# what should cruising afr be??



## 54blunts (Nov 6, 2003)

after an insane amount of time trying to figure out my car, i have got the idle afr down to ~14.7 most of the time. and in boost im reading 10.8-11.5 afr 

now my 2 issues are:
when cruising in gear, just maintaining speed my afr is anywhere from 15.8-16.5 according to the gauge. cruising at 60mph afr is like 16.5 constantly 
when the fans kick on while sitting at a red light, it goes lean, like 16.5 afr and starts to run rough


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## 12V_VR (Aug 11, 2010)

Are you running a chip ? My bet does the same thing .


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## 54blunts (Nov 6, 2003)

UM chip. 

whats BET??


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## 54blunts (Nov 6, 2003)

i drove it out tonight and it drove great, felt great, my cruising afr in 5th came down to around 16 flat. il go over the wiring, and a few other small things, but i think im going to leave it as is for now


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## 'dubber (Jun 15, 2004)

Good luck with that.


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## need_a_VR6 (May 19, 1999)

Peak egts are at stoich. Leaner will be cooler. 

There is nothing wrong with it running like that and very similar to how I would tune that area of the map. 

Now is it "right" for that chip to run that way.. who knows!


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## 54blunts (Nov 6, 2003)

need_a_VR6 said:


> Peak egts are at stoich. Leaner will be cooler.
> 
> There is nothing wrong with it running like that and very similar to how I would tune that area of the map.
> 
> Now is it "right" for that chip to run that way.. who knows!



i emailed UM today and described how it all is and asked how they set it up the tune... il post up the response if/when it arrives


i did alot of research into this, and from what i could gather from various different car forums of all makes. it seems that most actual tuning company's/ people who are experienced tuners were shooting for 15.5-16.5 cruising afr, i saw quite a few that even said they try to get to 17, and the majority of people who are doing the tuning themselves and dont have a TON of experience were shooting for stoich or close to it


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## planbmatt1 (Mar 26, 2013)

When I got my car it had apr stage 2 93 oct tune and it cruised at 17 afr and boosted at 12-14. Idle after driving was 16 and on start up was 13. I was very worried about these numbers so since im going big turbo i took my car to the vw specialty speed shop. Got the engine fully rebuilt. Nothing was wrong and pistons were perfect. I also had the apr tune removed because im going gonzo but Ill let ya know how they compare to stock afr's to see if my gauge is off. Also never had a problem driving ever. No misfires or anything. Just backfirs on off throttle sometimes like it was rich. idk


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## [email protected] Performance (Jul 20, 2011)

ME7/MED9/MED17 always targets 1.00 Lambda (14.7) at all times except:
1. On decel (fuel cutoff)
2. WOT
3. Cat heating


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## need_a_VR6 (May 19, 1999)

Good to know, are those editable or hard coded?

Op's car is me2.9 or 5.9 not sure if he did the obd2 swap or not.


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## 'dubber (Jun 15, 2004)

54blunts said:


> i did alot of research into this, and from what i could gather from various different car forums of all makes. it seems that most actual tuning company's/ people who are experienced tuners were shooting for 15.5-16.5 cruising afr, i saw quite a few that even said they try to get to 17, and the majority of people who are doing the tuning themselves and dont have a TON of experience were shooting for stoich or close to it


Yeah I took my post out since it was not really accurate. I took a look at some of my old logs which led me to believe what I had said and saw a couple of things that had led to me thinking what I had said, one thing being not noticing timing pull due to iat sensor heatsoak.


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## need_a_VR6 (May 19, 1999)

'dubber said:


> Yeah I took my post out since it was not really accurate.


Probably would have made more sense to edit it, or at least leave it and quote it, and explain why you thought what you thought; so you can teach others what you learned.


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## vr-vagman (May 15, 2010)

I think [email protected] is right. Only at stoich the CAT works as planned. What about your WBO2 meter. Was it calibrated/checked with ... a 4 or 5 component gas analyzer?


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## Nevaeh_Speed (Jul 9, 2004)

Um #42 race file mk3. 14.2-15.1 cruising. VRt


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## 'dubber (Jun 15, 2004)

need_a_VR6 said:


> Probably would have made more sense to edit it, or at least leave it and quote it, and explain why you thought what you thought; so you can teach others what you learned.


I wasn't thinking, that was the problem. =)


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## 12V_VR (Aug 11, 2010)

Nevaeh_Speed said:


> Um #42 race file mk3. 14.2-15.1 cruising. VRt


Same here


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## 54blunts (Nov 6, 2003)

specs on the car. 

its a vr6 obd1 distributor 30# chip tune. so its a pain in the dick from the start. its got 262 cams in it and some mild porting. 

my wideband is an aem uego so i cant calibrate it. and on my ****ty obd1 i have no way of reading any data from the car

things im thinking may be affecting it:
i just discovered there are supposed to be 2 different colored knock sensors, car has had white on front and back since i got it, found out its supposed to have brown on front.
im currently running a 1.8t iat that is zip tied next to the air filter. im going to switch it back to the factory iat later this week 

the car ****ing HATES cold weather, was running really lean this morning to the point i couldnt drive it to work, idling rough and around 17afr, im assuming this is from the 1.8t iat being out in the open. 

i really dont think there are any vac leaks, i have literally deleted everything i can, so there isnt a whole lot of vacuum lines to start out with, and all intake gaskets are sealed.




i received a reply from UM on sunday and didnt realize it.... kudos to jeff for checking that stuff on a day off, here is what it said

_look at lambda control while driving.

Lambda control should be driving afr to ~14.7.

you data sounds a bit lean for typical cruise. One fix is add fuel pressure.
you should be running 4bar.
a suggestion: install an adjustable fpr, add fuel pressure (it wont take
much)
until cruise afr is proper, but check full power is high 11's to low 12's

-Jeffrey Atwood_


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## need_a_VR6 (May 19, 1999)

The iat needs to be IN the intake post ic on a turbo car.


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## 54blunts (Nov 6, 2003)

need_a_VR6 said:


> The iat needs to be IN the intake post ic on a turbo car.


I know :/ I completely forgot about it being re-routed untill yesterday when it ran terrible


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## 54blunts (Nov 6, 2003)

so i swapped back to the factory iat, and now sometimes it idles at 14.7afr and sometimes it idles at 14.3 afr. but still seems to cruise at 16.0 afr 

if it decides it wants to be driveable in the morning im going to take it to work and test a few sensors. and if i find nothing, im going to put my isv back on with a check valve and just start back at square one


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## 2.0 Ho (Sep 27, 2006)

IIRC thats about exactly where mine cruised at probably more like mid 15's but idles around 14.5-15.2. WOT is about 12. Sounds good to me. Not really sure I would terribly worried about it.


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## Bx V-dubber (Dec 17, 2010)

iirc from reading book......14.7 @ idle and it should be ok around that range during cruising. in my opinion 16 is pushing the envelope but im not a dedicated tuner, just a wrench-er. wot.....i've seen from 10.8 to 12 on certain tunes/turbo set ups.:beer:


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## 54blunts (Nov 6, 2003)

bumping an old thread i made, just to post some form of answer.... 

the car became completely unusable in cold weather. i tried adding the isv back and that didnt matter. afr at idle went 17+ and the car would barely run, couldnt even get it out of the driveway. i essentially gave up on it. and i started the conversion to obd2. currently have it switched from distributor to coil, and have been waiting to install the obd2 ecu/harness but family/weather has slowed it down, im hoping to get most/all of it done by sunday morning


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