unable to control warmup injector pulse width

[bachig24u]

Hi Matt,
I'm having trouble altering the pulse width during warmup cycle in the VLT image.

It appears that during the time from cold start (+10deg) through warmup to (60+deg) the warmup tables have little or no noticeable affect on reported injector pulse width after the engine is started and running.

The only way I have influence on injector pulse width is by changing MAF VQ table, K etc which is not what I need control over during for satisfatory. It appears that the pulse wdith during cranking is controllable. Only the after start (running condition doesn't seen to have a table for it that changes pulse width).

the combination is;
454cc inj
Z32MAF
0.10.11
Win7 32bit

The light green table traces various enrich tables but changing values has no noticeable affect on reported pulse width.
or Lambda readings.

I ran through the debug file and found some bit length errors and disconnect/reconnects. not sure if they are related to the issue. note: the car was started and stopped several times during testing to prevent warming up to quickly so as to troubleshoot coldstart enrichment issue.

any help greatly appreciated as this is causing vehicles with larger than stock injectors to have poor cold running characteristics.

Kind regards
Sime

[Matt]

Try changing both warm and cold enrich tables at the same time on these. I have sat there and monitored the pulsewidth changing before on my RB30E+T setup

The tables are meant to be selected whether above below 15 deg C at crank time. Nistune tries to determine this from the last crank when connected. If its dropping out might not be selecting the right ones

The other one I adjusted was 'After idle enrich' map on my tune

[bachig24u]

Thanks for the expedient reply..

although I did changed the values on all the tables relating to enrichment but the pulse width remained at 2.6ms to 2.7ms.

Would it be possible that the VLT image used on a ECCS, 3EA or 3EM ECU could cause this not to adjust?
I'm thinking to try a J7100ECCS with a CR31 type 1 imaged board in the vehicle to see if I have the same results..

Are any of the parameters not real-time or require sync before memory is re-read?

KR
Sime

[PL]

I had a similar problem but changing both the maps fixed it.

I wrote this in my VL tuning notes file:

"Cold Start

When using larger injectors and Z32 AFM it's often necessary to add fuel for cold running after start up. There are 2 tables for this. Cold Enrich and Warm Enrich. Which map is accessed depends on what the coolant temp was at startup. Once the engine is started it will continue to use whatever map was accessed from startup therefore it's important to copy the tuned map to both maps once tuning is finished."

PL

[bachig24u]

I'll change them together and see what happens.

Thanks Pete and Matt.

[bachig24u]

ok, had some sucess. it turns out the 'warm enrich' doesn't have any impact on cold running after start or warm running after start even when table highlighted.

'cold enrich' has a some adjustment starting only after a specific temp is reached, maybe around 30deg.

Still bewildered why the warm enrich table starts at -40deg when it's influence is 15> deg though or none at all.

'after idle enrich' seems to affect TP up to a specific temp even though the table highlighting activates. may have been limited by 'warm up timing temp max' although it was not highlighted.

[PL]

Yeah, I don't understand why they have 2 tables either. You'd think one would do it but there's obviously more to this than meets the eye. Until I know more I'll just edit both tables the same.

PL

[bachig24u]

what I find completely out of kilter is the fact that with larger injectors, massive increases to the (percentage based) enrichment tables seems to be in order to achieve resonably good warmup running chararteristics.
This necessary action leads me to believe that they can't be directly tied to duty cycle alone.

Maybe a possibility that the tables are still a calculation based on percentage of inj multiplier or some other hidden variable instead?

[Matt]

Simon I have seen this exact same problem on my R31 setup. It occurs once upgrading the MAF using the opamp modification

The AFM normally measures 2-7 volts and the opamp drops this to 0-5 volts. When using any other later Nissan AFM then we remove the op amp

However usually with these AFMs the load scalings are a lot larger so we have to adjust the K constant to suit

I find that using the auto calcs in Nistune we actually had to double K constant in addition (compared to normal MAF resizes) for R31/Z31/VLT ECUs

I think this doubling whilst making things run again then throws everything else out of wack

I dont completely understand why that is necessary however. But I have found it causes issues with running lean at cold start and also when the aircond is used I'm running 18:1

Did a test on Monday with this. The aircond switch off 14.7:1 idle and then on 18:1 idle. Obviously the car runs like shit almost cutting out. The injection time did increase however to compensate for a/c switch. However the increase of 0.5ms or whatever is not enough with GTR injectors/Z32 MAF. There would be a constant which is not affected by K const and needs increasing also for A/C to be happy

Also looked at JWT cobra tunes and they dont seem to do anything out of the ordinary to address the above issues on Z31s. I'll have to have another look to see if they tweaked code at all but I dont think so

[bachig24u]

interesting...

Do you thing any more addresses are likely to become available for these ecu's?

[Matt]

Yes I am quite eager to fix the air cond prob and other issues and I will add these as I find and test them

[bachig24u]

look forward to seeing some of those nissan top secrets.

I wish we could find one the original programmers and get the low down on all the parameters.
surely 20 years on they can spill the beans!!