chriscar

Here's my situation, I'm currently running my T28 NX with the 370cc 4bar bored maf program. I just bought a used ecu with the 444cc z32 program.

Now it's my understanding from searching the forum that 370 injectors at 4 bar are the equivalent of 420 injectors at 3 bar. If that is the case, what fuel pressure should I run my 370's at in order to compensate for the 22cc difference? Or am I oversimplifying things, and shouldn't be running the 370's with this ecu?

I drove the car last night with the new ecu, and the 370's at 4bar fuel, left the boost controller off and ran off the wastegate, and the car ran fine. It pulled cleanly to redline in 1st and 2nd. Loading it up in 3rd, 4th and 5th didn't produce any audible pinging, and my injector and maf readings on the Techtom were fine.

One other thing, my 370 ecu is programmed for DE 9.5:1 compression, the new ecu came off an Avenir 8.5:1 motor. Is it safe to assume I can run a touch more timing because of the compression difference?

Thanks in advance,
Chris

__________________
cogito ergo zoom................
1994 SE-R / DE / S4 / Nismo LSD / Calum Realtime / Hyperco - AGX / 15x7 RPF1
1995 Turbo Miata R Package / GT2560R turbo / Megasquirt / Flyin Miata suspension / 15x8 949 6UL

Calum

Using different injectors than the tune was originally developed for is hit or miss (even if they're the same size but different brands). If the injector latency is different enough between the two types you get really odd idle problems and wierd part throttle response (wot doesn't seem affected as much).

Who tuned the ecu? Are those gti-r injectors? What I would do is compare the current latency times between the two programs, and replace the 440 program with the 370/4-bar latency.

On the fuel pressure, just set your fuel pressure at 4-bar and adjust your k-value for the slightly smaller injector size. Obviously your close because the car runs fine, so you shouldn't have to do much tweaking if any.

chriscar

Thanks for the response Calum. It's a JWT ECU, and the it was tuned for S15 444 injectors. Do you know how the latency compares to DET 370 injectors?

C

chriscar

Oh, where would I look at the maps to see the latency times?

C

Calum

Nope, never worked with those injectors. Check what Jimmy Wolfie set them to, they're usually right on the money. There are two latency values, but the one that counts is labeled 'void blast-off time' in rom editor.

chriscar

Thanks Buzz Lightyear.

To Infinity and BEYOND!
C

Calum

I heart engrish!

Calum

Chris, the stock void blast-off for S15 injectors is 3B, which is really really close to stock 370s. In other words, your pretty much good to go.

chriscar

Most excellent, thank you. Do you think I should increase the fuel pressure a bit to compensate for the 22cc difference?

C

Calum

No, adjust the k-value instead. Honestly your close enough that I bet the ecu is self-learning the size difference. Drive it around for a while (crusing, no WOT) and check what the two alphas are doing.

chriscar

I still say you need to hold a tuning seminar at next years convention. Hell, how about a Web Meeting - you know I'll be there.