R33 Gtst Issues

[Ricky_Bobby]

Hey guys,

So took the car out to Mallala last weekend, generally it went well except for a couple of issues.

1. No matter what I did on the blitz dual sbc , I could not achieve more than stock boost . Naturally thinking it was the restrictor within a stock boost line we went hunting, the boost line that carries the red mark is not longer used and we could not feel through any other lines a brass restrictor. Is it possible somebody has screwed with the internal wastegate ?

2. As the day progressed we noticed some misfiring in high revs, however given we have an aftermarket fuel pump and only achieving stock boost we are possibly going to test the coil packs, any other possibilities come to mind ?

I searched the forums for both issues but only the things I have already stated seem to come up.

Any help would be appreciated

Cheers

Bobby

[Ricky_Bobby]

It seems I now have some boost control after bypassing the black carbon filter , but still experiencing the misfire on boost (got worse with more boost of course) but never pushed it above 11 psi ?

[Jayden.K]

you cant just up the boost and expect it to work, you have to get at least a piggy back ecu to correct your AFR and adjust timing. the standard computer will most likely restrict you if you run higher the standard boost, and get new spark plugs and gap them from 1.1mm to 0.8mm. problem solved

[Ricky_Bobby]

hmmm, in previous S13, R32 and S15 I have owned I never had that sort of drama when I up the boost, what makes the 33 different ?

[GTSBoy]

A shit ECU is what makes it different.

[sonicz]

A shit ECU is what makes it different.

I thought the stock ECU could handle up to 10-12 psi no mods or piggy bak needed.

[benelli]

hmmm, in previous S13, R32 and S15 I have owned I never had that sort of drama when I up the boost, what makes the 33 different ?

R33 has a boost solenoid that sometimes need to be left plugged in on some cars. Did you remove it, loop it back into itself?

Regardless of the similarity, no two cars or engines will behave the same.

need more info on your setup

how did you hook up the blitz boost solenoid?

did you set the boost controller to work with EWG or IWG (lots of people usually have it set to EWG/Poppet valve by accident at first when they are running IWG)?

[FordyR31]

R33 ECU's dont like more than stock boost. Some ECU's have allowed a couple more psi but some dont like even 1 more psi. A friend had a 32 and stupidly ran 15psi all day every day for 2 years on the stock ECU. All my friends that have owned 33's haven't liked any sort of adjustment. Its common in the 33 ECU. Get a SAFC or Power FC/some other aftermarket ECU

[marto184]

I run 10psi on my Series 2 33 all day. Stock ECU. Stock fuel pump stock injectors. Car never has an issue at all.

[Trex]

The reason why some ECU's work and some don't is faulty sensors, it has nothing to do with a computer that is 'special' or made in a certain year.

Edited April 20, 2013 by OS80RN

[sonicz]

The reason why some ECU's work and some don't is faulty sensors, it has nothing to do with a computer that is 'special' or made in a certain year.

What? I thought they ECUs were a neural net processor, a learning computer. I.e they were A.I and had personalities.

[paulr33]

the 33 ecu does not have a boost sensor, it has no idea how much boost you are running and doesnt have sort of boost cut

it does, however, watch how much air the airflow meter is showing and if its too much at certain load points the ecu cuts all the timing and richens up to protect itself

the ecu thinks something has gone wrong and goes into a failsafe mode - ie cut timing, richen up - most people call this "boost cut"

it certainly would not be triggered by running 1psi more than stock - that is stupid

its typically around 10 or 11psi is where you will hit this excess airflow protection

if you hit the stock ecu excess airflow protection, just drop 1 or 2psi and try again

there will be a magical number where you can run more boost and stay under the factory limit on the 33 ecu

[Trex]

if you have a computer that is getting the 100% correct signals and information it will always out perform one that is 'guessing' because of faulty sensors. The computer only has a few sensors that tell it how much fuel to put in and etc. If these are faulty you will never get a car running 100% right.

Boost cut feels like someone has slammed on the brakes.

R&R feels like big flat spots.

Happy to be corrected, as I'm still learning, and no way a mechanic.

[GTSBoy]

Unless the water temp sensor is drastically wrong, there is no reason why it would trigger R&R with a say 10% wrong reading (and probably even a bigger error is acceptable). If the water temp sensor was wrong enough to cause R&R (if it even could) then the car would probably be belching black smoke. So we can probably discount the water temp sensor.

The AFM is the main load signal. These can be faulty, in that they might read a little bit wrong. But realistically, the car will either be running leaner than it should (if AFM reading lower than it should) or richer than it should (if AFM reading higher than it should) before it gets to R&R. One will feel fast, the other will possibly be smokey. But there are limits to how far wrong these can be. Too lean and it will go pop anyway. Too rich and it will be a slow arse bucket of piss. Well, a lot of R33s are like that, so maybe AFM faults are possible causes of some R33s not wanting to boost up very high.

The CAS is the next most likely. Timing jitter will make it think it is at the wrong rpm, looking at the wrong part of the maps and so could trigger R&R earlier. This is quite likely.

But I still reckon the biggest cause of variation between these cars responses to extra boost is the actual physical variation in their states of physical health and modification. Add a better exhaust, intercooler, inlet pipe etc so that it breathes more, and of course it will pull a higher AFM signal at the same boost as a car that doesn't have these things. Same with physical health. Healthier rings = more flow.

[Trex]

Ricky, missfires are usually caused by plugs & coilpacks. also happy to be corrected on this.

Mine wasn't accepting 10-11psi very well and would run slow till it got over 5500rpm. at 4-7psi it wasn't as noticeable because i didn't expect it to climb the revs very quick anyway.

Changed o2 and water temp sensor, ran 11psi and it now climbs the revs freely and it doesn't slow down or speed up in revs. It drives like a normal car should.

My guess was for peoples problems of not being able to run higher boost was a fuel and air problem caused by o2, water temp and AFM.

I've read countless threads where people had the same problem as me, and not one had a changed the o2. They all talked about changing it, but always left with a SAFC or new AFM's. Most never fixed their problems.

I think the standard computer is fine for small boost levels such as 10psi, and if you're having problems running that, it's not the computers fault, it's a sensors fault.

At the end of the day in a 33 you're better off getting a z32 ecu and nistune, i don't think you need to touch the sensors, i think they tune with them.

[GTSBoy]

O2 sensor has no effect on open loop (high load) operation. Any perceived effect from changing it is placebo.

[Trex]

What's open loop high load?

I just found a thread where the o2 would cause flat spots in lower rpm on an rb25det. Here's a funny one: http://performanceforums.com/forums/archive/index.php/t-67158141.html

or the coolant temp sensor was completely gone because the car has definitely changed a lot

Edited April 21, 2013 by OS80RN

[Trex]

Sorry to spam your thread Bob.

[GTSBoy]

On R33 and similar vintage cars, the ECU only looks at the O2 sensor at low loads. Unless you are just at cruise or accelerating very lightly the ECU will stop looking at the O2 sensor and just work on the rawe fuel map values to adjust fuelling. This is because you can only run these engines at 14.7:1 AFR when at light load. As soon as you load it up more than a little bit, you need more fuel to hit a lower AFR than 14.7 (like you need to get into the 13s and then down into the 12s and 11s as the load increases) but the typical narrow band O2 sensor can only allow control at 14.7. Ergo, the ECU has no option but to ignore it.

The O2 closed loop flag is set over the bottom left corner of the fuel map (low RPM, low load). As soon as the ECU is working from a cell that doesn't have the flag set, it goes open loop.

[Trex]

thats interesting, thanks for clearing it up