binder

iTrader: (8)

it will be low with ported heads and cams. Mine is between -13/-14mmhg which is about -6.5/-7 psi

ported heads and cams

djamps

iTrader: (1)

Stock erry-tang

MR RIZK

iTrader: (7)

Update.. after numerous scenarios and tests last night I think i may of made some progress. Last night the car through code P0102 Mass or Volume Flow Circuit Low Input. When this happened the car was hard to start. Thinking it was related to the numerous tests I cleared the code and continued what I was doing. Later on the code appeared and again the car was difficult to start. To the point I had to clutch start it. Drove the car home and parked it.

I think the stock ecu still uses the MAF as the Haltech ecu has an option not to “intercept” the MAF but to reference the MAF Output table. I configured the ECU to reference the table which disables pass-through then I set the idle cells to 15 degrees ignition. Started the car and let it go through the warm cycle. Once it came close to operating temp the car tried to target 650 rpm idle but it couldn’t which is expected. I raised the idle with the cipher to 850rpm and the rpm stabilised and never went to 1000rpm.

According to the manual it states that MAF volts at idle should be around 1.1v however the cipher is reporting the maf at 0.5v. If I set the haltech back to MAF output table I can see in the cipher that the voltage is 1.2v which is correct since the haltech is sending raw values based on the output table.

I cleaned the MAF with MAF cleaner, cleaned the earth points but no joy so I will have to get my hands on another one to test. Checking courtesy parts OMFG $450 bucks for a MAF. I know some mistake the Nissan for a Porsche but I don’t want to pay Porsche prices.

Anyway I’m happy to run without the MAF but I don’t think I will be able to tune out the return throttle from stalling. I have tweaked ignition timing and fuel so that standing return throttle holds correctly but as soon as I drive the car and stop I cannot catch the return. Anyone successfully removed the MAF from the Z with haltech that can provide comments?

PS: a failing maf could be the reason i could not idle with just the stock ecu also.

Michael

binder

iTrader: (8)

sounds like you are onto something.

try to find a junkyard like i suggested. I'm not sure how easily parts can be found down there. if you were here in the states it would be easy to find a used one.

The staling could be from a light flywheel if you have it. I had to get up past 900 rpm for my car not to stall out like that on my built engine. It didn't do it on my stock block.

djamps

iTrader: (1)

I got a OEM MAF if you need one.

MR RIZK

iTrader: (7)

thx djamps.. will do a quick hunt locally first and see how it goes..

I really hope this is the issue.

Jeff the nismo twin does have a lighter flywheel but I don't believe by much. When you say u needed to raise over 900 is that running with a MAF or without?

ddc665350ztt

check amazon. the reason its so expensive at the dealer is that they sell it with the whole housing too. i had just bought one online on amazon for around 230. just the maf itself.

MR RIZK

iTrader: (7)

Bad news

Replaced the sensor and same issue. Reads the same voltages as before. I tested the maf harness to the ecm as per manual and seems to be okay. I have also confirmed the voltages from the signal wire at the maf and they match what is being sent to the ecu.

If i remove the pipe work pre maf and restrict air flow I can see idle drop (expected less air) and I also see the maf voltage rise to approx where it should be.

Stupid question is it possible that my engine is sucking to much air? I know it sounds stupid but ideas are getting thin and the smoke test elimiated the leaks.

My only other viable option is to tune with the maf output table but having a hard time getting this not to stall when driving regardless of rpm set with the cipher. ie: maf eliminated

str8dum1

iTrader: (11)

if the car runs fine besides the high idle, why such a big concern?

have you tried artificially lowering or raising your APP/ TPS settings to make the car think that the gas pedal/ TB is in a different spot?

MR RIZK

iTrader: (7)

The concern is that if the ecu throws P0102 code then it will go into limp mode. Also i have noticed if it does throw this code then the car becomes very hard to start. There is a high chance of this happening due to the low voltage that is being seen.

I have tried raising the values but have seen no postive improvment. keep in mind that i dont think the haltech feedbacks the tps/app values to the oem ecu. they are only read values for haltechs calculations. If it provided feedback then in theory the haltech would have DBW control.

