iansw

iTrader: (7)

So as many of you know I've been slacking on getting a Z32 MAF in to fix my lean condition up top.

I FINALLY got around to doing it.

Ben at JWT was pretty nice and shipped the new chip out the same day I ordered it. I just got it today.

So I removed the A32 MAF and installed the Z32 MAF. I've had the wiring done for some time, so that wasn't an issue. The Z32 MAF Harness is spliced off the A32 harness.

Anyway - Install the MAF, remove the old chip from the ECU, insert new chip.

Started the car and it was idling rough. Looked at the vacuum and it was at 15! (I'm usually 18-20).

I re-checked every vacuum line I have, even though I'd driven the car 30 minutes before and it was at 19 then and I hadn't touched a single vacuum hose during the install.

Everything checks out. Can't see any vacuum leaks anywhere.

So I took it for a drive. It's wet out, so it was hard to really get on it - but mainly I just wanted to make sure this thing works.

So now I've noticed I get hesitation under boost between 3-4k RPM on intermittent runs. (sometimes I feel it, sometimes I don't.) I checked the FP two of the times it did this and FP is steady and rising at that point. EGT's around 1100F and climbing steady. EGT's at 1350 @ Redline.

Not sure what's going on....anyone have any ideas? The ECU throws no codes and other than the low vacuum and hesitation at 3-4k, it pulls like a beast.

Thanks!
IanS

iansw

iTrader: (7)

no replies?

heh - that's surprising - I figured some of you would jump on this like a fat kid on a cake.

Prodeje79

Did JWT send the wrong chip originally?

I am not sure about the hestitation sorry.

Bernardd

Other than a bad maf, I'd say it's in the chip itself. Can you bump up the base fuel pressure to see it's going lean at 3-4k? Can you retard/advance the base timing to see that's what's effecting 3-4k range. Are you happy with the egt's or are they higher than before? Lower? Strange how the idle is being effected. Can you get the idle to clean up by change fp?

Quicksilver

iTrader: (1)

MAF or chip...it's the only change (or the wiring splice job)...

IceY2K1

iTrader: (3)

I vote wiring splice.....did you just tap the old MAF plug or did you do a CLEAN cut/splice/sodder connection?

slimer

iTrader: (13)

i have hesitation under partial throttle that i cant figure out, so this is a mystery to me.

iansw

iTrader: (7)

Well, I touched nothing else last night and went to bed. WHen I left it it was idling a little rough, but not too bad.

Started it this morning in a "cold start" configuration - and it BARELY Ran. No black smoke out of the exhaust, but it was acting justl ike it was the MAF.

JWT matched the number on my chip with the one they sent me - so I don't think it's the chip - the number on it is the exact same but with "Z" on it. there's no codes happening either for MAF or cylinder problems or anything.

So I fiddled with things a little by checking vaccuum lines and wiring and such - and then it started idling somewhat normal. However, vacuum is still at 15 instead of the usual 19-20 and twice on the way to work in stop and go traffic it stalled on me from the idle dropping too low.

The wires are tapped - I checked them with a voltmeter in the parking lot before work and they are all reading correctly. Airflow on the AFC shows 1.9-2.2% at idle and about 50% at WOT.

I still think I should fix the wiring this weekend - which I will.

This MAF also has been tested in a 300z - and it worked great even up to 15PSI. So I know the MAF is in good shape.

Now - after the 3-4k hesitation, at WOT, the car runs beautifully. Pulls great.

What's that saying? something about open/closed loop maybe?

Thanks for the help dudes.

Stephen Max

iTrader: (59)

The vacuum loss is bizarre. The only thing that could explain that is a leak. Is your idle speed the same as before? A lower idle speed can result in lower vacuum.

As far as the stumble is concerned, I get an ever so slight stumble at 3 krpm if I depress the accelerator to about a 45% throttle position. I think that is where the ecu transitions from closed loop to open loop.

iansw

iTrader: (7)

THe strange thing is that before I did this, the vacuum was 19 and steady daily pretty much.

I didn't touch any vacuum lines at all during the install.

Just to be sure, I went ahead and checked every vacuum line anywhere near the SC Piping and couldn't find anything amiss at all. Also checked the throttle body and connectors on the SC Piping (although this wouldn't cause low vacuum, it's before the TB).

Just to be sure I'll break out the soap and water mix and start spraying when I get some time. Idle after accelleration drops to about 300 then goes up to 600....sometimes it dies when this happens. Idle before was 650 and steady.

