Tuning complications with Crome
 

Alright. Well, I will start from the beginning and explain all the details of the build

First off, started with an SS Autochrome turbo kit. Therein lies the first problem. Cracked manifolds, etc. Currently running the T3/T4, 550cc injectors, Crome tuned with stock fuel pressure. The motor is a completely stock B18C1. So I get it back from the shop, the build has been completed. I put in a basemapped chip courtesy of phearable.net and it runs half ass as expected. So we throw the wideband on and do some tuning.

We take it out for an hour - hour and a half and dial in the WOT to 11.5:1 from 4000 RPM to 5500 RPM and then 11:1 until redline. Timing is has been untouched as per phearable's basemap. So I believe it ends up in the 16-18 range at final map. Part throttle is still fucked, running way too lean, its bouncing around like crazy at part throttle, it hardly idles. Alright, well, whatever, have to pack it up for the day. That was the last time I tuned my car and it was relatively low temperature (around 0 degree Celsius).

So I drive it around for 3-4 weeks, seems to be running well. Pulls hard under boost, makes good power, not running overly rich. But then something changes.

All of a sudden its running like ass, running extremely rich, bounces and bogs hard under part throttle. So obviously the tuning is out.

A lot more than was expected though. Put it on the dyno and its insanely lean under idle and extremely rich under boost pressure. But its changing dramatically from pull to pull. Spiking at some points in the map from where it was previous extremely rich (9:1) all the way up to 11.6:1.

Now here is where my question lies. Could the tune possibly be affected that drastically over a period of three weeks where the temperatures have warmed from 0 to around 20. Does air density change the tune that drastically. Also, why would my air fuel ratios be spiking all over the place as they are?

Any help would be appreciated. This whole turbo setup has been a big nightmare for me and I'm just looking for the slightest possible hint of a solution to my problems. :(

Re: Tuning complications with Crome
 

tunes will change with temps, yes, and sometimes very much



if you tune in the col dand it warms up, you will run more on the rich side, as air is way more dense in the cold, and when it warms up you get a crappy air mix, as compared to cold weather

as far as YOUR tune goes, what do your 2D maps look like? post them up for us and maybe we can help more

Re: Tuning complications with Crome
 

Alright, my buddy has them on his computer so I will get him to send them as soon as possible. I just want to figure out where the massive fluctuations are coming from.

Re: Tuning complications with Crome
 

even with LARGE injectors...leaving the stock correction maps untouched I have NEVER seen AFRs fluctuate as much as he is describing...

something mechanical has gone wrong...

You said SSAutoshit right? maybe your Turbo isnt flowing like it was now...

Re: Tuning complications with Crome
 

Its very possible. But even when the weather changed to -5 today, I could notice a major difference in the amount of power available as well as driveability. I've heard mention of the stock O2 sensor screwing with the settings but I have the O2 heater disabled as well as open loop mode engaged. The turbo is still holding constant boost at 7 PSI and very steadily with no creep. I'm just completely baffled by the whole situation. I've considered the mechanical side of things but I can't understand where the discrepency is coming from because it is running completely off the chipset and it works fine under colder temperatures.

Re: Tuning complications with Crome
 

stupid question, but did you adjust just the cells you were hitting while tuning or did you adjust all the rows/columns while you were tuning? if so it sounds like mechanical issue.

Re: Tuning complications with Crome
 

I know nothing about tuning or turbos for that matter, but it almost sounds like you have an injector dumping fuel at times and then none at times. ID do a simple check of the injector by ohming them down and try tapping on them to see if the readings change. Broken winding? It sems like a viable guess.