattening up, but barely scratching 140kw! and still missing at that most lean point....

then then spark plugs came out, gapped from .8 down to .7.... made a significant difference to the missing when leaning out, just enough to keep it from going any higher than 12.5 afr.

But still no power.....

Then with timing set at 15/16 at idle, we did a power run whilst monitoring timing.....

AAHA!!

the timing was moving around then settling at about 10deg retarded when under full load/max throttle. Instead of a desired 10-15deg advanced, it was 20deg out... retarded no less!!! for those who know, that 20deg easily accounts for my 60-80 kw lack of power.

PROBLEM SOLVERED!

unfortunately it has to stay like that until I can get someone with the appropriate

tools/hardware to get into the ecu and alter it... but never the less, at least it is no longer an 'unknown' problem

ASAP will have it done!

YEEEE mutha-f**kin HA

Cheers to everyone's info, most of which was very useful weather it ended up being the problem or not.

will let ya's know what it does make and how it goes when sorted out....

CHEERS

[The Dan]

3LIT3 FOR3:-"Fuel pressure means nothing"..... what the F**k?? SO if the fuel pressure doesnt rise under load how is it going to run the correct ratios?

Ratios?....the ratio is proportional to the air flow not fuel flow.

A fuel pump can still pump 90psi but only flow 0.5 L per minute. In which case the car will severely lean out. Fuel systems have to be checked in multiple ways. You can't just say, do a pressure check and if pressure is ok, expect everything to be good. Fuel flow is just as important. Other checks should include injector pulse and duty cycle, leak checks (including injector leaks), injector flow, fuel filter (for blockages and cleanliness), fuel lines (for crimping), pump filter/pickup (for cleanliness), voltage to pump + signal to ECU, and regulator (for pressure hold).

That's what I mean by fuel pressure means nothing.

That's assuming the problem lies within the fuel system. If he has an air/intake problem things should be checked like: Air filter (clean?), turbo (noisy, shaft play, oil residue, blockages, visible damage to impellas or housings, exhaust leaks, wastegate actuator - which can be done with a tyre inflator , ensure wastegate is all the way closed, oil/water lines all sealed, intake tubing intact before turbo), inlet pipework (any visible leaks, corrosion?, take apart and inspect internals of tube for excessive oil deposits, hoses all clamped tight, spray water or carby clean over all connections to check for other inlet leaks or crimp blowby control hose from drivers side rocker cover to inlet plenum to ensure idle drops), throttle body (cleanliness), plenum (sealed?), inlet manifold (sealed, check for oily deposits around gasket), compression test (correct valve seating, leak down test to check for cracked ring land or ring).

Then if there is a problem with ignition, things should be checked like: Spark plugs (discolouration - red tips means ignition fault - creamy white means perfect, black means rich and white means lean - there are others but that will get you by), coil packs - ensure that there is between 0.6 and 0.9 ohms resistance between + and - terminals on each coil pack (remove and inspect for cracks in bakerlite- greeny yellow at top of coil pack, pull off plug insulator and check coil electrode for cleanliness and ease of movement), wiring to coil packs (breaks or worn wiring), check ignition module for damage, make sure there is a STRONG earth connected to where the earth should - if not, DO IT, check wiring harness for breaks or heat stress - including harness to cam timing module and injector harness.

After all these things have been checked and cleared - then, and only then, do you start picking at sensors and computers.

If I looked at every car that I have ever worked on that had running faults and problems under load, have a guess how many of them I have replaced an ECU in. something like 2. An EL falcon because the AAC valve draws too much current and burns out the idle circuit in the ECU.....and our all time favourite - the TR Magna.

If it has to be said again - START WITH THE BASICS

More often than not your spark plugs will tell the story. If they don't, then look elsewhere.

Gimme the car for 1 day and I could find and fix your problem. It's unfortunate that you live interstate or I would be tempted to do so.

[The Dan]

OK!

It's official..... my car is retarded... literally!

Tonight we did voltage checks to fuel pump, coils, etc.... all showed up fine power supply.

We tried another ecu, another afm and another crank angle sensor..... almost un-noticable differences.

Did another fuel return test, fuel returned fine.

