Idle surge after Stillen supercharger install -SOLVED
 

Hi Forum,

I'm having issues with idle after my S.C. Install. At startup in closed loop, idle is fine. After warmup and transitioning into open loop, the idle is terrible. Will go up to 1K RPM's and bounce around up to 1,500. I do see the fuel trims increasing.

The tuning shop went through a compression and leak down prior and numbers were good. 210 on average across the cylinders and leak down was less than 10%.

A boost and vaccum test was done and all is sound. MAFs were cleaned out and I also pulled the throttle bodies out and cleaned them (battery disconnected and unplugged the TB's before taking them out)

If I cap the PCV, the idle surge disappears, which would lead to a leak somewhere... But boost and vac test came back fine. I changed the PCV after that test and still nothing. I may have an exhaust leak between the drivers side manifold and high flow cat. Can an exhaust leak cause this idle surge with forced induction? I had a leak there before and I never had idle issues. I figure the supercharger has changed the dynamics and wanted to ask.

Some info:
07 350z Nismo @53k miles
Standard Stillen kit (no upgraded pulley, no fuel return, walbro 255 fuel pump with the regulator tapped with provided drill bit)
Kinetix HFC and a Tanabe Y pipe to factory OE Nismo exhaust
Probably irrelevant, but I also added a Mishimoto oil catch can(closed)
Has a custom tune (dyno'ed at 350wHP), idle set to 800rpms
1+ step colder plugs (370z spark plugs- standard gap)
Replaced Stillen provided BOV with a authentic HKS
Z1 oil pan spacer
34 row oil cooler

Never had any issues before, solid as a rock


Much appreciated,

-NT

There were a couple of threads that I read with slight idle surge at the set idle
RPM's. I believe this is not my case, the reason for my post.

Was able to get a couple runs today. A couple lights came on:

P0300 - random misfire
P0507 - power train idle control system RPM higher than expected

The past few days I was ruling out a few items. Vacuum was near perfect and no boost leaks. I may/do have an exhaust leak but I wouldn't think it would DRASTICALLY change the idle.

The issue is with the HKS SSQ BOV mentioned above. It's a BOV usually used in turbo applications and the spring rating is above 6 PSI for sure. Just recently learned that the BPV needs to be partially open with a centrifugal supercharger. This translates to using a BPV with a 1-1.5PSI spring rating OR using an adjustable BOV that can get down to that area. Made sense. S.C. is constantly running (unlike a turbo) and excess pressure needs to go somewhere.

Replaced the BPV with the Bosh one and ran an idle volume relearn and then viola! Problem solved.

-------- BUT -----------
As some have said... what a $h|itty design. The MAFs are soooo close to the filters that the moment the fans kick on, fuel trims start changing because of the air flow and temp change. Did they test these kits in a vacuum 0 gravity facility?

As other have done... they did away with them or created a better shield. I used the one they provided (350z HR single intake pipe dual MAFs) and it does 0.

Well... the P0507 came up again. The idle turned on me again.

If I go through the Idle relearn, the car idles fine. After driving around, it starts to idle at 1,500 etc..

The exhaust leak got worse, so I'm going to take care of this today

Probably tune issue, if i remember correctly, i'm on uprev and my nissan mechanic couldn't relearn idle because tune had it locked out.

You may be right. I'll have to get in touch with Kaizens next week after my track event at Thompson.

Got the exhaust leak fixed. No Cel light after 50 miles, but the idle is still screwed up.

I always see the p0507 code related to cleaning the throttle bodies. When I had everything off when installing the S.C., I did clean the throttle bodies. Not sure if this is related

Reset the ECU, went through the peddle release, tb closed position, and volume relearn. I used NDISIII to start the relearn. Waited for idle to get to 650 +/- 50 and then shut the car off.

Started it back up... idle like a kitten. Great.

Went to drive around the block... idle surge again.

Was curious about the purge valve connections and double checked the Stillen directions for it. Left side of the valve goes to back of the manifold. Other side goes to the EVAP. So everything looks good.

arrrrrgggggghhhhhh... back to the drawing board.

