Weird AFR readings

[jantheeven]

Just hooked up my wideband LC-1 kit and was watching the readings...
When I start the car it starts around 13-14, slowly increasing to high 14s for a few seconds, then drops to between 7 and 8 and remains at that number. During normal driving and even @ WOT it doesn't go higher than 10.5. I adjusted the mixture screw to almost max to get a higher reading, but it doesn't want to go up. Do I need to recalibrate or what? :rolleyes:

[Brigsy]

Might just be a poorly jetted carb, whats your jetting/spec.

[jantheeven]

standard venturi, 1.2mm main, 1mm a/c, 1.2mm 2nd stage, standard needle jet... car runs fine and smooth, no stuttering or black smoke whatsoever

[James5]

Give the o2 sensor a clean and re-calibrate matey, might also be worth giving the carb another clean with some carb cleaner

[jantheeven]

That might help... because I just recalibrated (without cleaning... thing came right out of the box) and it's still completely off. When I turn the mixture screw out, the AFRs become higher!! :scared: WTF?

I did come across this in the manual:


Analog output one is 1.1V = 14 AFR and .1V = 15 AFR. This is
a simulated narrowband signal. Analog output two is setup as 0V = 7.35 AFR and 5V = 22.39

I think I connected it to a yellow wire (which is analog output 1)... should probably have used the brown wire (analog output 2) :rolleyes:

[jantheeven]

Yep... that was it... works fine now:

http://i54.photobucket.com/albums/g88/jantheeven/25102008.jpg

[jantheeven]

Anyway... now that I can see the oil temperature... at what temp can I start putting the pedal to the metal? ;) I now use mineral 15W40 oil...

[tiff_lee]

What gauages are those you're using there (not what do they measure but what model/manufacturer etc)?

[Nayls]

What gauages are those you're using there (not what do they measure but what model/manufacturer etc)?

nordskog

the air/fuel one comes with the innovate lc-1. :)

[tiff_lee]

Is the innovate one (air/fuel) the DB gauge?

[Nayls]

Is the innovate one (air/fuel) the DB gauge?

yes :)

[tiff_lee]

Thought so i'm thinking of getting one myself, just wondered about the other two as they looked to be similar style thats all.

[Bart GTTI]

New poster! (less than 10 posts)


Anyway... now that I can see the oil temperature... at what temp can I start putting the pedal to the metal? ;) I now use mineral 15W40 oil...


90 degrees, that's what I do. And I use Castrol RS 10W60 but my engine is slightly modified... :rolleyes:

Ook hier Jan? ;)

[jantheeven]

yes :)

No it's not... the gauge is from Nordskog mate... all of them are

http://www.nordskogperformance.net/products/auto/streetdigital/index.htm

[jantheeven]

Some people asked me to make some pictures of how I installed the gauges, especially Outlaw ;)
Here we go:

This is where I zip-tied the LC-1 controller:

http://i54.photobucket.com/albums/g88/jantheeven/IMG_2777-1.jpg

Here is where the wires enter the cockpit:

http://i54.photobucket.com/albums/g88/jantheeven/IMG_2790-1.jpg

http://i54.photobucket.com/albums/g88/jantheeven/IMG_2788-1.jpg

Here's how I installed the gauges... originally, they came with 2 thin studs on the back of each gauge. I cut them off, because otherwise they wouldn't fit. I used silicone paste to fix them to the stainless steel holder plate.
As you can see, it took quite some cutting and drilling to remove the original blow nozzles (how do you call that in English??), but hey... it's covered now by a shiny alloy plate now anyway ;).

http://i54.photobucket.com/albums/g88/jantheeven/IMG_2781-1.jpg

You can see I drilled 2 holes in the corners for the wires (4 per gauge) to run through. They exit here:

http://i54.photobucket.com/albums/g88/jantheeven/IMG_2783-1.jpg

The wires for the LC-1 controller and sensor wires from the oil and water temp sender enter the same compartment, but from the bottom.

When it's all put back together... it looks like this: ;)

http://i54.photobucket.com/albums/g88/jantheeven/IMG_2784-1.jpg

http://i54.photobucket.com/albums/g88/jantheeven/IMG_2786-1.jpg

[jantheeven]

Another thing... my AFR is around 14.5 when idling... and the same when cruising 80mph in 5th gear on the motorway (without boost). Is that normal? When putting my foot down, WOT and 22 psi boost, it gets no higher than in the low 11s. And I already drilled the a/c from .9 to 1mm... 2nd stage is still 1.2 and the rest of the jets is std... any advice on this?

[5teve L]

What size main ??

Just seen standard.. are you certain, have you checked the main jet ??

[Nayls]

No it's not... the gauge is from Nordskog mate... all of them are

http://www.nordskogperformance.net/products/auto/streetdigital/index.htm


yes i know that! :) nordskog supply the gauge for innovate though.

so most people on here will know that gauge as the db gauge.

