NISSAN Skyline R32 GTS4 Turbo AWD AFM & Airbox Mods

MID2004 – In doubling the size of the metered orifice that was the Original AFM I guestimated that the increased size for a given RPM would slow the airflow measured by the AFM so the
larger injectors would open less to keep the Airfuel ratio roughly correct.

Hopefully this would be enough to be able to drive it to a Dyno
to get it properly tuned for the modification so it is 100% smog legal.

This is how the AFM looked after cutting up the plastic tubing surrounding the post and electronics box and connector still intact and ready to measure a lot lower airspeed in the new larger orifice .

The AFM post assy then was refitted to the new larger diameter tube in the same position as original.

Obviously I expected to have to retune the ECU anyway to suit the fuel and air mods but may have not realised the timing implications.

Well as mentioned I took the Nissan HR32 GTS4 to Dr Drift – Sam Cornell this morning to see if we could sort out the bad noise problems and generaly check over the entire ECU etc.

As he is the only person that seems to specialise in remapping the Nissan ECU in Melbourne I was happy to only have to drive 20 klms instead of 1200 klms to Adelaide to see Martin Donnon again just to tune the car.

Sam seems to know what he is on about and said he would do a baseline run just to see what was going on regarding my concerns on the modified AFM I had created to allow the Mazda RX7 550cc Injectors to work OK on the
RB20 and at least be drivable to be able to get it to a workshop to be tuned.

I have to say that in talking to Sam, (Dr Drift) initially before taking the car over to his workshop, he expressed some concerns with the Mod AFM causing a problem with the AF ratio and the fact it may be extremely
difficult to map the mod AFM to get good stable AF ratio and it may be running lean.
he suggested that some of the 15yr old AFM units are causing some problems and maybe worthwhile to get a new Z model AFM that he
could easily map.

Well after running the RB20DET up on the dyno he logged the AFR at a steady 12.2 across the rev range! AFM Modification PROVEN TO WORK with 550cc Injectors near spot on. The timing needed a 2-3deg retard
but that was all on 13PSI the std gate non bled pressure. Admittedly the idle was a bit ordinary, mainly ok but occasionally hesitating and near stalling but at least fully drivable.

OK what was the RWKW?? – DAMN only 106!

The problem is that the virtually brand new $800 Soderstrom torque Converter is totaly slipping all the way to 5000rpm and Sam could not go any further until I get this issue fixed!

I remember that Martin Donnon did say when he tuned it at MorPowa up to about 180KW that he suspected that the trans was slipping then but I did not want to believe it because I had recently spent $3000 on getting it completely rebuilt and how could it possibly be the problem?!?

On the return journey home to Victoria I blew off one of the inter-cooler hoses passing a truck and was able to fasten it again without too much drama and I said to myself  “THATS why Martin could not get the
power up, it must have been loose and leaking” – Stupid me!

Glenn, (Turbine) suggested we drive over to Street & Strip Automatics in Seaford where he got the Jatco for the RB20DE+T Drag Car built to talk to Alex about what to do to sort it out.

Looks like I will have to book the GTS4 in for a week or so for him to remove the Soderstrom TCI 2700 Stall Torque Converter to get sent away for rebuilding. As well I intend to get the whole box disassembled to be rechecked that all the expensive kevlar clutches and bands are still OK after ONLY less than 5000K’s of driving around reving the car at no more than 3000RPM because of the noise problem that no one seems to be able to accurately identify.

I am starting to wonder if maybe the strange noise is the bloody transmission as well!!