chemicool

iTrader: (1)

Has anyone ever gotten 850 primaries to idle smoothly and idle well. I cannot for the life of me get my afr at idle to be any leaner than 11.9. I read through the posts. I have tried negative lag, inj correction and the like. I am wondering if something else could be wrong. I assume since a lot of people use the 850 primaries and places sell modified primary rails for the 850's that it is feasable? I hope I didn't make a mistake in using 850's.

rx7brandon

iTrader: (1)

what computer r u using? and yes mine idles good, perfectly streetable. i am using a power fc tuned by dee @ jpr in nj with 850/1600's .as far as what u need to change i dont know.

chemicool

iTrader: (1)

Thanks for the feedback. I assumed it could be done. I am wondering if someting is wrong with the inj or connections or something. I use a Power FC. I am gonna have it tuned by Chris at Rotary performance soon but I didn't want to go through the expense and trip up there if there is something wrong with it. When you say it idles good do you mean it idles smoothly like a stock car?

Cgotto6

iTrader: (8)

Mine idled just fine with 850 primaries

arghx

iTrader: (3)

What plugs are you running and do you have stock ports?

M104-AMG

iTrader: (8)

I have 4x850cc injectors controlled by a PFC, and tuned by Steve Kan.

Idle is perfect. Not so perfect when the A/C is on, but a couple of changes, and all is great now.

I've had this setup for over 2-years now.

:-) neil

arghx

iTrader: (3)

I think you will find limited useful (specific and quantitative) information from people who had their car professionally tuned with the 850 primary's.

rx7brandon

iTrader: (1)

yes, that smooth. it does idle a little higher (1100 rpm), but smooth. I do have a large street port, gt40r, 4 inch exhaust and other supporting mods. I made 442hp on 93 octane on 16 psi, going 11.45 in the 1/4.

chemicool

iTrader: (1)

OK so I guess there is something wrong or I am missing something. I am gonna pull the plugs and make sure they are not fouled. I am just trying to get it running lean enough and smooth enough to drive to my tuner. It runs pretty good at cruise. I am running all 9's on the plugs and it has a large street port. I realize it may have a loping idle but this idle is not that it is missing/ fouling out.

arghx

iTrader: (3)

11.9 is plenty lean enough if all you are trying to do is drive to your tuner. 13:1 is right near the limit of how lean it can idle stably anyway. just let your tuner handle it.

A lot of people get this whole tuning thing backwards. The WOT part is relatively easy a lot of times. It's these driveability issue that separate the good tunes/tuners from the mediocre ones. People think "well if I can just get this little idle problem/hesitation/whatever worked out, then I can get the real tuning done." Maybe. If to the best of your knowledge the driveability quirk is caused by a mechanical or wiring problem, yes you should take care of it on your own. If it is a pure tuning issue, you are either wasting your money by not paying the tuner to do the most difficult tuning (and letting him do WOT only), or you are wasting your money trying to half-tune the car yourself when the tuner is just going to overwrite your map anyway.

Sometimes it takes a professional just to tell you whether you have a tuning issue or just a mechanical/wiring problem.

oo7arkman

iTrader: (2)

I am running 850/1600 on mine and cannot get it to idle any leaner than about 11.9 just like you. Steve tuned it and said something to the like of " it will not idle any leaner due to limitaions of the pfc". I know there are others on here that have been able to get thiers to lean out more at idle with a pfc but so far, mine will not for whatever reason. Everything else runs/drives great, just the idle is stupid rich. With this the idle is OK a little rough, but I have no issues driving the car. I have the idle set at about 900-950. I also run the stock 9's all around.

I agree with the above, you are paying your tuner to do just that, let him take care of it and then maybe ask what he did to resolve that issue. If your fuel pressure is good, and everything else runs/drives fine, just get the car to your tuner.

chemicool

iTrader: (1)

OK well I don't what was going on or maybe I'm a dumbass. I got it to work by trying negative lag again. I guess the first time it wasn't writing the MAP to the Power FC. Another poss is that it has an intermittant problem. Anyway, at -0.1 lag it works out fine. Idles better and leaner. Thanks for the help folks. I will definitely have my tuner do it all. I just wanted to make sure I didn't have a mechanical problem so as not to waste a trip.

NeoTuri

iTrader: (2)

For those who are running smoothish idle with the 850 primaries, what does your timing split look like in that area?