sparks03max

iTrader: (7)

So Aaron and I have been talking, and we have been having the exact same problem with our UTECs.

Any time the UTEC itself is cold (45 degrees or less), we get a random/occasional misfire that is just like pulling a coil plug then plugging it back in. This only happens at partial throttle and idle, haven't had it happen at WOT. As soon as the cabin of the car heats up (the UTEC gets warm), it stops completely and never comes back. Obviously, this problem doesn't happen whatsoever when it's above 50 degrees.

I'd like to hear from other UTEC guys. Include how you have your UTEC installed and whether you notice anything similar.

Please don't clutter this thread with random opinions and comments if you don't have anything constructive to add.

maxgtr2000

iTrader: (29)

You will get more replies on my350z.com, try the forced induction forums. That engine management is more common there.

choiiiiiiiiiii

iTrader: (20)

mine happens when im pas 5.5k regardless if its cold or not....gonna wait till i get a legit tune to see if it is the utec at fault..

NiZMo1o1

iTrader: (45)

are you guys running a turboxs map sensor ?

sparks03max

iTrader: (7)

Why would we run a MAP sensor N/A? You can't get proper resolution for tuning that way. There are tons of threads on my350z that reinforce my opinion, if you want to dispute.


The reason I didn't post this on my350z is because they have a different ECU than us and do not have the same problems as us, it's as simple as that.

sparks03max

iTrader: (7)

That is surely a tuning issue. What we are experiencing is ONLY when the UTEC is cold, not at certain RPMs, and certainly not at WOT (ever).

viperboy

iTrader: (7)

I don't have UTEC but I notice the exact same thing when it's really cold out with a VAFC. This probably doesn't help your thread, but maybe it does. Sometimes my SES light will flash and that it just randomly stops.

NiZMo1o1

iTrader: (45)

dude chill the f out , I ask a simple question , most standalones use a map sensor or barmetric sensor , differnt climate changes so your A/F will change accordling in y our parameters.

if you want to sit here and dispute , I can have my Standalone tech guy dispute with you all day on a fourm on on a phone call , im not here to go back and fourth with anyone.

I was merely asking a question as my tech guy that tunes ask the same question , weather your N/A or F/I.

I have ZERO issue on what your describing , but I guess your a bit on the touche side for my opinion.

Good luck

MoncefA33

iTrader: (6)

+1 to NizMo.

The MAP/Baro could screw up cold operation if the signal isn't read properly. Maybe the TXS MAP sensor is a solution.

My buddy's stock RX8 had a bad MAP/Baro sensor and the first sub-45* day we had it would not start. Just cranked. Even though the car uses a MAF reference system.

Gemner

iTrader: (4)

the UTEC uses temperature compensation info from the IAT and since its MAF, the baro reading wouldnt mean anything. However, it sounds like theyre describing issues which are present when the UTEC is not altering signals, cause he said not WOT

Aaron92SE

iTrader: (128)

What sparks described in the OP is EXACTLY what my car does. I do not have my UTEC hardwired in though like he does. I am using a custom plug and play harness.

The colder the ambient temp gets, the worse and more frequent my misfires are. My misfires start to happen when the temp is below 60 degrees. This evening, I drove my car to the gas station real quick to fuel up for a meet tomorrow. It was 33 degrees outside. The coldest I've ever driven my car since getting the VQ35 engine and UTEC in my 92 Maxima. It was TERRIBLE. It not only happened more frequently, but it seemed to cut more cylinders at a time resulting in more of a stumble. The misfire only seems to happen during closed loop operation or whenever the UTEC does not take over (ie >70% throttle position). So the idle stumbles as well as very light partial throttle and cruising speeds (ie 55mph).

I talked to Jime via PM and he said he does not get any kind of misfire ever. Even when it's extremely cold up in Canada. His UTEC setup is hardwired. He should have used the exact same wires as you have Sparks.

I'm not. I believe I'm using the same or similar settings as sparks. Open Fuel MAF.

That could be useful since the misfire issue may not be a UTEC problem, but a wiring problem. My PNP harness is connected exactly like it would be from the factory. What I mean by that is that OEM ECU harness connectors were used along with the proper terminals that snap into place.

I believe Sparks setup is hardwired, but everything is soldered properly.

Yes. My Temp Correction tables have not been touched. Plus, as you mentioned, the problems seems to be happening when the UTEC should not be altering the signals. But I know for a fact that the UTEC does alter the signal, even on Map 0. Several 350z guys have confirmed this as well.

Also, one more thing to point out. I have never had my car misfire while at WOT. My timing and AFR is always spot on while making a WOT run. So at least the UTEC does it's job at WOT. That's all I really care about. But it would be really nice to be able to solve this misfire problem.

sparks03max

iTrader: (7)

Correct. It also has nothing to do with outside temperature other than that the UTEC, itself gets cold.

