Another Supercharger Idle problem thread | Starting to get desperate
 

Hey, Seb is doing me a solid and helping me on my idle issue. It is definitely something with the Z, not tuner related.

I believe these issues are all connected, but can't figure it out. I experienced very similar behavior on the on the stock A-W Stillen setup. I am also seeing this on the A-A kit. Pulling my hair out... almost 2 years with these idle issues.

Z never had idle problems before the supercharger install at 50K miles. Has 60K now. I did the install myself. I'm on the mid-experienced level "mechanics" wise. Full lift at home, had multiple projects in the past.

1) On cold start, sits at 900-950 with no issue. When things start to heat up, after some long driving, idle goes above 1,100-1,200 and can't seem to get it down.

2) When I put the clutch down while rolling to a stop, the idle surges between 950-1200. When I finally do stop, it takes a bit to come down.

3) If I free rev, as the revs come down, stops at 1,500-2K and "blurps" (stops, momentary rise, then falls). I feel this is related to above

Attached some VIDS:

High HOT idle:
https://drive.google.com/file/d/1rzc...ew?usp=sharing

Idle Surge while rolling to stop:
https://drive.google.com/file/d/1rs8...ew?usp=sharing

Descending Idle "blurp":
https://drive.google.com/file/d/1tnO...ew?usp=sharing


THINGS DONE SO FAR:

Boost leak done and what was found was addressed. Tried idle relearn but when it's hot, I can't complete because it is high.

Leakdown test ~8%.

Also, I went through some threads and some mention that the A-A kit "Deletes" the PCV. Is the actual PCV fitting replaced with a straight through fitting and then vented to atmosphere? I kept my PCV on but just vented to atmosphere.

Throttle-bodies were replaced with new ones

Supporting mods:


350z HR Nismo (MAF Tuning w/UPREV)
Uprev GT MAFs
A-A kit with 1.5" recirc Tial (on a filter)
Stock clutch/flywheel
Motordyne TDX
Stock Cats
9lb pulley (seeing almost 10psi)
Venting PCV to atmosphere through a mishimoto catch can
ID1050X injectors
Walbro 255 fuel pump(modified in-tank regulator)
Mishimoto T-stat
OEM 370z plugs (1+ step colder for 350zHR, gapped .032)

UPDATE:

Just added a fitting to replace the PCV so it's straight through the mishimoto catch can to atmosphere. Did not help.

When you say you replaced your throttle bodies, which did you replace them with: OEM or EPS? (I believe there was a third option at some point but don't recall 100%)

At first, I bought used ones from a low mileage Z. Then I got new Factory Hitachi throttlebodies. Although, these ones say Hitachi on them, not Nissan. Issue was seen before and after all the replacements.

Also forgot to mention, I made a custom TB cable for the driver's side. Each wire has hi-temp silicone-based sleeve and also individually shielded. They are then grounded. Still did not help. I'm using brand new cables I picked up from TopGunz.

.. tempted to do the same for the MAFs cables, but not really sure. It's a lot of work and I did not see a change when I did the TB

Just checked all hoses for kinks or awkward bends. All my hoses have factory style clamps on them. Didn't see anything out of the ordinary.

Going to use a vaccum smoke tester to pump the exhaust tomorrow and check for leaks.

I also have a brand new factory fuel pump assembly and a new Walbro 255. Going to reinstall and recheck my previous work.

Have you tried to take off the catch cans? Sometimes they can keep pressure in and since you took away the pcv system maybe some how it is getting stuck in there? I know precision turbo suggest to not have one for this reason.

I ran without a catch can initially with the A-A kit. I installed one just to rule this out. In both cases, still saw the weird idle as described.

Hey man,

I've been on this journey with Supercharging my Z since January/February. Stillen supercharger kit with the SOHO Motorsports A2A kit. I am still going through getting the car to a stable state as well. I just found another hose that was cut by the serpentine belt. I digress.

I used to have a very rough idle with an UpRev tune. Even rougher when a vacuum hose popped off unbeknownst to me. Hose was reattached but idle was still very rough. Last week I got re-tuned through EcuTek and it idles stably at around 688-700 rpm.

Just with that, I thought it worth the switch to EcuTek and a different tuner.

I'm still dealing with the engine heat issue. I went from 50/50 stock coolant to Waterless (temps were way too high still), and now in the process to switching to distilled water and water wetter. Then, I found the cut hose.

Good luck, man!

If he's using Seb, the problem is guaranteed not to be his tuner. Also, I'm betting he's already on Ecutek :twocents:

I'm on a 350z HR using Uprev. No MAP sensor so Ecutek wouldn't be worth while.

Have you checked your cats? I ended up replacing the engine because my tune was too rich for the cats and it melted it and sealed it up...

I went and got headers and test pipes to go with the new engine. Worth a shot?