The more and more I consider it, I'm thinking it may be the wiring throwing off timing and causing the vacuum to read low.

IceY2K1

iTrader: (3)

You've got to re-wire the MAF plug...the right way, ie no tapping.

I have no idea how/why the vacuum would change due to a MAF as long as RPM are the same like SM said.

iansw

iTrader: (7)

I went out during lunch and spent some time with her.

I tested the voltage to the MAF - it is dead on. SAFC reads 1.9% Afl at idle. I know the wiring isn't perfect, and I will be fixing it, but it's definately got a solid connection. I even grabbed the wires while my co-worker watched the voltage and moved them around. Readings did not change.

So while I understand I need to fix the wiring, I don't believe that to be the major problem.

This was the 2nd time I've cold-started it today. and both times vacuum drops to 10Hg and car will not run unless I push the throttle. After 2-3 minutes of this, the car settles to 16-17HG vacuum and idles rough, but runs well. RPMs jumping between 600-650RPM. If I let it sit for say 10 minutes, it will finally die.

However - with the MAF unplugged the car idles just as rough, but won't rev above 2500RPM.
With the MAF plugged in it revs until redline without issue. Proving further the MAF is working.

So it has to be a problem with the mapping on the chip I think. Under cold-start mode it's just screwed up. And under normal conditions it's not as screwed up, but still off.

IanS

Jeff92se

iTrader: (82)

Did you ever get ahold of the Auterra obdII scanner that can monitor your a/f / ign timing etc???? I thought at least one of you nw 4-gen+ / I30 guys would have this by now.

iansw

iTrader: (7)

I called JWT - they tell me it hsould work fine and I need to pay a Nissan Dealer to print out the Consult data on both a cold start and a warm start.

That costs $80.00 around here.

Jeff92se

iTrader: (82)

Auterra might be able to data log at least some of that info. I give up

iansw

iTrader: (7)

New theory:

Maybe the problem is that I do have a small vacuum leak somewhere and the Z32 MAF is simply far more sensitive than the A32?

Bernardd

If the maf voltage doesn't change the when wiggling the wires that's not the problem. If the ecu goes into limp mode when the maf is disconnected and then out of limp mode that proves, to me at least that's not it. It could still be a vacuum leak. Or if the tune is off the plugs could tell the story. What do they look like?

iansw

iTrader: (7)

OK - some weird things.

My trip home from work:
1) Get into car - it's been sitting for 6 hours or so.
2) Start car - car barely runs, vacuum drops to 10Hg and I have to keep feathering the throttle to keep it idling.
3) Start moving - car bucks HARD over and over again. Stop moving.
4) Wait 1 minute - idle levels out some and vacuum goes to about 15-16Hg.
5) Drive away. Car hesitates once on accelleration, but then it's fine until I hit the freeway.

6) Get on freeway - watching Afl on SAFC. Car hesitates every now and then while cruising from 2500-3000RPM the whole way. AFC shows normal readings, BUT everytime the car bogs the Afl drops 1/2%, then jumps 1%, then drops 1/2% back to where it was.

7) Get off freeway - hit stoplight - car bucks horribly but then levels out and I'm on my way.
8) 2 miles later, another stoplight - car won't stop bucking and is not moving at all.

9)Turn on hazards - pop hood - jiggle wires - restart car. Runs with rough idle but doesn't buk more than once the rest of the way home.

10) Get home, put A32 MAF in (with Z32 Chip still in) - car runs FINE. Seems to bog after 5000RPM but I didn't want to go much higher with that configuration, so I mellowed out back to the garage. Idle is still a little off, but it's not nearly as bad as before.

Well - looks like it's the wiring and/or the MAF. MAF worked fine a few weeks ago in my buddy's Z - so I'm guessing wiring.

Questions:
1) If it's the wiring, why is the AFC always showing voltage? Why no CEL?
2) Why is it far far worse on cold starts?
3) Why does the A32 MAF work fine, and what happens at high RPM with this configuration?

4) Why does god hate me?

Mad-MAX_SE

iTrader: (2)

only answer i have to those questions is to number 4. he doesn't hate you, but he loves testing you... tribulations are what give life meaning, they allow you to move past them by learning to deal with the problem at hand and be better able to handle the next obstacle.

Prodeje79

Man I gotta think that JWT chip is not programmed right. This is the second one they sent you though too?

