s13 vert - 1jz vvti high idle and fuel cut issue - help?

[bdavis]

Hi all, I have a few questions and maybe looking for some help or advice.I can’t seem to locate the source of these problems and neither can my JZ guru friends. I have a 1994 s13 vert with a JZZ30 1jz vvti with r154 MT. Recently completed at the start of March 2016. I am going to try to list out everything in as much detail, so I apologize for the long read. Overall issues with long story short, high idle & fuel cut/fuel smell at 12psi in higher gears. I don’t have any mods other than what is required to put this engine in my car. Intercooler, intake, downpipe back exhaust and a manual boost controller… factory ECU. We did the wiring ourselves instead of buying a harness (which I will buy one eventually sometime soon but the wiring was completed by a professional, not joe blow down at the corner).

High Idle Issue – So, the day we started my car up for the first time, it had a high idle. About 1200ish idle 99% of the time. YES, MY THROTTLE CONTROL SCREWS HAVE BEEN ADJUSTED. At this point in time, we removed the traction control sensor and the other sensor atthe front of the throttle body (I forget what it is) before we started the car for the first time. We milled it down on a lathe and cleaned it up really nice. The IACV was installed at this point in time. However, my IACV only had a breather on it. It was not hooked up to the Jpipe. The Jpipe essentially is blocked off with a cap but has a vacuum line that is hooked to the boost control solenoid. Eventually within a week, the car started having issues starting and staying on, misfiring… etc. I ended up getting a new igniter, solved the issue of it not starting every time. Once that was fixed, I was trouble shooting the misfiring and it starting and dying. It would rev up to about 2 grand and then die, or misfire and idle rough. I ended up swapping out my IACV for another one, same issue. I ended up unplugging my battery and hooking it back up, car ranfine for a few days. Then it started over again. I eventually ordered a IACV block off plate, and that solved my issue and now has got me to where I am now.

So, as of today my car starts and idles at 800 on a cold start. After about 2 minutes, it will bump up to anywhere from 1000 to 1500. I can’t find any reason that would cause the fluctuation to occur. I have the IACV blocked off, the Jpipe blocked off with a vacuum line going to the boost solenoid, throttle screws backed allllll the way out to where they aren’t touching the butterfly and the throttle cable is NOT too tight. I have sprayed the entire engine with carb cleaner twice and haven’t found any vacuum leaks. I also cleaned the throttle body when we milled it down. I do NOT know of any codes that the ECU is/could have been giving. I’m not sure if the stuff is hooked/wired up to read it to be honest, nor do I have a reader.

*NOTE* - I did notice that whoever owned this engine before me (ENGINE WAS IMPORTED FROM JAPAN) had a different MAF pigtail than the factory one. The factory pigtail was hacked off and rewired to a different MAF, just not sure which one. What I do know is that my MAF plug does fit with a little modifying f the MAF, but I am not 100% sure its wired right. I do know that my 12v switch power is wired correctly though. The car runs really well and feels strong, butI’m not sure if this MAF wiring could be an issue and maybe the wires aren’t going to the right areas with the stock MAF. Also, checked the capacitor in the ECU and it is fine.

***ANY ONE WITH A JZZ30 WITH STOCK WIRING, IF YOU COULD TAKE A PIC OF YOUR MAF PIGTAIL SO I CAN REWIRE IT WITH THE NEW MAF PIGTAIL I HAVE, THAT WOULD BE FANTASIC*** My wire colors are black with a red line, green with a black line (I think), red with a white line, brown, and then light green.

Fuel cut/fuelsmell issue – So I have read online and talked with a lot of people and from what I have been told, the factory ECU can push up to 15psi or so without anything tuning wise or running into fuel cut. I recently turned my boost up to12psi and the car ran great for a bit, then one day I attempted to race my buddies LS13 and I was in 3rd about 3 grand, about 3500 or so, I hit fuel cut harddddd for the 1st time. I then turned the boost down to 11psi tosee if anything was different, 3rd gear was fine now but instead it hit fuel cut in 4th at about 4000-4500. I have since turned the car down to 10psi and haven’t found out if it hits a fuel cut any more, only hit it twice and that was enough for me. I know 1st and 2nd are good though for sure haha I am running a Hallman PRO MBC and the factory boost solenoid. I am running NGK BKR7E’s and they are gapped at .028 or .28, whatever the measurement is… idk.

I know that JZs like to over fuel, but when I get on the car now, I smell fuel for a few seconds after I let off, then it goes away. I have checked for leaks and the car does shoot fireballs here and there, so I am thinking I’m running rich. I don’t have a AFR gauge, so I cannot confirm. Once again, car runs fine as of right now and the smell only occurs on WOT. The fuel cut only occurs in higher gears in high RPMs after it is already at full boost (11psi and 12psi – unconfirmed at 10psi). Maybe it could just be left over fuel coming out of the exhaust.

Overall, I am starting to think Ieither have a bad sensor somewhere, or that MAF wiring is my issue (not surehow it should be wired exactly so I haven’t attempted to rewire it yet, need apic to be safe!!!). I can’t find a vacuum leak, it holds boost at whatever setting I have it at and doesn’t spike or fall off. I have a feeling that whether it’s one of the reasons just listed or not, but once I figure out myhigh idle issue, my fuel cut issue will also be solved.

Any help or ideas would be greatly appreciated. I am mechanically inclined and did 95% of this swap myself. I have owned several schassis’ over the past 12 years with different engines. I have checked majority of the easy testing that I can think of. Other than these issues, this car feels and runs great!

Also, if any one wants to follow me on IG, it’s @fubigemo_s13vert

Cheers and thanks for the help in advance!