Nismo 740's And 50% Pfc Trim .

[discopotato03]

I finally had the Nismo 740cc injectors fitted to my R33 and the modded cylinder head . I'm told it idles a bit rough even though I set the PFC injector trims to 50% .

Is this par for the course with these injectors or should the trim be a tad less ?

I know propper tuning is needed but just need to drive my car home in the morning .

Cheers A .

[Shiraz200SX]

change the latency also mate.

[JonnoHR31]

latency needs to be +.14

latency will affect the afr's at idle a fair bit but doesnt make much difference at WOT

[discopotato03]

So I need to insert 0.14 in the row next to the 50% or multiply the voltages in the third row over ?

Still getting head around Datalogit so go easy on me . I don't muck around with tune settings but correction factors I can do if I know what to change .

The intention is to hook up my Tech Edge and go road tuning with one here who's an old hand at it , but need to get my car home from the workshop first .

Thanks all , cheers Adrian .

[saliya]

I finally had the Nismo 740cc injectors fitted to my R33 and the modded cylinder head . I'm told it idles a bit rough even though I set the PFC injector trims to 50% .

Is this par for the course with these injectors or should the trim be a tad less ?

Hey,

In Datalogit's 'Injector' box there are 2 columns; LHS is % correction and RHS is the 'dead time'.

So assuming that your 50%/ +0.14ms figures are correct this goes in the LHS/RHS columns for each injector.

(I'd have thought your correction should be more like 60%; I haven't looked up the proper dead time figures).

I found the best results when all adjustment values were set "properly" for my Sard 700s (including the battery voltage corrections).

The stock PFC settings were significantly different to a set that I calculated from http://injector-rehab.com/kbse/lag.htm

Note that they only show 10V-15V so you will need to extrapolate.

Cheers,

Saliya

[STATUS]

I finally had the Nismo 740cc injectors fitted to my R33 and the modded cylinder head . I'm told it idles a bit rough even though I set the PFC injector trims to 50% .

Is this par for the course with these injectors or should the trim be a tad less ?

I know propper tuning is needed but just need to drive my car home in the morning .

Cheers A .

i know its a bit hard without equipment but you should be able to get it close by ear and vac gauge. More vac is best and as you get it close AF wise the vac gauge will increase and the engine will smooothen out.

dont worry to much about the trims mathmatically for now as to be honest i will often play with it up to 5% and fine adjust with the latency so that the numbers in the map = the numbers coming out the front pipe.

[discopotato03]

Thanks all , silver ghost is home again .

I stopped not far from home , in the shade of a tree , and had a play with the correction and latency numbers to get quite a reasonable idle .

First I went fishing either side of the 50% and got a reasonable result at 45% . Then I went lower than the above mentioned 0.14 which was a mistake , went the other way up to 0.25 which was fine at idle but with a tap of the throttle the idle surged all over the place and it would stall .

I best I could get ended up being 0.57 on the size percentage correction and 0.20 with the latency one . If you prod the throttle it still goes down to ~ 500 revs before it pulls back up but I think thats a timing thing . I managed to run a basic log to see the engines parameters and the timing does bounce between 10 and 20 before stabilising at 16 then 15 .

I am curious to know why the Datalogit shows it idling at 15 when the ignition table only goes down to 20 . Not to worry , this car is not my daily and hopefully most will be revealed next week when I can get out with someone I know thats confident with these and a Tech Edge wide band .

I don't expect miracles because my car engine wise is std except the head porting/larger exhaust valves/Poncams/slight CR increase . The intercooler is an R34 side mount and the exhaust a Nismo the car came with which I added a 3" cat to .

In the new year I'd like to fit a pipe kit and a GTR intercooler plus that 52T GT3076R I bought a few months back .

At the moment I'd just like it to drive smoothly and be clean with reasonable mileage . The real dyno work should come later after the turbo and intercooler upgrades . Maybe a Greddy type manifold to clean things up .

One for the E85 people , how far can you get with E85 and these Nismo 740's on an RB25 ? I doubt I'd ever consider using/needing more than 270/280 Kw so is that possible ? Pump is an R33 GTR one that falls into an R33 GTS25T .

Cheers A .

Edited December 19, 2009 by discopotato03

[STATUS]

Thanks all , silver ghost is home again .

I stopped not far from home , in the shade of a tree , and had a play with the correction and latency numbers to get quite a reasonable idle .

First I went fishing either side of the 50% and got a reasonable result at 45% . Then I went lower than the above mentioned 0.14 which was a mistake , went the other way up to 0.25 which was fine at idle but with a tap of the throttle the idle surged all over the place and it would stall .