IceY2K1

iTrader: (3)

Take the plunge...CUT OFF THE OLD A32 MAF PLUG...and splice/sodder on the Z32 plug.

I've had a MAF plug/harness that was causing a rough idle. After I added a new ground wire per SR20.net tip, it helped smooth it out. You could even measure the difference with a multimeter something like 13mV before to 6mV after.

My theory is that your splice(read hack) job isn't 100% and that your ECU is compensating with IACV air which is causing the vacuum variations.

Redo the MAF wiring to eliminate that as a possibility AT LEAST. You can always put back on the A32 plug if needed.

Stephen Max

iTrader: (59)

Nothing in the chip could lower manifold vacuum except a change in IACV parameters. For instance a change in idle rpm could reduce manifold vacuum. But I doubt very highly that JWT would monkey around with that. Maybe you should call JWT and ask them, Ian.

The driving symptoms Ian describes also indicates leanness that could be due to a vacuum leak. The vacuum leak has to be found and rectified before any conclusions can be made about the chip.

Edit: What Icey says makes sense, too.

iansw

iTrader: (7)

Well - here's what I think:

1) It's the wiring - I WILL be hacking the A32 plug off this weekend and putting the Z32 back in.

2) The Chip is programmed right. The A32 MAF works down low, but it has issues up high. With the A32 Chip and A32 MAF in, the car runs flawlessly. One thing I left out is that the vacuum is still low (15-16Hg) with the A32 MAF I discovered last night - so I do have a very slight vacuum leak somewhere. I don't believe this is causing leanness up top however - I think it's the Z32 Chip and the A32 MAF together. If the Z32 MAF was working properly (again - now I'm 80% sure it's the wiring) then I think it wouldn't do this, since at high RPM with the Z32 the car pulls awesome. It's just low to mid-range and cold start the it's having issues. Most likely because of resistance in the line - at low voltage it has issues, at higher voltage (high RPM) it overcomes this with a stronger signal.

So basically - the chip I think is OK, I have a slight vacuum leak, and the wiring is the main culprit. I think that while there's a constant connection with the wiring, (Afl isn't dropping to 0 randomly) the signal is getting resistance going through those taps of .01v occasionally, causing the Afl to drop 1/2-1% and the car to hesitate.

On cold start, doesn't the MAF send a preset signal while the wire heats up? Maybe that signal is foobared, causing the cold start issue?

Let me know if you guys think my thinking is flawed in any way.

And thanks again for the help guys.

Icey - what's the ground wire fix? I have the ground from the Tomei connector going straight to a nearby engine bolt.

IceY2K1

iTrader: (3)

That was for a different car, my Sentra, I wouldn't worry about that in this case since we know what the problem is most likely. Just an example that a poor ground wire can cause the MAF to screw with the ECU and have a hunting idle, stalling, even slight detonation on light throttle. I'm not saying it cured all this, but it seemed to help and definitely showed a difference on my multimeter.

iansw

iTrader: (7)

Cool.

So I take it you fully agree with my hypothesis above.....

IceY2K1

iTrader: (3)

Everything but the "MAF send preset signal" part. I don't think that's true.

I agree a small amount of 'noise' in the MAF wire at idle would be more significant, then once there are large volumes of air moving.

iansw

iTrader: (7)

Yep - I re-thought the "MAF sent preset signal" also after looking at the FSM.

I hope the cold start issue isn't a totally seperate problem....that would suck.

But since putting the A32 MAF in solved that (she started fine this morning) - I don't think it's a seperate issue.

Quicksilver

iTrader: (1)

Remember when Bags had almost the exact same issues last year/earlier this year? It's b/c the wiring to the MAF was bad, even though he was reading proper voltage. Talk to Bags and BigDogJonX...they solved the problem. You are basically describing an exact duplicate of his ex-problem...

iansw

iTrader: (7)

So right now I'm running the JWT Z32 Chip off the A32 MAF.

Would this cause leanness or richness? the car bogs at mid-high and high RPM - but EGT's look fairly low....

So I'm thinking the higher voltage A32 MAF output is causing the readings to run rich.

IanS

IceY2K1

iTrader: (3)

Rich...the Z32 program is expecting less voltage from a Z32 MAF, but the A32 MAF is "fooling" the ECU into thinking more air is passing through with a higher output voltage.

iansw

iTrader: (7)

Cool - I was right.

Well, rich is safer than lean....so I'm happy for that.

