M35 Afm Troubles

[YangLIU]

The wire isn't the issue, the afm has an ecu inside it which fails. Could be low input voltage causing it, but I have seen a brand new Nissan afm blow the first time the car was booted, so it definitely isn't dirt or oil causing that fault. The hotwire isnt able to be touched in these really.

The original superseded OEM part number is the one to get, they last many years, it's the new Nissan part number that fails constantly. If only there was a batch of old stock laying around. Until then we are stuck trialling aftermarket afms till we find another good source.

everyone has to get spare one in glove box. my brand new genuine AFM lasts over 2 months, no full throttle during these months. so far so good. btw, i am using KN oil filter

Edited September 16, 2015 by YangLIU

[BoostdR]

My Nissan replacement/updated part number sensor is seeing max voltage quite a bit. Will see if it lasts longer than the Chinese one did. Will report back when or if it blows ;-)

[YangLIU]

My Nissan replacement/updated part number sensor is seeing max voltage quite a bit. Will see if it lasts longer than the Chinese one did. Will report back when or if it blows ;-)

What's the max voltage you got? ECU will cut fuel when AFM voltage is over 5.1v

And if you release your foot from acc pedal bit by bit, then you could see the min voltage is around 0.05v

[BoostdR]

5.11v but I have an emanage ultimate clamping it to 4.92v

[scotty nm35]

Depends which cell the ecu is in, it's not a set voltage it cuts at, I have seen it as low as 4.8v down lower in the map with smaller turbo's.

[BoostdR]

Yes, I have the clamp at 4.85 at 5500 and 4.92 at 6000. Seems to do the job

[scotty nm35]

The higher the better, as the gearbox line pressure is dropping with every .1v you clamp it down.

I hope you have the Transgo fitted.

[BoostdR]

I don't have the reprogram kit fitted yet. It currently changes pretty quickly as the voltage clamp at the shift point isn't clamped at all. letting it shift at a clamp point will certainly result in a longer shift as you have pointed out.

Edited September 17, 2015 by BoostdR

[BoostdR]

Ok so my 21A MAF crapped itself this morning. Lasted a few weeks longer then my last MAF. Have ordered the 'other' style Chinese unit. Will see how that goes. If that doesn't last I'll go to MAP&IAT with the EMU

Edited October 5, 2015 by BoostdR

[scotty nm35]

MAP tune still needs the AFM pass through for the gearbox, unless you can emulate an AFM signal using the emanage? You could even run another different AFM.

I ordered some AFM's from my old supplier if you want to try one Matt, before totally giving up on them.

[BoostdR]

I think the way the EMU works it replaces the MAF signal with a blended output from the MAP and IAT so the car shouldn't know any different. Problem is I need a working MAF to log the output vs load for a starting point for changing over. I'm getting warranty on my 21A MAF so that help but still a pain.

[BoostdR]

This is the other Chinese one I have on the way for testing.

[BoostdR]

Trying to guesstimate the MAF output vs MAP input from the logs. Should give a starting point.

I can't see why we can't use a 350z MAF with a conversion chart, would be as simple as using the 2nd MAF input and logging the voltage difference between them at all loads. Using this data to populate the Airflow output map.

[YangLIU]

MAP tune still needs the AFM pass through for the gearbox, unless you can emulate an AFM signal using the emanage? You could even run another different AFM.

I ordered some AFM's from my old supplier if you want to try one Matt, before totally giving up on them.

PM me the price please, i wanna grab one mate.

[conan7772]

Man what causes these things to fail ?

Not that mine has gone, but I'm expecting it will after a different turbo goes on.

Turbulence , erratic voltage ?

Are they supposed to blow to protect the engine ?

Have Nissan purposely designed them to limit modification possibilities to their cars after the Skyline Era..

I'm trying to get answers from tuners overseas.

[BoostdR]

Refer to this data at your own risk.

HDI cooler

Hypergear SS2

Full exhaust

OEM fuel system( does run lean in 3rd gear or above)

Boost approx 16psi

I'm now Running off the greddy map sensor which emulates the MAF. I cleared the error code from my faulty MAF and the car seems happy after a few hours of logging and road tuning with my O2 wideband. MAP is plugged into spare port in plenum and to option 1 socket on the EMU which you will need to enable in the software. Maps also should be changed to reference the MAP. I used relative pressure so I was working with actual gauge boost pressure.

I'm running partial E85 which will skew the figures but these settings have the car running quite ok. Well enough that I'll never to back to MAF. The response is great being MAP rather than MAF, no lag from accelerator pedal action to rpm change. I still need to setup acceleration enrichment and Intake temp compensation. The oem MAF is still sending the intake temp but the air density change is now not being compensated for. I would expect it to be off around 1.5-2% every 10degress still. So I'll update when I've set it all up. I'll chuck it on the dyno an do it properly.

Matt

This timing I found to work best with my Hypergear SS2. Gave a smidgen more useable boost from 2500-3000rpm. So it can keep up with normal traffic now when under 3000rpm

Edited October 6, 2015 by BoostdR

[scotty nm35]

Good, so you don't need much of a voltage input to emulate the AFM output to the stock ecu. Is there nothing the EMU won't do? Haha.

Man what causes these things to fail ?

Are they supposed to blow to protect the engine ?

Have Nissan purposely designed them to limit modification possibilities to their cars after the Skyline Era..

The original part number AFM's are still going in some cases, it's only the new part number Nissan sell that fails regularly. If I could find a stash of original AFM's they would be snapped up in no time. Until then the Chinese ones will have to do, unless you replace it with something else and tune for the differences. Ditching the AFM and running a MAP/IAT tune with AFM emulation like Matt just managed... Well that's even better.

[BoostdR]

What's even cooler Scotty is you can use the stock MAP sensor(up to its readable limit anyway). I just happened to have a 3 bar Greddy EMU sensor from my Starlet turbo build left over.

Some interesting findings using the MAP.

-Since I have a blend of E85 my MAF emulation voltages needed to be higher to get the right AFR's..as a result my shifts are now firmer. Another result looks to be that the gearbox now wants to be in 5th at anything over 50km/h... I'll take the firmer shifts thanks. When I adjust for my 1000cc injectors I think I'll over compensate so the AFM output voltage is skewed higher and then compensate with my pulse width correction.

I noticed the EMU doesn't want to output more than 5v however the OEM MAF will reach 5.11v. I could put a .10v positive offset on the MAF output line using a 10kOhmn potentiometer then take away .10v from the EMU MAF output map which would keep my AFR's correct but enable 5.10v output up top. Wish I knew if the shift time reduced/got firmer going from 5 to 5.11v.... Theoretically once I worked out the potentiometer set point(value/ohm) a simple resistor could used.

Edited October 6, 2015 by BoostdR

[scotty nm35]

Your dash is going to end up looking like mine.

[BoostdR]

Haha yep, why do I feel like I'm trying to crack open a safe ;-)