I have an 85mm LS/VTEC with Skunk2 stage 3 cams and when it's at idle my PLX reads 14.4:1 or so for about 30 seconds at start up. But then will jump all the way to 19:1 at which time I kill it to prevent any damage. The fuel is at 50psi at idle but will go to 80psi when I give it a little gas. I have a crome program in my P28 but it's not tuned yet. The fuel pump is a Aeromotive A1000 with 440cc injectors and the fuel is 100 octane. I have a 3" short ram and no PCV valve is installed. I don't think my Skunk2 intake manifold or PR3 head has a place for it. This problem wasn't happening when I had an AEM 2" diameter CAI intake on. Can anyone give me some ideas on what's going on.


Modified by 85mm LS VTEC at 2:28 PM 7/31/2005

 

Any ideas?

 

Bump

 

That's a lot of fuel pressure for those injectors, in my opinion. All you need is tuning on Crome to straighten that out. I'm thinking the short ram simply flows more air at idle than the long tube cold air.

 

get it tuned

 

It's at about 14:1 a/f for like 15-20 seconds and then jumps to 19:1 ~ 20:1 a/f on my Techedge. Now the plugs are dark brown though, and have unburned fuel on them.



Modified by JerseySiPOS at 9:26 AM 4/4/2006

 

open or closed loop?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Used2beAb16 &raquo;</TD></TR><TR><TD CLASS="quote">open or closed loop?</TD></TR></TABLE>


I tried to start it in open loop also, and really thought the a/f was gonna stay 14:1 this time, but it leaned out again to 20:1.


Modified by JerseySiPOS at 9:25 AM 4/4/2006

 

hmm.. i dont know what the deal is there i mean it seems that when its running of the maps for the first 15 seconds that the car is running your good but once the sensors become involved its leaning out?! doesnt make alot of sense.

Before I tuned my car it did the exact opposite.

 

If you have a leak it could lean it out at idle drastically. But you would know because it should idle high.

These lean issues are only at 0 throttle?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Used2beAb16 &raquo;</TD></TR><TR><TD CLASS="quote">If you have a leak it could lean it out at idle drastically. But you would know because it should idle high.

These lean issues are only at 0 throttle?</TD></TR></TABLE>

tried closing the throttle body screw, since i thought it might have opened completely from how i set it last week. i tried several timing and fuel adjustments for the 1st 3 columns up to 2500 rpms, and i did check the timing with the light again, and it's advancing the crap out of the ignition at idle.

also found water dripping under the 1st cylinder onto the ac bracket and also have water dripping between the collector and the exhaust. i really made sure they were sealed, and it's funny how the seal sucks, but im gonna try a new header gasket and metal collector gasket.

if that doesn't work, im ditching the vafc, and starting all over with crome pro since i have it now, but should work with my last basemap and Tuner Pro RT uploading...

 

yeah def getting the mechanical issues smoothed out first before tuning is the best idea because fixing things with tuning is kinda like just a band-aid.

You outta be able to ditch the vafc for good if your going with crome-pro. Have you tried just tossing in a stock p30 map fresh from crome pro to see what happens? I would do that and just start it up normally and see what happens in closed loop.

 

I had the same problem, until i lowered the fuel pressure from 45 psi vaccum on, to 35 psi vaccuum on, and it idled perfectly, and instead of the Wideband reading 18:1 at idle, it stayed rich, at 13:1, so i was fine with that.

Then yesterday and today, it's doing it again, reading 18:1 or so at idle and 0% throttle.

It's as if just driving it in the garage the day i fixed it, caused the lean idle issue again.

Appears that most of the fuel mix is going through the exhaust sometimes, and that one time it did not when i thought i fixed it.

 

your plx reads 14:1 on start up because it takes like 30 seconds for it to calibrate itself. during the first 30 seconds or so, its not actually displaying the afr, just stays around stoich til its calibrated then reads the correct afr.

really your problem is simple. just add more fuel at idle. i dont see whats so hard about that.

 

There is no problem wit a lean idle, unless it is skipping and popping or you hear detonation. Lean is only bad under load.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DonF &raquo;</TD></TR><TR><TD CLASS="quote">There is no problem wit a lean idle, unless it is skipping and popping or you hear detonation. Lean is only bad under load.</TD></TR></TABLE>

So your saying don't be scurred that it's reading 18:1 or so at idle, just leave it like that?
I tuned partial throttle, light and medium load, and engine appears to be healthy with even compression readings.

always was able to get a smooth idle richer than 15:1, with milder compression and big cams. This time the idle is a little rough and leaner than i want, just as long as i don't cause any damage, i really don't care.

 

You really need to hook up a vacume guage to the intake. The correct timing, air, and fuel will be the highest vacume reading you can get. If you lean it and vacume goes down, you are wrong, if you richen it and vacume goes down, you are wrong. You get the idea.

 

^^^gotcha...

 

i had the throttle body stop screw almost all the way down, but i didn't readjust the TPS. DUHH!!

So now i adjusted it back to .45V at closed throttle and it's pig rich at idle like it's supposed to be, so now just have to keep leaning it out it and should be able to get it close to 14.7:1.

 

sure u dont have a vacume leak somewhere

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 3a_eg_hatch &raquo;</TD></TR><TR><TD CLASS="quote">sure u dont have a vacume leak somewhere </TD></TR></TABLE>

the plugs were white before the TPS adjust, and now they are showing a very rich mixture. Has to do with the position of the throttle plate in relation to the TPS, at least i hope so...maybe someone can explain it better.

Thing is, i never had the lean idle problem with big cams til now, but not adjusting the TPS after adjusting the stop screw, is like working backwards, which the lean mixture at idle wasn't making sense to me. There is a first time for everything i guess.

 

So what is the best way to add more fuel at idle? I am having the same problem.
(SOHC vtec 1995) Super lean at idle. Hydro Carbon reading way off the charts.
Checked for vacuum leaks, and replaced 02 sensor. -nothin-