My M30 MPFI SWAP

[MY1PATH]

So you ran the wires individually through the boot? I pulled the harness from my parts truck as one big harness and tried to keep it together with the ECU plug on one end. I guess I could cut it and resplice them all once I get them through but that would be a lot of extra work.

 

Looks like you have a lot of fun issues to work out. Good luck! Would it be a problem to try a pathfinder MAF instead of the M30? Since your not getting any codes I would think it's a problem from mixing parts. Just a quick guess.

James

Re-read that... the large ECU PLUG, the relays... they all fit through the boot as a whole without cutting anything. That boot stretches like childbirth! and I'm not kidding just get everything soaked in wd40 and you can push the entire 100-wahtever-pin MPFI ECU connector thought it.

 

Mind you there are 2 boots an inner and outer nested inside each other and its easier to separate them by about 10" and run everything through the first boot and then the second.

 

Mixing parts would be using the Pathy MAF. the only parts that are mixed are the manifold, TB and injectors.

The only MAF compatible with the M30 is the M30 and the z32. all the others run on a different voltage and may cause damage to the ECU.

Besides the intake screech is so much more noticeable when your MAF is 75mm in diameter instead of a choking I'm gonna guess 50mm for the pathy MAF

Edited May 29, 2012 by MY1PATH

[krmiller07]

Maybe go back to the basics. Look for vacum leaks, loose connectiions. After all, you did burn the midnight oil on this. maybe you over looked something really basic and simple! I have thrashed so hard somtimes in racing, only to discover I overlooked something really simple as I stood there with clumps of hair in my hands ! lol.

Can you reset the ECU? Afterall, you haven't had it it running long enough for it to store a proper running mode or codes? Just throwing that out there : ).

[Kingman]

Have you unplugged the MAF to see if it clears up?

[MY1PATH]

Have you unplugged the MAF to see if it clears up?

The freak thing is, this can start up and run w/o the MAF and the o2 using only the TPS and RPM to guesstimate fuel management.

Unplugging the MAF does not improve things, all vacuum lines are new.

I've got some Ideas but but I'm parked nose out to keep the fumes away from the house and being parked nose out means I gotta wait till the weekend to pop my hood or I'll get evicted.

I am going to put a Fuel PS gauge on and see if maybe my FPR got whacked, I may even put an adjustable one on to see if turning down the pressure will lean things out.

I gotta check the TPS because there is a chance that when I cleaned the TB some cleaner leaked past the seal and damaged the TPS...

[Adam]

The knock sensor issue is a big one. You can't just bolt it to the intake manifold and expect it to work, AFAIK most knock sensors work by detecting a certain frequency, tuned to the material the engine block is made of. Attaching it to the intake manifold is attaching it to the wrong material, you need to attach it to steel, aluminum resonates completely differently from steel. You're basically going to have to find a spot on the block or cylinder head that you can attach it to.

Edited May 29, 2012 by Adam

[MY1PATH]

The knock sensor issue is a big one. You can't just bolt it to the intake manifold and expect it to work, AFAIK most knock sensors work by detecting a certain frequency, tuned to the material the engine block is made of. Attaching it to the intake manifold is attaching it to the wrong material, you need to attach it to steel, aluminum resonates completely differently from steel. You're basically going to have to find a spot on the block or cylinder head that you can attach it to.

Funny you should say that, they get moved to the top of the intake all the time on the z32. they have also been bolted to the bell housing plenty of times on all nature of vg30 and vg33. The knock sensor is not the problem. It is currenly bypassed with a correct value risistor until I find out what the problem is. A proper knock sensor location will be determined at a later date. All I was doing was giving it a bandaid so that I'm not running knock maps and IT WORKED. The results were instant but its still too rich. Edited May 29, 2012 by MY1PATH

[tmoore4512]

Hey bro, great thread... The whole MAF thing has me wanting to take mine and bore the hell out of it... But back on topic.

 

In my experience with GM motors and KS's, those puppies are PERTINENT to engine function. If one goes bad the whole thing runs like a 3 legged donkey in wet sand... a few things that have me thinking...

