Help Needed! Revs drop to sub 800 after warm up

[CrazySx]

Nice to meet you today Dan!

The drive home was a bit of a revelation, having driven yours there is something not quite right about mine too lol

On reflection yours feels much faster and nicer to drive, so thank you for letting drive yours

Hey Mark, the pleasure was all mine. It was VERY kind of you to drive all the way up here and spend a lovely summer's day helping me poke around my motor Lol!

If you ever need any favours.. well I owe you one

My car is lovely when it's not playing up. But it's like a marriage isn't it. After 12 years of marriage to the s14a every other Silvia starts to look attractive because you know every corner of the wife hahahahahahaha!

Good to get your perspective however, Nice to hear some compliments on the car. Makes a change from the Mrs telling me it's an old banger and to stop spending money on it and get rid Lol!



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[CrazySx]

Oh and I think yours Silvia is very nice too! Keep up the good work

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[CrazySx]

A thought just occurred, and obviously this has to be evaluated using a fuel pressure gauge, but do the FPR's (Fuel Pressure Regulator) fail on these cars? and if so, where are they located?

[Hugh Janus]

the FPR is on the end of the fuel rail.

if you look at top the throttle body then look backwards (towards windscreen) about an inch there on the side of the inlet manifold body should be a small black thin pipe (from a nipple...on side of inlet) that should be almost 90 degree curve, the end of the pipe goes to the FPR

[CrazySx]

the FPR is on the end of the fuel rail.

if you look at top the throttle body then look backwards (towards windscreen) about an inch there on the side of the inlet manifold body should be a small black thin pipe (from a nipple...on side of inlet) that should be almost 90 degree curve, the end of the pipe goes to the FPR

Thanks Mark, i will get a Gauge on there first to see if there is a pressure drop.

[CrazySx]

Hi Guys,

Thought I would give you a quick update on this. Basically the problem persisted so I called Horsham Dev to book the car in but they said they may need the car for more than a day and it's too far for me to travel so had to think about it.

The i called garage D on the advise of a few people on here and they are closer. The dude on the phone was really forthcoming but said he can't fit me in til week after next at the earliest. I need to get the car sorted before Jap Show.

What has transpire from speaking to both is that the both said it sounds like a boost leak.

So.. I decided to boost test again.

Click here for more details.
http://www.sxoc.com/vbb/showthread.php?t=592893

Moral of the story is I found a few little leaks but the one that could be the cause was a boost leak in the inlet manifold.

Took it apart and and ran a bead of PU sealant round both sides of the gasket and bolted it back up. Will give it a couple of days to set and then test it again.

In the process I burst my elephant trunk lol!!!

I just found the manifold leak at 1bar and then heard a massive bang lol! It was blown up like a balloon in all fairness.

If anyone has a spare one or a nice flash metal one please do get in touch.

I will let you know how it goes.



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[jon200]

Which bit of manifold is leaky? Top to bottom gasket?


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[CrazySx]

Which bit of manifold is leaky? Top to bottom gasket?


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Yep top half to bottom half. The flat gasket. At 1 bar there were soap bubbles in more than one place around that area. Wish I had taken pics now, but it's about the time my trunk went bang so had bigger things to worry about hahahahaha!

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[jon200]

I had a split in my gasket when it came off the remove the injectors, also the iacv one was split. Fingers crossed all is well.


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[CrazySx]

I had a split in my gasket when it came off the remove the injectors, also the iacv one was split. Fingers crossed all is well.


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No splits in mine, it's just a flat bit of metal so sealed it up with PU sealant. I wasn't likely to get a Nissan one in a hurry and don't like leaving things in bits for too long as you tend to forget where things go or bits go missing Lol!

My IAC has a hairline split in the gasket too.. might seal that up tomorrow too

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[JC SX]

As said above I'd check maf, replace with a known good one and test, I'd also check all spark plugs for fouling or any difference in colour. Have you tried replacing coil packs? I'd maybe try to borrow a set of four coils and an s14a maf and see if the problem arises. Someone local to you could lend?


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[CrazySx]

As said above I'd check maf, replace with a known good one and test, I'd also check all spark plugs for fouling or any difference in colour. Have you tried replacing coil packs? I'd maybe try to borrow a set of four coils and an s14a maf and see if the problem arises. Someone local to you could lend?


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Hey JC,

I have done all of the above. Checked the plugs again at the wknd and they look normal. Changed the coils with known working ones and then went the whole hog and did the VAG conversion.

Changed the maf twice. I have 4 now Lol!!

Also change the fuel filter, lambda, IAC, decommissioned the charcoal cannistor and a few other things I have forgotten about..

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[CrazySx]

Ok I think I have found the culprit. So I boost leak tested the whole system again. Found a number of little leaks. Found one in the manifold where it splits so sealed it up. Then found one under the manifold. It was a vac line that I had blocked off, but was leaking air.

With all of that sorted I pressurised the system again to over a bar and the dump valve was leaking of air like a good un! From here:


Replaced it with a cheap ebay one (for now) and it's 100% air tight now!!! Yay!!

Even holds 2 bar with no leaks!!!

I let the car warm up for ages and the idle remained steady. Just need to take it for a good blast now and enjoy



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[CrazySx]

Ok, I can confirm it was the dump valve. Now that I have got rid of all my minor boost leaks and changed the dv (cheap ebay one for now) the car drives the way I remember AWESOME!!!!

I have bought a GFB Mach 2 dv which should be here on Tuesday. See my project thread for more updates

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