off idle adjustment on IDFS(china)

[ORANGECRUSHer]

So I feel like I've explored this subject before, but I can't find anything after a search.
I've got my 2110 with dual 44's running acceptably for the most part, but I keep running into a problem off idle and I think it's something I'm doing wrong or troubleshooting wrong.
Right now I'm jetted at:
145 main
210 air
52 idle
dual airbox intake
The symptom: Brief hestitation off idle. Doesn't matter how quick you get into it, but it does clear out quicker when you get further into the pedal. Worse when it's hasn't warmed up yet to the point where sometimes I need to floor it to get it moving and then I'm spinning the tires and looking like an idiot.
It does it warmed up as well. It doesn't always equate to a problem. Sometimes it is just a flick of the needle on the AFR to extreme lean. But it seems the worst when taking off from 1st gear or creeping in low 2nd and then accelerating. The lean condition can take several seconds to clear out. The AFR will show ----- as it's pegged lean for a few moments. I think this condition has been slowly killing my O2 sensors. Once I'm under way it runs great until my rpms get back down under 1500 and then I'm driving on egg shells again waiting for it to hesitate.

The adjustment:
I've been trying to find a sweet spot in my accellerator pump adjustment, but it doesn't seem to matter where it's set. It doesn't have any effect on this problem. I have the big pump jets installed that came with my RedLine jet kit. Does it sound like I need a new diaphram? Last I checked they squirt.

Is this an issue with the idle jet I have selected? My idle sits at 12.5-13.0. But instantly dives until I get to the transition ports. Are my air jets still not big enough?

Could this be a vent size issue? Feels like the vacuum(flow) is just disappearing when the throttle plates are cracked open.

Maybe there's something I'm not thinking about?
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Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-Dual 44IDF-cut/turned front beam-AEM wideband-Auber CHT-Donaldson Dual PowerCore filters-custom AL air boxes

[ORANGECRUSHer]

I don't know if it makes a difference , but it's been very humid since this got bad.
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Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-Dual 44IDF-cut/turned front beam-AEM wideband-Auber CHT-Donaldson Dual PowerCore filters-custom AL air boxes

[Zed999]

Ref killing sensors, mine did too until I fitted a switch on it so it doesn't try and heat the sensor when the engine is cold and the exhaust contains a lot of cold moisture. i wait until I've done a few miles before I switch it on.

Pump jets? Mine are dells put the pumps were draining back and it behaved like yours before I fixed them. Lovely and smooth now.

[ps2375]

Have you tried a larger idle jet? My motor is now a 2110, up from a 2087, and was recommended to use a 55 idle instead of the 47 that had been in it, by a knowledgeable carb tuner.

[Dale M.]

Move up to 55 idles.... 52 is to lean even for my 2080...
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All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...

[Alstrup]

[ORANGECRUSHer]

[ORANGECRUSHer]

So I did a little refreshing on the bleed valve and yeah I remember now.
Redline also includes what it calls a ZERO Pump By-pass valve.

So I'm probably not returning any fuel to the bowl.

It looks like a lean swing, but isn't there times when a lean afr reading can actually be a rich condition. I thought that was when fuel was burning in the exhaust..
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Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-Dual 44IDF-cut/turned front beam-AEM wideband-Auber CHT-Donaldson Dual PowerCore filters-custom AL air boxes

[oprn]

No, that is when there is no fire at all. Remember an AFR is measuring OXYGEN not fuel. It can be dead rich but if it is not burnt then the oxygen is still ALL THERE! So... you can have an extreme situation where the mixture is too rich to burn and your wide band will read lean.

Go around the back of the car and with it idling hit the throttle hard and quick. If the exhaust is black then you have too much accelerator pump action. If it never goes black after several quick hard hits (no need to hold it on, just 1/2 second hard hits) then your accelerator pumps could be too lean.

On my engine it takes about 4 consecutive quick hard hits to see black exhaust.

I hope this helps.
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Our cars get old, we get old but driving an old VW never gets old!

[mikedjames]

It can be a collapse in air speed before the engine picks up- making venturis smaller may help.

If you are having USB comms issues it might help to get hold of a USB isolator- it breaks ground loops on USB cables. Its a box with a male and female type A socket , one on each end, it feeds everything including enough 5 volt power to run a serial adaptor through isolating transformers.
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Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[ORANGECRUSHer]

[ORANGECRUSHer]

_________________
Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-Dual 44IDF-cut/turned front beam-AEM wideband-Auber CHT-Donaldson Dual PowerCore filters-custom AL air boxes

[ORANGECRUSHer]

[ORANGECRUSHer]

Went to a 55 idle, adjusted screws to same afr as the 52s, ~12ish. Runs the same.

