Fluctuating RPM at idle - Page 2

12-02-2015, 12:33 AM

#26

ironj221

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My issue was indeed the fuel injectors. Sea Foam solved it, so I'd recommend that as cheap option #1.

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05-13-2023, 10:03 AM

#27

Tomo

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I have a similar problem:
The engine is several thousand km after rebuild and recently something like this happened:
The idle speed of the engine began to rise and fall with regularity exactly every second (it didn't seem random) by about 500 revs.
Even when I added gas and kept it at about 4000 rpm. it still happened with the same accuracy.
After less than minute it just stopped (not the engine

) and since then (+-300km) nothing like that happens.

Any ideas?
Should i be worried?

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05-13-2023, 10:23 PM

#28

Left4Dead

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I would look for vacuum leaks
Clean and reset the ess sensor
maybe even bad gas
if not then there are more things after to check but those are first

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Tomo (05-14-2023)

05-14-2023, 04:26 PM

#29

gwilliams6

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Quote:

Originally Posted by Tomo

I have a similar problem:
The engine is several thousand km after rebuild and recently something like this happened:
The idle speed of the engine began to rise and fall with regularity exactly every second (it didn't seem random) by about 500 revs.
Even when I added gas and kept it at about 4000 rpm. it still happened with the same accuracy.
After less than minute it just stopped (not the engine

) and since then (+-300km) nothing like that happens.

Any ideas?
Should i be worried?

RX8 Engine Power Loss

chokes as revs increase
- O2 sensor failure (too rich)
- MAF failure
- MAF disconnected
- e-shaft sensor fouled
- accessory belt fraying
high end power loss (hard fuel cut)
- Rev limit reached
high end power loss (jerky and stumbling)
- Ignition failure
- fuel pressure loss
- e-shaft sensor fouled
high end power loss (smooth)
- Catalytic converter clog
- air filter clog
low end power loss (smooth)
- Engine compression loss
low end power loss (stumbles)
- Ignition failure
- front O2 sensor failure
revs slowly but smoothly
- O2 sensor failure (too lean)
- catalytic converter clog
- air filter clog
sudden power drop at a specific rpm
- Intake valving actuation problem
trouble getting to redline
- Ignition failure
- front O2 sensor failure
- catalytic converter clog
- air filter clog
- e-shaft sensor fouled
- fuel pressure loss
- MAF failure

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wcs (05-15-2023)

05-24-2023, 08:03 AM

#30

sethstephens21

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Quote:

Originally Posted by ironj221

My issue was indeed the fuel injectors. Sea Foam solved it, so I'd recommend that as cheap option #1.

so I have the same issue as you it fluctuates from 750 maybe even lower sometimes back up to 100 to 1200. Would you recommend seafoam to help me with this issue? I have a gutted cat and sounds like an exhaust leak but I have exhaust leaks on my other cars and they never do this. Sorry for years late response but I just found this thread.

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05-26-2023, 02:24 PM

#31

icemantbi

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Check coils. wires and plugs. When I had a rough idle like that, it was time to change out the coils, wires and plugs. That fixed it for me.

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05-28-2023, 08:16 PM

#32

cfletcher592

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Quote:

Originally Posted by gwilliams6

Generating Power at Full Throttle
• Ignition Coils
• Spark Plugs
• Spark Plug Wires
• Engine Compression
• E-Shaft Sensor (ESS)
• Air Filter
• Intake Valving
• Throttle Body
• Mass Air Flow Sensor (MAF)
• Fuel Pump
• Fuel Injectors
• Catalytic Converter (Cat)

Keeping the Engine at a Cruise
• Ignition Coils
• Spark Plugs
• Spark Plug Wires
• Engine Compression
• E-Shaft Sensor (ESS)
• Intake Valving
• Throttle Body
• Mass Air Flow Sensor (MAF)
• Fuel Pump
• Fuel Injectors
• Front O2 sensor
• Catalytic Converter (Cat)

Keeping the Engine at an Idle
• Ignition Coils
• Spark Plugs
• Spark Plug Wires
• Engine Compression
• E-Shaft Sensor (ESS)
• Mass Air Flow Sensor (MAF)
• Front O2 sensor
• Catalytic Converter (Cat)
• Intake Vaccum

im having this issue and I hope I’m lucky I think it’s my cat since it is smelling like gas 24/7 my exhaust has a really bad rattle to it and it also take awhile to pick up speed.

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05-28-2023, 10:32 PM

#33

Loki

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Quote:

Originally Posted by cfletcher592

im having this issue and I hope I’m lucky I think it’s my cat since it is smelling like gas 24/7 my exhaust has a really bad rattle to it and it also take awhile to pick up speed.

Yeah you're going to want to stop driving it and check the cat, and replace if necessary before it takes out your engine.

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gwilliams6 (05-29-2023)

11-26-2023, 06:52 PM

#34

sethstephens21

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Quote:

Originally Posted by icemantbi

Check coils. wires and plugs. When I had a rough idle like that, it was time to change out the coils, wires and plugs. That fixed it for me.

I’ve had the coils wires a plugs changed for awhile, I’m still having idling issues, fluctuating from as low as 500 up too 1500 back and forth. I checked my solenoids for good connection my connectors are fine but idk if the solenoids are good. Anyway to check that without a voltmeter? Also air pump delete was done on this car as well. Comp is good seals are good engine was rebuilt. Just having these idle issues. Wonder if it’s a pcm problem. Guy before me says he went too have it tuned but doesn’t think the guy put a “real” tune on it. Somebody please help me

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11-27-2023, 02:51 AM

#35

gwilliams6

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Quote:

Originally Posted by sethstephens21

I’ve had the coils wires a plugs changed for awhile, I’m still having idling issues, fluctuating from as low as 500 up too 1500 back and forth. I checked my solenoids for good connection my connectors are fine but idk if the solenoids are good. Anyway to check that without a voltmeter? Also air pump delete was done on this car as well. Comp is good seals are good engine was rebuilt. Just having these idle issues. Wonder if it’s a pcm problem. Guy before me says he went too have it tuned but doesn’t think the guy put a “real” tune on it. Somebody please help me

RX8 Engine Power Loss

chokes as revs increase
- O2 sensor failure (too rich)
- MAF failure
- MAF disconnected
- e-shaft sensor fouled
- accessory belt fraying
high end power loss (hard fuel cut)
- Rev limit reached
high end power loss (jerky and stumbling)
- Ignition failure
- fuel pressure loss
- e-shaft sensor fouled
high end power loss (smooth)
- Catalytic converter clog
- air filter clog
low end power loss (smooth)
- Engine compression loss
low end power loss (stumbles)
- Ignition failure
- front O2 sensor failure
revs slowly but smoothly
- O2 sensor failure (too lean)
- catalytic converter clog
- air filter clog
sudden power drop at a specific rpm
- Intake valving actuation problem
trouble getting to redline
- Ignition failure
- front O2 sensor failure
- catalytic converter clog
- air filter clog
- e-shaft sensor fouled
- fuel pressure loss
- MAF failure