need a little safc tuning help (high idle)

[jasonlee]

k here is the setup first,
1998 dodge avenger awd conversion with 2g wiring, and trans/rear end
not my avatar pic.. this one: www.redefinedrides.com/kyles.html


fresh rebuilt 2.0 1g with stock big rods and .020 mitsu pistons. stock 2g head with cometic hp head gasket and arp head studs. also 1g CAS wired for timing adjustment.

16g turbo with injen intake, and dnp header, apexi down pipe (catless) and 3" cat back

greddy egt in #1 runner, FJO wideband, SAFC 1, apexi TT, FIC 650cc injectors

small precision fmic, with short route piping.

k, i set the TPS to just a hair over .9k ohms, set base timing to around 5 deg.

when i start the car it revs to like 3k or so, then idle surges a little back down to about 1600 or so.

I lean it out ... then lean it out some more... and more... till i am at like -18 or mabye a touch more.. and the rpm comes down... but the wideband says like 18:1 or 19:1.. eeek scary! the egt shows around 475-500 deg. Celcius...

if i richen it back up to get even in the 17:1 range it revs way high again...

how can i bring the idle down??

 

[steve]

To start with since your using a 2G ECU it would be a good idea to use a 2G TPS and adjust it per the 2G procedure, based on where the IPS switches.

Are you using a 1G throttle body? ISC and FIAV functional?

Have you run a pressure test (boost leak test) on the intake system?

The base correction for 650cc is on the order of -30% over the stock 450cc injectors so how come your reading so lean at almost half that correction? Increased deadtime would explain part of it. What are you using for a MAF? Is it hacked?

Steve

 

[jasonlee]

its a 2g throttle body, and 2g TPS sensor. unhacked MAF. only had the car idling a few times since the install, and I am waiting to get a decent tune to drive to my buddies house and do a boost leak test... im sure there will be a couple of small leaks because i welded up some IC piping and 1 of the welds doesnt look exactly pretty. the ISC and FIAV are there, but dunno if they are working 100% either

guess i wasnt aware there was a difference in adjusting the TPS sensor from 1g to 2g.. I had EMS in my car with a mustang TB, and my buddies always used DSM link.. this is my first time with the safc

there is a chance the FJO o2 sensor could be reading off, its used, so i dont know for sure that its working 100% just yet.

the apexi TT says the factory o2 sensor is showing something like 15.9 a/f but i know that those arent very accurate.

j

 

[steve]

The most common cause of a high idle and the resulting surging is too much bypass air from a leak or problems with the TB. It doesn't take much to cause the idle to soar.

The TPS procedure in the VFAQ isn't correct for any DSM but really wrong for a 2G. I've posted the factory procedure several times. A search under my name should find it.

Steve

 

[zippyshoe]

One additional item you can check besides the ISC and any leaks after the throttle plate (throttle body vacuum lines, throttle body-to-intake manifold gasket, intake manifold-to-cylinder head gasket, etc.) is to verify that the throttle plate closes fully when the gas pedal is released. There should be at least enough slack in the throttle body cable to allow the throttle plate to close fully. If it is unable to close fully, this can cause a high idle. Hope this helps!

 

[jasonlee]

well, ive got the car idling pretty well, i had to put the fuel at about 0 adjustment, and once i got the BISS in from being way outta wack the idle came down a bit.... now i just gotta get the axles inthere, and get it over to my friends house to leak test the ic pipes


j