Starts me thinking about the idle vents.
_________________
Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-Dual 44IDF-cut/turned front beam-AEM wideband-Auber CHT-Donaldson Dual PowerCore filters-custom AL air boxes

[modok]

44idfs usually do not have the kind of problem you are describing.
So there must be something different about yours, and I don't think it's the air boxes.
if a different size idle jet made no difference, then that's a clue, it may mean that the idle system is ok and it's a problem with the main system.
So, does changing the main jet do anything to the problem spot?
Does changing the fuel level do anything for it?

If the fuel level is too high, covering the main ring of holes in the emulsion tube, it can cause a slight delay in the mains starting, followed by a rich spot.
OR, if the fuel level is too far below the holes, then the opposite.

One fellow recently found the 8 holes weren't drilled at an angle, just straight, I mean....it could work anyway, far as I know, tho will jet different, but that's not following the blueprint.

[ORANGECRUSHer]

Yes, I'm following you. I have my floats set for 10mm. Whether that's enough stands to be seen.
I have never seen it done, but who's to say you can't unscrew a main and pull it out to see where the gas level is reaching on the stack.

I know of one person who happens to have a youtube channel that has done a lot of his own testing with the emusion tube holes. Adding and subtracting holes. Putting them higher and lower. All to see where he could influence the progression. I'd love to see his notes.

I feel like I need to be an expert on every system with these damn carbs, but I know I'll never get there just shooting in the wind.
_________________
Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-Dual 44IDF-cut/turned front beam-AEM wideband-Auber CHT-Donaldson Dual PowerCore filters-custom AL air boxes

[BFB]

What size chokes are you running?

At this juncture it’s usually good to start a carb “blue print” , take both carbs off and tear them down. Document every part , clean , reassemble, and reset everything so theres no doubts.
Then when you get them back on and make changes you can document it and reference back to previous jets , chokes , aux vents, etc.
i have a carb sheet if you don’t and would like one just let me know.
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An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
Most experts aren't.

[ORANGECRUSHer]

38's.
I have all that info. It's more the journey that screws with ya.

Like right now. I've played with the idles. 55's definitely don't work. It's 52's. But now I'm trying to figure out if a smaller vent will help, I think my other set are 36, or if maybe I should come back down with the air jets.

The last thing I did was modify the chamber inside the air boxes so that they were a lot more open above the stacks so I can remove the stacks. I also went up a size in the airs. I experienced a dramatic improvement with the 2500 transition hesitation I was dealing with before that. I don't feel that anymore. Now I feel it down lower. At this moment my theory is that my airs are pushing my mains down to low creating a bog. It shows up on my afr as a lean because the air is practically stopping and the charge isn't getting burnt completely. I don't get any popping though and that's kinda throwing me off this theory. When I run 52 idles I get no popping. 55 idles and there's some at times. I just ran 55's and I was having all kinds of lean swings all over the rpm range. It was so chaotic I had to put the 52's back in because I felt like I was going to lose my O2 sensor again.
I also need to get my ignition back to where I can adjust it. I think I need to use a different laptop on it. Might check out that USB booster someone was suggesting.
_________________
Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-Dual 44IDF-cut/turned front beam-AEM wideband-Auber CHT-Donaldson Dual PowerCore filters-custom AL air boxes

[ORANGECRUSHer]

i really need some nomex sleeves. All these exhaust burns are getting annoying.
_________________
Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-Dual 44IDF-cut/turned front beam-AEM wideband-Auber CHT-Donaldson Dual PowerCore filters-custom AL air boxes

[sled]

I went through some of your old topics looking for more detailed engine specs, seems like you have a cam that's similar to a w110 with 8.8:1 compression and 42 intake valves (these seem large for engine displacement and cam choice) in your heads.

if that's all still true, and this is in a Baja beetle, I would definitely use smaller vents if it were me. I don't think that's necessarily your only problem, but 38s are pretty big. Vacuum signal is going to be weak at low rpms.

also, when it comes to tuning your idle jets, you do NOT pay attention to the AFR at idle, you should be doing "lean best idle" and nothing more. Take out your main stacks completely and go drive around on just the idle circuit. Drive around for a WHILE to really see what's happening. This is how you dial in idle jets

my guess is the large vents will make it tough to drive and tune on just the idles.
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