180sx Stutter Issue!

[kjm180]

My otherwise sound 180sx has developed an occasional stutter when accelerating, almost always in 2nd gear around 2-3k revs. Usually stutters once or twice then pulls through absolutely fine, doesn't happen every time I drive it but does seem to be happening slightly more often. Car is stock aside from intake, decat & catback.

First thought was a failing fuel pump? It's stock as far as I know. However i'm not sure this makes sense as recently the cars been driving fine and I got around 28mpg on a trip up to Edinburgh a month or so back.

Should I be looking more towards spark plugs/crap AFM or injector issues? Not really sure where to start, thinking about just ordering and fitting a walbro 255 to see if that cures it.

Only other thing i'm thinking could be connected is I have a noisy EGR Valve - makes the typical humming noise on idle usually after sitting for 30 seconds or longer. I've been told by the local import garage that it's nothing to worry about, it's just chucking crap in the intake.

Anyone who knows their SR20DET's thoughts/input would be greatly appreciated!

[shikari chaos]

Could be so many things but here's some places to start... Coil packs, dirty AFM/MAF, spark plugs, fuel filter, fuel pump, lambda, boost leak seeing as from memory that's roughly the rev range the turbo comes in at. (Standard turbo)

The search button is your friend

[kjm180]

Quick update - potentially may have found the problem!

Spent a good 15-20 minutes checking all the hoses and pipework I could get my hands on in the engine bay and came across several vacuum lines that were worn/split/barely connected to their hoses:







Found a Vacuum line diagram for an S13 SR20DET online and i've circled the two areas shown in the photos:


The first split single hose in the first two pics feeds into the throttle body, but it's hard to tell from the diagram where it comes from. Think it might be from the 3-way-connector on the other side of the engine.

The second knackered one is part of the '3-Way-Connector'. The hose that's got the massive split I think is the one marked '3-way-connector to Air duct' on the diagram.

Think i'll be ordering some new silicon lines!

[immy21]

Fixing boost leaks is part of routine maintenance on our cars
Once you fix the ones you found, pressure test the whole pipework from MAF hose to throttle body. Search out a guide but in a nutshell block at throttle body, idle control valve breather next to oil cap and then hook up a pump on the plastic intake pipe nipple.
Split wing mount intercoolers are common, I can sell you a S15r wing mount intercooler (thinker core) if yours is split.

Stock fuel pumps are known to fail, it's worth while replacing it with a Walbro 255 especially as your boost will be higher than stock.
Follow the hose, should be easy to find were it goes, likely stock blow off valve or carbon canister.

[kjm180]

I figured it would be

When you say split wing mount intercooler, do you mean the pipework/hoses or the intercooler itself? The fender liners are off as of today so i'll have a look at it tomorrow.

Would worn, split and clearly unsealed vacuum hoses account for the stutters and occasional lack of power?

[auz200sx]

I figured it would be

When you say split wing mount intercooler, do you mean the pipework/hoses or the intercooler itself? The fender liners are off as of today so i'll have a look at it tomorrow.

Would worn, split and clearly unsealed vacuum hoses account for the stutters and occasional lack of power?

Yes although the actual metal elbows fracture on the welds.

And yes a boost leak is what I would place my money on then change and regap your spark plugs and test the resistance in your coil packs. Such SOC.com for how to and fix guide.

[immy21]

Nissan had a notice of fractured elbows but what's common is the core separating from the end tanks. For a quick easy check remove and fill with water, my then stock s14a, wmic leaked like a sieve.

[shikari chaos]

Glad to see you've found some obvious issues, hope they resolve it.
If you clean the intercooler with water just make sure you drain it FULLY! My mate had an apprentice not fully drain the intercooler on a freshly built RB. Turns out water doesn't compress like fuel and air.
"I think it works better when the rods inside the engine"

[immy21]

Ouch!
Fair warning. Once drip dried I stuck a hair drier in one end and let it cook.