EGT's are pretty low (1000F when crusiing on the freeway instead of the normal 1150-1200) so that's good.

Can't wait to fix this and get the full power out of the car finally.

Bags

iTrader: (3)

Ian- my issue was the white and black wires from the ECU were shorted to the shielding surrounding them.

It was hard to track, it was lots of wire bending, but I ran 2 NEW wires outside the car and spliced them in just to see what happened.

Problem solved.

If it helps, I found the short was at the bend right off the block. The main harness coming across the center of engine and coming off the engine right next to the crankcase hose near the diver side of the motor.

If you need any more info let me know.. I can take pics as well

iansw

iTrader: (7)

Thanks man.

I'm thinking my short, if I have one, has to be at the wire taps or somewhere after the A32 Harness, since the A32 works fine. Sounds like a very similar issue however. Thanks for the confirmation.

I got a hold of an NProbe and took some data under load in xls format if anyone wants to see it, let me know.

I took it as my baseline so I can compare the voltage rise and fall rates relavant to time (ie: see if there's sudden voltage changes) comparatively with the Z32 MAF on Sunday.

Nealoc187

iTrader: (23)

On cold start, when the engine is stumbling all over itself and trying to stall unless you keep your foot on the gas, have you tried revving it up to abtou 3000rpm for a second and then letting off? When I start my car under cold start conditions it does the same thing you are describing, wants to stall, but a quick rev to 3000 cures the problem entirely, and will idle down just as a normal car would. I'm using Z32 MAF with 370cc injectors and a stock ECU with emanage. My car has no emissions equipment (EVAP, EGR, O2 sensor) and is in limp mode constantly I believe, but after I manage to get it started (which is very difficult when its below abotu 35 degrees out) the idle behaves as described above.

iansw

iTrader: (7)

I don't usually don't dare rev the SC above 2500 when it's cold out without being fully warmed up first.

I guess I could try it, although I'm so sure now that the problem is solved (hoping I don't eat my words) that I'm just going to try re-wiring first thing on Sunday.

(The wife has me all day today)

Nealoc187

iTrader: (23)

Yes I understand, I too don't really like revving right off the start, but I think that if you give it a good 10 or 15 seconds to get the oil circulating throughout the engine, and then just blip it up quickly it would probably cause no harm. You're not putting any real load on the engine. Might be something to try if your rewiring doesnt solve it.

iansw

iTrader: (7)

Average temp in Seattle is about 45-50....

But hell - why not - I'll give it a shot.

iansw

iTrader: (7)

Thanks again Bags...




<edited by Bags>

iansw

iTrader: (7)

OK - so I soldered the connections together this morning, verifying the wiring against JWT's diagram for the Z32 MAF:
A = Not used
B= 0-.5v signal
C=Ground
D=Ground
E=12v

Tested with a voltmeter before doing anything. Everything is right (I haven't changed it since I hooked it up to pass emmissions anyway - but I am being safe)

Soldered all the joints together - moved the ground #1 to the battery directly. Tested the resistance on the grounds

To battery=.002mv
to ECU=.009mv

So that looked good.

Put the Z32 MAF back in, started her up with the Nprobe plugged in. voltage from the Z32 is about equal at any RPM compred to the A32 MAF and the car runs like azz. Timing with the A32 MAF in at idle is 15 and steady. Timing with the Z32 in is 25 and jmping wildly on occasison down to 7 and up to 30 - more down than up.

So I ran some more tests:

Unplugged the piping on the SC end to eliminate any "turblulence" from the SC - car still idled just as bad.

Put the A32 JWT Chip back in and the Z32 MAF stayed on - car ran smoother, but not great...timing still at 25 at idle.

Put the stock ECU in with the SC still unplugged and Z32 MAF on. (this is how I passed emmissions) Car runs fine. Timing is slightly jumpy, but in a much narrower range (idles around 11-15 - jumping back and forth.)

So that proves my wiring is good and the MAF is good because the car runs fairly well with the stock ECU.

With the A32 MAF and Z32 ECU - the car idles perfect at 15 degrees timing.

I'm banging my head up against the wall here.....wtf is going on!?!?

Bags

iTrader: (3)

I'd think the Program for the Z32 maf is AFU.

It "seems" to be the only variable that you can't check.

With the Stock ECU and z32 MAF everything runs fine and with the Z32 ECU and Z32 MAF is does not, seems to me that the Prom for the Z32 MAF sucks.