I am using 370z spark plugs (1+ colder, since I have a vq35HR). I've heard everyone using them once they go forced induction. Is there a reason I may have an issue? I left the standard gap on them.

My old man and I installed a magnusson supercharger on his C7 vette and we initially used 1+ colder plugs. Turns out they were no bueno and we tossed the stock ones back in.

Previously, i had the p0300 missfire, but I figured that was because the BPV was not opening up properly when going into vaccum... since I was using a high spring rated BOV (HKS SSQ) with the recirculation adapter.

tuner needs to set the idle

^ that. Either that, or give it some time for it to learn the fuel trims for the different IATs. I usually have a somewhat erratic idle when I first reset my computer or retune. But it usually settles down after a few days. I think it goes by number of ignition cycles before it stops the learning mode. It's probably something to do with the readiness monitors, but that's just a guess.

Went to Thompson speedway yesterday for a HSDE. I have to admit that I had 0 optimism going into the event. I brought basically my entire workshop with me.. extra belts, pulley, fuel pump, etc... Car handled very well and the charger just took me by surprise. Zero issues (minus the already known idle and cylinder misfire CELs). Power was great, which just gives the nismo an entirely different purpose on the track.

Update on the idle Info:
1) Decided to replace the throttle bodies. I got a set from a 370z with only 30K miles for $115.00. Cheap enough to replace. They will be here Thursday, so I'll install them on the weekend and go through the idle relearn procedure and post.

2) Found out that the P0300 Multi-cylinder misfire only occurs at startup on cold mornings. I'll replace the TB's first and revisit this.

3) Gas tank level reporting is off. Car gas meter showed that I had a quarter tank of gas and I had issues starting the car. I was very careful taking the fuel assembly out of the tank and installing it back.

EDIT:

On item 2 above, it may also be the TB. That p0507 is barking at me all the time due to ISC. If the T.B. is screwed up, at startup... it would most likely misfire.

check the maf harness extension as well as TB extension
most people who run the kit extend the harness itself instead of using the extension harness that comes with it which proved to be problematic.

I actually have their new revised harnesses.

I'm trying to fab up a new shield for the filter. It has been idling fine, but when the fans kick on... that is where the idle surge occurs.

This is most likely it.

I have an 11' 370z nismo with installed Stillen SC and oil cooler. I bought the canned tune from Stillen and for what it's worth I too have an occasional P0300 pop up. I want to make a few mods and then I hope to get it to a tuner soon which will hopefully fix the problems I'm having with the shitty Stillen SC kit.

I ordered some material for a shield... I'm going to make an attempt this week to get it done. I'll switch out the TB's as well. I just haven't had the time.

My last resort will be back to the tuners, but this will wait until the spring. I'm considering TopGunz A-A kit and would rather just put that on and re-tune. I have a true dual exhaust as well to install.

Having the MAFs so close to the filters is just a terrible design. You normally want them closer to the T.B's. Especially when there is a difference in Temperature. Maf's are reading directly after the filters... then goes through the charger and maybe not significant, the air temp/density is not the same. I have a feeling this initial design has something to do with their CARB certification.... as well as the crappy in house tune

I talked with someone that mentioned that this Stillen S.C. kit, if installed by a SAE certified tech at Nissan, will not void the factory warranty. Have to use the Stillen tune to stay CARB compliant

In for the results.. I am also having this issue. Definitely when my car is up in temps

Another option is to extend the intake with sections of the Y pipe to mount the filters onto. I've thought about doing this, but never really needed to. But my thought was to buy piping from Pep Boys or Home Depot, either a 3" exhaust pipe section, or pvc from the plumbing section, and cut it into two 10-12" pieces, and get two silicone couplers. You're still pulling from right in front of the radiator, but the filters would be on the right-side of center instead of the left-side. But you'd have a decent length of straight pipe before the MAF takes it's reading, so it would eliminate this variable.

Caveat here is that I don't use the Stillen heat exchanger, so the front of my radiator is the same on both sides. YMMV if you're using the Stillen unit.

