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Discussion Starter · #1 ·
almost every time i cold start my car (which is a 1991 NX2000), it wont die, but it sounds/feels like it's going to. when i let it idle, it'll go from 800 RPM's, and dip repeatedly down to around 500. it definitely isn't supposed to do that. and once the car warms up it's fine. it idles around 800 RPM's like it's supposed to, and if i start it while the engine is warm, it's fine. any ideas what that could be? i'm thinking idle control valve or something to that effect, but i'm not so car savvy that i want to start my own diagnosing quite yet.
 

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I would check the PCV valve on the passenger back side of the valve cover. It is a screw in part and easy to change out. I had an issue with cold starts, and that valve was clogged.
 

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hey my car dose the same at start up. but i also bogs down sometimes under acceleration and somtimes back fires..just wondering if yours did that too.
 

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Discussion Starter · #4 ·
no, mine doesn't do that... mine's lacking some power on the low end... and prolly on the high end too, but i'm pretty sure that's cause there's an exhaust leak. at least, it sounds like there's one...
 

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Discussion Starter · #9 ·
it very well may be a vacuum hose leak. i hear a lot of whistling when i accelerate. almost like a turbo spooling up, but i have no turbo. that, combined with the sound of the exhaust leak makes me think possibly a crack or something in the manifold, and the whistling maybe air escaping from the crack? i havent had the time to take the heat shield off the manifold yet to check... i want to do that soon.. and as far as the vacuum hoses.. i keep periodically checking for a loose one or something, maybe cracked... but i cant ever find one...
 

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Here's a good diagnostic procedure to find vacuum leaks on any vehicle:
http://www.ehow.com/how_5584244_auto-vacuum-leak.html
Pinpointing a vacuum leak can be difficult, since so many of the devices used on today's cars and trucks are vacuum-operated under the hood, and deciding where to start can be confusing. The most common sources of vacuum leaks are vacuum hoses and intake manifold gaskets. The key to pinpointing the cause is to identify the general area under the hood where the vacuum leak is, and finding its cause.
Difficulty: Moderate
Instructions
Things You'll Need:

* Can of carburetor/intake cleaner

1.
Step 1

Do a visual inspection. Check all of the under hood vacuum hoses, connectors and plastic lines for softening, collapsing and cracking. Pay particular attention to the PCV and evaporative emissions systems. The vapors in these two systems attack rubber, and are a common source of vacuum leaks. Replace any softened, deteriorated, or collapsed hoses and connectors. Big leaks can be identified by a tell-tale hiss. If no visual leaks are detected, move to the next step.
2.
Step 2

Slowly spray carb/intake cleaner around the intake manifold and throttle body, with the engine running. If the vacuum leak is one of these gaskets, the spray will restore the air-fuel ratio momentarily and the engine speed will change as a result. Go slowly and allow the engine speed to stabilize before moving to the next area. Any place that the spray causes a change in engine speed is the source of a vacuum leak. Avoid spraying the cleaner directly into the intake tract. This will give a false indication of a leak. If no leaks are found during this test, move to the next step.
3.
Step 3

Pinch each vacuum hose closed until the one that changes engine speed is found. Begin at the throttle body and eliminate them one by one, then move to any remaining vacuum trees (these are multi-ported vacuum tees that supply vacuum to more than one device) located on the manifold, firewall or fender well. Pay particular attention to the large vacuum hose attached to the brake booster. A sticking valve or ruptured diaphragm in the booster is a common vacuum leak source.
If no vacuum leak is found during this test, there are no vacuum leaks.


Read more: How to Find an Auto Vacuum Leak | eHow.com http://www.ehow.com/how_5584244_auto-vacuum-leak.html#ixzz0uhQ7fezY
 
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