RudysSC

Let it warm up for the drive home last night - about 55 deg outside - it drove absolutely flawless. It does make me think that perhaps temperature has something to do with what's going on. I'm going to try and spend some time with it within the next couple of weeks and will let everyone know if I find anything. Otherwise - an ECU Masters order may be in my future sooner rather than later.

Bimmerbill

Hey Rudy,
I know this is crazy but thirty or forty years ago I had the same symptoms with a bad coil. I had always heard that a coil either worked or did not and nothing in between. It took a friend and I some time to find the problem. Do you have multi coils, if so ? Just a few words trying to help. I have faith in you and I know you will work it out.
Good luck,
Bill

RudysSC

Hey Bill,

Thanks for the input man! I did just put three new coils in (I retained the three coil wasted spark set up how it comes from the factory) - however, it was doing this before swapping coils (I thought the exact same thing, knew I was about due for them anyway, and decided to swap them out). I suppose it could be the igniter, but man, without being able to pull any codes I am just not certain! I'm going to get a few buddies, put our heads together, and once we have a free Saturday spend some time tinkering to see if we can narrow it down before I pull the trigger on anything crazy lol.

joewitafro

Standalone will save you headaches in the long run. The EMU black looks pretty nice, and I like they have a diagnostics mode to allow you to test your outputs individually. This is a large reason I went with the Link G4X over the haltech elite.

Then you can record logs, and see where your hiccup is occuring. But from what you describe it sounds like ignition breakup, either caused by... 1) your ecu, 2) your coils, 3) your igniter, 4) your grounding system or a broken power wire/cracked coil.

KahnBB6

iTrader: (5)

Rudy-- That's a good investigative result so far. There may be something to what you say in regards to temperature possibly being part of the issue. This is probably redundant but when was the last time you replaced your ECU Coolant Temp Sensor which is located on the front side intake side of your cylinder head?

It could very well be related to something else that gets affected by temperature of course but I thought I'd ask.

Joe, do you consider the Link G4X ECU system to be near "OEM level" in terms of reliability along with the deep ability to diagnose as you have described?

I also recall this thread explaining that the Link ECU is one of the few that can be set up to control factory sequential twin turbos:
https://forums.linkecu.com/blogs/ent...ith-link-ecus/

RudysSC

Joe - I agree 100%. That's always been my long term plan, but I suppose, sometimes plans do force themselves in sooner.

Craig - I've actually never replaced it... The thought has crossed my mind (granted, it seems to change with outside/ambient temp, not engine temp...). Do you think that could be a factor? Always open to your thoughts man!

KahnBB6

iTrader: (5)

It couldn't hurt because there can be issues if your ECU Coolant Temp sensor has gone bad. Although I don't know if it is a progressive thing or not.

It's a mystery to me too, your situation. Just as my current one is to me.

RudysSC

Man it sure is Craig. I do suppose there's a chance it's on the fritz and is causing the engine to not know where it's at temp wise on occasion. I've noticed when this happens it seems to run SUPER rich... If that temp sensor isn't reading maybe it's dumping fuel in thinking it's cold... Maybe I'll go ahead and pick one up and give it a shot. I believe most of the 1J's and 2J's all had the same 2-wire sensor.

joewitafro

Still waiting on my harness/ECU, but from what I've seen and learned over the years it really comes down to the competence and care of your tuner. Its easier for a tuner to focus on idle and WOT maps, but covering every aspect of drive-ability takes time. The benefit of a good tuner and most standalones is you can just let them remote access your laptop while you drive, or record logs for them.

But in my opinion standalones like motec, haltech, link and even AEM have a greater hardware capability than OEM ECU's, just far less test and tuning unless its a race team or a tuner with his personal car.

If someone was able to get the stock sequential turbos to work with the link, i have no doubt you'll be able to find someone to get the EGR to work. Whether 90% of them will give any care to do it is another story. Biggest issue I think would be a ODB2 emissions car with standalone working correctly with the plug in emissions scanners.

RudysSC

I just put a similar reply in Craig's post lol. A good experienced tuner is truly worth their weight in gold!