Another comment, about how it happens more when the car is warmed up, have you guys monitored IAT (Intake Air Temp)? I monitor that on my car, and it heatsoaks really bad when sitting in traffic, or if the car is parked for 30mins to an hour. What I've seen with ambient temps around 80*F, is that if the car is warmed up and driving around, the measured IATs are about 5* higher than ambient. But when you park and get back into the car, IATs are commonly in the 120*F range. Sitting in traffic, I see around 105-110* IATs. This results in whacky fuel trims, definitely different fuel trims than IATs in the 80-90* range when the car is just cruising without traffic. The constantly changing fuel trims seems to be a source for the idle surge for my car. In other words, the car hunts for a way to stabilize AFR at 14.7 while idling, and it does this by adjusting the fuel trims.

My current running theory is that the ECU is logging the fuel trims for each condition it sees (idle RPM/high IATs), and eventually, it will have the data stored, and it will just go to that fuel trim and idle correctly the next time it sees the same conditions. It's sort of playing out like that, but not perfectly. I'm trying to give it more time on this reflash.

I have a 350z Vq35HR motor (07) and that kit actually comes with only 1 pipe with 2 maf's. I may consider this as well.

I have one of the larger units from frozenboost type 101.

This is a good point. I have not been monitoring IATs. I'll have to take a look. If IAT's increase, the fuel trims are obviously going to change... and the idle surge will occur if it needs air.

Possibly look into doing a PCV delete/catch can system.

I am going to try and do this to maybe fix my surge, and it is also very beneficial to the engine.

Question, When you have the idle surge, does your vacuum flutter, and do you run rich?

I added a catch can... but I did not delete the PCV.


When i notice idle surge, 80% of the time I get the p0507 ISC. The fuel trims are increasing... so i actually have a lean condition. From my cheapo logger (NDS or Torque Pro) I see STFT's increase when the fans kick on.

Unfortunately, I still have not found time to rip the front bumper off.

-----------------------------------------------------------
Diagnosing with Fuel Trims
Fuel trim can be a valuable diagnostic tool - Eastern Manufacturing


Fuel trims can help you zero in on the problem, especially when there are no other trouble codes present. Knowing whether a vehicle is running too rich or too lean will help narrow down your diagnosis. Fuel trims that differ greatly from one cylinder bank to the other will also point you in the right direction. Always evaluate fuel trims at idle and at 2500 RPM.

Running too rich – High negative fuel trim corrections can be caused by MAF sensor problems, high fuel pressure, leaking fuel pressure regulator diaphragm, faulty evaporative emissions components, leaking injectors, defective O2 sensors, exhaust leaks/pinholes before the O2 sensor, coolant temp sensor problems, and base engine issues such as low compression and incorrect camshaft timing.

Running too lean – High positive fuel corrections can be traced to MAF and O2 sensor faults, vacuum leaks from intake gaskets/hoses, unmetered air (intake snorkel leak), clogged or dirty fuel injectors, fuel delivery issues, and exhaust restrictions such as a clogged catalytic converter.

With the warm weather, I started working on the Z again. I got rid of the P0300 and p0507 by replacing the throttlebodies. Idle surge is now directly related to the fans kicking on. I'm solving it with a new charge pipe with the MAFs closer to the throttle bodies. This effort can be tracked here:

http://www.the370z.com/forced-induct...e-mafs-tb.html

... and p0300 is back. Looks like this is a cold start issue. I'm 1000% convinced it is in the tune. I'm dropping it off this week for a tune, so I'll mention it.

I cleared the cel the other day and it didn't come back until today. The past couple days have been warm out. I now suspect that it is cold starts when it is cold out... too much air causing a misfire?

There might not actually be a misfire. P0300 is a catch all code when the ecu gets confused. It can be 1000 different things triggering it. When it was cold, I would get it because the flywheel would rattle and trick the ecu into thinking there was a misfire. I ended up having the code turned off. There are codes for the misfires of the individual cylinders, so it hasn't been an issue.

