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

[XGTRX]

Wow.. well said

[XKLABA]

Reversion will also cause high fuel consumption

[Dose Pipe Sutututu]

Thus I suggest to just vent his BOV and tweak it out with the PowerFC

It can be done, I've done it before back in the days

[rondofj]

OK,

So I return to this after quite a few posts, but based on most recent feedback from Ron and various of the replies since I see the following as being the most likely scenario.

1) Sudden pulse of AFM signal upward with consequent increase in ECU load signal up 5 or 6 cells definitely implies it's a reversion problem. Blocked BOV will of course cause that - and you have seen it occur with blocked BOV. Wrong BOV return design will also cause it, and you have seen it with the BOV connected. Therefore....

thats right seen it happen in both scenarios, with blocked bov though, seems to run smoother and better low down

2) BOV return is not right. The connection from the cam cover hose doesn't matter - only the angle of the BOV return does. I suggest further speculation on the cause of the hesitation problem should be put on hold until someone remakes the BOV return.

maybe I need to have my intake pipe bov entry angle modified - does anyone know a good fabricator in Sydney whos not expensive

3) High fuel consumption. As I see it your coolant temperature is 10 degrees too cold and that could easily cause the ECU to add a bunch of enrichment - especially if it was at the correct temperature while it was being tuned. This should be the work of 5 minutes for Yavuz to look into and report on what the ECU is doing. And to fix it might take only as much as another 5 minutes if it needs fixing in the tune or maybe 30 minutes if you need the thermostat changed.

Set water temp correction at 50C to 1.00 and 1.00 (low-hi loads)? Currently it is 1.04 and 1.07, and at 80C is 1.00 and 1.00 -- its only adding 4% and 7% more fuel at 50C though

4) High fuel consumption. The tank breather situation is a bit special on Neos anyway. The stock ECU has a whole bunch of maps (only recently uncovered and correctly identified by Matt at Nistune) around the emissions purge control logic. There is a solenoid valve that is only allowed to open under certain conditions to allow the vapours to be purged. If the PFC doesn't do this properly and/or there has been a physical f**k up of the system with various works (like FFP installations) then perhaps there is an avenue here for fuel consumption to go high. But I would imagine that if the ECU was properly running closed loop and most miles were done under cruisey closed loop conditions then it shouldn't be as bad as Ron reports.

My purge valve has 1 nozzle broken and the hose from intake plenum that connected to it has a block-off screw now. The other hose is removed (doesnt go to charcoal canister) Charcoal canister has that opening blocked off with a little hose and bolt and the other hose goes down to chasis along radiator and somehwhere - fuel tank vacuum? Any suggestions on this setup??

5) High fuel consumption. A f**ked O2 sensor will do this to you. Replace it or plan to live without it. Choose one.

Currently O2 is switched off in power fc but sensor still plugged - hence displaying changing voltage depending on throttle. Do I need a new sensor even with O2 switched off? Remember it doesnt hesitate at 1500-2000 and idle bounce with O2 off but rougher idle and runs a bit rough. And Yavuz did mention the sensor is going funny but not to worry...yet

As to Yavuz's statement of the load jump causing R&R - well, it's not R&R because there's no such thing in a PFC unless it is deliberately tuned that way (ie the tuner makes the top end of the maps as mentally retarded as Nissan did!). But I suppose functionally it is equivalent to R&R if those load cells add a lot of fuel and have less timing. Terminology doesn't really matter - I think we can be sure that it's a reversion problem and that you need to fix the reversion!

Is on cards now. But what do you guys think of a bad earth/ground as the car sometimes runs like a dream? 15-20% of the time really.

Please see my response in red above ^^^

Edited August 6, 2014 by rondofj

[GTSBoy]

The fact that behaviour is same but different with the BOV open/blocked should be instructive. I suggest remaking inlet or asking for Jonny's advice in tweaking it out in the PFC (as an experiment or permanent fix, depending on result).

If you have no connection between engine and fuel tank breather, then take that stuff off the table for discussion. Not real legal though - something to look at later perhaps.

As to the intermittency of the problem, not happening 20% of the time........maybe there's an ambient temperature factor, or maybe the solder joints in the AFM need attention and sometimes they behave properly. That aspect of your problem is really hard to work through.

[CEF33Y]

Has Yavus or Mark been for a drive in it?

Surely with a "5 second delay in power on a down shift" they'd be able to at least give some suggestions.

I had my car tuned there, no issues, but thought it was a bit strange they didnt take it for a road drive after the tune.

Every other tuner i've used has did a quick check on the road. Saying that, my car has been ok.

I also run with the 02 sensor turned off. (issue on the dyno, kept stalling when turned on) and get 10l per 100km on a cruise. (240rwkw RB20).

When you downshift are you rev matching? or just letting the clutch out? does it make a difference to the hesitation?

[AngryRB]

I just checked and my canister is doesn't recirculate either, but wont hurt to check that the fuel return hose is hooked to the right nipple on the pump just in case their is a blockage..

Also, what if the fuel reg was cracked/damaged/internally rusting? you could end up with fuel leaking into the manifold, which would make the O2 react, but this would certainly make it thirsty.

[rondofj]

^^^ That is highly possible, thanks for the suggestion, I'm definitely guna check that..