 

The KS retards and advances timing as needed... if it is NOT actually reading the harmonics of the motor due to the resistor, then the ECU cannot properly adjust timing, deal with pre detonation etc... Mind you, I am referring to my experience with domestics (4.3, 5.0, 5.7, 6.0 etc), NOT imports. I have only scratched the surface on the VG30's and 33's.

 

Not running an O2 sensor? Again, the ECU is missing a vital signal... The absence of this information doesn't allow the A/F to be adjusted to whatever the perfect ratio is with the type of fuel you are running...its sort of running blind...or did I miss something?

 

The other suggestion (again from domestic experience) is to check the heat on the plugs. I imagine you have already covered it, researched and tested for it... but I thought I would throw it out...

 

Pre-detonation or dieseling? Or is it simply running rich?

 

Please don't take offense, you are on another level when it comes to the Nissan's, but I gotta be honest, your motor issues intrigue me...

 

For the record guys, MY1PATH has helped me out a ton in my pathfinder ventures, so I mean no disrespect in my reply!

[MY1PATH]

Not running an o2 sensor? I only said it was capable of starting and running without it.

 

There are 2 basic types of KS tuned and un-tuned. They all use a piezo electric element that sends a voltage (varied by resistance) back based on vibration the

1. Un-Tuned sensors ecu determines if that signal is a knock or just regular engine noise.
   
2. Tuned sensors only send feedback when the specific (knock) frequency is detected thus the ECU doesn't have to interpret anything.
   

The KS does not retard advance anything. The ecu retards and enriches ONLY when the KS detects a knock So most the time on a happy running engine the KS just sits there ignored waiting for a knock to happen. This is how ALL knock sensors work on foreign and domestic.

 

A stock N/A VG30 does not knock under normal load so there is no need for one until I get to the tuning phase. The resistor trick tells the ecu there is a sensor but that the harmful frequency is not detected. This is an effective diagnostic tool that eliminates variables and helps find the problem and worry about where to put a real sensor once the root problem is solved. Focusing on the properly bypassed knock sensor will not help the problem any more than focusing on my mismatched headlights that still light up the road.

 

And as said above and above and above, it is just running pig rich. If Nissan didn't have such strong ignitions it would probably foul the plugs and die.

 

The plugs are factory spec. I am running 87 octane and 87 ran fine on the M30 before I tore it apart.

Edited May 30, 2012 by MY1PATH

[tmoore4512]

Okay then. Just trying to think outside the box bro.

 

I will go back to observing...

[Kingman]

Most of Nissan's factory knock sensors are in the plenum already, which is aluminum. On Z31-Ts the knock sensor doesn't even do anything in boost! How rediculous is that? Essentially it's useless unless you're tuning.

 

So most the time on a happy running engine the KS just sits there ignored waiting for a knock to happen. This is how ALL knock sensors work on foreign and domestic.

 

True, but what if a bad sensor is sending false signals? That's what makes a lot of rigs with bad knock sensors run like sheit. My Subaru did the same thing, gutless and sputtery until I replaced it.

 

Being able to start it without the MAF is normal since the ECU has pre-set values to idle and at least run without it plus the input of the Coolant Temp Sensor. If you don't have the TPS adjusted correctly the idle switch won't trip and it'll idle like poo (off open headers it'll sound like a burbly drag boat in the water). Have you checked/ohmed the Coolant Temp Sensor? I would think your ECU is smart enough to pick up a problem but maybe not and it's thinking you're in the antarctic? That is still the main source for fuel management but at least with the newer ECUs ('88+) there's a back up daughter board for it in case the ECU looses the signal.

 

I haven't looked, does the M30 only use the O2 sensor above 2,800RPM like almost everything else?

 

The injectors being a little bigger shouldn't matter because the ECU is still metering the same amount of fuel just through a larger injector that has the capacity to flow more. A few CCs shouldn't be a problem, it's not like you're running fatty 800CC injectors on a stock ECU.

 

I saw something above about the engine running and codes. Neat thing these do, after a few seconds of cranking the ECU knows what's up. They don't necessarily have to run to pick up what problems there are.

 

Psssst - don't forget to change your oil after all of this.

[MY1PATH]

I will check the CHTS again, its fairly new but it never hurts to check and they are cheap.

 

Good one on the oil, I'm actually thinking about changing it now because its not near a rich as the first few starts (liquid fuel out the tail pipe) and then, of course once its running normal, change it again.

