Power Loss On Downshifts, Bouncing Idle And Slight Hesitation At Specific Rev Point -R34Gtt

[GTSBoy]

I have a Nistune log from my Neo from Monday night. Standard turbo and AFM, so not quite in the same league as what you're doing. Nevertheless, I got to 4.8V on the AFM signal, ran off the top of the stock fuel map (actual TP 180 vs last column TP 160) but still on the stock timing map (which has last column at TP 208). So....4.8V is fine (although deep into R&R territory!) and I would guess that 4.9V would be fine on my ECU too. But that's pretty much the limit - they don't go much higher than that. IIRC I ran my RB20 AFM to about 5.1V.

[rondofj]

Lol 5.1V, mine is ALWAYS a touch over 4.9V close to redline and it was just selected on the Powerfc options VG30 airflow meter

[rondofj]

Dont know how it was scaled or what exactly scaling an afm is - but yeah it is selected as the VG30 afm in the drop down list, if 4.9V is deep into R&R category maybe thats why its drinking fuel like a fish! But wouldn't the tune allow the car to rev to redline in high boost without maxing out the afm voltage? Wouldnt drink so much then..

Edited July 30, 2014 by rondofj

[Dose Pipe Sutututu]

PowwrFC doesn't have any form of R&R it's just the state of the cruise part of the map drinking fuel

[GTSBoy]

PowwrFC doesn't have any form of R&R it's just the state of the cruise part of the map drinking fuel

Yuh, there's either something wrong with the tune's fuelling in the areas you drive it most (cruise and medium load) or there's a sensor problem, as we already suspect.

[AngryRB]

cant you figure out whats doing with an hour on the dyno? or find a tuner that can monitor/tune it while driving it on the road.

Edited July 30, 2014 by AngryRB

[rondofj]

Cars been to Yavuz n Mark 3 times, they've gone over it and they stress each time that theres not anything else they could do to improve the tune, suggested me to try relocating afm/ modify intake pipe (already blocked bov return to rule the pipe out) , I suspect a sensor myself and this is what Im trying to do- rule them out one by one- afm is still a suspect throwing high voltage in 2nd @wot high rpm, wasnt doin this before. What it was doin before was throwing high knock values and high afm volts aswl in 3rd (nothing on 2nd) @wot high rpm, now the knocks strangely disappeared- all on same tune. This change happened after I overboosted several times n snapped wastegate hose. Loud gunfire sounds too. So coolant temp sensor to ecu is ruled out as its giving correct temp readings with time. O2 sensor ruled out as problem is still there with it disconnected. Next to test is TPS, MAP sensor on firewall and borrow CAS. And I wana change thermostat cos it takes too long 10-15 mins incl 5-7mins idling to reach 78C. Have I missed anything else?

The idle bounce is pretty inconsistent- doesnt happen most times n only happens when fully warm. So electricals/sensor again. Gotta check afm ground too, maybe run a wire spliced to its ground and onto chasis, problem is its got two ground wires..

Edited July 30, 2014 by rondofj

[scotty nm35]

Easier to just buy a Haltech and be done. You can't beat a map tune.

[Badgaz]

^^^yes you can.

[AngryRB]

I think maybe the coilpacks failed when you heard the machine gun noises at 30psi, have you checked the engine compression after that event?

Why is the voltage of the Z32 important, pretty sure that's accounted for in the tune , mine never had a problem with 320kw, the high fuel consumption and roughness sounds too much like

a vacumn leak, I had same issue after a few 20psi runs, overboosted to 25psi in third and now cyl 5 is low in comp and it runs rough similar to yours. The intake manifolds warp over time too, which I never thought could happen, they have to be perfectly flat to seal.

Downshifting with a vacumm leak will make it loose power because your under vacumn and therefore running very lean, on boost it will drink because its bleeding the air away. But if that was the case it should run like a pig most of the time.

If there is a leak, then that could explain why it isn't knocking in third now when it did before or possibly because its lost some compression from the machine gun damage.

Edited July 30, 2014 by AngryRB

[Dose Pipe Sutututu]

Easier to just buy a Haltech and be done. You can't beat a map tune.

