Idle Issues after Rebuild


DV8

DV8

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Hi Guys,

just finished the rebuild with some massive help from a good mate of mine (write up soon)...

All went really well, done most of the running in process and engine is feeling amazingly strong. :nice:

Just having some issues with the idle at the moment (i swear I attract idle issues)... Keeps dropping revs when I come to a stop and sometimes it dies completely.

Am running a JDM B18C-R P73 ECU so my guess is either the TPS or Idle control valve... already checked the TPS and that's been set to 0.45v (is this right for the P73... or should it be 0.5v). Also checked all the vacuum lines.

Tempted to try the spoon ecu but seem like something else TBH... might swap the IACV for a spare I have and see if that sorts it.
 
Are all coolant hoses hooked up correctly ? Are all hoses hot when engines hot (no air locks) ?
 
More than likely the IACV is a little sticky, try cleaning it out.
 
check your plugs are all tight after the rebuild.
 
Rich777 said:
Are all coolant hoses hooked up correctly ? Are all hoses hot when engines hot (no air locks) ?
Click to expand...

Yeh all the hoses are nice and hot... will double check though :nice:

Vtec6000 said:
More than likely the IACV is a little sticky, try cleaning it out.
Click to expand...

Will try swapping it with my spare one... see if that helps :nice:

tama666 said:
check your plugs are all tight after the rebuild.
Click to expand...

Will double check those too... :secret:
 
Right... checked all the above and still not managed to sort it :(

Swapped IACV with a spare and no luck... checked all the plugs and they are fine too.

No trapped air in the system either, I'm a bit stumped.

Tried another ECU too to check it's not that.


When the engine is hot it seems to idle a bit low which make me think the TPS may be faulty or set to the wrong voltage.

On a positive note covered around 50 miles now and the engine is amazing... can't wait to see what it's like in the VTEC :D
 
You might need to raise the base idle speed on throttle body. Unplug the IACV and turn idle screw on throttle body till idle speed rises slightly then plug back in IACV and reset ecu. Also worth checking your distributor timing if you haven't set it already. Should be set to 16degrees btdc with service connector bridged.
 
I had the exact same prob with a stock B16B i fitted. Turned out to be the distributor position was a few mm out. Just find a timing light and set up correctly. Sorted mine in about 2 mins.
Dont forget if you adjust your cam gears it will throw out your ignition timing.
Dunx
 
Thanks for all the replies guys... will check the timing first and then adjust the idle if needed. :)

Hopefully that'll cure it.
 
Just had the Timing Checked... its spot on... LOL

I'm not too keen on adjusting the idle as this only seems to be an issue when hot and it idled fine before the rebuild (what I mean by that is that nothing in essence has changed).

Does anyone know of any checks we can do to tests the TPS is in good working order?
 
Once your getting .4-.5 volts with throttle closed and 4.5-5.0volts with throttle fully open the TPS sensor should be fine.
Perhaps your 02 sensor is bad, which is causing the car to run really lean when running closed loop. Try unplugging it next time when car is hot and see how it behaves, you'll get a cel code but don't worry about that.
 
Vtec6000 said:
Once your getting .4-.5 volts with throttle closed and 4.5-5.0volts with throttle fully open the TPS sensor should be fine.
Perhaps your 02 sensor is bad, which is causing the car to run really lean when running closed loop. Try unplugging it next time when car is hot and see how it behaves, you'll get a cel code but don't worry about that.
Click to expand...

Cool will give that a go... its the one on top of the throttle body isn't it?
 
DV8 said:
Cool will give that a go... its the one on top of the throttle body isn't it?
Click to expand...

no that's your map sensor. The 02 sensor is in exhaust manifold, near collector where manifold bolts to cat. If you reach down behind intake manifold you can plug it out from there, the connector plug should be clipped on to a mounting bracket just under I.M so unclip it from that first then disconnect the plug.

Edit, assumed you were on about 02 sensor. TPS is one located at side of throttle body facing bulkhead
 
Vtec6000 said:
no that's your map sensor. The 02 sensor is in exhaust manifold, near collector where manifold bolts to cat. If you reach down behind intake manifold you can plug it out from there, the connector plug should be clipped on to a mounting bracket just under I.M so unclip it from that first then disconnect the plug.

Edit, assumed you were on about 02 sensor. TPS is one located at side of throttle body facing bulkhead
Click to expand...

Yeh I was on about the O2 sensor... will give the Lamda sensor a go as I've had problems with that in the past...
 
Right I don't think it's the Lamda sensor... this is doing my head in now... :(

Basically it seems to idle fine but whenever I blip the throttle it goes back dangerously low (and sometimes stalls)...

I'm going to do some more IACV checks and cleaning and maybe try this out? :
newbie007 said:
So after looking at the service manual I followed the steps to troubleshoot the IACV,

1-started engine with no load and held the engine at 3000 rpm until the rad fan came on, then let it idle. the idle wasn't below 550rpm.
2- turned off the engine and removed the intake duct from the throttle body
3-started the engine and let it idle
4-placed finger in the hole of throttle body, once i did that the engine stalled out.

so I adjusted the idle speed with this procedure found on another forum:

1: bridge the 2 pin blue plug behind glove box (the diagnostic plug)run engine to as closes as possile to 500 rpm on idle (no load) by adjusting the butterfly.

2: turn off engine un plug idle control valve

3: with ingnition off remove the 7.5 amp back up fuse for ten seconds

4: plug idle control valve back in

5: repace 7.5 amp back up fuse

6: the idle control valve is now reset
thanks to ash-EK4 for these steps

I know its not the correct procedure to reset the idle speed but it seemed to have worked. I didn't even adjust the idle speed screw because i didn't know where it was at 1st (didn't read the haynes manual at the time)

Been driving around now and I haven't stalled ("crossed fingers") like i was stalling last night at every red light/turn/stop sign.

Here are the pics of my idle with no load


and now with load with lights and ac blasting and rear defrost


i'll update if the car stalls out in the future (i hope not :angry:). Hope this helps others.

Also getting the gasket for the IACV, its only 6 bucks, should i install it or wait ?

thanks for the help.
Click to expand...
 
Also should I reset the ECU after i swap the IACV for my spare, would this make a difference?
 
What have the valve clearances been set to? You rechecked them after running it for a bit after assembly?

Also worth taking the plugs out to see how it's been running
 
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