Another SR idle surge issue

[roushman90]

So, redtop SR with GT2560r, Hks step 1 cam, FMIC, bov to atmosphere, still has a stock KA exhaust w/ catco, haven't taken it off yet because it's welded on. Stock injectors, SOHC maf, no tune! Yes, I'm getting it tuned, but I want to fix my idle issue first. It actually runs fine when I'm on throttle through the RPM range but it surges from 2k to 2500k at idle. Before replacing the iacv I noticed it wasn't plugged in so I did so and still no dice. So I replaced the iacv, didn't have a new gasket so I used RTV, which I am considering as a possible issue. After replacing it was the same deal, surging 2k to 2500k. So I tried to mess with the TPS and the CAS, still no dice. Then I tried unplugging the MAF while it was idling, when unplugged it doesn't run much different, which makes me think the MAF or it's wiring is shotty, which would make sense. Still not sure how it could be the MAF only though as it runs fine once on throttle, most times I had a bad MAF in the past it wouldn't go past like 3000k rpm. I'm planning on going tomorrow to the yard to get another SOHC maf and also got a spare SR tps from a friend.

Any suggestions? I want to set the timing to stock spec and set timing and I've looked that up but I'm not sure where to start since I'm having this issue.

Thanks in advance!

[4x4le]

Your getting unmetered air from somewhere after the throttlebody.

[roushman90]

Thanks, I was thinking about smoke testing and removing/reinstalling the intake manifold tomorrow since it's an Isis and I have a feeling the previous owner installed it shittily as there is a lot of ghetto shit going on in the engine bay. Thanks for the reply!

Another thing I forgot about is by bov doesn't seem to be blowing off, just sounds like compressor surge. Need to look into that too..

[4x4le]

Because your not making vac

[ultimateirving]

What you can do is makea boost leak tester and pressurize the system, This will show all leaks.
Also RTV on the iacv probably isnt a good idea. It doesnt form the best seal not to mention if any dripped inside would gunk up that valve pretty bad. The gasket is cheap and you can buy at local auto parts store.

[4x4le]

Personally I have always cleaned the iacv mating surfaces really good and used a tiny bead of rtv to seal it. I prefer grey rtv to gaskets most of the time.

Boost leak testers can be somewhat difficult to detect IM leaks. Also before anyone suggests the propane method for the intake manifold leak it really isnt going to work either because of how the ecu deals with the problem it already knows it is having.

First thing would be to just inspect the TB. If the problem cannot be resolved there take off the IM and inspect it and tear it down and put it back together.

[roushman90]

Because your not making vac

Thanks, I'm thinking you are right

What you can do is makea boost leak tester and pressurize the system, This will show all leaks.
Also RTV on the iacv probably isnt a good idea. It doesnt form the best seal not to mention if any dripped inside would gunk up that valve pretty bad. The gasket is cheap and you can buy at local auto parts store.[/Q
I ended up doing this just using the cap to a can of spray paint, drilled a small hole and forced in my air compressor nozzle. First did from the intake pipe found there was a small unplugged hole, so I plugged it.

Then I pressurized the IM from the throttle body and found that the IACV was leaking like I figured. I decided to just pull the whole intake manifold and replace with real gaskets, clean everything, and all that. Also the nipple on the back of the IM next to the brake booster hose was previously stripped by the looks of it and was barely hanging in by some rtv from previous owner =__= I'm assuming that was also leaking. Man this Isis IM is a PIECE OF SHIT. Fitment, quality, everything, just SHIT.

[QUOTE=4x4le;5326212]Personally I have always cleaned the iacv mating surfaces really good and used a tiny bead of rtv to seal it. I prefer grey rtv to gaskets most of the time.

I tried using the black RTV, small bead, all that, but I think it had the wrong bolts on it, I'm using OEM bolts when I re-install with a real gasket.

Boost leak testers can be somewhat difficult to detect IM leaks. Also before anyone suggests the propane method for the intake manifold leak it really isnt going to work either because of how the ecu deals with the problem it already knows it is having.

First thing would be to just inspect the TB. If the problem cannot be resolved there take off the IM and inspect it and tear it down and put it back together.

I've got it all torn down in the garage, awaiting gaskets. Not sure if I can get them from a local store or I have to order Nissan OEM from frsport.

[roushman90]

What you can do is makea boost leak tester and pressurize the system, This will show all leaks.
Also RTV on the iacv probably isnt a good idea. It doesnt form the best seal not to mention if any dripped inside would gunk up that valve pretty bad. The gasket is cheap and you can buy at local auto parts store.

I did just that, found leaks. What car do I say to get the gasket? IACV and intake manifold to block gaskets? I was under the impression the IACV and intake manifold are "JDM" sr20det specific parts only?

[roushman90]

Bump! Does anyone know of USDM crossover for the intake manifold and IACV gaskets, valve cover gasket!? I'd like to get stuff local so I can get the manifold back together.

Thanks

[ultimateirving]

Roushman, stock intake? i remember buying some gaskets from an SER sentra of 91-93 i think. Take your old gaskets if you have them with you to the store and have a look. I remember when i bought the gasket, the set came with two gaskets one was used the other was not.

IACV gasket i think is the same as well, and if you bring the IACV with you try to match it too.

[roushman90]

Roushman, stock intake? i remember buying some gaskets from an SER sentra of 91-93 i think. Take your old gaskets if you have them with you to the store and have a look. I remember when i bought the gasket, the set came with two gaskets one was used the other was not.

