How Much Would You Charge Me For a EPROM To Gid Rid Of Boost Cut?

[T88lexus]

always wacth your AF is key to eveyrthing beisdes timming.

wideband is your freind..

doing back to back tunning session as on street tunning, dyno tunning is little different. you get good reading off from dyno, that does not mean that car will run the same AF on street. always consider intake temp, outside temp, ect. you will find more cool stuff.

tune it property. drive it hard.

[slw240sx]

thats the plan! we are goin to motonitor the AFs, exhaust temps, and timing. i really really need to get a datalogger unit built . im not shooting for alot of power daily but i would like to get 400+ out of it on ocasion.

[Notchbackca]

slw240sxI don't know if you realize this, but in order to make over ~200hp you HAVE TO REMOVE boost cut, even with a 300zx maf, its still in the same place, which is about 9lbs of boost

[WeldingHank]

i don't see that at being possible. the Z32 MAF puts out a much lower voltage at 9lbs compared to the CA18 MAF's voltage at 9lbs.

[slw240sx]

ca18det maf maxes out around 200hp, 300zx reached 5vlts around 500hp which is when it maxes out.

i was hitting fuel cuts on a z32 maf at 7-13psi. but i was also blowing so much black smoke i could have blacked out NYC. so i think i had some problems causing my fuel cut like no piston rings, and a bad leak somewhere. my BB turbo crapped out so i messed up somthing bad.possibly over spinng the thing from a bad boost leak

[Notchbackca]

i don't see that at being possible. the Z32 MAF puts out a much lower voltage at 9lbs compared to the CA18 MAF's voltage at 9lbs.

it doesn't matter what the voltage is, boost cut is determined by AIRFLOW not voltage

[WeldingHank]

it doesn't matter what the voltage is, boost cut is determined by AIRFLOW not voltage

Hotwire MAF - The principles behind a hotwire MAF are very simple, and also very consistent, which makes it one of the better ways to count air. Basically, there is a single wire that passes through the middle of the MAF, which is nothing more than a pipe with an airfoil in the middle of it to support the wire. That wire is heated to a certain temperature, which is verified by some thermistors (temperature sensitive resistors) attached to auxiliary wires.

An analog circuit measures how much current is required to sustain the desired temperature, and as the number of air molecules coming through the meter increases, so does heat transfer, and the necessary current to keep the wire warm increases. This change is directly proportional to the number of molecules passing through the MAF, or the mass-flow of the intake charge.

Because of the way the meter works, there is no need for secondary pressure or temperature sensors, since pressure and temperature changes re compensated for by the primary measurement system.

Hotwire MAF's are very free-flowing, allowing more air with less restriction than anything besides speed density systems. They automatically compensate for ANY and all changes to the vehicle and any changes to the air coming into the car.

as you can see, voltage is dirrectly affected by airflow. . a smaller MAFs voltage will max out quicker than a larger one. at 9lbs the CA18 maf may show 5 volts, but the Z32 may only show 1 volt (i don't know the output of a Z32 maf on hand) the CA18 ECU is none the wiser, which is why you need an SAFC to accout for the extra air.

[Notchbackca]

DUDE, BOOST CUT IS DETERMINED BY THE CALCULATED AIRFLOW VALUE, AND IS INDEPENDANT OF WHAT MAF YOU ARE USING, FUEL CUT IS DETERMINED BY THE MAF VOLTAGE MAXING OUT, HOW MANY TIMES DO I HAVE TO SAY IT???

boost cut will occur long before the maf maxes out, and you can't remove fuel cut by programing, you need to add circuitry

[biosehnsucht]

If the TTP_MAX (IIRC it's called in romedit) table is as you claim based on the airflow value determined from the MAF table, as opposed to the MAF voltage itself (likely since changing MAFs doesn't require more than changing MAF table when they make design changes), then it would seem likely you'd have to max that out.

now when you say add circuitry for fuel cut, are you meaning the MAF limit cut where the ECU can no longer determine airflow and therefore it just cuts fuel? In that case by circuitry I assume you mean gizmos like the FCD? If so yes, that's true. Altho really, shouldn't matter - getting a CA ECU reprogrammed for a larger MAF and changing MAFs is far too easy to go chasing after such expensive, dangerous gizmos.

[WeldingHank]

DUDE, BOOST CUT IS DETERMINED BY THE CALCULATED AIRFLOW VALUE, AND IS INDEPENDANT OF WHAT MAF YOU ARE USING, FUEL CUT IS DETERMINED BY THE MAF VOLTAGE MAXING OUT, HOW MANY TIMES DO I HAVE TO SAY IT???

boost cut will occur long before the maf maxes out, and you can't remove fuel cut by programing, you need to add circuitry

you have yet to give any factual information backing up your claims. Just because you say it, doesn't mean I will believe it.

[Notchbackca]

you have yet to give any factual information backing up your claims. Just because you say it, doesn't mean I will believe it.

don't just assume that boost cut is anything like fuel cut

boost limit 3690h-369Fh now why would boost limit have that many hex values, each one being a different RPM range, if it was simply voltage comparator that cut fuel when it saw 5v

there is your proof, have you programed your ecu lately?

[biosehnsucht]

Obviously it covers RPM ranges, but that doesn't mean on its own that it is VQ Map referenced vs Voltage referenced, nor does it mean the opposite necessarily. It would take actual testing (or reversing the ECU code, I think I'll say testing is easier) to determine which it is.

[Notchbackca]

if you did a little research you'd already know what boost cut is, how to fix it, and what causes it

[Projex240]

whew!!

Heated!

[Notchbackca]

if you boost to 10lbs with the stock maf, you will hit boost cut

if you reprogram the ecu for 300zx maf and use that instead, you will hit boost cut in the exact same place as you did before

I know, I've done it

[slw240sx]

i recall talking with jez,and paul about certain values in teh ECU you have to reset to get rid of it, but can you simply raise it so its still there?? i havnt really read up on it in like a year and ive forgotten alot of what i learned

if you boost to 10lbs with the stock maf, you will hit boost cut

if you reprogram the ecu for 300zx maf and use that instead, you will hit boost cut in the exact same place as you did before

I know, I've done it

[Notchbackca]

yeah, with the stock ecu you can just make it really high... its still there

[WeldingHank]

finally got a boost gauge on my hooptie. I am hitting 12 psi steady! on an KAE MAF (also have an SAFC.) hitting 75.7% air-flow.

[Notchbackca]

(also have an SAFC.)

...

[WeldingHank]

...

i thought i would hit boost cut at 10 psi no matter what?