240SX stutter till 2600 RPM

Post by **SeeingWhite** » Sun Nov 30, 2003 4:10 pm

For the past few months I have been having a new problem with my '92 240SX, 4 cyl manual trans. Once the car warms up, the car stutters and/or stumbles until it reaches between 2600 and 2700 rpm; it takes longer to get to 2600/2700 because of the stumbling (in other words there is hardly any power.) Once it reaches this point, the stutters disappears completely and the engine takes off like normal until I change gears. Then the same things repeats. However, If I change gears at a high enough RPM, then the next gear will be above 2600 RPMs and so the problem is not present.

The stutter/stumble ONLY occurs from when I put the car into gear through 2600/2700 RPM.

Thoughts and ideas please?

(One more thing. The car idles OK, but if I dont really get on the gas before putting it into gear, then the stutter/stumble will cause the car to stall.)

Post by **NISTECH** » Sun Nov 30, 2003 4:10 pm

start by checking your timing. also listen for any vaccum leaks at idle.

Post by **SeeingWhite** » Sun Nov 30, 2003 4:10 pm

Nistech -- thanks for the reply. I think the vacuum is fine, I will have to have the timing checked, though.

Btw, the check engine light NEVER comes on.

Post by **NISTECH** » Sun Nov 30, 2003 4:10 pm

does the light come on when you turn the key to the on position when you go to start it?

Post by **Altiman94** » Sun Nov 30, 2003 4:10 pm

engine grounds?

Post by **SeeingWhite** » Sun Nov 30, 2003 4:10 pm

NISTECH wrote:does the light come on when you turn the key to the on position when you go to start it?

NISTECH, yes the orange light below the check engine symbol does come on when the key is in the ON (not start) position. Isn't the light supposed to on in the ON position?

-----

ALTIMAN94 -- engine grounds?

Post by **NISTECH** » Sun Nov 30, 2003 4:10 pm

yea when the car is not running. was just curious if it was working. hows the timing?

Post by **SeeingWhite** » Sun Nov 30, 2003 4:10 pm

Thanks again for your replies.

I will try to get the timing checked today or tomorrow. Just my two cents, though, it really seems like an exaust/emissions problem... almost like a sensor is getting a bad reading until the rpms get up to 2600/2700. I could be way off, but I just have a feeling that the culprit lies somewhere in the emissions system.

(One other thing to note -- the exaust does smell funny after I exit the car after a drive; I dont smell anything inside while driving though. It doesn't smell like rotten eggs, not like gasoline, or even like burning oil, but something strong. Can't place my finger on it... maybe like bad gas, but not quite(?). Sorry I cant give you a better description on the smell. I use high quality gas, btw.)

Post by **NISTECH** » Sun Nov 30, 2003 4:10 pm

well the timing could play a big part in accel problems off the line if the chain skipped a tooth. but would also take a good look at airflow meter harness and connection and your coolant temp sensor connection. could just be running really rich just because of corrosion in the coolant temp connector. just some ideas for ya.

Post by **p00t** » Sun Nov 30, 2003 4:10 pm

Altiman94 wrote:engine grounds?

i agree with altiman, i had very small stumble problems when i first got my car. new engine grounds cleared it up, one of the biggest problems with the 240sx grounds from my experience are:

1. rear engine to chassis ground, this is a real flimsy wire and it's often corroded, sometimes completely gone on high mileage cars. it goes from the corner of the valve cover to the firewall right under the brake lines coming from the master cylinder (right side if your looking from the front of the car)

2. the chassis to battery ground often gets corroded. basically the line from the engine goes to the battery tray (chassis ground point) then to the battery terminal. the ground is just a 2" section of exposed copper wire crimped against a bolted bracket. I highlighted that because if you have ever seen the statue of liberty or a copper shingled roof you know what happens to copper exposed to the elements.

those are your two main colprits, but also check your MAS ground, it is very important it gets a clean ground or the readings will be skewed.

I also might add that i have very slight power dip at about 2600rpm, redoing the engine grounds helped but i never could get rid of it. Its small that people riding with you wont notice it, but if you drive the car everyday youll notice. This probably isnt your problem but might as well state as much relavent info as possible.

Post by **SeeingWhite** » Sun Nov 30, 2003 4:10 pm

Okay, Guys... Here's an update.

First, thanks for all who have read/replied to my post.

I had the timing checked, and it is perfect (right on spec.)

Second the grounds all look okay. They all seem to be making good a connection.

Third, the wiring harness to the MAF looks good, too. It looks pretty new and clean, so new that I think it must have been replaced around 60-80K before I purchased the vehicle (125K now).

Today I checked the oil and it was about 1.25 quarts low! I changed the oil about 2000K ago, and it is not leaking underneath. Also, while idling in my parking space, the car does reek of gasoline in the exhaust -- not oil. I think it must be running rich somehow.:help

(AGAIN... the stumbling only starts once the car has been warmed up)

Post by **NISTECH** » Sun Nov 30, 2003 4:10 pm

check your coolant temp sensor connector for corrosion.

Post by **SeeingWhite** » Sun Nov 30, 2003 4:10 pm

NISTECH,

Okay, I'll check the sensor... are you talking about the one described here:

http://www.240sx.org/faq/artic...r.htm

Thanks

Post by **NISTECH** » Sun Nov 30, 2003 4:10 pm

yep thats the one

240SX stutter till 2600 RPM

240SX stutter till 2600 RPM

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