 

I never removed the TPS and the slotted holes don't look like they've been rotated in the past. If its a problem I'm thinking its because some crab cleaner got past the throttle shaft seal and into the TPS. I did try unplugging it yesterday, the switch side did nothing to idle but made revving a little grainy (normal) POT side seemed to make idle smoother(suspect) and of course it refused to rev without the POT side plugged in as the M30 uniquely uses the POT in its fuel enrichment calculation. Certainly high on my list of things to check when [HOA] isn't watching.

[Kingman]

I say CHTS because I have a brand effing new one and it's a piece of crap. It's a little difficult to track down the other issue(s) I'm having because of that stupid China sensor interfering with my bizznizz.

 

I got off on the wrong foot with my engine just being rebuilt with unseated rings, then firing it up and having it run pig rich. The oil was pretty dark but now that the rings have mostly seated and the rich situation taken care of (adjusting the TPS to trip the idle switch), it's mostly clear.

 

I find it a little silly that they use the POT for fuel calculations...

Edited May 30, 2012 by Kingman

[MY1PATH]

I think Its a load-based and demand-based fuel calculation instead of purely a demand-based calculation.

What I think this means is;

• Load is Throttle position over RPM; The result is quick throttle response due to the enrichment before the MAF actually sees the draw. But its not as accurate for anything other than its initial response.
  
• Demand is MAF and o2; the advantage is more accurate metering during all other conditions.
  

The two combined allow for snappy response that is accurately metered. All of Nistune's fuel maps are done on a load based table. This allows you to run leaner, more efficient when your not getting on it but richer and stronger when your put your foot into it a little more.

Edited June 1, 2012 by MY1PATH

[MY1PATH]

I found 2 small problems that would make them selves easily known if the big problem was not covering them up. The o2 sensor and throttle switch (not sensor) are wired differently on the pathfinder TB and Titania o2 sensor. This problem will get ANYBODY who is not looking for it so I will post wire corrections with pictures later.

 

The BIG problem! INJECTOR LEAK.

No, The guy at Dr. Injector did not fail me, let me walk through it...

I hooked up my fuel pressure tester and primed the pump. The line barely made it to 35psi before the pump kicked off. No vacuum FPR should go to about 43. I primed several more times with the same result. I started the engine and at idle the line was only 28 psi. Under vacuum the FPR should go about 36.

 

So I shut it off and started reading spark plugs; 1 was dripping wet. 3 was normal, maybe even a little lean and 5 was normal. Trusting the work done at Dr. Injector I decided to suspect electrical mishap...

I unplugged #1 and primed the pump again and I got about 43psi; started the engine and got 36psi. So now I gotta pull apart my harness and find the short that keeps #1 open all the time. Good thing I did not fully wrap the harness just yet. I saw that happen to somone else's MPFI conversion and he had regrets...

 

Oh and Dennis will love this one, the only reason It did not pour my entire fuel tank down the exhaust the first time I took the pathy around the bock is because of the Variable Voltage pump controller on the M30. If it was not putting a limit on the VOLUME of fuel going to the rail I doubt I would have even made it home on one tank of gas.

 

So, now I have my work cut out for me this coming weekend...

Edited May 31, 2012 by MY1PATH

[MY1PATH]

Ok, I just Tested every pin on the ECU Plug against the #1 injector (cheeked ground too) and ONLY pin 101 had continuity (the correct pin).

I did observe that with the ECU unplugged the fuel pressure held and if I extracted pin 101 from the connector and plugged it in pressure also held... but as soon as I slid pin 101 back the pressure dropped.

If I had a short in the harness more than one wire would have continuity right?

 

So I guess my #1 Injector driver is stuck open?

I'm about to buy another ECU off of eBay and that should get it running properly again. Or am I missing something?

Edited June 2, 2012 by MY1PATH

[Adam]

I would contact the people who cleaned up the injectors...

[MY1PATH]

He won't do anything, its not his problem.

The injector drivers are part of the ECU, the injector is fine.

Edited June 2, 2012 by MY1PATH

[snowboard419]

Sounds like a damaged ecu, that's got to be a pain in the ass when figuring out a swap like this.

[Adam]

He won't do anything, its not his problem.

