Standard S14 SR20DET MAF

S14200sx · Post by **S14200sx** » Sat Jun 21, 2008 5:25 pm

I don't understand.According to the list my MAF should only support 280hp but my car is making 370 hp and i do not have a problem yet.Is there something wrong with my MAF? or maybe another problem?

300sx · Post by **300sx** » Sat Jun 21, 2008 5:46 pm

dont take the following the wrong way , but perhaps your car doesnt quite put out 370bhp? i mean ,bearing in mind that many dyno's give out overly optemistic readings.. especially if the paticular dyno operator has done the mods in question ..

lots of crooked operators in this country..

else, have you ever checked if the maf maxes out at full load? meaning does the voltage it returns stay at max while running at full boost for a few seconds? if so, it might be maxing , and you might be running lean at full load..

what mods have been done to your car?

Doctor G · Post by **Doctor G** » Sat Jun 21, 2008 6:10 pm

the figures are given as hp at the wheels. So are you making (370hp) 276kw at the wheels??

According to that data that maf should be good up to +/-208wkw.

Doctor G · Post by **Doctor G** » Sat Jun 21, 2008 6:19 pm

Oh and this is in the wrong section. This is the Classifieds.

Pinkfluffybunnys · Post by **Pinkfluffybunnys** » Sun Jun 22, 2008 6:02 pm

Are you using any type or method of altering you mangment? Like Uni-chip

S14200sx · Post by **S14200sx** » Mon Jun 23, 2008 11:32 am

I had the car at 2 different dyno's and both of them gave a reading of around 275kw at the flywheel neither of them had anything to gain from the reading so i assume that they were correct. I am using a uniQ and have a breakup of spark at around 4500rpm and again at 6500rpm i have replaced the coils and had the same problem so my next step will be to check the ignitor chip.What are the symptoms of an AFM maxing out?

Pinkfluffybunnys · Post by **Pinkfluffybunnys** » Mon Jun 23, 2008 12:29 pm

I can’t find the wiring in diagrams of the “unichip” but if the intercept the voltage returned from the AFM they could stop the AFM from returning a 5.1 volt value to the ECU and forcing boost cut.
The Stock ECU uses the value returned from the AFM along with TPS to get a TP value so the car can work out how hard you are jumping on the throttle if you intercept the Signal you can technically keep the car in the last column of the full map like just returning 4.9 volts to the ECU then just richen up the graph by increasing the Millisecond pulsewidth (This is just a theory however)

The same type of method is used with an Apexi S-AFC/HKS fuel cur defender and on extreme “hillbilly” set-ups when a pot resister is placed between the voltage return and the Voltage is pulled back to below boost cut and the mixture increase is done with a FPR

Everything I have been able to get my hands on is that the s13/S14/S15 SR20AFM is good for 290 HP boost cut can be removed on the stock ECU but it’s not recommended

Doctor G · Post by **Doctor G** » Mon Jun 23, 2008 12:35 pm

S14200sx wrote:I had the car at 2 different dyno's and both of them gave a reading of around 275kw at the flywheel neither of them had anything to gain from the reading so i assume that they were correct. I am using a uniQ and have a breakup of spark at around 4500rpm and again at 6500rpm i have replaced the coils and had the same problem so my next step will be to check the ignitor chip.What are the symptoms of an AFM maxing out?

Okay if they gave you a flywheel reading then it was most likely a coastal figure too. So working it back with about 10% loss for altitude seeing that it's a turbo car, and a further 22%-30% for drivetrain losses (RWD) I'd say you are making roughly between 190 and 200kw to the wheels. So you're pretty close to maxing out your std s14 MAF I'd say. It's probably a good idea to upgrade it to a N60 or N62 maf.

As for your spark breakdown problem it can obviously be a variety of things. What spark plugs are you using? It could be something as simple as the plug gap, or it couldbe that you're not runnig a Resistor type plug or vice versa.
It is also possible that you need to change to a hotter or colder plug.

If you run the car again on a dyno or if you have access to a wideband then check your Air/Fuel ratio's at higher rpm especially. If it's leaning out and you are finding that you need to adjust for a lot more fuel then your maf is being maxed. Or if you have datalogging check what your maf voltages at high rpm are. Ifyou start seeing a constant 5.0v at higher rev then the maf is maxed out.

S14200sx · Post by **S14200sx** » Mon Jun 23, 2008 7:46 pm

ok thanks for the reply's i will let you know if i get it sorted out.