Tuning a 165 ECM for large cam
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Tuning a 165 ECM for large cam
Could someone point me in the right direction for tuning a 165 ECM for mods? I am new at this and am looking forward to the challenge. Nothing scares me. Don't mind the work, just don't want to do it wrong a hundred times before getting it right. Thanks for your help .... This site is Great 
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From: The Bone Yard
Car: Death Mobile
Engine: 666 c.i.
Re: Tuning a 165 ECM for large cam
Tuning for the 165 is relatively simple. The MAF system works on "air volume" so once you nail the AF ratio down (around 12.8:1 in WOT), then minor additional modifactions typcially don't require much more timing.
The most common problems with tuning the 165 MAF are typically:
1) The INITIAL tune is off. Thus no matter WHAT you do, the MAF compensates incorrectly.
2) You have maxed out the MAF (255 gms/sec) in WOT. This is easily adjusted by modifying the fuel in the P/E (wot) Fuel Tables. BUT, once you have a "maxed MAF", ALL modifications will require re-tuning the P/E fuel tables. Basically you are operating like an SD system at this point. However, your "part throttle" will still be okay.
3) The fuel injectors have been changed. You need to adjust for this in the eprom.
4) The MAF has been modified itself. Either the screens have been removed, the MAF has been "hogged out" to permit greater air flow OR you are using a different brand of MAF. In all cases, you will need to "re-scale" the MAF Scalar Tables. The simplest way to do this is with a WB O2 sensor, an "on-the-fly" tuning system (such as the Romulator or TunerPro RT) and then tune in "open loop" with P/E disabled. You drive around placing various loads on the engine and re-adjust every entry in each of the 6 tables until you get 14.7:1 (or possibly another AF ratio if you intend to always run in "open loop"...which some people prefer).
Once you got ALL entries properly tuned, you engage P/E and then strive to tune WOT for 12.6-13.0:1 (each engine has it's own preference which you can find on a dyno). In fact, some people prefer to do this on a dyno.
Just remember you should try and nail down your spark FIRST and then tune the fuel. Once you adjust the fuel, you MAY need to adjust the spark a little more.
If you do fuel FIRST, you may end up re-doing it all again because as you change the spark, it also changes the AF ratio.
BTW, can you specify exactly what your engine specs are AND which MAF calibration you are using? Most people prefer $6E (1989) MAF calibration as it is the best defined and known.
Also, many people prefer to start with the ARAP as their base but you must make a couple changes (such as changing the Fan Switch as the ARAP originally is from a Vette and it works the opposite...as well the spark curve is TOO aggressive/high) to name a few of the common problems just off the top of my head. I suggest doing a "search" on ARAP on DIY Prom Forum for a list of changes & modifications required for the ARAP bin as a starting point.
Also, if you don't have an EGR or Air Diverter, you will need to adjust for those too.
This is NOT a complete list, but should help get you pointed in the right direction.
The most common problems with tuning the 165 MAF are typically:
1) The INITIAL tune is off. Thus no matter WHAT you do, the MAF compensates incorrectly.
2) You have maxed out the MAF (255 gms/sec) in WOT. This is easily adjusted by modifying the fuel in the P/E (wot) Fuel Tables. BUT, once you have a "maxed MAF", ALL modifications will require re-tuning the P/E fuel tables. Basically you are operating like an SD system at this point. However, your "part throttle" will still be okay.
3) The fuel injectors have been changed. You need to adjust for this in the eprom.
4) The MAF has been modified itself. Either the screens have been removed, the MAF has been "hogged out" to permit greater air flow OR you are using a different brand of MAF. In all cases, you will need to "re-scale" the MAF Scalar Tables. The simplest way to do this is with a WB O2 sensor, an "on-the-fly" tuning system (such as the Romulator or TunerPro RT) and then tune in "open loop" with P/E disabled. You drive around placing various loads on the engine and re-adjust every entry in each of the 6 tables until you get 14.7:1 (or possibly another AF ratio if you intend to always run in "open loop"...which some people prefer).
Once you got ALL entries properly tuned, you engage P/E and then strive to tune WOT for 12.6-13.0:1 (each engine has it's own preference which you can find on a dyno). In fact, some people prefer to do this on a dyno.
Just remember you should try and nail down your spark FIRST and then tune the fuel. Once you adjust the fuel, you MAY need to adjust the spark a little more.
If you do fuel FIRST, you may end up re-doing it all again because as you change the spark, it also changes the AF ratio.
BTW, can you specify exactly what your engine specs are AND which MAF calibration you are using? Most people prefer $6E (1989) MAF calibration as it is the best defined and known.
Also, many people prefer to start with the ARAP as their base but you must make a couple changes (such as changing the Fan Switch as the ARAP originally is from a Vette and it works the opposite...as well the spark curve is TOO aggressive/high) to name a few of the common problems just off the top of my head. I suggest doing a "search" on ARAP on DIY Prom Forum for a list of changes & modifications required for the ARAP bin as a starting point.
Also, if you don't have an EGR or Air Diverter, you will need to adjust for those too.
This is NOT a complete list, but should help get you pointed in the right direction.
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