[jantheeven]

What size main ??

Just seen standard.. are you certain, have you checked the main jet ??

I'm pretty sure it's 120... but now you've got me doubting myself ;)

[jantheeven]

Anyone some other thoughts on this? Do I need to have an AFR of 14.7 when cruising 80 mph in 5th gear without boost?

[jantheeven]

Bump ;)

[Scoff]

you'll not get cruise afr's of 14.7:1, but you might get close. you should see 14's atleast with the standard main jet and a 90 a/c.

did you solve the "rich" idle problem ? fyi, a car will not run with 8:1, let alone 7:1. I saw that problem on many of the rubbish LC-1's I came across a couple years back, mine too.

[jantheeven]

you'll not get cruise afr's of 14.7:1, but you might get close. you should see 14's atleast with the standard main jet and a 90 a/c.

did you solve the "rich" idle problem ? fyi, a car will not run with 8:1, let alone 7:1. I saw that problem on many of the rubbish LC-1's I came across a couple years back, mine too.

Yeah I solved the rich idle problem... turned out I connected a wrong wire :ashamed: so I got a "simulated narrow band signal" (a brown instead of a yellow wire :D).
Well I do see 14s when cruising... readings are a bit "nervous", if you know what I mean... they jump back and forth very quickly from low to high 14s. Still have low 11s at full boost & WOT and I already drilled the a/c to 1mm...

[Scoff]

yeah, at cruise speeds you won't get a stable AFR, thats normal. you'll probably find it is more stable on-boost though :) low 11's is a bit rich, maybe you could go to a 1mm air corrector.

[jantheeven]

Already drilled the a/c from .9 to 1mm... main jet is 1.2 and 2nd stage is 1.2mm

[Scoff]

thats very rich for very little carb jetting. what turbo and camshaft do you have ?

[jantheeven]

I have the K-Tec power system camshaft and a MD84R turbo...
I'll take the carb off this weekend and make 100% sure I didn't fit a 130 main jet accidentally...

[jantheeven]

little bump... ;)

[James5]

Did you double check the Jettings??

[jantheeven]

Did you double check the Jettings??

Finally had some time to take the carb off today and check the jets...

Main jet is 1.2, a/c is 1, BUT the 2nd stage is 1.3-1.35 (when I insert a 1.3mm drill into the hole it's a little loose, but I can't fit in the 1.4mm drill).

I probably used the wrong drill when I opened it up to what I thought was 1.2mm :sad2:

Is this the cause of the low AFR's (too rich) at WOT?

How do I fix this? Solder? :scared:

[DaveMayGTT]

Sounds like a reasonable explanation! Other peeps have said solder and redrill is the way to go.

[jantheeven]

The last time I soldered anything was in highschool... about 15 years ago :laugh:
It's probably a pain in the arse trying to solder a little hole like that shut :scared:

[James5]

Finally had some time to take the carb off today and check the jets...

Main jet is 1.2, a/c is 1, BUT the 2nd stage is 1.3-1.35 (when I insert a 1.3mm drill into the hole it's a little loose, but I can't fit in the 1.4mm drill).

I probably used the wrong drill when I opened it up to what I thought was 1.2mm :sad2:

Is this the cause of the low AFR's (too rich) at WOT?

How do I fix this? Solder? :scared:

This would be why your are extrelmey rich @ WOT.

There is no easy way of going back on on the 2nd stage, the only 2 options you have are get another standard carb body or drill out the 2nd stage on your carb body and tap it then put an a/c jet in it's place and then you have adjustable 2nd stage.

[jantheeven]

Okay thanks so far...
I do have an old group A carb body lying around somewhere... but group A isn't good, is it?

[MR TURBO]

Okay thanks so far...
I do have an old group A carb body lying around somewhere... but group A isn't good, is it?

Why?? Whats the crack with the group A's???:confused::confused:

[jantheeven]

Lots of people say it's better to use a standard carb with modified jets... I'm not entirely sure why though. Maybe it's better to use a group A body with the larger venturi, but with a 1.2mm main jet, 1.2mm 2nd stage and 1mm a/c jet in my case (22 psi turbo boost)
Would that boost cause the bowl to empty if I use the larger venturi?

[MR TURBO]

Lots of people say it's better to use a standard carb with modified jets... I'm not entirely sure why though. Maybe it's better to use a group A body with the larger venturi, but with a 1.2mm main jet, 1.2mm 2nd stage and 1mm a/c jet in my case (22 psi turbo boost)
Would that boost cause the bowl to empty if I use the larger venturi?