The injector drivers are part of the ECU, the injector is fine.

 

Have you moved the injector to another spot to ensure that the problem isn't the injector? What testing are you basing the idea that the injector is fine on?

Edited June 2, 2012 by Adam

[MY1PATH]

Have you moved the injector to another spot to ensure that the problem isn't the injector? What testing are you basing the idea that the injector is fine on?

Easier yet, I moved the connector to another injector and the problem moved with it.

When I find a problem with a wire itself I stop diagnosing the part it effects... Its actually very simple and lets me narrow down the problem.

 

Really, what testing? So everything I've done and listed above is not a test?

You mean disconnecting the ecu controlled ground wire that turns the injector on is not a legitimate test?

You mean running a muti-meter across every circuit related to fuel injection is not a form of testing?

You mean the fact that an injector closes properly and holds pressure when disconnected from a shorted wire is not enough to prove that the injector is not the problem?

Are you trying to be productive or are you just reading the the first and last words of every post so you can fire off a reply and get your post count up?

 

ANYWAYS, to spell it out for you one more time... In this case I found the injector connector is always grounded (on) I found that with a multi-meter. This pretty much rules out the injector, combine that with the fact that the injector closes when un-plugged and the fact that the injector itself is isolated from ground COMPLETELY RULES OUT THE INJECTOR.

Edited June 2, 2012 by MY1PATH

[Adam]

Easier yet, I moved the connector to another injector and the problem moved with it.

When I find a problem with a wire itself I stop diagnosing the part it effects... Its actually very simple and lets me narrow down the problem.

 

Really, what testing? So everything I've done and listed above is not a test?

You mean disconnecting the ecu controlled ground wire that turns the injector on is not a legitimate test?

You mean running a muti-meter across every circuit related to fuel injection is not a form of testing?

You mean the fact that an injector closes properly and holds pressure when disconnected from a shorted wire is not enough to prove that the injector is not the problem?

Are you trying to be productive or are you just reading the the first and last words of every post so you can fire off a reply and get your post count up?

 

ANYWAYS, to spell it out for you one more time... In this case I found the injector connector is always grounded (on) I found that with a multi-meter. This pretty much rules out the injector, combine that with the fact that the injector closes when un-plugged and the fact that the injector itself is isolated from ground COMPLETELY RULES OUT THE INJECTOR.

 

Not really sure why you're getting so touchy here, you never indicated that you performed the connector swap in any of your previous posts. Just trying to help.

[Nefarious]

Wow hostility, the guy was just trying to help.

[MY1PATH]

Ok the connector swap was a first mention but the rest was all old news.

Trying to help is fine but spitting out answers without taking note of whats already been diagnosed is useless.

And he did it on the previous page with the knock sensor too. If a problems has been solved or ruled out through a legitimate means of troubleshooting diagnostic than one should move on to the next item. Otherwise nothing ever gets done.

[ejin4499]

Any thoughts on why you were able to drive the M30 down the street no problem but when you did the swap you now have a problem with an injector circuit? What happened to the ecu in between times?

[MY1PATH]

It may have been dropped or smacked on; I do have a toddler who gets into everything high and low when I'm not home...

Or something corroded; I did have some water damage to the inside of the case, maybe some of the corrosion was inside one of the drivers.

 

I haven't completely ruled out the wire harness either. Allot points to the ECU so I have a spare coming on the way but I can still run more tests and observations on the harness.

 

I spent 6 months trying to get this together. My work schedules constantly being rotated, being called away from it for work, having to set it aside for a month because of work...

there was a lot of mismatch with where I picked up and left off each time, and a lot of very tired days where I did it anyway because I was tired of not making progress. So I'd say mistakes in the wires somewhere are very likely and should be kept in mind as a possibility.

 

Today I'm going to install the MPFI Accessory bracket so my A/C can be mounted back to the block. (TBI bracket makes compressor block the intake.) and then I'm going to de-pin injectors 1,3 & 5 from the ECU(pins 101, 103, 105) and measure each ones ground circuit at the source to see if #1 is still showing closed and compare it to 3 & 5. Its not actually a complete short (but its enough to open the injector) so the beep test won't work, I have to look at the OHM value for each pin on the ECU.

Edited June 2, 2012 by MY1PATH