Thread: SR20 strange behavior + video!

I am already running out of ideas - please help!

Here's the story - since I bought the car, engine has this strange behavior, mostly noticeable at idle, but also up to 2-3000 rpm. At first I thought it is normal, but then I found out it is just my SR20 out of many others I compared it with. I already put about 30.000 miles on this engine and no matter all mods and everything, it is not getting any better or worse.
Sounds like a misfire, feels like a hesitation, engine/car shakes a bit strange. When you are inside the car, it feels like a minor vibration at non equal intervals.
Car runs great, I don't find it weak compared to others with similar mods.

Changed are:
- MAF, TPS, IACV, O2 - all replaced with new OEM parts
- spark plugs, spark plug wires, distributor cap, rotor - new OEM parts again
- fuel pump, fuel filter (actually all filters), fuel regulator, injectors (checked)
- new battery, alternator works great, all grounds are checked, new belts

ECU does not throw any codes. I haven't replaced the knock sensor and the coolant temp sensor. Engine does have a great compression (I run dry and wet test few days ago and all cylinders shew 12bars with the S4 cams). I am neither losing coolant, nor oil. Different fuels and additives don't help. Using stock *.bin and set up as per my signature. (This issue is different than the S4 cams loop!).

ny5speed gave me an idea to check for injector leaks. I will try that soon.
Question is what else this might be. I am not sure if a camera will capture this issue but if needed, I can make a video.

Thanks,
Martin

so you have a Nistune with the stock SE-R .bin?
if thats the case i will say that you check your afrs, since you have I/H/E + S4cams the problem might be tunning...

ditto

Sorry for my delayed answer but I was busy at work.
Yes, I have Nistune RT but using stock P10 10:1 UK SR20 bin (64kb).
I've checked AFRs, even played with them but nothing actually happens.

As I was told, I checked the whole intake system for leaks, spraying carb cleaner. RPMs didn't change a bit no matter where and how much I sprayed, so I assume I have no leaks, including injector leaks.

Here is a low quality video from my nokia. However, you can notice how the timing jumps when engine at idle. The RPM field also does vibrate. Funny is that when I set the engine at some rpm, the timing reading matches the value as per the timing table in the *.bin file. But when engine idles, the crazy jumping starts and the vibrations/misfires as well:
http://vimeo.com/13804125

Any suggestions?

you can watch the air fuel ratio as well while doing the spray test, some times leaks are so small you will not see an idle jump, some leaks also close up as the engine heats up, usually when they are that small they won't cause a huge running concern

what kind of spark plug and what kinda gap are you running?

Spark plugs are NGK BKR6EIX, gap is 0.9.
I have a spare set of copper BKR6EY spark plugs which I tested from gap 0.7 to 1.2 and tried them every time with no result.
I don't have a wide band o2 or afr gauge to run such test. I assume that if there is a leak that small that won't cause any rpm change, then this shouldn't be the reason for having that sort of idle problem I have.

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I think that would be running lean idle, just go inside the bay and bend the gas line coming from the FPR, that will raise your pressure and must show you a way to go

That makes sense to me - will try it in the next few days and will let you know if it changes a thing.
Thanks!

I think you have a problem with the Nistune computer or perhaps your consult cable, who installed the Nistune board for you, what consult cable are you using? Looks like you got some major delay along with funky data going on there in that lil video, diff somehting isn;t right.