maf tuning problems

[matt]

The main reason for this post is the im having trouble tuning the fuel for a VT V8. The car has a 5.7L stroker,bigger cam, supercharger with bigger injectors using the CNPJ bin.

Firstly with the car on a dyno the blm coolant temp was raised to a high temp but this did not disable closed loop so the o2 sensors were disconnected fixing the problem. Lean cruise was also disabbled and the base injector rate was lowered.

From there the injector rate constant table was modified but the values seemed a fair way out and i couldnt get the fuel curve i wanted. I changed the open loop afr table which didnt really make much of a difference.

Firstly has anyone added wideband logging for V8 VT's, on other bins there is a wideband history table but not in the VT bin?

Secondly does anyone know a proven way the completly remap the fuel or can point out whats going wrong?

Any help would be greatly appreciated.
Cheers Matt.

[Holden202T]

really on a MAF engine you should be re-calibrating the MAF tables to get the fuelling right, i have adjusted that injector table you refer to and it just doesn't have the range in it for what you need, its more like a fine tuning type of thing more than the main table.

disabling the BLM will only stop it applying fuel offsets to the engine, closed loop will still be active, but unplugging the sensor will probably get the results you need

i haven't done it with VT V8 but you can possibly use the injector voltage monitor line for wideband like can be done on earlier models, unfortunately i can't offer much more advice as im very un-experienced with MAF systems, some of the other guys will be able to give more detailed info though.

[antus]

That sounds about right. Im not experienced with VTs either, but you need to adjust the injector rate by the % difference between the old and new injectors, then get wideband in the datastream via the injector monitor line and if target afr is there, and you can log target and wideband AFR side by side also with maf hz, then you can apply the difference to the maf hz via yoda's spread sheet and tune it that way. It will work much better. You should also get off CNPJ and on to the1's "VT V8 5.0L N/A PCM" code with extended maf tables here: viewtopic.php?f=27&t=2518

[jca]

Is it playing up on boost may be running out if maf

[The1]

so you adjusted the base injector rate appropriate for the injectors your using? along with all the usual, batt offsets and low pulse offsets? With that setup id recommend using the enhanced bin with extended maf tables and a LS6 MAF, id say with that setup you'd peg out the stock maf. Once the base injector rate and tables are set properly try adjusting the injector table 0-2 multiplier for fine tuning, if it's still out of range then adjust the MAF tables via % to bring the injector table back in range. There is a spreadsheet in the enhanced thread you use to adjust the MAF tables. Unfortunately ive found the MAF code in the Holden ecu's is not as flexible as the US ones so i dont recommend adjusting MAF tables unless needed, upto 10% adjustment ive found ok beyond that it seems to do weird things and never quite found out why.

[matt]

Ok this is where im up to with the car, the standard maf went above 11000hz at 4000rpm and the standard bin ran out of cylinder air in the maf tables so I put The1's enhanced bin in the car and swapped the maf for and ls1 type for testing.

The problem is that on high rpm runs tunerpro has data errors with the blue connected bar flashing red.
I have the latest v1.47 ose plugin and latest tunerpro, eco is ticked, have tried the bcm wire disconnected and connected with the vt option selected on the ose configuration settings, a new usb cable but cant fix the problem!

Any help would be appreciated.
Cheers Matt

[antus]

It sounds like an electrical interference problem rather than a software problem. Check where you are running your cable (keep it away from spark), check for missfire, check condition of everything related to spark under the bonnet.

[matt]

The data cable runs under the steering column so that shouldn't be an issue. The car has new cap, rotor, spiral core leads and non-resisted plugs. Everything is good on an oscilloscope.

[delcowizzid]

fit some resistor plugs and see if the issue goes away the resistor plugs stop RF interferance in efi applications

[The1]

can also try usb cable with ferrite cores on them