Hi all,

 

Any suggestions for the above?

 

I've been testing after being off the road for a couple of years. Previously untested mods are 550cc injectors, FMIC, straight through exhaust, AIVs gone, EGR gone, carbon can gone, aircon gone, plenum water bypass, stock boost solenoids gone, std recircs gone, Nistune daughterboard ECU management (set up roughly correct for 550cc injectors).

 

Other stuff I've been running for a while, Blitz BOVs, AVC-r, intake, decat exhaust, SE chip (prior to Nistune).

 

I have to lean the injectors out to approx 1/3 of what they should be running at to make it idle, I still get black smoke and sooty plugs. Hardly any power at any injector setting.

 

Whilst I know I have a lot of adjustment to do to the fuel and ignition maps to make it fulfil it's potential, it's running far too poorly with what should be a reasonable base setting for it to be a problem with the ECU program. Changing settings in the ECU isn't really making much difference at this stage therefore I have to assume I've made a b*lls up elsewhere.

 

I'm running an AVC-r, stock boost solenoids and their pipework have gone, just wondering if a problem with this may cause wastegates to stick open thereby richening the mix when it comes onto boost (?)

 

So far I can only think it might be a MAF sensor problem (reading around 1.5V at idle - think this is ok(?)), a massive boost leak allowing all the air to escape after it's been metered or possibly a badly routed vacuum line having a similar effect, maybe crappy injectors or seals (doubtful as all plugs are equally black).

 

Any suggestions greatly appreciated, I suspect I may be approaching the issue a bit narrowmindedly - I could have missed something which is galringly obvious to someone else...

 

Cheers

RobH

What brand of injectors are they?

Hesitate to say it, Venom...

Don't see this makes a difference though as all cylinders are running equally as over rich...

 

One further point, I unplugged the MAS earlier this eve and it actually idled a lot better. The revs seem to bounce between about 1200 and 300 in 5 second cycles, min revs seem to drop further and further and it will eventually stall.

Change the injectors end of story!

Fuel pressure OK?

Are you getting readings back to Nistune? I.e. is the daughterboard working OK and it's not running on default settings?

Temp sensor OK?

What K value are you using (should be ~205), is the latency set correctly for venoms, at idle, latency is a pretty big % of total duration, try trimming it.

Is it rich right throught the rev/load range or have you just had it idling so far?

A note about Venom injectors for anyone searching threads!

 

Venom injectors are reknowned for having differing flow rates across a supposed 'matched set' - this would not cause all 6 injectors to run over rich regardless of what injection multiplier I run. Another historic issue which gave them 'bad press' was that the seals supplied with them were cr*ppy, this issue has been resolved so whilst they may not be perfect they are not causing my current issue. My experience has not been great, one of the set I purchased was stuck open and caused a hydraulic lock, I eventually got it replaced after a delay of around 2 months. I'm now under the impression that Venom may actually remanufacture injectors as reference was made to 'cores' being available for my replacement part. Another observation was that if the set is actually flow matched, Venom (Python injection) would have noticed that one was stuck open. In retrospect I would not have chosen these injectors but that's not to say I could have been lucky and had no problems at all and saved myself £300 on a set of Nismos. Some people have had issues with one particular guy who sells these, I suspect they approached him with an aggressive attitude and he didn't respond well, he was helpful enough to me.

 

John, the Nistune software and product is excellent, I'm sure the fault lies elsewhere. Pete programmed it with what he thought would be a good base image for my setup. K constant was 193 - this is what the resize injectors feature calculates and should be roughly correct. I've experimented with a few different maps, starting with a very basic standard map and changing only the K constant (and related TP and TTP scales), the best results I've had at idle were a K constant of 70-100 (!). I've tried K constant of 193 and tweaked the Latency from the 1500 micro seconds default right down to zero, Venom suggest starting at around 700 and to be fair it does run a little better (but still awful) at 700.

 

It's not running well enough to rev much above idle as it is, if I make it idle by using a low K value it will barely rev above that at all...from the evidence so far, it's extremely rich across the entire range. I haven't checked the fuel pressure as yet, my mate also suggested this - are you thinking perhaps the pressure regulator is shot?

 

Temp sensor is ok afaik, is the consult reading the gauge temperatue or the ECU temperature?

 

Cheers

H

any pinched o rings leading to an injector leaking fuel into the cylinder?

Oh, I know nistune is good, I use it myself. What I was getting at was that if you couldn't get comms on nistune because the NVRAM was not programmed correctly then the ECU would run on it's hard-coded values (which are set for 370cc). Obviously this is not the case.