Again I will repeat myself. After the UTEC heats up with cabin heat (ITS STILL COLD OUTSIDE), the issue goes away and there is not a single hiccup. I can leave the car running for 2 hours without the heater on and it will keep doing it. The moment I turn the heater on and the UTEC unit gets warm, it stops. This is obviously related to the temperature of the UTEC itself, and not with my tuning method since it runs perfectly in cold weather as long as the UTEC is warm, and has ZERO issues at WOT (when the UTEC is acting as a standalone) even when the UTEC is cold.

I looked into running the map sensor N/A and was turned away from it by several of the "pro tuner" UTEC guys on my350z saying that the MAF had much better resolution and less problems tuning on a N/A vehicle. As a bonus you still get to use maf pulldown in open loop using MAF for load indication instead of having to fill in IPW for each load cell as you do with the MAP. It is much more simple to work with when self tuning and very precise. I'm not just pulling this out of my *** and I am not willing to argue on this thread about it. If you feel the need to keep cluttering the thread with it, you can PM me instead and tell me how horribly wrong I am.

I am not asking you guys to speculate on how it could be my IAT, or the fact that I'm not using a MAP sensor. This happens whether it's on map 0 or otherwise, and goes away when the UTEC unit warms up, which pretty much rules out this being tune related.

I am asking for other people who have spliced or patch harnessed a UTEC into their older (non 6th gen+) ECU to chime in on whether they experience anything similar. You guys can take it as me being an *** hole if you want, or you could just read what I'm saying and try to understand.

sparks03max

iTrader: (7)

Yeah what I'm really trying to get at with this thread is that it's possibe that Darren has spliced(connected with patch harness) a wire or 2 that other hardwired/path harnessed UTEC users did not that is causing the issue without his/our knowledge.

If I can get more information about others installation and whether they have this issue or not, it will be easier to track down. Thus why I said I don't want random comments... lol

Gemner

iTrader: (4)

i dont THINK i have this problem, but my UTEC doesnt work 100% so it hasnt been in the car for a while. ill try to check it and confirm, sooner or later

you should try to log the ignition and the a/f when it is doing this to see if the UTEC will show what the problem is

Aaron92SE

iTrader: (128)

As far as I've seen, Darren's wiring is top notch. But I, and I assume, as well as Darren, would like to see the exact wires people used to wire up their UTECs to a 5.5gen ECU. It may be possible that it's different in some way. It wouldn't hurt.

Also, one other thing I'd like to note. On a nice cold morning (45 degrees), I decided to put a space heater in my car for 30 minutes to get the cabin nice and warm. When I cranked up the engine, no misfire. Nothing. And 45 degrees has always made my car misfire 100% of the time.

When I would reach down and feel the cover of the ECU and UTEC and they would be cold to the touch, that's when it will misfire. When the cabin gets warm enough that they do not misfire, the covers on the ECU and UTEC do not feel cold at all.

I feel the more information I provide in this thread, the better of a chance that someone will be able to help out.

sparks03max

iTrader: (7)

Ok. Also list the wires you've spliced/patched if you have them handy. I'll get with darren (or he'll find this thread) to illuminate exactly which ones he's putting through our UTECs.

sparks03max

iTrader: (7)

I totally agree and thanks for all the information and input. I wasn't even considering in-car temperatures causing it until you turned me on to the idea and it tested true.

edit: And I'm not at all down on Darren's work. His wiring is extremely professional and down right perfect in my car, I wouldn't have picked anyone else for the job. I'm just saying wire choice could be a possibility with our problem, since it's perplexing that we're the only ones (that I know of) experiencing the EXACT same problem without any word of such a problem on my350z

Aaron92SE

iTrader: (128)

I did try logging for a little while in 50 degrees and couldn't see anything out of the ordinary when it would hiccup occasionally. But I'd like to datalog when it's misfiring often with temps in the 30s. When it's 30 something outside, at idle, the engine would stumble about every 3-5 seconds. When it's 50 degrees, it would only stumble at idle about every 15 seconds.

Also, I do notice that when it misfires, my wideband gets a tad richer for a split second. It would go from about 14.5 to 13.5 all in that fraction of a second and right back to 14.5. But that is due to unburnt fuel most likely.

Gemner

iTrader: (4)

Heres my install thread
http://forums.maxima.org/5th-generat...installed.html

sparks03max

iTrader: (7)

I datalogged it misfiring for a while about a week ago when it was in the low 30s. It would go rich momentarily with a TINY increase in ignition timing (1 degree or less) during the moment it did it, then go back to normal. As you said, the drop in A/F must be 99% due to unburned fuel.

