Revs surge
In the last weeks I noticed that when slowing the speed downshifting the gears, i.e. approaching a crossing with a stop in 2nd speed, revs approx 1200 rpm, when I desengage the clutch I notice a little revs surge may be 3-400 rpm, like a wave.
Then the engine runs smoothly idling.
Accelerating the engine without load, it returns quickly to a stable idling, as well during normal shifting uop-down the revs go down as I press the clutch pedal.
The problem appears only slowing down, no other problem
The VAC valve was replaced lat year, approx 5.000 km.
he accelerator cable is properly adjusted, few mm of end play under the accelerator pedal
The 1st idea is to check and clean the throttle and lubricate the shaft, but I'm not sure being idling correct.
May the MAP sensor be responsible ?
THe difference, between the different conditions, probably stays in the inlet manifold pressure or better vacuum.
Then the engine runs smoothly idling.
Accelerating the engine without load, it returns quickly to a stable idling, as well during normal shifting uop-down the revs go down as I press the clutch pedal.
The problem appears only slowing down, no other problem
The VAC valve was replaced lat year, approx 5.000 km.
he accelerator cable is properly adjusted, few mm of end play under the accelerator pedal
The 1st idea is to check and clean the throttle and lubricate the shaft, but I'm not sure being idling correct.
May the MAP sensor be responsible ?
THe difference, between the different conditions, probably stays in the inlet manifold pressure or better vacuum.
by Titanium
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Sounds like an unmetered air problem to me
I would go about the task of trouble shooting, one step at a time - easiest first - to know what (if anything) fixes the problem.
Be sure to have some slack in the throttle cable at rest - *at the throttle body end*.
Ensure the throttle body is not warped by an overtight air filter feed hose, else the throttle butterfly can stick..
Check all rubber air hoses are tight and free from splits.
Check air filter is not clogged with debris.
IACV and Throttlebody have O rings - check for good condition.
Reduce the possibility of poor sensor feedback to the ECU - clean relevant connectors with switch cleaner.
Spraying carb cleaner at suspect joints with the engine running - it can help detect air leaks.
Jeff
I would go about the task of trouble shooting, one step at a time - easiest first - to know what (if anything) fixes the problem.
Be sure to have some slack in the throttle cable at rest - *at the throttle body end*.
Ensure the throttle body is not warped by an overtight air filter feed hose, else the throttle butterfly can stick..
Check all rubber air hoses are tight and free from splits.
Check air filter is not clogged with debris.
IACV and Throttlebody have O rings - check for good condition.
Reduce the possibility of poor sensor feedback to the ECU - clean relevant connectors with switch cleaner.
Spraying carb cleaner at suspect joints with the engine running - it can help detect air leaks.
Jeff
by xad3888
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- David Aiketgate
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- David
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I've been giving this a bit of thought and realise it's similar to a problem I had on my Nissan. I cured it by resetting the base idle position on the throttle position sensor.
Try switching the ignition to position 2, Fully press and release the accelerator pedal 5 times, wait 10 seconds then turn the ignition off. Wait a minute then restart the car.
The only other thing i could think of was big feet!:rofl: I sometimes press the accelerator and the brake at the same time.
Size 11(EU 45) feet to blame!:lol:
Try switching the ignition to position 2, Fully press and release the accelerator pedal 5 times, wait 10 seconds then turn the ignition off. Wait a minute then restart the car.
The only other thing i could think of was big feet!:rofl: I sometimes press the accelerator and the brake at the same time.
Size 11(EU 45) feet to blame!:lol:
David
:shrug:
Last Edit:13 years 2 months ago
by David Aiketgate
Last edit: 13 years 2 months ago by David Aiketgate.
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