DEAD SPOT @ low IDLE AND SPEED

ONLY for ADVANCED technical discussion about the 240sx!
enjoilife
Posts: 7
Joined: Mon Jun 15, 2009 4:53 pm
Car: 1990 nissan

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Im not sure if this is the right place to start this thread, new here, so go easy on me. :ohno:

Anyways, I have a 1993 240sx coupe SE. I got it smog the other day, but could not even finish the first test. Which was the 15 mph constant speed test.

The car idle perfectly fine, NO CHECK ENGINE and i just sea foam the car and did a full tune-up. Car has 300zx fuel filter and K&N drop in filter.

Problem of the car is that, it cant maintain a 15 mph speed steady w/o the RPM dieing then jumping back up. This problem occurs between 2K to 3K RPM. The smog tech said it could be a faulty TPS, or injectors. That there is a "deadspot" some where in the throttle. But he was not sure himself. Before i go a head and take a part my only daily, thought id get some ideas from here.

After the 3K rpm and i punch the car, or drive normal @ higher RPM, it seems to not have a problem. :wtf2:

I got injectors ready if that's the problem. But would like to hear more ideas. Thanks :dblthumb:


Did i mention ive been searching for 5 days and the only one similar to my problem is an automatic and she got her problem fix by just replacing and re-gapping all sparkplug, and i did all that already.


enjoilife
Posts: 7
Joined: Mon Jun 15, 2009 4:53 pm
Car: 1990 nissan

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Nothing?

loyalone
Posts: 47
Joined: Sun Jan 10, 2010 5:10 pm
Car: 93 240sx ka24de 5spd
86 Nissan 720 Kingcab for sale

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how does the motor sound in neutral at part throttle? does it surge? or is it smooth?
i have a similar problem on a 94 Nissan pickup it would clear up if i put the throttle to the floor for a split second then held steady.

enjoilife
Posts: 7
Joined: Mon Jun 15, 2009 4:53 pm
Car: 1990 nissan

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Well it idles fine.. at part throttle, it would climb but theres a point between 1200-2500RPM where it would completely drop below it 1000RPM then would shoot back up as if it tries to retain power back up... but when i floor it from dead stop and shift gear past 3000K i wouldnt feel anything. It only happens on normal driving, which thats why it really annoys me.

User avatar
EnjoiNismo
Posts: 1127
Joined: Tue Jul 24, 2007 5:18 pm
Car: 93 240sx
Location: AZ

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It feels as if its losing power and bogging at lower speed?

however at high speeds its okay?

enjoilife
Posts: 7
Joined: Mon Jun 15, 2009 4:53 pm
Car: 1990 nissan

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yeap.. exactly..

got any ideas'


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