Brandon2350

My project is a 1993 p/u with 16168625 ecm. I removed the stock motor and installed a late 70's 350, (.030 bore, healthy cam, 10.5:1 cr, geardrive)hooking all the original components to the new motor (intake, tbi, exhaust ect.)

After several months of tuning and chip burning I cant seem to get it to run lean at idle in open or closed loop, and it's no where near running well enough to even think about taking it down the road. Here are a few of the issues and things i've done.

Leaned out fuel tables, disabled knock retard due to gear drive, removed all added bwp to startup fuel, added timing at idle area, checked several times for vacume leaks, moved air flow tables around slightly, added for the additional 5 cu/in in the constants table, and a bunch of other tinkerings with tables that didn't seem to have much affect on leaning out the idle.

Here are some of the things that i've discovered:

disconnecting one of the two injectors briefly while it's running makes it run better and even out...confirming it's overfueled. When jabbing the throttle quickly, the egr is being activated and pops thru the intake even though i have changed the setting to corrosond with it's idle kpa of around 11. I'm not sure of when it should activate but i assumed it was only during cruise conditions.

Changing the injector size in the chip seems to help but it becomes rich shortly after starting and the idle isn't as stable.

When idleing you can hear it sucking air as the iac is operating. almost as though it's choking, needing more air but noting really seems to make it run any smoother than it does now. And it's rich enough to blow black sooty smoke at idle almost the entire time.

Is my tbi not big enough...not allowing in enough air? or am i missing something?

The cam is installed 6 deg. advanced...Is this the majority of my problem?

Maybe someone can shed some light on this for me. Maybe even a step by step to do if "it was yours" because i'm running out of ideas!

Thank you Brandon

Grumpy

Back to the basics.
Compression test.
Crossed plug wire.
Triple check the *obvious*.

Try running without the O2.
New engines are great for contaminating the O2 with silicone, and some of the Sensor Safe Claims are BS.

Cap and rotor?.
Are you sure the grounds are really good?.

If tuning doesn't work then often there's a mechanical or elec problem.

Brandon2350

I've done a compression test...153 at all 8 cyl. Plug wires, plugs,cap, rotor all new a few weeks ago. plug wires are correct.

I replaced the main braided wire that goes from the engine block to the firewall before i slipped in the motor...Could a bad ground really be the culprit?

I know the timing is dead on also. I had never installed a gear drive before and in the directions at the very top were the words "DO NOT INSTALL AT #1 TDC. INSTALL at #6 TDC. That really confused me but after figuring out the timing events it didn't mean anything. Why it said that I have no idea. I might just take the gear drive out, install the cam "strait up" and see how it goes from there...Could the 6deg installed advance have anything to do with my problems?

When you say try running without the 02....Do you mean simply unplug it and see if it runs any leaner?

dimented24x7

iTrader: (2)

The IAC sucking in air like that means that its likely that there are very high MAP values at idle. This means that all adjustments to the areas that the engine would idle in have no effect. IOW, the computer thinks the engine is under alot of load, and uses the high MAP portion of the VE table, which may have way too much fuel. It could also be an additional problem of not enough timing at idle as well, especially around the high load areas. This will cause the engine to surge/stall and the MAP values to fluctuate.

Can you datalog? Posting a log might help pinpoint the problem areas.

Brandon2350

That seems to make sense...but what would I do to go about correcting the problem? What you said is exactly what I seem to find happening. I cant remember but I want to say it idles around 64 map (I dont have equasion handy but it idles around 11" with a vacume guage) I've datalogged and noted the map readings at idle and adjusted my tables within those same map areas and it doesn't seem to help it any. I'll try and zip up one of my datalog sessions tonight and see if anyone can shed some light on this for me.

Brandon2350

There should be a zipped datalog file if I have done it right.