Some updates:

1) Replaced the throttle bodies with brand new ones
2) Moved the MAFs closer to the throttlebodies (revised piping)

http://www.the370z.com/forced-induct...e-mafs-tb.html

3) netted 25 extra wHP with AFR 10.5.
4) GODDAM p0300 is back. Tune shop states that the Z is trying to hit an idle target of 700, it bounces at around 780, then cel comes on. Went through the idle relearn several times

The voltage on the throttle bodies were checked and what would be the drivers side, which has the T.B. extension, is seeing lower voltages than the passenger side w/o the extension. If the passenger side is .80, then the driver's side with Extension is .74.

I am going bananas over this. So possible that TB extension is an issue?

Yeah, many people have had problems with the Stillen wiring.

I'll just elimiate the cable harness and add my own wiring. I thought I had Stillen's revised harness. But for sure, if there is a resistance change on the harness, the ECU is going to report a different voltage.

Just for curiosity's sake, do you have pics of yoru piping completed? And how is your idle now?

I will have some pics, logs, and dyno chart once I go pick the Z up.

As my previous posts, still having Idle issues. I'm going to pick it up and eliminate the Stillen extension cable for the throttle body and just extend the OEM cable by soldering extended wires.

Some pics before complete install. Shop sent me these while they were connecting the piping up. They had to take the front bumper off later on and add a new filter... but now MAFs are closer to the TB's and bypass valve vent to atmosphere.


https://farm2.staticflickr.com/1734/...83e6b6bf_h.jpg

Picking up the Z tomorrow. I am going to remove the Stillen TB extension harness myself and extend the wires. Go through the song and dance for calibrating the TB's and report back if the p0300 went away.

-NT

So I have a 2018 370z Nismo and just got the stillen SC with oil cooler kit and upgraded radiator. The car has 600 miles on it and never had this p0300 code until the shop reported it before picking the Z up after the Stillen SC install. They did a smoke test and there was a small leak on the first cupler from the plenum. Driving home the cupler popped off. I since put on upgraded straps so the cupler no longer pops off when I hit boost but I’m STILL getting this random P0300 code. So annoying. I’m going to test for a leak in the cupler but if there is none I’m guessing it’s the stillen tune. I take my Z in this Thursday to get a custom tune and map from scratch and Dyno. If this doesn’t cure the problem I’m gonna go crazy. Somebody suggested colder heat range plugs w/a tighter gap. Will report back.

Well, I lost faith in all shops in this area for sure.

I just picked up my Z with such a horrible experience from this shop. The entire time, they said the car was done. I go to pick up, car does not rev past 2K RPMs. Just bounces after 2.1K. Idle is even WORSE... to the point where it wants to die. Apparently there was a lot of frustration there before I got there. The brother of the tuner got into a heated conversation with my old man and I because i was not satisfied. Drove the car not more than 1 mile... had to tow it home. Anythin past 2.1K rpms, the needle would just started bounces all over the place.

***SIGH****

I am going to contact UpRev and tell them my experience. This shop is listed on their web page. If you want to avoid this shop in the future, send me a PM and I'll give you the name of it.

I'm considering an E-Tune... Any takers?

I have +1 step colder plugs. It shouldn't be an issue. Tighter gap maybe... but i am getting p0300's at idle on cold starts. Not sure if it is similar to your situation.

Normally I would go copper plugs + 1 step colder with a tighter gap for large boost. Not quite sure for this charger though.

Would be funny if the +1 step colder plugs WERE causing the random misfire. So essentially, the 350z HR spark plugs are 1+ step colder for the 350z DE. The 370z plugs are 1+ step colder for the 350z HR. I kept them on the stock 370z gap... since they are iridium and it is difficult to gap those without destroying the electrode.

The simple way is to use the GTR plugs if you are boosted. Rockauto has the best price on them.

I can tell you that the piping you have on now will make the airflow to the banks very uneven. Should of just bought topgunz A2A kit.

How is this different from Stillen's pipe? My goal is max 400wHP. Topgunz kit is certainly the way to go, but I will get his full S.C kit when I get the 370z next year or so.

In addition, not to throw any negativity, but topgunz Y pipe also introduced uneven flow. There is a 45 degree to straight coupler on one TB, and a 45 degree to 90 degree coupler on the other. The idea is that it is "negligible" since all air converges in this particular Stillen manifold.
-NT