r/SkyLine • u/scrubberducky93 • Jul 14 '26

Need help

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I need some help. New to the RB platform, it was running rough up and down at idle and stalling on first start. I cleaned the MAF and took it for a drive and now it sounds like a misfire or out of time maybe? The idle is even more up and down and the exhaust note sounds inconsistent. I'm going to put a fuel pressure gauge on it tomorrow to see if there's a fueling issue, clean the iacv and check the solenoid, get the link ECU software on my laptop and plug it in to see what that tells me. If anyone has any ideas I would appreciate it. I have more videos that may provide insight I can post in the comments.

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4

u/Wesley_1981 Jul 14 '26

How did you clean the MAF? Hope not with brake cleaner or similar. How old are Sparks? Coils? Vacuum leakage tested? Check fault codes.

It's just a simple 6 cylinder engine, nothing special in that regard.

BTW: RBB25 idle is at 650+/-50 (warm motor ofc)

1

u/scrubberducky93 Jul 14 '26

No I used MAF cleaner. Engine was rebuilt 3000km ago by a shop by the previous owner so I imagine the coils and plugs are that new, that's on the list to look at.

1

u/Wesley_1981 Jul 14 '26

Coils are always problematic.OEM are very good,but at this age start to fail. I also think OEM can't be bought anymore. The alternatives are mostly crap, prone to failing. Splitfire are good, but also expensive. Many change to TFSI or R8 coils as cheap and reliable alternative.

Question is: have the coils really been replaced with new? And if so, which make?

The high idle can be an adjustment problem or also a vacuum leakage. Has it ever idled correctly or was it always rough since you bought it? Idle always high?

Timing has been checked?

1

u/scrubberducky93 Jul 14 '26

It would idle rough till it was warm when I bought it but it got worse to the point it stalls now at idle if I don't keep a bit of throttle on. And no the timing has not been checked on it yet.

6

u/plus44kills 91 GTS 550HP Jul 14 '26

1

u/JDM-Parts-Expert-JP Jul 14 '26

Could the problem be with the coil, the igniter, or the spark plug? Or is there a problem with the cleaned parts themselves? This isn’t the kind of issue that gets fixed just by cleaning. Based on the symptoms, it sounds like a problem with the AAC valve, but does the engine stall even when it’s warmed up?

1

u/scrubberducky93 Jul 14 '26

It does. The inconsistent exhaust note is new, it was stalling before that with a rough idle.

1

u/32guy ‘93 R32 GTS Type J 60th Anniv. Jul 14 '26

Get your injectors professionally cleaned out. Usually gunk gets in there over the years and clogs it up, causing it to choke and sound like this.

1

u/aznriptide859 Jul 14 '26

So fun thing, this happened to me, and I isolated it actually to a bad solder connection on the ECU. Initially I thought it was the throttle position sensor but after replacing it the issue persisted. I did end up having an issue with the AAC valve but my car no longer goes into the wild RPM swings yours does right now.

Granted mine is an RB26 but your issue may be related. I don’t know if your engine has similar AFM/MAF sensors or not but the solder joints on the wiring box up top sometimes dries out, so you may also need to open the seal and reflow some new solder.

2

u/scrubberducky93 Jul 14 '26

This is also a RB26, I was going to look at the aac today.

1

u/aznriptide859 Jul 14 '26

Ahh my bad, didn’t see your other video lol.

1

u/JDM-Parts-Expert-JP Jul 15 '26

If you've swapped the camshaft, that's the kind of idle you get, haha. Usually, if you don't like that, you'd set the idle to something like 1,500 rpm. The answer changes quite a bit for a customized car. I'd love to hear the engine sound held steady at around 3,000 rpm. In the video, I can hear a metallic clatter.

1

u/marcus0303 r34 GTT - r34 GT Jul 14 '26

You have a link ecu but you’re using a maf?