I did have a standard carb with modified jets b4 i took it off because i thought a group A would be better but to tell you the truth i never had any issues with my standard modded one at all as for the group a it still aint running right so it may just be back to standard car with modded jets or as i have a couple of carbs lying aroung i may just rebuild one and do all the drillings etc myself:D:D

[Rob@Backyardracing]

Lots of people say it's better to use a standard carb with modified jets... I'm not entirely sure why though. Maybe it's better to use a group A body with the larger venturi, but with a 1.2mm main jet, 1.2mm 2nd stage and 1mm a/c jet in my case (22 psi turbo boost)
Would that boost cause the bowl to empty if I use the larger venturi?

I wouldnt have thought so, but you would have to raise jetting tho to match a larger venturi as there wouldnt be the same effect over the 25mm jobby. Doesnt mean its using more fuel though (in theory) so i cant see it making any effect to your bowl..... Ive only used a larger one once years ago and hated it so stayed with 25mm ever since so im not gospel..

[jantheeven]

I wouldnt have thought so, but you would have to raise jetting tho to match a larger venturi as there wouldnt be the same effect over the 25mm jobby. Doesnt mean its using more fuel though (in theory) so i cant see it making any effect to your bowl..... Ive only used a larger one once years ago and hated it so stayed with 25mm ever since so im not gospel..

Well that's what some people say... that the large venturi causes the float bowl to empty at high boost levels. What didn't you like about the large venturi carb?? They say that gp A is better because the standard carb can cause a pressure loss of up 5psi through it due to the bore size of the standard venturi...

[Rob@Backyardracing]

I didnt like it as i had flat spots, but back then i never had a WB either, maybe today i could make one work well if i tried. I just never had a big problem with a std one and was good to the power level i wanted. :)

[Mr 5]

iv wondered for months now,what is WOT? guessing it stands for something like full throttle,but just want to be sure

[James5]

Wide Open Throttle

[jantheeven]

Also... how do I set the correct length for the accelerator pump rod on the carb? How far does the throttle have to be open for the acc pump to kick in?

[samb5]

Also... how do I set the correct length for the accelerator pump rod on the carb? How far does the throttle have to be open for the acc pump to kick in?
id also like to kno this an also the second stage, is it boost sensetive or rev sensitive for when it kicks in?? :)

[James5]

You need a 5mm drill bit (not used for drilling but for measuring the gap and then you adjust the rod so that it fully pushes to acc pump arm out:)

[James5]

So what yo do is open the throttle with the carb removed from manifold insert the 5mm drill bit between the wall of the carb (part with the straight line gap) and let the throttle butterfly rest on the 5mm drill piece then adjust the screw if necessary so it has allowed the accel pump to be compressed.

http://www.rtoc.org/files/Technical%20Files/Solex%2032%20Dis%20Carb%20Information/IMG_2944.JPG

[jantheeven]

Thanks James... sorted :agree:

Now I need to either drill and tap the hole for the 2nd stage so I can screw in an a/c jet OR find another carb body. Scoff convinced me not to try the gp A with the 27.5mm venturi. ;) Do you agree?

[jantheeven]

Is there a part number for the plastic ring thingy that holds the rod in place (marked by the arrow)?

http://i54.photobucket.com/albums/g88/jantheeven/IMG_2944.jpg

[jantheeven]

id also like to kno this an also the second stage, is it boost sensetive or rev sensitive for when it kicks in?? :)

2nd stage enrichens the mixture when boost kicks in ;)

[James5]

Thanks James... sorted :agree:

Now I need to either drill and tap the hole for the 2nd stage so I can screw in an a/c jet OR find another carb body. Scoff convinced me not to try the gp A with the 27.5mm venturi. ;) Do you agree?


I agree with whatever Scoff says matey:agree::cooter:

[jantheeven]

I agree with whatever Scoff says matey:agree::cooter:

LOL... don't you have an opinion of your own? ;)

[djinuk]

So what yo do is open the throttle with the carb removed from manifold insert the 5mm drill bit between the wall of the carb (part with the straight line gap) and let the throttle butterfly rest on the 5mm drill piece then adjust the screw if necessary so it has allowed the accel pump to be compressed.

http://www.rtoc.org/files/Technical%20Files/Solex%2032%20Dis%20Carb%20Information/IMG_2944.JPG


sorry to ressurect a old topic but iv just read this about setting the acc pump correctly with a 5mm drill bit, i didnt do this, will it cause any major problems ?

[jantheeven]

sorry to ressurect a old topic but iv just read this about setting the acc pump correctly with a 5mm drill bit, i didnt do this, will it cause any major problems ?

Well it changes the timing of the accelerator pump obviously... which has to right for optimal fueling and power, but no... you won't have major problems if it's off a bit. But why not check it? It's such a simple job mate :)

[djinuk]

Well it changes the timing of the accelerator pump obviously... which has to right for optimal fueling and power, but no... you won't have major problems if it's off a bit. But why not check it? It's such a simple job mate :)

Yea i think i will for what its worth, i just followed the carb rebuild guide that states (do it up all the way)