IACV gasket i think is the same as well, and if you bring the IACV with you try to match it too.

Thanks man but I just went ahead and ordered the intake mani, iacv gaskets OEM off FRsport. It's an Isis Manifold.

[roushman90]

Little update, after finding leaks all over the intake manifold and having issues tapping and finding new fittings etc. I also noticed my turbo to ex. manifold hardware was loose as I could move turbo. So my motor is all torn apart now, it's just the block and head in the car now haha, no exhaust or intake. I'm pretty much decided on pulling the motor now, replacing gaskets and front/rear main seals, inspecting clutch and trans since I'm at it. On exhaust side found bolts missing on almost everything and some even no gaskets! Previous owner obviously didn't know shit or was lazy as shit! Dealing with this headache but haven't had time to wrench on my own car as I've been busy doing a fwd Honda clutch for a friend and a L28 swap for my other friend's Maxima.

[cotbu]

Previous owner obviously didn't know shit or was lazy as shit!

The previous owner could have been busy, doing rb25 swaps and Toyota supra clutches!

[roushman90]

The previous owner could have been busy, doing rb25 swaps and Toyota supra clutches!

Whatever, the swap is a total hack job

[roushman90]

So, it's been a while and I finally have an update. I ended up taking intake/exhaust manifolds off and redoing everything, replacing all hardware and gaskets. It's all back together finally and I also redid my vacuum lines with new hose and fixed shotty wiring issues all over. Started it today after priming the fuel and oil with fuel fuse pulled. It started up okay and idle but immediately had to shut it off as my fuel pressure was shooting up to 2x what it should be AND leaking fuel from the line directly on the bottom of the fuel filter, AND on return line from the hard line to the soft line! So we, primed the fuel and started it again to check the fuel pressures quickly. It hit about 300kPa at prime before start, then spiked up to above 400kPa right when we started it. I believe stock fuel pressure is around 230 to 240 kPa so I'm obviously way too high!

My Fpr vacuum source is straight to intake manifold but the boost gauge is T'd off of it. So we also tried un "T"ing the boost gauge from the FPR vacuum and it still did the same thing. The only two things I can think of right now is the fpr is fucked or lines incorrect somehow, which is unlikely since I never messed withing anything but the top connections. The FPR adjusting bolt is already backed out as far as possible with the Isis intake manifold.

Any input would be greatly appreciated, also if it makes any difference, I'm running oem hard lines from the back to front, walbro 255, z32 fuel filter, nismo fpr, 370cc stocks, oem fuel rail, isis intake manifold.

So simply asking, what could cause a doubling of my fuel pressure!?

[ultimateirving]

So, it's been a while and I finally have an update. I ended up taking intake/exhaust manifolds off and redoing everything, replacing all hardware and gaskets. It's all back together finally and I also redid my vacuum lines with new hose and fixed shotty wiring issues all over. Started it today after priming the fuel and oil with fuel fuse pulled. It started up okay and idle but immediately had to shut it off as my fuel pressure was shooting up to 2x what it should be AND leaking fuel from the line directly on the bottom of the fuel filter, AND on return line from the hard line to the soft line! So we, primed the fuel and started it again to check the fuel pressures quickly. It hit about 300kPa at prime before start, then spiked up to above 400kPa right when we started it. I believe stock fuel pressure is around 230 to 240 kPa so I'm obviously way too high!

My Fpr vacuum source is straight to intake manifold but the boost gauge is T'd off of it. So we also tried un "T"ing the boost gauge from the FPR vacuum and it still did the same thing. The only two things I can think of right now is the fpr is fucked or lines incorrect somehow, which is unlikely since I never messed withing anything but the top connections. The FPR adjusting bolt is already backed out as far as possible with the Isis intake manifold.

Any input would be greatly appreciated, also if it makes any difference, I'm running oem hard lines from the back to front, walbro 255, z32 fuel filter, nismo fpr, 370cc stocks, oem fuel rail, isis intake manifold.

So simply asking, what could cause a doubling of my fuel pressure!?

Hooked up the liens backwards on the fuel rail? read through your updates and yes you had a lot of gremlins to fix.
The fuel should go like this Pump>rail>FPR>return to pump

[roushman90]

That's what I thought it could be too but I swear I only disconnected the two lines from the rail and I swear they are in the same spot as before I removed. Only other change I made I can think of is I replaced a non-working FPR gauge for a new FPR gauge in the feed line.

I'll try to throw up some pics of the fuel lines and how they are hooked up

[roushman90]

It turned out to be my most likely suspect, the FPR took a shit apparently. Sourced an OEM Sr fpr from a buddy of mine, slapped it on, and BAM, fuel pressure now sits between 200 and 260kPa. Pretty close to right, keeping in mind I'm not sure how accurate the gauge really is although it is new, but I think it's a fake SARD gauge. Anyways, will be able to drive it tomorrow and really see if everything is all good now. Should be after all this work!

[ultimateirving]

It turned out to be my most likely suspect, the FPR took a shit apparently. Sourced an OEM Sr fpr from a buddy of mine, slapped it on, and BAM, fuel pressure now sits between 200 and 260kPa. Pretty close to right, keeping in mind I'm not sure how accurate the gauge really is although it is new, but I think it's a fake SARD gauge. Anyways, will be able to drive it tomorrow and really see if everything is all good now. Should be after all this work!

Awesome man, lets hope for the best.
FPR would be easy solution and not always the easiest to diagnose