Author Topic: My U13 vibrates... and I'm not sure where should i be looking at next  (Read 2807 times)

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Offline altimaSSS

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First of all, a big hello to all of you here and this is my first time posting... although i've been frequenting this site for a while now..  this is a great site and more relevant compared to the american altima sites.. and sometimes i envy those of you driving the Attesa U13 AWD..  :P

i'm from Malaysia and my ride (& my pride ;D) is a 1996 U13 SSS-G AT SR20DE NA, owned it since 2003.

Now to my problem, hope anyone of can give me some idea... Ever since I bought the car, I've been putting up with the rough idle (not erratic but just rough), the whole cabin area was a rattling madness especially when gear engaged on D or R, and more so with AC on. All 3 mounts were shot so i replaced them all.. vibration reduced significantly but it was still there, the next thing was I removed the entire throttle body, gave it a good cleaning using fuel injector/carb cleaner.. only very mild improvement after that..  :(

Feeling frustrated, i drove to a local nissan service centre, they did the power balance test, and checked AAC valve (only from the OBDII reader).. according to them, everything was perfectly alright but refused to investigate further claiming the car is already old hence the vibration.. bla bla..

After some reading, I replaced the distributor cap + rotor, spark plug cables after.. no improvement.

Some symptoms I think worth mentioning are that
1) The engine idles much rougher during very hot days.. it's kinda toned down during cold weather or at night
2) When the AC compressor turns on, the RPM drops momentarily (from 850 to 500rpm) for a couple of secs before stablizing (back to 800-850 rpm).. this also happens when i shift the gear to either D or R. Is this normal ?
3) When the engine is cold, the temperature is around 1k - 1.5k rpm, there is no vibration at all when shifting through D and R.

Guys, what should I do next ?.. Im thinking of cleaning AAC valve and but it seems kinda PITA to get to the screws.. anyone has experience in cleaning it ?
Or, should I be looking at EGR system ? or, is this thing called "Dynamic damper" installed on our front crossmember a possible culprit? :-\

Pls help.. i love the car so much but sometimes little things like this really drive me up the wall...  :(

TIA
Cheers


Offline phreeky

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First of all, it's hard to guage how "rough" your idle actually is - I don't think the SRs, DE or DET, have the silkiest of idles - certainly nothing comparable to a typical straight 6 (i.e. RB engines) or a good V6 (i.e. VQ engines).

I've pulled the whole intake off before, it's probably worth it in that you can give not just the throttle body (which IMO is not gonna be the dirtiest/greasiest part), but the plenum, runners, AAC valve, etc. You can also inspect and possibly replace all those evil little coolant lines hiding back there.

Possibly try this though - plug up the intake so it's completely air tight (i.e. at the end of the hose coming off the throttle body, jam something in there firmly), grab an intake hose off the manifold (maybe the one from the fuel pressure reg or something), and blow into it (or if that doesn't work, put a compressor on it at a relatively low pressure) and listen for leaks. Any intake air bypassing the air flow meter is sure to cause troubles.

Offline wicked

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Hey mate, IMHO, the best way to go about doing this is to do the diagnostics one step at a time instead of guessing what's wrong. Dave_Trx has sent me this link for U13 service manual (for KA24DE), double check if it applies for your SR20.

http://phatg20.net/modules.php?name=Downloads&d_op=viewdownload&cid=69

Go through the in car diagnostics and isolate various systems like ignition, fuel system, mechanical etc. This will save you time and money.

Good luck and keep up posted of your progress.  :)

Offline altimaSSS

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Thanks alot guys for the suggestions.. really appreciate it...  :)
I'll go thru the altima FSMs.. and I've just downloaded the B14 FSM which covers SR20DE

But anyhow, im planning to pull the intake manifold off for some cleaning and that will also allow me to get to the AAC valve, air regulator and those "evil" little hoses  ;D easily... my question is what are the items that i need to have ready before I start working ? i.e. do i need to get new intake manifold & AAC valve gaskets, the hoses, etc... ??

thanks alot  :)


Offline altimaSSS

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Hi all.. im back
I've done a lot reading past couple of weeks and got the following done at the same time:
1. Serviced the IACV unit... it wasnt that clogged as i expected
2. Checked the PCV valve - OK
3. Replaced most of the vacuum hoses including the large one that is going from the air duct to the plenum, power brake booster hose - no leaks

The car runs very much smoother now.. ;D I dont have that weather-sensitive roughness anymore, it's pretty consistent. BUT however I still could not get rid of the idle vibration and the light "thud" when engaging to Drive or Reverse, especially with AC on. The RPM drops as soon as I engage to these gears and due to that, the car starts to vibrate. It gradually comes back up to around 750-800 rpm.

I read that this could be due TPS malfunction or incorrectly set. Once I disconnect the TPS, I dont get that "thud" anymore, it shifts more smoothly but the RPM drops and remains there. What do you guys think ?

I have yet to check the Air Regulator valve the air hoses running there. Would this help ?

Would appreciate any opinion.