M3DK - can't get idle through IACV

[timbo]

I have refitted my IACV rail & IACV in an attempt to get a steady ide at start up & warm without have to use the TB butterfly opening to manage idle @ startup. The twin bodies are perfectly balanced now.

 

When I put the IACV to manual control even on the live adjustments stage with the IACV set at position 120 (fully open) the engine cranks, gives 1 or 2 fires then dies. I have first set the IACV to closed by switching the ignition on/off a number of times inorder for the ecu to get a ref. value then open it to position 120. I can hear a very faint whir from the IACV as a close/open it on the live adjustments page 9hmm - I must remove the IACV & check as I always remember the IACV having quite a loud whiring noise). At the same time if I unblock the pipe that comes off the back of the fuel pressure regulator and runs across the bleed nipples on the TB bodies she runs for a couple of seconds @ c. 300 - 500 rpm - then dies. If I advance the ignition timing at load site 0, rpm 1000 to 25 with the fuel pressure pipe unblocked she runs very roughly at a very low idle (500). The lambda reading is permenantly in the green (rich) rather than swinging. I have leaned off the micture on the live adjustments - no improvement in getting close o an idle. I don't believe it is a fuel pressure issue as she runs clean at higher revs (on the road).

 

My throttle pot closed ref no. is 124. I have set the 'conditions for idle' at throttle pot below 131 & below 1350rpm. IACV shuts off load site 5.

 

Whats more disconcerning is that with the IACV set to mapped control I don't even get an attempt at an idle. (I must check that 'ignition advance alignment' is not set to locked). Preferably I want the ecu to control my idle. In the 'additional settings' on the idle 'tab' I have noted that I have no values. Is this the norm?

 

Any suggestions:

Perhaps someone could mail me a Map for VHPD TBs running an IACV on mapped idle control settings from which I can use as reference to check my own settings?

 

JLZ7447

1.6K this week

[allegro]

Timbo

I have a map for my VHPD with the IACV set to mapped. This was done by Emerald. I will send it to you.

I however have switched the iacv off after setting the IACV manually to 100.

 

Andy Mac C7 GON

😬 Team Langoustine. Hard Core Prawn here 😬

[garyo]

I'm having a very similar problem with my IACV - the ECU insists the IACV position is zero, despite me having everything configured, as far as I can tell. When I try to manually control the IACV using pgUp and pgDn in 'live adjustments' the laptop 'beeps' at me, suggesting this isn't possible...

 

Could you send me a copy of your map too... deargary at hotmail dot com

 

Thanks,

 

Gary.

[timbo]

Garyo, mine keyboard beeps too on the same keys - but if you listen closely to the IACV valve you can hear a very slight whiring noise on each press. But good point - why does the keyboard produce this beep sound - almost like a computers lock out sound? No other adjustment keys on the live screen operate in this way.

 

JLZ7447

1.6K this week

[garyo]

ah okay - I'll have to give it another go and see if I can get the thing to idle then... I'm pretty sure the 'IACV position' value wasn't changing when I pressed keys though.

 

Gary.

[allegro]

Gary

When set to manual, I think the ignition must be on and the engine might even have to be running to adjust the IACV position. It did take me a while to suss it, but it will definately increment on the screen. Once set, I then switch to 'OFF' and it retains the manually set position.

I am no expert and am learning all the while, so this is only a suggestion.

 

Andy Mac C7 GON

😬 Team Langoustine. Hard Core Prawn here 😬

[Julian Thompson]

I had these problems when I first set my VHPD up with the Emerald.

 

One issue is that the MEMS runs the IACV at a much more open setting than the Emerald from cold.

 

Even with the IACV fully open on the Emerald software there is still less air than with the MEMS but it is much, much better.

 

I still use auto control of IACV but have it set to open fully with a cold engine which ensures a good start every time.

 

[Julian Thompson]

And having reread timbo's question I think I'm right.

 

The airspeed at cold crank is very low. This means that you are sort of right in thinking of weakening the mixture but wrong because you need so much more fuel when everything's cold.

 

I bet if you whack the IACV to fully open and leave the fuel mixture you'll have enough airspeed and enough fuel to ignite the spark.

 

But again, although I've had practical experience of the very problem you're describing and have solved it on my engine I add that I am no engine genius.

[timbo]

I think I am now going in the right direction.

 

1st the IACV will operate ('manual control') with just the ecu powered up (no eng run) & (& with eng running). Guess what - I found the IACV jammed closed. It must have fixed itself somehow to the sealing trumpet.

 

Now with the IACV set at 50 I can get an idle. I has to ramp up the ignition to 15 at load site 0, speed site 2 to get the cross hairs more in the bullseye plus a little inj correction of plus 5. Idle now sits reasonably well in line with idle coolant temp correction map. I did have to bring the IACV position back to 40-45 with the higher coolant temp to get a better idle (lower c. 900rpm). This has sacrificed abit of cold start smoothness.

 

I am shutting the IACV off at load site 3 for now which at higher coolant temps appears to be ok - but at lower temp may cause her to fluff abit at small throttle openings.

 

 

 

 

JLZ7447

1.6K this week

[SLR No.77]

Gary, the possible problem with the IACV control in the live adjustments screen is with the programming. When the ecu is programmed for "mapped position" of the IACV, purely changing this to "fixed position" will not allow manual adjustment of the IACV - you must re-program the Emerald with the change, then the pg-up & pg-dn will function properly. When you've finished, change back to "mapped position" and re-program the Emerald again.

 

Allegro, if there's any chance of your map also?

 

Stu.