Sent from my SM-G975U using Tapatalk

Oh yeah... duh! :facepalm:

Interesting, I would think that going too lean (increase in heat) would cause the cats to go. I have a lift at home, so i'll put it up this weekend and check the cats. I used to have HFCs and I blew through those. I put stock cats on and has only been 1K miles tops on them with the S.C. Cats have 50K miles on them. I have been planning on using some testpipes and welding on some Cats from a v8 or something.

I just learned that after I'd melted my HFCs. Basically running rich has excess fuel that exits the engine and into the cats causing another detonation/combustion. In this case, it's a lot hotter than the exhaust since the cats are having to deal with direct flame which exceeds it's heat tolerance and causes it to fail.

When HFCs failed, it sealed up and blew back debris into the engine. Hopefully, this isn't the case with you.

Sent from my SM-G975U using Tapatalk

But I agree with you. It's definitely NOT Seb. Just something strange post supercharger install. Saw the issue with a local nissan tuner that was around before they closed (Kaizens). Only thing left that I have not revisited is the in-tank fuel setup. I have another basket and Walbro 255 and just going to re-install and double check there. I did drill out the jet/swirl and the regulator. Was very careful in doing so.

It is definitely not the tuner. He actually gave me a couple extra tunes addressing it and gave unexpected results, more evidence that is could be something with my Z.

hmm... there was a light bulb for a second there. But, i had the hot idle issue with the HFC's before one of them blew up. I probably should have done a second leak down before going to the A-A kit. I did one before the supercharger set up somewhere between 40-50 miles just to be sure.

Check list for the weekend:

1) Pull the front bumper off again. Drive around and do a boost leak test while still hot.

2) use a vacuum smoke tester and pressurize the exhaust system, check for leaks. If anything, would be at the manifolds at this point.

3) Put the Z on the lift and pull the stock cats out and examine.

4) inspect the Fuel pump assembly. Have a new basket + pump and will re-install.

Still have yet to do this, clutch burnt out and it's been super hot here. Work got busy as well.

So... Have most of the Z apart to take the transmission out for the clutch replacement. Just waiting for a transmission lift to arrive in the mail. While I had it on the lift, I took a look at the cats. I did not remove them yet, but I noticed on the passenger side, the cell is loose. As in, I can pull it in and out with my fingers.

I'm assuming this is bad?

I'll take them off once the transmission is off and see what they look from the upstream side.

Is your Z a 2007 by chance?

It appears so

You probalbly need an 08 ecu. I had idle issues with my 07 after my turbo and my tuner said that the newer 08 ecu was able to correct throttle body and idle issues more than the 07 could.

Interesting. I think it is more of the ECU ROM type. Each ECU type has different features. My 07 Nismo ECU is EVC12

https://uprev.com/romlist.php

UPDATE:

So clutch has been switched out. Just have to put the tranny in when a set of OEM cats come in tomorrow.

I examined the cats. Besides the passenger side down stream cell that was loose, all seems in order. No clogging/melting at all.

Seb did give me a possible "Eureka" tune that addresses idle. Can't do much with it still car is back together.

Next year, I will possibly modify the exhaust. Put some resonated test pipes and put a couple of Mil-spec cells on my motordyne TDX2, possibly on the Y section of post muffler. Spent too much $$ this year.

Sounds like a vacuum leak, umm disconnect all the vacuum hoses from the intake manifold and pug every thing up, start the car and see if its still doing the same thing, if its nice and calm ~700 rpm, turn it off and connect a hose back with a new metal non OEM tie thats proven to work, start it up and check for problems, continue until you find the one that is leaking.

Boost leak checked and all is good.

Update:

Finished the clutch install... Finally. I'm only able to put in hour or 2 there and there. Married with 2 younglings takes my time away. Went with the Zspeed stage 2 quiet setup with steel flywheel. Upgraded to a Wilwood master. Can't wait for the throttle response change with the lighter flywheel.

Also got a tune from Seb for the idle. Guy has been pretty solid this summer. Have to fill up the tranny and bleed the clutch tomorrow, but I'll flash it some time this weekend.

I chased that idle thing forever. Mechanically the car was perfectly sound. I used a consult to do an idle air relearn and it was the same. Got retuned by a different tuner, instant fix.

Seb gave me a new tune I'm going to try today

UPDATE:

So been driving the Z around after the clutch install. Also replaced the cats with another set of stockers. Idle still all over the place.

I got another tune and flashed it. Was pretty brutal. Just "huffed and puffed" at cold start between 2K and 4K rpms. No clue what he did there.

Update:

Well Boys and Gals, Looks like Seb did it. One of the main issues was getting the car to go through idle relearn. The rpms would never settle below 1,100. Turns out, the 2007 HR ROM has a hard time with this. He set me up with a tune on a 2008 ROM and viola. Pain and agony vanished. Idle is set for 850, just sits there and purs.

Going to have to tip this guy real good. Went well and beyond trying to hunt down this issue.

Thanks for the input and advice everyone!

Well, you were right. Seb set me up with a 2008 ROM and fixed the issue.