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VE table numbers

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Hi all

I'm still messing about with my RB26 and Link G4+, trying to get a base fuel table that I can drive the car to an MOT with.

I have the main Fuel table set up with MAPxRPM and the 4D table set to TPS (although TPS table is all 0s at the moment).

The strange thing is the VE numbers are very high at idle and seem to slope downwards (rather than up as I was expecting) as the rpm and load rises. Is there something obvious that I might have set up wrong?

Thanks for any help or input in advance


Has it been mapped already or is it just the Link base map?

What Injectors are you using?

Hi Chris

The plan was to build the fuel map from scratch.

I'm using Destchworks 800cc injectors, I did post a while ago asking about lag times for them. So far I've got two different sets of figures from Destchworks (non of which seem correct) and another different set from elsewhere on the net (which I also don't trust).

I was expecting incorrect lag times to cause problems at idle but my VE numbers are still going down at 3000rpm to get 14.7:1AFR.

I've given up on VE now as I've got no idea why the numbers don't follow any kind of pattern.

I've also given up on lag times for the injectors as all the info I've got contradicts it's self.

That's just typical of DW injectors.

Would you fancy posting up your map so you may get some technical input, would be good if you could post it along side a data log

Hi Crewcutchuck,

I've seen the same thing on several different engines (and different ECUs) when tuning for MOT smog test. With no load on the engine (neutral), with rpm going up, the VE-number goes down. I'm not sure why, but maybe it has something to do with air velocity, pressure and cam profile...? If you have a look at the PW in "runtime values", you will probably see that the engine receives more fuel as the rpm goes up (as you would expect).

If you're tuning an RB26 on a Link G4+ then you should start by using TPS as the main load input instead of MAP (assuming you still have the ITBs). You set up the ignition table relative to MAP as well as the AFR target table. There is a webinar we ran on this configuration using the traditional fuel model a while back that may be helpful to you - https://www.hpacademy.com/previous-webinars/4d-tuning-link-g4-plus/

You will tend to see the main fuel table when tuned like this will tend to drop away in values as rpm increase at low throttle opening.

Hi guys. I've been messing about with this off and on for ages. I ditched the DW injectors and have now fitted a set of ASNU 1000cc. I've added the injector dead times at 3bar and tried to get it to idle. Its rough as a badgers arse and stinks of fuel even when the AFR reads 14.7:1.

I'm still using the traditional fuel modeling and belieave its set up correctly in regards to the fuel load axis? On idle the effective Injector Pulse Width is around the 0.5ms area. should it really be that low? i was told by many people that the ASNU 1000cc would be perfectly fine at idle.

Thanks to all that replied before. I've watched the 4D Mapping Webinar and watched through 90% of the Understanding AFR and Tuning basics corses. Sadly it still seems i have no idea what im doing though.

Attached Files

Good day.

Can you provide a data log to match the calibration file shared? There are a few things which seem curious but I think that a matching log reflecting the awkward behavior of the engine. If need be you can try to assist the engine with some throttle input to keep it going. Also, just in passing, is this a box standard Nissan RB26DETT? If not, can you give some feedback with respect to any deviations from the OEM setup.


The engine is stock apart from 1000cc injectors, Greddy T517z turbos, HPI dumps, Trust frontpipe, Tommei exhaust, 24 tooth CAS trigger disc, uprated in tank fuel pump, Apexi filters and an innovate Wideband.

It was running with an apexi PFC up untill I bought the Link G4+ Making a safe 500hp at 1.2bar.

If I'm honest I've not played about with the logging function much yet. I did try recording for a while with the DW injectors at one point but it I could only play back a couple of seconds of the log. I'll try again when I get a chance.

What stands out as being odd? Thanks for the quick reply

You're more than welcome, and I hope that everyone else thinks of this form as a very reliable support network.

From what you've described the engine itself has many bolt-on modifications but little has been changed in the way of OEM actuators. With respect to the sections of the calibration file which stood out, I would have to say the fuel compensation tables for one. So that would be the Intake Air Temperature Trim table as well as the Warm Up Enrichment table. The injector dead time values seems curious enough to warrant some verification, although, I haven't ever used either of the brands you have mentioned.

With respect to the logger on the G4+ there are two basic options open to you, which would be the ECU logger as well as the PC logger. As the name indicates, the log file itself is stored either on the ECU itself (limited to number of channels, channel frequency and log duration) or on the PC (laptop) you have attached to the G4+. The help file within the G4+ is pretty good at explaining but should you need further assistance please feel free to direct your questions accordingly.

With the log file in place I will be able to see how the engine is responding to the instructions within the calibration file. This should allow for problem indication along with proposed solutions. Also, should anything not seem clear or confusing while you are taking any of the courses here at HP Academy please feel free to ask questions at your convenience and the forum community along with Andre will make an effort to assist you as best as possible.