Gemner

iTrader: (4)

i would guess thats a spark problem, causing the unburnt fuel. then the ignition advance you see is due to the drop in RPM as the engine tries to recover

sparks03max

iTrader: (7)

Oh yeah of course it is. I said in the original post it's a coil not firing. I just need to find out why the UTEC unit being cold causes this.

Gemner

iTrader: (4)

yeah, or how its related to the difference between how we wire it and it being plug and play. i was tempted to say that its a problem with the wiring/resistors in the UTEC but then it would be causing a problem in plug and play apps too

sparks03max

iTrader: (7)

Yeah I'm really not sure what would cause the UTEC to misfire when cold in my car, but not in a G/Z, and not consistently like would be expected in the case of a wiring/resistor problem.

I know for sure that I'm stumped as to the cause, and I'm very glad it's easily remedied with a little heater action. I almost want to hardwire a heat gun into my car and spend 30s heating up the UTEC before I start it in cold weather

Aaron92SE

iTrader: (128)

I thought about that today. But I don't want to use a heat gun since I'm scared I will overheat things too quickly. Plus, I don't know yet if it's just the UTEC, the ECU, or wiring in the car. A blow drier would be better and safer to use and could help eliminate certain components. Just try to block the heat from getting to the part you don't want to heat up while doing your testing.

Gemner

iTrader: (4)

have you tried contacting turboxs? they might have some idea even though the install is not z/g

sparks03max

iTrader: (7)

Their customer support is notoriously horrible since they outsource the production of the actual unit (somewhere in Australia maybe?). I'll try contacting them at some point anyway.

VqMoNsTeR

iTrader: (10)

i have a bad o2 sensor.. sounds like a wrx before warm up.

QNO_A32

iTrader: (7)

if you are PNP try and bring the ECU in over night and see what happens

Gemner

iTrader: (4)

yeah, but the customer service is handled in the US. Your experience will be completely based on luck. I have emailed them before where I exchanged 4+ emails in one day, and other times where I waited weeks for a response

sparks03max

iTrader: (7)

Well what I mean by bad customer service is them having no idea how the internals of their device works due to the fact that they don't actually make it. I believe Darren was telling me that he's tried to call them many times asking questions and in general they have no answers.

That doesn't mean I won't give it a shot, but I'm not exactly hoping for too much.

sparks03max

iTrader: (7)

Hmm that's a pretty good idea. Maybe aaron can take his UTEC inside with him one of these days and put it back in the car nice and warm when he starts it up. That would narrow it down between the UTEC unit itself and the wiring connections/stock ECU.

Aaron92SE

iTrader: (128)

I can do that. Easier than messing with a blow drier as I mentioned earlier.

sparks03max

iTrader: (7)

If only the haltech platinum wasn't $2200-2500. It's amazing what you can do with it. Delete the MAF and use TPS or MAP for load reference while sending the stock ECU a simulated MAF signal, full control of VTC timing, two-step, both coolant and air temperature correction, real time active tuning with wideband 02, configurable sensor outputs, nitrous and meth control (even progressive), individual cylinder trim for each injector and ignition coil, full configurable digital guage panel replacement... and even capability to run as a FULL standalone (would kick *** for you, Aaron).

I doubt we'd be tackling any missing issues with that beast in place

Oh well, I can wish. haha.

Aaron92SE

iTrader: (128)

This morning, it was 40 degrees outside when I wanted to start the car and run a quick errand. Instead of just starting the car, I unplugged my UTEC and brought it inside and set it front of the heater for about 10 minutes. I made sure the unit was up to room temperature and no more.

I plugged it up and started the car, NO MISFIRE! Not a single one as I drove the car for 7 miles. With 40 degree temps and the UTEC sitting in the car all night long (low of 30 last night), it would have misfired every 3 seconds while idling.

sparks03max

iTrader: (7)

Well that narrows it down to the UTEC unit, itself. Thanks for that, Aaron!

Aaron92SE

iTrader: (128)

It still could be a combination of things. But the more info we have, the better. If it was strictly a UTEC issue and nothing else, then we'd see the 350z or 6th gen Maxima guys posting about this problem.

sparks03max

iTrader: (7)

Well it could still be a problem with the UTEC that isn't apparent on the 350z or 6th gen ECU because of some difference in input/output voltage that is fine for them all the time, but isn't for us when the UTEC is cold.

Aaron92SE

iTrader: (128)

Yeah, that's what I was thinking. The way we wired up our Maximas may make things a tad more sensitive.

Shift_Max

iTrader: (18)

How old is the UTEC unit? Since the older units had issues with them.
Also there was an issue with a grouding point that the 350z users had issue with.