RPM fluctuation when out of gear

wipdesigns

Member
Messages
16
When commuting to and from work I don‘t see the issue.

I went the long way home tonight to stretch it‘s legs but half way through I noticed that while driving in traffic when I eased off the accelerator the car didn‘t coast in gear smoothly until I pressed the accelerator again, you could really feel the engine stop coasting and start to slow down the cars momentum, then when accelerating again it wasn‘t as smooth to accelerate as if I was pressing and depressing the accelerator sharply., when I was pressing it smoothly.

Shortly after this I pulled up at a junction and the revs bounced from 1.5krpm to 2krpm over and over..

Any advice on this issue?
 

SamDC5

Advanced Member
Messages
1,433
Sounds like a clogged IACV (Idle Air Control Valve)

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wipdesigns

Member
Messages
16
That‘s two votes for the IACV, only happens when really warmed up at this stage, not just general commute.

SamDC5 said:
Sounds like a clogged IACV (Idle Air Control Valve)

Sent from my SM-G955F using Tapatalk
 

wipdesigns

Member
Messages
16
That‘s two votes for the IACV, only happens when really warmed up at this stage, not just general commute.

SamDC5 said:
Sounds like a clogged IACV (Idle Air Control Valve)

Sent from my SM-G955F using Tapatalk
 

Lynchdc5

Member
Messages
33
Mine does the exact same . And I have fitted a.brand new iacv from honda at 200 pound !

I'm still trying to figure it out. Really bugging me at this stage .
 

wipdesigns

Member
Messages
16
Gutted, makes me wonder what it could possibly be if you‘ve replaced the entire part not just cleaned it :(

Lynchdc5 said:
Mine does the exact same . And I have fitted a.brand new iacv from honda at 200 pound !

I'm still trying to figure it out. Really bugging me at this stage .
 

kyle'87

Advanced Member
Messages
389
First thing is to check for a vac leak. Take off everything before the throttle body and start the engine, now hold your hand over the throttle body inlet to make a seal and the engine will cut out shortly. If the engine doesn't it means it is getting unmetered air from somewhere which is causing the bouncing revs.

Note: Do this when the engine is cold as the throttle body conducts heat so if doing form hot will burn your hand.

Let us know what you find out.
 

wipdesigns

Member
Messages
16
Thanks for the feedback and sorry for the delay in replying I‘ve not been very well of late.

I‘ve cleaned out the iacv and the throttle body plate and surround. I‘m hoping to give it a try over the next couple of days when my health is better. I‘ll let you know most likely next week.

I tried the hand over the intake last week but quite honestly felt like it would have ripped my hand off before it stalled out and didn‘t want to try covering the intake with anything else in case it sucked it into the intake!

kyle'87 said:
First thing is to check for a vac leak. Take off everything before the throttle body and start the engine, now hold your hand over the throttle body inlet to make a seal and the engine will cut out shortly. If the engine doesn't it means it is getting unmetered air from somewhere which is causing the bouncing revs.

Note: Do this when the engine is cold as the throttle body conducts heat so if doing form hot will burn your hand.

Let us know what you find out.
 

kyle'87

Advanced Member
Messages
389
wipdesigns said:
Thanks for the feedback and sorry for the delay in replying I‘ve not been very well of late.

I‘ve cleaned out the iacv and the throttle body plate and surround. I‘m hoping to give it a try over the next couple of days when my health is better. I‘ll let you know most likely next week.

I tried the hand over the intake last week but quite honestly felt like it would have ripped my hand off before it stalled out and didn‘t want to try covering the intake with anything else in case it sucked it into the intake!
No problems.

Try not to clean the throttle body too well, those black marks on the walls and plate are there to seal the throttle plate. A lot of people clean them off and air can now get past when closed.

I know what you mean with hand over the intake, be brave hahaha, give your hand a slight cup to get the rigidity in it and whack it right over. The car will stall soon and if it doesn't start to look for that Vacuum leak using other methods you can find on Youtube (smoke tests etc).
 
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