Yet another misfiring CA

[skyshack]

Had a bad but intermittent misfire for some time. Only on part throttle with vac, it needs a lot more throttle and boost gauge will show around 0bar and even show a few psi at ~2.3K rpm. Open the throttle more and it makes boost, misfire clears up and it takes off. It's better from a very cold start, sometimes I can go 10 miles to work without a trace of it, other times it will show up part way though warm up.

Mode II it keeps showing lean or even fails to go to closed loop.

New plugs.
Checked comp 10.2, 10.5, 10.5, 10.8.
Checked TPS / Idle switch.
Checked AFM was clean.
Checked AAC etc.

Inlet Leak test, 5 psi > 2 psi in about 15 secs.

Anyone with an engine on a stand? Should I be able to see this much inlet gasket under the plenum / inlet mani joint?

Inlet 1 peeping out


Inlet 2 looks bad


Inlet 3 has some staining


Inlet 4 has a lot of stain

[Mitch]

Pop across and I can smoke test it for you if you like?

[skyshack]

Thanks,

MOT said it made black smoke on acceleration.

Has poor fuel consumption.
Tail pipe sooty.
Yet plug nose is very white while body is black.

[Jonny Wilkinson]

A leaking inlet mani would make it run lean on vac and rich on boost, wouldn't it ?

That would explain the black on acceleration and white tips as its mostly driven on vac.

What's your vac reading at idle ? It should be around -18 inHg.

[R3K1355]

Have you tried the old carb cleaner/wd40 spray around the inlet gasket to see if it effects the idle?

[ANDY black s13]

Gasket don't look right to me dude,I got some pics of my forged CA that someone else built with OE nissan gaskets to my knowledge
from my FB as not got photoplop or any of that shinizzle
https://fbcdn-sphotos-d-a.akamaihd.n...60486782_n.jpg
https://fbcdn-sphotos-g-a.akamaihd.n...38956122_n.jpg
https://fbcdn-sphotos-f-a.akamaihd.n...76882990_n.jpg
https://fbcdn-sphotos-e-a.akamaihd.n...82238224_n.jpg
No major gasket overlap or hang out like yours looks like matey
Ignore the Bit's of Blue Holymar hanging out from the joins,Its all coming off for another Inlet Plenum I making atm

[ANDY black s13]

Thanks,

MOT said it made black smoke on acceleration.

Has poor fuel consumption.
Tail pipe sooty.
Yet plug nose is very white while body is black.

No idea on your stage of tune or engine spec,But they look like Grand Canyon size plug gaps, might just be the pictures?
But they look massive even for a stock spec CA to me

[Jonny Wilkinson]

No idea on your stage of tune or engine spec,But they look like Grand Canyon size plug gaps, might just be the pictures?
But they look massive even for a stock spec CA to me

They're iridium plugs so they'll be pre-gapped. I guess he could try swapping them for some cheap but reliable BCPR7ES coppers

[skyshack]

Gasket don't look right to me dude,I got some pics of my forged CA that someone else built with OE nissan gaskets to my knowledge
from my FB as not got photoplop or any of that shinizzle
https://fbcdn-sphotos-d-a.akamaihd.n...60486782_n.jpg
https://fbcdn-sphotos-g-a.akamaihd.n...38956122_n.jpg
https://fbcdn-sphotos-f-a.akamaihd.n...76882990_n.jpg
https://fbcdn-sphotos-e-a.akamaihd.n...82238224_n.jpg
No major gasket overlap or hang out like yours looks like matey
Ignore the Bit's of Blue Holymar hanging out from the joins,Its all coming off for another Inlet Plenum I making atm

I'm sure those gaskets are only about 6-8mm wide on the flange joint and I've got what looks like 6mm hanging out.

Seen Mitch. Couldn't get smoke out of the manifold. Didn't go though breather system and come out the filter either - PCV blocking flow? - like it should.

No idea on your stage of tune or engine spec,But they look like Grand Canyon size plug gaps, might just be the pictures?
But they look massive even for a stock spec CA to me

Stock gap 1.1mm. Fine wire plugs will take a bigger gap.

Blueflame 3" exhaust. Filter.

Swapped coil packs.

Got spare AFM, ignition amp, dropping resistors, temp sensor, TPS and CAS to go at. All except the temp sensor are easy to swap over. After that it's take plenum off at weekend and with ign on turn CAS to check each injector gives a good blast and doesn't drip.

I ran to work and back with a fuel pressure gauge cable tied to the wiper, it moved in sync with the vac/boost gauge. Sock on pump inlet probably needs a clean.

[Jonny Wilkinson]

I swapped the ETS on mine at the weekend without removing anything else. Its a bit fiddly and would have been easier if I had had a 19mm socket that is "medium" long (which I didn't)

I cracked the ETS loose using a 19mm ring spanner. This was a bit filldy but I only needed to manage a quarter turn. Then put a 6-sided 17mm socket with an extension bar but no ratchet over the plastic connector and unwound it gently using my fingers. Refitment was the opposite of removal

[R3K1355]

I'm sure those gaskets are only about 6-8mm wide on the flange joint and I've got what looks like 6mm hanging out.

Is it possible to install the gaskets upside down, they fit but also hang low and block the port abit?

I remember removing some that were installed like that off my own car, but I can't remember if it was the S13 inlet or exhaust gasket, infact it could have been on my MX-5

Refitment was the opposite of removal

Loose 3 pints of blood and swear profusely?

[ANDY black s13]

I'm thinking the the plenum gasket is upside down,the ports are off-set to the studs not central and it will locate on the 4 center studs
I don't think any of the other studs will locate though, I'm surprised the smoke test revealed nothing as must be sealing on 1/2mm of gasket
And its overlapping the ports a fair bit most likely, the gasket is 6.90/7mm around the ports so I would pull the plenum
as that would bug the hell out of me if it was my engine,your have to pull the plenum to check injectors so no biggie job wise

[ANDY black s13]

.

[skyshack]

Is it possible to install the gaskets upside down, they fit but also hang low and block the port abit?

I remember removing some that were installed like that off my own car, but I can't remember if it was the S13 inlet or exhaust gasket, infact it could have been on my MX-5

Gasket is visible in right place at top of joint. I've had the car a few years, done 40K of the 120K. It hasn't always done this.

[Jonny Wilkinson]

Gasket is visible in right place at top of joint. I've had the car a few years, done 40K of the 120K. It hasn't always done this.

Have you done any other mods that might have increased the manifold pressure and caused the gasket to blow through ?

[skyshack]

Have you done any other mods that might have increased the manifold pressure and caused the gasket to blow through ?

There may have been a couple of washers.

But it was doing this before the Blueflame was fitted. The Unipart peashooter had rotted out and would have failed the MOT and the BF was all I had to fit. Last year on re-test I got ZERO emissions, the guy shoved the probe so far in he poked a hole out the front of the back box.

[Jonny Wilkinson]

There may have been a couple of washers.

Do you mean a FBU ?