Dyno's were all over the show, leaning out, then phattening up, but barely scratching 140kw! and still missing at that most lean point....

then then spark plugs came out, gapped from .8 down to .7.... made a significant difference to the missing when leaning out, just enough to keep it from going any higher than 12.5 afr.

But still no power.....

Then with timing set at 15/16 at idle, we did a power run whilst monitoring timing.....

AAHA!!

the timing was moving around then settling at about 10deg retarded when under full load/max throttle. Instead of a desired 10-15deg advanced, it was 20deg out... retarded no less!!! for those who know, that 20deg easily accounts for my 60-80 kw lack of power.

PROBLEM SOLVERED!

unfortunately it has to stay like that until I can get someone with the appropriate

tools/hardware to get into the ecu and alter it... but never the less, at least it is no longer an 'unknown' problem

ASAP will have it done!

YEEEE mutha-f**kin HA

Cheers to everyone's info, most of which was very useful weather it ended up being the problem or not.

will let ya's know what it does make and how it goes when sorted out....

CHEERS

You must not forget that knock sensors and AFM have a DIRECT effect on your ignition timing so just because your timing is jumping around, doesn't mean your computer is at fault. It could just be reacting to a faulty signal from something else.

[Cubes]

Knock sensor.

Mine went from 28degree's to 8degree's when the knock sensor was activated.

I was able to see this via a consult that was hooked up to the stock ecu.

As pressure is increased fuel flow is decreased. I agree with mr 3Lit.

Which is why you always check the return flow.

[The Dan]

Trust me, i have been logging these thing for the past few months in the hunt to get my emanage running properly (stupid emanage, i'm getting a pfc). TPS maxes at about 3.8V, afm is seeing the high side of 4V as i'm not maxing the Z32.

Previously, on my rb20 afm it would be seeing 4.9V plus from about 4500rpm.

I dunno if this will post right but here goes.....

[Deli Rep]

You boys might be onto something with this knock sensor theory......

Apparently the ecu wouldn't be controlling that timing (not retarding it that much anyway)

something else must be causing it, and first thing would be knock sensor......

Back to the dyno...............

[Deli Rep]

Does anyone know how they work exactly?

To find out if they're what's causing the problem, can I just unplug them? Does the ecu need a signal or certain voltage? could I earth out the plugs to get around this?

We just unplugged both, took it for a spin and now it feels f**kin 30deg retarded! much worse than with them in, but I know for a fact it's not right when they are in cos I watched the timing myself settle at about 10deg retarded under full load on the dyno?

This timing thing is definately the area at fault, just need to nail the cause still.

[The Dan]

Does anyone know how they work exactly?

To find out if they're what's causing the problem, can I just unplug them? Does the ecu need a signal or certain voltage? could I earth out the plugs to get around this?

We just unplugged both, took it for a spin and now it feels f**kin 30deg retarded! much worse than with them in, but I know for a fact it's not right when they are in cos I watched the timing myself settle at about 10deg retarded under full load on the dyno?

This timing thing is definately the area at fault, just need to nail the cause still.

If you disconnect the knock sensors, you should feel it very laggy until about 3800rpm then it should pull like a lonely uncle until about 5500rpm and go laggy again. If you overtighten the knock sensors they give a knock signal constantly. I forgot to ask also, does the car go better when you start driving it from stone cold or is it the same cold or warm? I ask this because your timing curve is different when you are in cold start mode.

[BHDave]

I dunno if this will post right but here goes.....

That's the trottle switch, not the throttle position sensor. It's either on or off and i'm pretty certain it's only used by the auto ecu. The manual r33 actually has it blanked off. It's seems to cause a bit of confusion.

The TPS has a variable voltage from almost 0 when the throttle is closed to about 4V at WOT where as the throttle switch drops to 0 as soon as the throttle is opened slightly.

[The Dan]

That's the trottle switch, not the throttle position sensor. It's either on or off and i'm pretty certain it's only used by the auto ecu. The manual r33 actually has it blanked off. It's seems to cause a bit of confusion.

The TPS has a variable voltage from almost 0 when the throttle is closed to about 4V at WOT where as the throttle switch drops to 0 as soon as the throttle is opened slightly.

I am sorry, I was definately mistaken and you were right.