Has anybody had success in keeping the MAF system , upgrading the MAF to a much larger one to meet 1000cfm + demand for the specific engine and getting past the cap on the 255 gram limit the 165 ecm has ??

 

Yes. Since this only occurs in WOT on a N/A engine, you tune WOT with a WB and add the correct amount of fuel via the P/E Fuel Tables.

 

The problem is the MAF's problem. The ECU also only has 255 bits of resolution, but 255 doesn't necessarily HAVE to equal 255 g/s. If you modify the MAF housing, you can change the scale of the calculations to make 5V = whatever 5V equals in flow on the new MAF housing. The easiest way is to change the injector constant, and then just ignore what the numbers of g/s are, or you can change the display of the numbers such that 0=0 and 255=new max (just remember to change the display in the tables, and in the telemetry/ALDL stuff).

Of course doing this hurts your resolution, on an already resolution compromised system, but if done right, will net a wider range.

I've also heard of dual MAF setups, and then just cut injector flow rate number in half. Not sure how to average the signals together though. One could be a dummy, but if one air filter or ducting is worse or changes over time, then all heck could break loose.

 

Ya, keep the MAF system on the shelf in the garage, and go with a SD setup....

Or figure out the R/C on the input section of the 165, and then run a later model MAF. Prolly will need to do some code work to get it to work... But, it's all on the chip, so you do have access to doing that.

Heck if you did that, and included some code for the reporting error on throttle transistions you'd probably have a decent setup.

 

165---> 808 code just sucks b/c the baud rate but the 165 locks serial any way
2 bar MAP / 808code 165 ECM => Boost

 

Thats not error if you have TBI On MPFI/TPI though, the sudden inrush of air into the plenum on tip-in will cause a rich spike if not properly handled. The later MAFs are lighting fast, and will see the inrush as it occurs.

Its impossible to interface directly with the later GM MAFs with any ECM. The hardware required for this didnt appear until the 93+ truck/car/LT1 PCMs. They have the needed inputs to read the high freq. MAF pulses in with a high degree of precision.

If you want to keep the MAF, get a converter and an LT1/LS1 MAF. The resolution will suck hardcore with the A/D, but it will work and see over 255 gms/sec. I did this with a C3, and the commanded fueling couldnt hit a broad side of a barn. The AFR would ratchet up and down and not remain steady at low airflows.

I personally like MAF, as it allowed me to neatly side-step all of the steady state fueling issues with TBI. With MPFI/TPI, though, its a wash. Given the resolution requirements for a MAF system to work properly, SD is probably the optimal choice if using an ECM.

 

Has anyone researched the use of DUAL Maf sensors and recalibrated the ECM ? I found an aftermarket last year for these Dual MAF sensor translators, that would combined two standard MAF signals and create a Mean value of the two.thought it was an interesting concept, but seemed alot more work then just going SD. either way tuning is always a factor..

 

Would be easier to use an LS1 MAF and translator. Tuning with MAF is fairly easy. All your doing is fitting a curve. the big thing is that the resolution is going to be very poor with the stock computer regardless of which setup is used. There are some translators for the LS1 that allow you to tweak the output from the MAF, which could help you overcome the resolution problems.