It does have all the signs of a stuffed fuel reg - excessive fuel use, fuel smell, oil out the exhaust (concrete survace behind exhaust has oil spray), no black smoke though. The vacuum hose from reg is guna be coming off to sniff for fuel there :S

Edited August 6, 2014 by rondofj

[hy_rpm]

Like I said before have a look in converting the afm to a r35gtr unit it has been done with nistune so best to ask them for a map and to see if it's possible to program into PFC

As it's shielded from the reversion and is only mounted and works one way facing the air incoming so it suffers less from reversion than the z32 afm

Or just make a new intake and run your plumback bov which will work out cheaper

I was suffering bad from reversion in my 180sx with no bov metal intake to the point at the drags doing the burnout on and off the throttle it flooded the engine and stalled

when I first cranked the engine felt like it was locked up with fuel also use to stall at drift days on and off

Also that was with a low mount t2 frame turbo so I would say with a precision turbo it will be amplified

Solving the reversion and new o2 sensor should get back abit of your economy if not make it the best it can be

As your on and off the throttle every time you drive so the reversion will be happening constantly

Remember you can't compare your fuel economy to a std car pushing the boost and power your at

[hy_rpm]

Now I'm using a apexi intake and plumback bov still z32 afm

Fuel economy has gone up from 15l100km to 14l100km on e85 but

And the flooding I'm yet to test at the drags/drift day

[Badgaz]

what size and type is your BOV?

[rondofj]

Stock. Why are some people still sayin to get a new O2 sensor when Im supposed to leave the O2 feedback off

? Sorry dont get this one.

[Ben C34]

Ideally you would have a functioning 02 sensor working woth a correctly tuned ecu.

You can get by without an O2 sensor though if need be.

[Kinkstaah]

All the narrowband 02 does is really trim the fuel on cruise/idle/low load situations.

02 sensor being bad usually has symptoms of doing a full tank of highway driving and draining the tank in 300kms when you're off boost and 5% throttle the entire duration of the fuel tank. It wouldn't even be in the mix of things occurring if you're driving in any kind of spirited fashion, unless this problem of bogginess happens when shifting gear entirely off boost from 2nd to 3rd at 25kmh at 5% throttle

[rondofj]

I dont think I've ever got 300kms to my usual 50L fill-up, I'm generally in the 250kms range, dont think anyones done it worse? :S. I'm goin to get an O2 sensor - either an NGK/Bosch and see if the f*cker makes a difference. Maybe a Ford EL one.. And while at it, raise the TPS to 0.45V at idle from 0.41V and check/clean all earths including ECU one. And another boost leak test-basically try to pump 30psi through the mofo.

Last call would be the intake pipe bov entry mod - do I do it to existing pipe or get a new one made, might cost more

Edited August 7, 2014 by rondofj

[GTSBoy]

My stock (engine, turbo, injectors, AFM) Neo with stock (but Nistuned) ECU returns just on 400km to a "full" tank. ie fill at damn near reserve light on, therefore pretty much 50 litres and ~12.5 l/100km. This is driving in heavy traffic to and from work 27km each way. So it gets warmed up properly (no short trip cold running trouble here) and does a lot of stop start and crawl. It does better on the open road at sensible speeds. It uses more in the hills.

This is with a newish O2 sensor and closed loop functional. Boost is ~11.5 psi, so when I get up it it uses a lot of juice, being into (and off the end of) the rich part of the map. Soon to be fixed though!

I plan to switch off O2 feedback when I tune it and set the cruise mixtures to something somewhat leaner in hopes to emulate the ~500km range that others who have done the same report.

What this means with respect to yours Ron is that your consumption is f**king woeful. You should be at least able to get the same as stock. When cruising your engine should be pretty much no different to mine. It's doing the same job, pulling the same sort of load (OK, so an R34 is a bit heavier than my R32, but nevertheless). If your closed loop was working properly then you should be running ~14.7 mixtures at 2000rpm and 32-40 TP (Nissan load index, not PowerFC). Typical cruise conditions in 4th or 5th at 60 or 80. If it is using shit tonnes of fuel at those conditions then the mixtures must be hell rich.

The various ideas that others have floated about how you could be using heaps of fuel from broken fuel regs etc cannot be discounted. Same for wrong thermostat to a certain extent - I know you've reported knocking the temp based enrichment back).

Don't mess about with using the wrong oxy sensor either. Get the right one for the Neo. The EL falcon one was a substitute for the RB20 sensor - I'm pretty sure it's not viable for the Neo.

As to your TPS setting - I would have thought that it shouldn't be a problem for a PowerFC. Can't you just tell the PFC when it is at idle? Isn't that how it's done? And for reference against my car - Nistune reports my idle TPS voltage is 0.42 and it is fine. I think you should/would be fine at 0.41 on a Nissan ECU. UNless the PFC is somehow more fussy, it shouldn't be an issue for you.

And for the inlet pipe mod - I would just mod the one you have. Just get the BOV return knocked off, remade with a better entry angle and so it still hooks up to the hose, and try. Got to be relatively quick and cheap compared to making from scratch.

Edited August 7, 2014 by GTSBoy

[XGTRX]

Reversion will also cause high fuel consumption

^^^^^^^ This!^^^^^^

Don't ignore the elephant in the room. I think as a thread consensus this is the thing causing all your issues. As people have already fixed similar issues by addressing reverberation problem you might too. Don't you think? Seems logical. Doesn't it?

Edited August 7, 2014 by XGTRX

[scotty nm35]

It seems logical to most of us, and has so for a year or more. There are only so many times you can tell someone...

Perhaps you should change the o2, and the engine, and then the whole car... Hey that would fix it Ron.

[rondofj]

Yah man..doing my head in. Change the whole bloody engine man, put in a CA18DE. Much better mileage and powers not too bad..hah

Anyones a pic of a good intake with bov entry angle that has proved to work great?

Edited August 7, 2014 by rondofj

[Dose Pipe Sutututu]

don't waste more money on the wrong things.. buy a wideband o2 that does narrowband simulation..