Currently on idle the haltech shows 0% TPS

rcdash

iTrader: (18)

So I believe the MAF works by sending voltage to a heating element which is cooled by the incoming air. The more voltage it has to send to maintain a specific temperature indicates the mass air flow. If you are reading an abnormally low voltage, then for some reason the MAF is getting very little air (not too much air), so very little voltage is being supplied OR the sensor temp reading is cooler than it should be for whatever reason (obviously its not broken if another sensor does the same thing). There is also an ambient temp sensor in the MAF also and I am not sure if the stock ECU needs to see that temp signal to process the MAF voltage it supplies. Are you passing the temp sensor data along to the stock ECU? I have an FCON air temp sensor in the plenum and I spliced that into the MAF air temp sensor wiring and it seems to work well (calibration curve nearly identical to stock MAF temp sensor curve).

Just to clarify, you can set the car with the Haltech generating MAF output voltages and everything works fine, correct? Why not just do that and remove the MAF?

djamps

iTrader: (1)

Maybe the haltech is screwing up the MAF voltage? Have you measured it at both the input to the haltech and also the ECU to make sure they are both the same? When you said you restricted the flow and the voltage went up, that makes no sense... it should go up as flow _increases_. The lowest voltage you will see is when the engine is off. Idle will always be higher than that.

binder

iTrader: (8)

The reason the haltech sees 0% only because there is a user defined voltage in the main setup. That's the tps/app when you do the "calibrate" and it shows voltages. Those are the tables i posted and you posted back.

The haltech only sees that voltage and says "you said .79 volts is zero so it has to be zero". I'm almost 99% certain that the APP is what haltech uses to figure out if you are pushing on the pedal or not which is why i thought the app voltage you showed being lower than the tps would be an issue. By doing the adjustments you have kind of ruled it out though.

What i want to know is why it worked when you swapped the TB but then didn't do a relearn or update the settings in haltech. That's odd but it seems to work so maybe swap it again and don't change any settings? lol....worth a shot 1 more time.

I do not tune by maf with haltech. I tune VE (internal map) but i still have the maf enabled for IAT's.

MR RIZK

iTrader: (7)

Raj the FSM implies this also but the odd thing is if i block the air in the intake tube the voltage goes up on the maf. If i blow in the intake tube when car is running i see the voltage drop. Actually maybe what is happening is that when i reduce he intake size the air velocity is faster hence the higher reading

Just to clarify. I'm happy to remove the MAF as the car is tuned with VE and MAP sensor. The only reason I didn't want to get rid of the MAF is i'm having a hard time tuning out the return throttle when driving ie: it stalls coming to stop at the lights consistently. However stand still free rev is fine.

I removed the haltech and checked the maf voltages which read the same with the oem ecu. this should eliminate the haltech from being the issue with the MAF

Jeff i tried swapping out TB's the other night trying to simulate what happended before but cannot reproduce it again

rcdash

iTrader: (18)

So stalling is the primary issue that precludes removal of the MAF. Do you have a Haltech data log of timing, AFR, TPS, APP when that happens? Are you using copy through timing under vacuum?

MR RIZK

iTrader: (7)

I will get a data log. Keep in mind though if you switch the Haltech to use the Maf output table you cannot use copy through.

MR RIZK

iTrader: (7)

YAY the issue is fixed. Idles at 850rpm with idle bump.

First of all i would like to thank all that have contributed in resolving this issue. I was so angry last night and wife made me leave the car alone. "just leave it and the solution will come to you" she kept saying. Anyway I stopped working on it and left it.

All last night i'm thinking what Raj and djamps were saying. What was going through my mind was that i know the harness and voltages are checking out but what the hell could be reducing the air flow. Thinking i may of left a rag in one of the pipes but this was ruled out when I was running with only the intake pipe and no IC hooked up. Then suddenly i thought it can't be. Ran out to the garage in my undies and f$uck me the MAF sensor tube was the wrong way around. I feel like an absolute f'in idiot.

I hope the thread is of use to others that need to troubleshoot similar issues and how to check different aspects. We also found out reversing the MAF is an easy way to idle at 1000 rpm

rcdash

iTrader: (18)

LOL. Yep the tube orientation per se doesn't really matter but the MAF sensor must face the correct way and of course it only fits one way in the tube. Congrats.

I haven't tried this myself so I was hoping you can clarify what you mean by you cannot use copy through timing if you enable the MAF output table? What does copy through timing have to do with NOT copying through the MAF?

MR RIZK

iTrader: (7)

yes the sensor goes only one way into the tube but i have an adapter on the pipe which was part of the hks kit which allows the tube to sit in either direction. So maf was installed correctly but tube wrong way around.

If you go into the haltech Main Configuration > inputs outputs tab > Mass Air Flow Settings

Once you set it to "MAF Output Table" then the "Copy through settings" are highlighted in RED meaning it is not set correctly. See image below

failsafe306

iTrader: (38)

Congrats!