Car surges when driving at 2,000 RPM's

Tiny
ALLEN CHRISTOPHER
  • MEMBER
  • 1985 NISSAN 300ZX
  • 3.0L
  • V6
  • 2WD
  • AUTOMATIC
  • 78,000 MILES
When driving and reach about 2,000-2,500 rpm's my car surges. Can't get it to go above 2,500 rpm's. It starts and idles fine. Cleaned MAF no difference. Unplugged TPS and there was no change in how it ran. Not sure where to go from here? Please help.
Sunday, March 31st, 2019 AT 6:53 PM

5 Replies

Tiny
JOETECHPRO
  • MECHANIC
  • 705 POSTS
Hey ALLEN CHRISTOPHER,

Can you get the engine to rev over 2,500 rpm when the vehicle is stationary?

Have you also tried driving with the MAF unplugged?

Do you have the turbo or naturally aspirated version?

Regards, Joe
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Monday, April 1st, 2019 AT 4:49 PM
Tiny
ALLEN CHRISTOPHER
  • MEMBER
  • 14 POSTS
Car will not go over 2,500 rpm's when stationary. I have not tried driving with MAF unplugged. I did clean the MAF. My car is naturally aspirated.
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Monday, April 1st, 2019 AT 4:56 PM
Tiny
JOETECHPRO
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Hey ALLEN CHRISTOPHER,

Please try unplugging the MAF and retesting.

Also i'm sure you already have but please check the air filter.
A limit on engine revs could point to a restricted intake/exhaust.

Also please try and check that you are getting full opening of the throttle. If you remove the air intake watch the throttle plate as you get someone to press the gas pedal. If you have a cable issue or restriction in pedal travel you will also get this issue.

Let me know how you go.

Regards, Joe
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Monday, April 1st, 2019 AT 9:59 PM
Tiny
ALLEN CHRISTOPHER
  • MEMBER
  • 14 POSTS
Air filter is good and there is no blockage in the exhaust system. If I unplug the TPS while the car is running. Should there be a change in the way it runs?
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Thursday, April 4th, 2019 AT 9:25 PM
Tiny
JOETECHPRO
  • MECHANIC
  • 705 POSTS
Hey Allen christopher,

If you unplug the TPS and the throttle position sensor is your issue it will potentially clear your rev limiting issue. This is because it will run on a reference value. With the TPS sensor unplugged the vehicle may still run okay but with a delay in throttle response.

If there is not change then it is likely this is okay.

Have you tried driving the vehicle with the MAF unplugged?

Do you have a catalytic converter fitted?
If so how are you sure you have not got a restricted exhaust?

Have you replaced the fuel filter?
If not please replace and retest.

Do you have access to a vacuum gauge?

Regards, Joe
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Friday, April 5th, 2019 AT 9:31 AM

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