 

Fuel pressure, yes thinking the reg is shot. Another possibility is that the fuel hoses are reversed so you have full pump pressure on the rail all the time (bit difficult to do on a Z with stock layout).

 

May also be worth trying another ECU with a 555 chip just to check yours doesn't have bad drivers or something. Can you hear each injector click when running?

 

If none of this works then maybe get them flow tested to see what you're actually dealing with, maybe they used the wrong drill!!

Hi John, it was you that pointed me to Nistune in the first place - just wanted to make the point that I was happy with your suggestion and was in no way suggesting Nistune was at fault ;-)

 

I have been thinking about the pipes etc for the pressure regulator, this and the dampener were mystery items to me when I pulled the plenum off, still not confident in my knowledge of them so am going to investigate this fully and ensure all is hooked up correctly.

 

Looking at it slightly differently, it's evident that the engine doesn't actually idle at all, it is either about to stall (revs dropping) or the ECU is compensating by revving the engine to approx 1200 rpm - there is no inbetween although it will idle when cold (about 1200), maybe this provides a clue??

 

As for the MAF, checked at below 0.5V with ignition on, engine not running, at 'idle' it shows 1.8V or thereabouts - these figures look bad to me. My MAF has only 4 pins, connector has 5 wires - is this an NA MAF in a TT chassis?? There seems to be some confusion as to whether there is actually a difference between MAF sensors in TT and NA.

 

The injectors click as expected. I think if the were drilled oversize and flowing too much then changing K and latency values would improve things to an acceptable level.

 

Jaffa, I know where you're coming from, I was extremely careful fitting the new injectors and rings, I've kind of ruled this out as all cylinders are running over rich, if the odd one was pinched it would show when reading the plugs - v unlikely I've pinched them all(although anything is possible for me ;-))

 

Cheers again

 

H

Oh man!! I'm such a fkin dunce!! Think I've put the fuel pressure regulator on upside down (didn't think it was possible!!) - hence supplying the rail at pump pressure =:-O

Oh man!! I'm such a fkin dunce!! Think I've put the fuel pressure regulator on upside down (didn't think it was possible!!) - hence supplying the rail at pump pressure =:-O

 

:nelson:

Oh man!! I'm such a fkin dunce!! Think I've put the fuel pressure regulator on upside down (didn't think it was possible!!) - hence supplying the rail at pump pressure =:-O

 

Lol, easy done! Hopefully it's just that :cool:

Hmph - apparently this wasn't the problem, still runs exactly the same!! Points of note are that K constant needs to be below 100 to make it idle (latency has very little effect, it won't rev with the K constant this low) OR the MAF has to be disconnected - it will idle with a reasonable K constant then, plugging the MAF back in stalls it, obviously can't rev it with the MAF unplugged....

i know this may sound a bit like teaching u to suck eggs but when you fitted the injectors did you pressure test them up with fuel pipes before fitting in lower plenum just to make sure there was no leaks, as this has caught me out in the past and only takes a few extra minutes to do at time of fitting, cos if you have a dodgy injector or a seal not seeling correctly for what ever reason it will leak straight into the lower plenum giving u a rich afr

rich

I'd stick a fuel pressure gauge on there and see what you have. It's possible the reg was damaged by being connected backwards maybe?

Hi guys, I'm waiting on delivery of a fuel pressure gauge which may or may not help. I'm keeping my fingers crossed that I've damaged the regulator (!?).

 

The point I'm trying to make about the possibility of cr*ppy or badly installed injectors is that it's extremely unlikely that they'd all be bad - hence not all plugs would be carbon fouled. If one or two were fouling then I'd definately be looking at that as a priority. Thanks for the input though.

 

H

Hi guys, I'm waiting on delivery of a fuel pressure gauge which may or may not help. I'm keeping my fingers crossed that I've damaged the regulator (!?).

 

The point I'm trying to make about the possibility of cr*ppy or badly installed injectors is that it's extremely unlikely that they'd all be bad - hence not all plugs would be carbon fouled. If one or two were fouling then I'd definately be looking at that as a priority. Thanks for the input though.

 

H

 

ah... that's good then, just got back and haven't been able to find a gauge! Have got a a couple of other bits for you tho... will try and frop them round tomorrow, let me know if you;re about around luchtime...

It seems it is impossible to connect the FPR upside down - don't know what I was thinking of!? It was correct the whole time, I must have removed it and put it back on just the same - i.e. correctly. duh!