Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum - View Single Post - SR20det ignition timing issues/engine getting hot

Kingtal0n · 08-14-2021, 06:11 AM

The engine needs tuning even if you don't install cams;

The cam part isn't what necessitates the tuning part- the engine has a MAF sensor which means it can compensate for additional mass of airflow when the cams are installed easily. It also uses an O2 sensor for cruise/idle to adjust for inconsistencies in the MAF caused by changes to the head/cam/etc...

So, on one hand, the cam upgrade should be handled by the maf and O2 sensors. There is no need to "tune" anything because the maf and O2 adjust a/f ratio based on their measured values.

On the other hand, the OEM tune is not ideal, or even intended for our climate or gasoline in some cases. The OEM tuning for sr20/2jz tends to use too much ignition timing and a slightly leaner a/f ratio than we desire.
Furthermore, the aging of the MAF sensor and inconsistency of the user-end plumbing (the style of intercooling and type of plumbing components) adds variability to how the maf is going to interact, as a perfectly positioned maf sensor is rare.

Next, the maf itself is a question as the OEM maf can only supply maybe 300rwhp? Or so. After that you would need a Z32 maf (something larger) which obviously requires a re-tuning as well. And of course, larger injectors to support the increased power.

Thus, it isn't the cam install that facilitates the re-tune. It is really these:
1. the necessity of removing the OEM Maf sensor and adding Z32 sensor
2. adjustment for the age and position of the different maf sensor
3. tuning for larger injectors
4. "fixing" the oem timing and fuel maps

To put this into perspective, If you bring me an OEM sr20det engine with all factory maf/injectors/ecu/turbo/etc....
I could easily replace the maf, injectors, ecu, and perform a re-tune that would work well with the OEM turbo and engine.

Then, you can take the car and drive it for 5 years or whatever, then do a mild cam and turbo upgrade and it would not require any re-tuning because I've already fitted the new maf and injectors to work with the engine at any Mass-airflow-rate (up to approx 500hp).

08-14-2021, 06:11 AM	#21
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 41 Posts: 4,829 Trader Rating: (17)	The engine needs tuning even if you don't install cams; The cam part isn't what necessitates the tuning part- the engine has a MAF sensor which means it can compensate for additional mass of airflow when the cams are installed easily. It also uses an O2 sensor for cruise/idle to adjust for inconsistencies in the MAF caused by changes to the head/cam/etc... So, on one hand, the cam upgrade should be handled by the maf and O2 sensors. There is no need to "tune" anything because the maf and O2 adjust a/f ratio based on their measured values. On the other hand, the OEM tune is not ideal, or even intended for our climate or gasoline in some cases. The OEM tuning for sr20/2jz tends to use too much ignition timing and a slightly leaner a/f ratio than we desire. Furthermore, the aging of the MAF sensor and inconsistency of the user-end plumbing (the style of intercooling and type of plumbing components) adds variability to how the maf is going to interact, as a perfectly positioned maf sensor is rare. Next, the maf itself is a question as the OEM maf can only supply maybe 300rwhp? Or so. After that you would need a Z32 maf (something larger) which obviously requires a re-tuning as well. And of course, larger injectors to support the increased power. Thus, it isn't the cam install that facilitates the re-tune. It is really these: 1. the necessity of removing the OEM Maf sensor and adding Z32 sensor 2. adjustment for the age and position of the different maf sensor 3. tuning for larger injectors 4. "fixing" the oem timing and fuel maps To put this into perspective, If you bring me an OEM sr20det engine with all factory maf/injectors/ecu/turbo/etc.... I could easily replace the maf, injectors, ecu, and perform a re-tune that would work well with the OEM turbo and engine. Then, you can take the car and drive it for 5 years or whatever, then do a mild cam and turbo upgrade and it would not require any re-tuning because I've already fitted the new maf and injectors to work with the engine at any Mass-airflow-rate (up to approx 500hp).