KahnBB6

iTrader: (5)

Joe and Rudy-- I agree with you both about the key ingredient being the skill and competency of the tuner whom you use. Gerrb also has said this many times to me when I have asked him about his own explorations into various aftermarket ECUs: the hardware needs to be good to begin with but it is the quality of the tune that really matters in the long run.

The hardware now seems to be VERY capable and flexible for a variety of custom applications. I also hear of fewer reliability mishaps with them now from a hardware and firmware standpoint.

Joe, I also agree with you that it may be of less interest to most tuners whom I might approach to try to get the stock twin and EGR functions dialed in close to stock programming. Other than the line by line function description and diagnosis breakdown matrix in the 2JZ-GTE TSRM I also question how easy it would be to fully replicate all the programming that Toyota R&D testers put into those original hard coded chips in the ECU as to EGR and stock twin function.

Nonetheless there is a lot of support for standalones on JZ powered vehicles so I know there is at the very least great expertise out there to get an engine tuned well with enough seat time and data logging being sent back for analysis.


I can't say for sure if it's your ECU coolant temp sensor but if you've never replaced yours then it couldn't hurt. Check to be sure if yours is different from any of the others. If you buy the sensor for an Aristo 2JZ-GTE VVT-i or Supra 2JZ-GTE VVT-i you cannot go wrong.

It might also be O2 sensor related. When those begin to wear down and become less efficient and accurate the ECU tends to throw in more fuel.

More than one reason can cause a stock ECU to dump in more fuel for a richer mixture to protect the engine.

RudysSC

I'm going to do some messing around tomorrow and see what I can come up with. I went to start it this morning and it was idling like ****, surging up and down, and running insanely rich. I'm almost starting to think my vvti 6-speed ecu is going bad after all of this. I'm going to try and throw my auto aristo ecu in that Gerry sold me a while back to see if that makes any improvement. The car always ran a little better on the 6-speed ecu than it did on the auto, however, I was also running the wrong O2 sensor originally LOL. I did get a new O2 sensor in last year so I don't think that's my culprit.

I'll swap ECU's tomorrow, tinker with some things, and will report back!

Thanks for being such a great sounding board guys. If only I could hook up an OBD reader to this car my life would be a million times easier..

RXRodger

iTrader: (2)

Are you sure you don’t have a boost leak? Just on the surface that’s my first thought.

KahnBB6

iTrader: (5)

With the surging up and down at idle I also thought it could be his Idle Air Control Valve acting up but I am not sure if 2JZ-GTE VVT-i's have the same IACV's as the Non-VVT-i's where this has been known to happen on occasion.

At idle these engines run in vacuum. Even at very low engine speeds under load they are mostly in vacuum until the boost builds up enough to go into positive manifold pressure. One time after doing some service I forgot to tighten down an engine intake to intercooler hose and only noticed the issue when driving down the road under very little power. But at idle everything seemed fine... except for the telltale hissing at the loose hose connections.

However a regular vacuum hose leak could cause this and even a 2JZ-GTE VVT-i is still full of almost as many as the older Non-VVT-i version. I think the electronics are where the likely culprit may be for Rudy but it certainly can't hurt for him to check all his vacuum hose connections if he hasn't already

RudysSC

I don't believe the VVTI motors have a IACV - they perform this through the throttle body (at least that's what I've been told). I've got a lead on borrowing a smoke tester so that I can check for boost/vacuum leaks so I'll be doing that soon as well!

In the meantime - I swapped ECU's this weekend and the car ran even WORSE on the auto ECU after a short drive. However, I put a fresh tank of gas in the car (who knows, worth a shot maybe I got a bit of bad gas), put the 6-speed VVTI ecu back in, and the car drove AMAZING all weekend LOL. It was a bit warmer out, however, I did a 27 deg cold start this morning, drove it to work again, and it was wonderful.

At this point, all I can do is laugh lol. Who knows, maybe it was a weird spout of bad gas? Either way, hoping to smoke test it soon, going to change the fuel filter just in case, and do a few little things to see. I still can't help it's got to be electrical with how intermittent it is but I'm yet to find a completely dead sensor, any kind of traceable error code, a short, etc...

I sure appreciate you guys' input as always. Fingers crossed but I'm going to keep tinkering and will let you guys know what (if anything) comes up LOL. I'd love to enjoy this car as-is for another summer before I tear it apart to go standalone...