Fast355

iTrader: (2)

VE tables are off
Spark timing table not right for the camshaft (specs?)
TOO much IAC opening (Just like having a vacuum leak, confirmed by 100ish steps at idle and your hissing noise)

In your log, you never even hit closed loop after 2 minutes. Is this a single wire 02 sensor in a long-tube header? If so, it may never be getting hot enough to operate properly. A 3-wire sensor should be considered if you have long tube headers.

I actually have a $0D based calibration for a production LT4 cammed 350 with Dart Iron eagle 180 heads and 4L60E transmission in a 1994 G10 Van.

I will however give you the warning that this was a serious combination. Try 375-400 FWHP, 105 lb/hr of injector (stock van 68#s @ 30 PSI), 454 TBI unit, bored edelbrock 3704 intake, thorley Tri-y headers. Just to give you an idea, with 3.42 gears and P255/70/R15s it came out of 1st at 50 and 2nd at 95. Fuel shut-off was 6,300 rpm with shift points of 6,100 @ WOT. It was mild enough that it still passed smog easily, cruised 75 all day, drove like a soccer mom, until pushed. I put the vortec run 305 TPI in place of this engine prior to selling the van. The engine is still sitting on the pallet in my garage.

HaulnA$$

From the log, the idle fuel doesn't look too rich to me. With a target afr of 13.1 and 14.1 and O2 millivolts of 500 to 600 it is very close to stoich and should'nt be too bad. Closed loop did'nt happen because the timer had'nt timed out. From the note in the log, you adjusted the IAC vs. airflow vs. coolant tables. Looks like you went the wrong way. The main problem, as Fast355 stated is the IAC counts at idle. Here's what I'd do IIWY. Go back to the stock .bin, adjust the constants to match your combo and then adjust the idle screw for 10 or less IAC counts with a warm engine in P/N and readjust the TPS for .53 to .57 volts. This should give it a little more vacuum at idle and help with the fuel atomization. Then you can get the fuel dialed in then adjust the idle timing for the best vacuum (lowest MAP) at idle. HTH

Fast355

iTrader: (2)

Haulin, most of the COLD closed loop timer delays are under 80 seconds that I have seen. After 120+ seconds, I see no reason for it not to have gone into closed loop. I did notice that the delay hadn't passed though. I wonder if he changed that constant. Then again the O2 sensor ready light never came on either.

Brandon2350

I kept as many of the stock doo dads as possible when I did the motor swap assuming that it would make tuning that much easier, so i am currently still running the stock exhaust and stock exhaust manifolds...including the stock intake and tbi and the o2 is a one wire. So asside from the actual engine block and it's internals, everything is originally from this vehicle as was bolted back on. (this was my daily driver up until I decided to do a "quick weekend motor swap")....more than two yars ago!

Fast355

iTrader: (2)

I finally got un-lazy to prove a point. Your TBI engine can be tamed. I just pulled out the Dyno Sheet for the engine and borrowed a friends scanner (don't have one oddly), emailed the picture to myself, then posted it. With the above combination, the above .BIN file (minus transmission changes for dyno purposes), 68# injectors at 30 PSI. There are two runs here, both in 2nd gear, one open cutouts, the other through the mufflers. The open cut-outs really helped pick up the power. The PCM was tuned to go into 2nd very early and stay there, for dyno purposes. The TCC is also force locked very early. Most of the little dip in torque.

Brandon2350

Haulin, I will try that this weekend and see what happens. I'm still not sure though why it didn't go into closed loop?

Fast, I'm using the E6....or is it 6E... I cant remember... but anyways, My constants table doesn't have an option of changing the timing of open / closed loop (not that I'm aware of anyways). I tryed using my definition file to open yours and it said I needed the "0" definition file. It opened but your injector constant was like 1,000. LOL NOT

Brandon2350

What about the cam? Do you think having it advanced 6 deg could be making this more difficult to lean out?
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Fast,
I forgot....I dont have the cam card, but when I get home I look and see if I can find my notes of when I degreed it....Just to give you an idea

Fast355

iTrader: (2)

The $0D XDF.