IROCBOY

So, I have my fresh 383 engine build, I used a FIRST fuel injection intake manifold, 36 lb injectors and airflow research 195 heads. Some days I can get it to start and run and idle, I can get it to enter closed loop and adjust VE tables through BLM.

My issue is the days where I can’t get it to start. I have to believe that it’s too rich while cranking and during initial startup.

I am using tunerpro and modifying an stock 305 BIN file. It is a 7730 ECM, I have adjusted all of the scalars and the flags correctly for my build and the only tables I have adjusted are VE tables and I adjusted the crank PW vs coolant down in an attempt to lean out the mixture during cranking. It did not help.

Any help would be appreciated.

Orr89RocZ

iTrader: (20)

Does it fire at all while cranking and die? Or nothing at all?

After cranking for a few seconds, stop and pull a spark plug. Is it wet with fuel?

Also what is base timing set at? Or what total timing do you have commanded at idle? Cammed 383 may want 5-8 deg more than stock at idle areas to fire consistently

Also, i would disable closed loop and use wideband to tune ve tables, then when everything is close, enable closed loop and make adjustments there

ULTM8Z

I'd also start with S_AUJP rather than a factory 305 bin. Once you get seriously into the tune, S_AUJP has a lot of cool additional features that'll come in handy (like logging the WB data through TP RT).

IROCBOY

It starts to fire initially and dies in about one second. Like I said, some days it starts and runs (not perfectly smooth).

Base timing is set to 6* BTDC.

I have a wideband installed, I will try disabling closed loop and tune that way. I'm always watching that wideband, its usually in the low to mid 14s while the engine is running.

I spoke to you last year I believe and you mentioned advancing spark to get started. I'll give that a try.

IROCBOY

I have that BIN file on my laptop. But I've played with it a lot trying to adjust the scalars and flags and it's a little overwhelming to me compared to the stock BIN. I'm trying to simplify things until I have some success and get results that make sense.

Orr89RocZ

iTrader: (20)

If its starting and dying within a second or two, give it more fuel via open loop vs coolant or increase the ve table more, however once warm it may end up being rich again so may have to change open loop vs coolant anyway

IROCBOY

If this makes any sense: The last time I had it running it started and idled nicely at 750 RPM and 70 KPa. when the loop closed the BLM count was 123. I raised the RPM to about 2000 and the BLMs went to 160 and stayed there (I was there for about ten seconds) then I brought it back to idle and the BLM stayed at 160 (about 15 seconds) then I tapped the throttle and had no rpm rise so I shut down believing the lean indication. That was the end of my testing that day. The next day it would not start as I have stated above.

My entire ignition setup is new (same style distributor and coil) and I have confirmed I have spark. I wanted to make sure that there wasn't some mechanical reason I'm overlooking

ULTM8Z

If you're running Bosch III injectors, you probably want to get the right voltage offsets in place before doing too much more.

Orr89RocZ

iTrader: (20)

Kind of makes sense. 305 based file, the 383 should take alot more fuel so i would try giving it more across the ve table if you saw 160 blm at 2000 holding throttle

IROCBOY

IROCBOY

RBob

iTrader: (1)

According to their website those injectors are modified. They are listed to be able to flow from 33 to 48 #/hr. So they are what is known as "drilled." Unless they have been characterized there is no telling what the compensation values should be.

They also have a Bosch 36 #/hr, white skinny body. These would be the ones to use.

Is there a part number on the injector body?

RBob.

IROCBOY

IROCBOY

ULTM8Z

Oh man...

Without naming specific injector companies... my experience with "modified" injectors (as some of the regulars on this board probably remember) was an EPIC UTTER failure...

You can search on Bosch-III's in the DIY PROM section...

I absolutely could not get them dialed in. They were 30 lb units. BLM's, AE, PE, etc.... seemed like everytime I fired the car up it would run differently enough to invalidate my previous tune.

Soon as dumped them and got factory 30 lb injectors, all of those problems disappeared.

You could try putting in the attached voltage offset tables and see if that helps. Unexpectedly high BLMs (in the 150-160 range) seem to be a leading symptom of this voltage offset issue with Bosch-III's...

These values worked on my car as well as few others... They're specific to my particular 30lb part number, but they seem generic enough to get really close on other people's Bosch-III's.

ULTM8Z

I was swinging that injector scalar around by up to ~50% IIRC trying to get those modified injectors to get inline. Again, I had to essentially $h*t can them and get box-stock factory injectors in order to get good results.

IROCBOY

ULTM8Z

Well just consider this a heads up. You may not have the same issues I had. Before you scrap them, try to get them dialed in. Otherwise it's just throwing money away.

I was maxing out the duty cycle on my old 24 lb early-style Bosch injectors, so I just made the jump to 30 lb. Probably overkill for a mildly built 350, but I'd rather have the margin.

If you end up with new injectors, nothing wrong with running 36 lb once they get dialed in. Then if you do any future mods for more power, you have the injector capability already there (which is also why I made the jump to 30 lb).

IROCBOY

Thank you for the PW info. I will try it out. I did get characterization data with my injectors when I bought them, but it’s just the manifold vacuum/ flow numbers. Nothing about PW. think it’s worth asking the seller if they have that info? Or has that been tried a million times?

ULTM8Z

You could try asking about it. Again, my experience may have been a one-off...

IROCBOY

Just an update on my starting and idling issue. I put in the voltage offset table that you posted and things seem to be improving. The car starts ok and is responding correctly to the tuning adjustments. Thank you