I'll head out and try to log the engine running now. The Injector lag times came from here http://www.asnuinjectors.co.uk/tech/1000volt3.pdf.

What channels would it be best for me to log?

Many thanks again :-)

Edit: I've just realised I attached the wrong file. That was with the old DW injectors fitted. Sorry.

No problem, you can attach the correct calibration file being used with the log file you'll be working on. This is okay.

Thanks for the ASNU link, I was looking at the USA website which doesn't seem to have the injector dead time data.

When it comes to logging there are a couple usual suspects you want to look at, very similar to the run time information output used on an initial start up. However, for a quick turn around, under the logging tab within the PCLink software then select logging setup. From there you should be on the PC logging tab of the present window (logging setup), and you can click on the Add All button in the lower left hand corner under the logged parameters section. This should add all parameters so you don't miss anything, I've attached a screen shot which should help. Also, you can use the manual option for control of the start/stop of the logging, this works by pressing F8. Saving the log file is pretty straight forward using the 'save log file/save log file as' options under the logging menu.

We're all more than happy to help where possible. Cheers!

Attached Files

I just tried to do a few logs of it running but i dont think it was logging all the data you want. i've run out of time tonight but i'll have another play after work tomorrow.

this is what i have along with the File used

Attached Files

Using this data, can anyone tell me what the Minimum pulse width should be set to?






Also does this not say that they flow more than 1000cc at 3bar? If I try using the modelled fuel equation again and I put 1000cc in for injector size will it throw everything out?

I'll have another go at logging tonight.

OK so i changed the fuel equation to modelled and added all the parameters to the logging(i think).

This is the ecu file and a log file. The engine will still not hold a steady idle or AFR.

Attached Files

Good day,

Firstly, I would like to express my sincere apologies for a very late response on my path.

From the first three data logs you shared it would appear that the engine was left to idle and warm up, is this correct? I didn't see some of the points you raised previously, which was very rich air-fuel mixtures and a very unstable idle. Did I misunderstand the nature of the help you were requesting? Can you give some feedback on your perception of the idle quality?

What I did notice is that the engine was fairly lean, or close to lambda 1 which performance engine tend to be a little unhappy with at times. Having an idle mixture of lambda 1 doesn't automatically equate to a good quality idle. In my opinion, achieving a very table engine speed using mixtures that won't result in fouled plugs are better tell tale signs of a good idle. This is discussed at length by Andre in the Road Tuning course as well as the Practical Dyno Tuning course. In both instances we goes through the procedure step by step and discussed what's happening. I'm not sure if there's a webinar which deals with this.

Also, the Intake Air Temperature trim table must at least be setup to reflect the ideal gas law so that realistic air density calculation can be applied. I would also want to look at the Warm Up Enrichment table as you will need to stabilize the air-fuel mixture here and not on the main fuel table as the engine warms up. Making adjustments to the fuel table should be taken care of when the engine is fully warmed up, replicating the same idle quality (stability) from a cold engine status should be done through the warm up enrichment table which gives you a table where engine coolant temperature can be plotted against engine load where the values entered are trims applied to the main fuel table. Does this make sense to you, or do you have questions regarding this procedure? Andre does a way better job at explain this with great clarity.

In addition, you may also use an idle ignition table along with the idle control valve to enable a stable engine speed during engine warm up and at warm idle. It's best to start off in a basic manner then employ supplementary measure to suite.

With respect to the injector short pulse with adder table, please leave all values at zero unless you are given very clear and very specific instructions by the manufacturer. You shouldn't really be operating the injector below it's linear area of operation to begin, however, some manufacturers have completed the relevant testing to advise their customers specifically. I would try to explain this to you better but I'll attach a link which has a write where it is dealt with thoroughly. If after reading you still have concerns then I will try my best to address them accordingly.


Please note that the write has nothing to do with the injector manufacturer who has shared but instead, it was their way of address the concern to the general public with respect to the injector technology in question.

Please allow me an hour or two to review the most recent data log and calibration file shared. I am hoping that I can give you the insight you are seeking.


Thanks for the response. Honestly, don't apologise for not replying instantly.

Yes the first three logs were done as the engine was still warming up. It was a quick attempt to document a log incase you were looking for a triggering issue or something.

As far as the idle quality I'm expecting goes, I was under the impression it should be capable of idling like a stock engine would? Untill I changed from the DW injectors to the ASNU injectors the idle (at operating temp) was smooth and stable but smelled like there was unburned fuel exiting the exhaust. This was with an AFR at 14.7:1.