In theory an AFM/MAF will always be better than a MAP sensor because it measures air density and factors for different temperature & altitude where as a MAP just measures purely pressure. Yes a MAP sensor can work well, when ran in conjunction with a barometer & an intake air temp sensor.

In practise - there's no real difference, to the driver it feels the same if not better because there's no issue with reversion and all that kind of shit.

This is another reason you see premium cars with AFMs yet MAP for their cheaper variants... good example is an EVO vs. a Lancer/Mirage.. EVO runs an AFM/MAF where as Lancer/Mirage pov spec runs a MAP sensor.

I personally run a MAP sensor because I don't run a BOV and like the flutters (it gets the slarts giggly)

[scotty nm35]

In theory an AFM/MAF will always be better than a MAP sensor because it measures air density and factors for different temperature & altitude where as a MAP just measures purely pressure.

Until you get a small air leak. Then you may be stranded on the side of the road, or worse, a large air leak and instant stall. It happened to me many times, the higher the boost the more it's an issue.

I was so glad when I could ditch the AFM, then I found out the auto box needed it for line pressure adjustments so it's still there.

[Badgaz]

at least with a MAF it'd be obvious you have small air leak or large....with map it'd be less obvious.

[XGTRX]

What timing belt you running.

[rondofj]

Gates kit, did it myself, no squeals, perfect 15 degrees timing at idle

[XGTRX]

Interesting. I have heard around the traps that the gates belts can cause issues with the cas signal. Something to do with vibration frequencies is the theory. Typical symptoms are idle hunting and loss of signal synchronization with the ecu which may cause detonation on boost. Be interesting to see if there is timing fluctuations on idle. I have heard there can be up to 10 to15 degrees on idle and worse when engine is under load and on boost... Very similar to what you are describing as I understand it. Just something to investigate perhaps.

[rondofj]

So far the sensors ruled out and how/why:

Coolant Temp Sensor to ECU - displays increasing temps with time to max 78C operating temp in power fc , also shows varying voltage over time in power fc sensor check

TPS - with ignition ON engine off it shows 0.4V @zero throttle and 4.02V pedal to floor and varying voltage in between depending on throttle stabs/ pedal position

O2 Sensor- car runs and idles a bit rough with it unplugged and O2 Feedback disabled in Power fc,. Shows variable voltage depending on how you stab throttle on idle- think idle is 0.5V. With O2 Feedback enabled car is smoother and nicer and not much or almost no fuel smell.

Z32 AFM - 0.5V with ign ON and 1.1ish V @ idle, and increasing voltage with increasing airflow/ boost/ power runs. Always goes to 4.8-4.9V during redline in 2nd and throws up engine check light so bit funny I think. Havent ruled this out completely.

Sensors left to test - CAS, MAP sensor on firewall - how to test this, just unplug?

Edited July 31, 2014 by rondofj

[rondofj]

To the guy above, my timing on idle after warmup is a rock solid 15degs and startup is first time each time so Im giving the CAS some points here.

One last thing that COULD be the problem is my large breather hose from cam cover to intake could have a leak because theres a funny join at the intake pipe- cant really access/observe it fully without removing stuff so something to do.

[XGTRX]

The problem i mentioned has nothing to do with the cas itself, It is the signal to the ecu that is being compromised. Generally Gates belts get noisy as they heat up and can interfere with the signal. So the car will run quite well until the belt heats up and becomes noisy and then the symptoms occur. Others have fixed this by either changing back to a nissan belt or trying to run seperate wiring from the cas straight to the ecu which is less successful. I believe haltech were having these type of interference issues and advising to run external crank triggers, dont know if it is a current issue though. I dont know anything about powerfc but is it possible to view your timing real-time or logging these events? As i said the variance in timing could be anywhere from 10 degrees up so not something you want to happen on a regular basis at WOT.

[GTSBoy]

Ron,

78°C is not hot enough for a Neo. They should be 10 degrees higher than that. Perhaps you have the wrong thermostat, or perhaps the coolant temp sensor is reading low. You could still have some cold enrichment going on, although at least with a PowerFC it should be trivial to get rid of that.

The boost sensor connected to the crossover pipe is an issue with Nistune but should not even be used on PowerFC, so shouldn't be a worry.

You need to find out why the ECU is flashing the light. There's a clue there, no?