IROCBOY

I am just beginning tuning for my .383 engine project. It is a 7730 ECM and I'm using tunerpro rt and the autoprom from moates.net

My engine is actually a .377 stroker as the block is brand new.
I have AFR 195 heads 75cc chambers
My rotating assembly is internally balanced and all forged
I'm using the first fuel injection intake manifold assembly
I have 36 lb injectors
My compression ratio is calculated at 9.8:1
I'm using a comp cams hydraulic roller cam with 236/242 duration at .050 with a gross valve lift of .520/.540 and a 112 lobe separation (this was a recommended cam by the folks at comp)
And I'm using 91 octane fuel without ethanol.
Everything on this engine is brand new so, new spark plugs and new ignition components.
Base timing set to 6 BTDC
I also installed a higher volume fuel pump in the tank

My problem is this: I can't get the car to idle smoothly with the stock BIN file (it is a 305 engine bin file) the exhaust is producing soot and due to the much larger injectors I believe it's attempting to run very rich. There was one time out of about 7 attempts where I got the ECM to enter closed loop mode and the BLM count dropped from 128 to 108. So i dropped the VE tables by 20% in 5% increments and attempted to start it at each increment. It doesn't seem to make any difference in the very rough and sporadic idle.

Tunerpro is recording 4 knocks in the minute of rough idle but the engine sounds as though it's knocking about every 1.5 seconds on average but not consistently. And it pops or backfires loud about 5 times in a minute.

I have also tried advancing the idle across the entire table by 2 or 3 degrees and as much as 4 degrees over the stock bin and it doesn't seem to change a thing except it runs even more rough and choppy.

I have a wideband o2 sensor connected as well. It is an AEM brand unit. It only reads double dashes though after startup and the Dial indicator is pegged to over 19 for an AFR mixture so I assume the actual mixture is out of range one way or the other.

This is my first and realistically probably last engine build ever. It has taken me 1.5 years of research and acquiring the proper combination of parts and measuring and fitting. I have been extremely careful assembling this engine and now with its terrible attempt at idling and knocking and backfiring I'm getting very nervous and very frustrated.

I'm not asking for somebody to make a magic Bin for me or tune this monstrosity for me (although that would be fantastic). But I am looking for any guidance that you'd be willing to give me. I have been researching for months on this subject as I completed my engine installation and I have read the FAQ guides and stickys that apply. I'm just kinda lost right now. Head spinning and worried. Any suggestions?

As a side note I have been a licensed mechanic on private jet aircraft for the last 11 years after I was a mechanic on fighter jet aircraft for four. So I have experience with electrical systems and schematics and anything mechanical. (Just not tuning automobile fuel injection.)

ULTM8Z

I'm glad to hear you have a WB O2 installed and are taking data.

First thing, I'd start out by ditching the 305 calibration and start fresh with the SAUJP_V5 bin as well as the corresponding xdf and adx files for Tunerpro. It has a lot of features that are going to come in very handy later once you start getting this set up dialed in.

Even with SAUJP, you'll have a number of things you need to get ironed out... some of which you may have already done on the 305 bin...

Displacement - need to set it to 784 cc/cyl in the constants (for a 383)

Injectors - need to set to 36 lb/hr

Also, if you have Bosch-III injectors, you'll need to get the voltage offsets correct. A quick search on that should net you what you need.

I wouldn't start playing with the VE tables until you get those things ironed out and properly set up. Otherwise you'll be chasing your tail.

Once you're into VE tuning on the idle region, take a look at LakeEffect's thread on tuning idle... his situation sounds very similar to yours...

https://www.thirdgen.org/forums/diy-...lli-volts.html

Also, if you're running full length headers, and the NB O2 is in the collector, you'll want to make sure it's a heated O2 so that it reaches the correct temperature to get into closed loop and stay there.

Tibo

iTrader: (15)

Your timing may be far off, possibly 180*. Nearly every time I start an engine that I've pulled the distributor I end up off by a tooth or 180* Try to verify the timing by pulling a valve cover and watching the valves open and close. When the intake valve begins to open, check the balancer to ensure it is coming up also and you lashed the valves correctly. Then plop the cap on with the rotor just before the plug's tower on the cap.

After you verify that I would lock out the timing so to say. Make the entire idle section of the table 20* total timing regardless of vacuum. Then slowly advance the timing on the table. You want the table to look 2D and not 3D. At this point the only thing you should have to think about is fuel. Verify fuel pressure is in check. Start it up and if the table seems way off try adjusting the injector size.

Orr89RocZ

iTrader: (20)

Dashes on wideband means lean! It needs fuel.

If plugs are black and fouled, thats rich. Now just need to find where its rich and where its lean. However if its sooo rich its misfiring it can read lean on wideband

Start with above suggestions on getting cyl size entered and injector size. Start with 350 bin. Go from there

IROCBOY

I will try the SAUJP_V5 from here on out. I forgot to mention that I had previously set up my Scalars for the injectors and cylinder volume. I did not change the voltage offsets (I must have missed that in Scalars?) And my O2 sensor is in the collector but its a stainless shorty header so I don't think it'll have a problem getting warmed up. Thank you very much for the help and suggestions so far!

IROCBOY

I have checked, and double checked my base timing on this engine the exact way that you have described. But tonight i'm going to triple check it. Also, I lashed the valves per comp cams instructions. But i'm going to redo that as well tonight.

IROCBOY

I think that you have described my situation exactly with the too rich for the O2 sensor to read properly. The exhaust is actually producing light soot and the plugs are blackened.

Orr89RocZ

iTrader: (20)

Is this happening on first cold start? Is it rich then?

Clean plugs out or get new ones. If its rich on first cold start, look at your open loop vs coolant temp table for fueling. Take some percent out of there. Watch your wideband and check plugs.

Do not continue to run motor this way to operating temp until fuel is lean enough to not foul plugs and it idles somewhat wel. You'll fuel wash the cylinder and rings wont seat. Or if already broken in, you'll just get fuel in the oil.

May want to force open throttlebody screw to get a fast idle speed at first to establish the ve map before backing it down

RBob

iTrader: (1)

You also need to increase the idle speed, try it in the 850 - 900 RPM area to start off. Once the idle and tune get better may be able to lower it a little.

RBob.

ULTM8Z

I guess the O2 in the collector... it'll be self evident if there's a problem with that. It'll fall out of closed loop off and on...

IROCBOY

I also increased the target idle speed to exactly this two days ago. I'm glad to see we're thinking the same though

IROCBOY

Yes, its happening on the first cold start. I have to think its rich. I'll remove plugs and clean em tonight too.