With the ECT fuel correction at 0% (and engine warm) i'm still struggling to get the engine to idle smoothly or hold a steady AFR. On your advice I'll try aiming a bit richer than 14.7:1 from now on though.

I'll leave the Dead time table blank as you sugest and have a read of the link you supplied.

I'm not too bothered about the warm up side of things at the moment as long as Its not damaging to the engine. The logs were just done in that state as I was pressed for time.

I really do appreciate you taking the time to respond. Thank you.

I had a look over your calibration and your base fuel table and open loop AFR look pretty typical of what I'd expect so I think you're on the right track here. For the combination you're running, I'd expect to be able to achieve a perfect idle quality on a 1000 cc injector - Personally I haven't used the ASNU 1000 however I've tuned plenty of RB26's on the ID1000 which are at least in a similar ball park for flow.

The latest log file you've attached and to be honest it doesn't look too unreasonable to me. You've got a gentle swing in lambda between about 1.015 and 0.980 however there are some factors that may be responsible for this and could give an improvement.

1. In your current modelled fuel calibration you have the charge temp estimate table set to 100% everywhere. This will use ECT as the input to the charge temp in the ideal gas law and you will find this gives a large swing in AFR as the engine warms up. If you check the help file for this function there is a thorough description of how it works.

2. Your main fuel table has a value of 45% at 1000 rpm / 0%TPS and 43.5% at 1500 rpm / 0% TPS. The area you're idling in (1100 rpm) will have the ECU interpolating between these two values as the rpm moves up and down slightly. I'd start by setting both cells to 45% and see if that helps lambda stability. Often I'll add an rpm zone at my target idle speed to give me very precise control at that point in the table.

3. Your idle ignition table is best set up with the Y axis set to none and the x axis set to Idle Error. This gives the best ability to control in my opinion. There is a webinar on idle ignition control that will be worth a look.

Regardless if you are using traditional or modelled fuel equation, this shouldn't affect your idle quality. Ultimately the ECU is only providing a pulse width to operate the injectors and as long as the values in the fuel table/VE table end up the same, the output to the injector will be identical.

As sardengineering has mentioned, if you don't have short pulse width data then it's ok to leave this table set to zero. If you have the data then by all means complete the table, but with the table set to zero the ECU will behave the same way it did prior to this table being introduced. The short pulse width adder table however is very different to the dead time table and it looks like you have that data from ASNU so use it.

I'll also agree with sardengineering that a richer target AFR at idle may go some way to improving your idle quality. This 'shouldn't' be necessary on a stock engine however and I find is more typical once you start modifying the engine - Particularly if you've fitted larger cams. There is a tradeoff between how rich you can go before you end up risking fouled plugs - Typically a target AFR of 0.95 can help improve idle stability, and I wouldn't go richer than about 0.90.

You note that you had a fuel smell on the DW injectors when idling at 14.7:1 however you haven't mentioned if the car is still fitted with a cat converter. If the cat has been removed it isn't unusual to have a fuel smell from the exhaust even at 14.7:1. This doesn't mean there is anything wrong with your tuning or injectors.

Your clarity and attention to relevant details has been spot on as always, cheers!

I'm hoping our friend is in much better position to progress forward with the confirmed understanding needed.

Thanks for your replies, both of you.

I'll try matching and adjusting the 1000rpm and 1500rpm cells together when I next have a chance to play. I'll also have a read of the charge temp estimate help file. I'Ve not to my knowledge adjusted anything in that table so I'm not sure where the 100% figure has come from.

The unburned fuel smell is there with cat in place and without. I would normally use the car with the cat removed but the first trip for the car if I can get it running well enough is going to be for an MOT test.

I've just had a friend send me a file from his ecu. Same engine, same injectors and same ECU. The only difference is his runs a single turbo. The file is however a .pcl and I cannot open it even after renaming the file or trying to open it while connected to my ecu. On the ecu it says cannot open file and after renaming as a .pclr it says it's locked to an ECU. Is there anyway I can get around this?

I'm pretty sure you can still load the earlier .pcl file into PCLink G4+ however I seem to recall it brings up a warning message. Ultimately there are so many changes between the G4 and G4+ firmware though that this file might not be as useful as you think. There will undoubtedly be a lot of memory locations that will not line up between the two maps and you need to go through and thoroughly check all the tables that didn't exist in the G4 map.

An alternative is that you can just load the .pcl file into an older version of PCLink and then copy/paste the relevant fuel maps into your calibration (just have two copies of PCLink open simultaneously).

PS. If you set the charge temp estimate table to 0% everywhere this will have the input to the ideal gas law using solely IAT which is a little easier for most people to understand.

The G4+software can't read the G4 files but if you load the file onto the ecu it will convert it for you. The one thing to watch out for is the extra functions that the plus has, the short pulse width adder caught me out the first time.

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