I best I could get ended up being 0.57 on the size percentage correction and 0.20 with the latency one . If you prod the throttle it still goes down to ~ 500 revs before it pulls back up but I think thats a timing thing . I managed to run a basic log to see the engines parameters and the timing does bounce between 10 and 20 before stabilising at 16 then 15 .

I am curious to know why the Datalogit shows it idling at 15 when the ignition table only goes down to 20 . Not to worry , this car is not my daily and hopefully most will be revealed next week when I can get out with someone I know thats confident with these and a Tech Edge wide band .

I don't expect miracles because my car engine wise is std except the head porting/larger exhaust valves/Poncams/slight CR increase . The intercooler is an R34 side mount and the exhaust a Nismo the car came with which I added a 3" cat to .

In the new year I'd like to fit a pipe kit and a GTR intercooler plus that 52T GT3076R I bought a few months back .

At the moment I'd just like it to drive smoothly and be clean with reasonable mileage . The real dyno work should come later after the turbo and intercooler upgrades . Maybe a Greddy type manifold to clean things up .

One for the E85 people , how far can you get with E85 and these Nismo 740's on an RB25 ? I doubt I'd ever consider using/needing more than 270/280 Kw so is that possible ? Pump is an R33 GTR one that falls into an R33 GTS25T .

Cheers A .

pfc uses a fixed idling regime and is not adjustable (one failing of the AFM PFC on a wild setup) with datalogit you should be able to input anything but it still wont adjust the idle timing. Once you tap the throttle it uses the map tming.

[JonnoHR31]

what was it like with 50% and +.14? should have been close enough

57 and .2 will probably give around the same result at idle as 50 and .14 but it'll be leaner under load. latency is the dead time in milliseconds, at idle the injector pulse is usually around 1ms, so a dead time of .76 (740s) means the injector spends 76% of its time just opening and closing and only 24% spraying fuel, so latency settings here have a huge effect on the amount of fuel injected. whereas under full load 100% duty at 6000rpm opening time would be 20ms, where a dead time of .76 doesnt make much difference.

as for e85, theres a couple of guys making over 300rwkw with 555s so 740s will be more than enough for a 3076

[discopotato03]

It had a grumbly sort of idle with 50% and 0.14 .

I'm not sure what difference those 256/8.5 lift Poncams make - most people reckon they idle quite well with them .

Something I don't know at the moment is if the CAS was set to what the PFC thinks it is .

The impression driving it home was initially a little flat till it started to boost , stock std turbo , but probably a bit better part throttle torque from that point .

The people who's upgrade path I'm following were able to run considerably more advance with the same head and cam spec so that will very likely bring it alive , its also been my finding when using less restrictive (exhaust side) turbos - IMO hot side restrictions aid detonation .

LOL I can understand why people get frustrated with the whooshing std turbo when other breathing mods are done . I'm very keen to see what the mid comp trim 0.82 A/R GT3076R can do though its going to need something better than a GTt SMIC .

Really today I was just soft pedaling the thing to transport it home . The workshop started it twice from completly cold and went to a bit of effort to make sure the cooling system was bled properly .

A little off my own topic but it was discovered that RB25 water pumps are unique so needed a genuine one which I don't mind because generally Nissan OE pumps are pretty good I believe . Because my car is at 91K it was getting the major service and the head and cams at the same time , pump time anyway .

I gave them new Nismo injectors and genuine seals because for the work involved to root out side feed injectors I wanted these right the first time .

I am wondering if the 13-14 year old fuel pressure regulator is worth replacing just to be sure , I wouldn't think an adjustable one is necessary with these squirters but if its cost neutral why not .

I'll know more on Monday when its had a a bit of road tuning and will pass on some details . I don't really need or want to drive it until then and can't see the point of risking engine damage unnecessarily .

Cheers A .

[JonnoHR31]

if you have an antisurge comp cover the gt30 wont be much quieter than a stock turbo, they make a fair bit of noise.

nismo regs are cheaper than genuine standard ones and should be of even higher quality

[discopotato03]

I was going to buy or make the bell mouthed insert for the ported compressor housing like HKS do with their GT3037S turbos . I think the value is covering the outlets to the surge slot in an attempt to muffle the tip speed scream of the inducer tips . GCG do sell them but my turbo being a slightly smaller 52 trim probably needs to have one turned up . Their grub screws should work though .

Good news on the reg , cheers A .

[bradsm87]

740's in an RB25 or SR20 need +0.08 latency, NOT +0.14