I have been trying for some time to tune my 1993 TBI 4l60 p/u and I cant seem to lean it out. Ecm 16168625 / E6 or 6E...cant rembember, but anyways,

Everything is stock and original to the vehicle except the block and its internals which are new. I have covered all the basics, vacume leaks, sensors, plug wires, dist, rotor, comp.test. all good.

It blows rich black smoke and fouls plugs idling. Not road worthy yet. Heres what i've done.

Changed all open / closed throttle fuel tables.
Rearranged both open / closed spark tables.
Raised idle 100 rpms in all idle tables.
Changed injector constant to allow for additional 5 cu/in (.722 L/ per. cyl.)
and finally after none of this seemed to prevent it from fouling plugs I opened up the butterflys and readjusted the iac to about 10 counts which seemed to help but its still pig rich. It Idles around 11" on a guage or around 60 map when logging.

I posted a while back my datalog session and everyone seemed to think my setup looked pretty good, almost stoich. spark was off a little but not much. What am I missing here? Is my stock 2 barrel 1 3/8" tbi too small or am I just overlooking something in the programming?

 

Hey Brandon, I have a 93 5.7 , 4l60e truck with 16168625 pcm $E6 also. I have a new engine and tuning mine with tunerpro. Mine seemed very rich at idle with the new engine at first, I used 91 iron L98 tpi heads and a comp cams 206,212 at .050 and .425, .440 lift , 112 LSA. I messed around with fuel tables for a while with no help and then switched to a main spark table for a 91 L98 tpi which has way more timing everywhere than the lame truck programming and the truck instantly ran a million times better. It burns the gas instead of blowing it raw out the exaust. My base timing is 8 degrees and the initial spark timing is set at 6 in the bin. I use 93 octane. It doesnt seem rich now- should have some datalogging going on soon to help me fine tune it. Do you have the stock heads? What is your fuel pressure? Jon
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Also you say you changed injector constant or cylinder volume? which one?

 

Hey Jon, The heads i'm using are the older GM 202 iron heads. they have been massaged a little though, porting, polishing, 3 angle valve job ect. I cant remember my exact cam specs but when I degreed it I want to say its around 212-214 @ .050 with a pretty good overlap and my FP is stock. For programming / tuning I'm using tunercat and Datamaster. To allow for the additional cylinder volume (bored .030 over) I changed the constant "injector flow rate" from the original 6 something liters per cylinder to .722 liters per cylinder. Mines fouling plugs constantly, was yours doing the same? Did you have to open up the butterflys and readjust your IAC?
My cam is installed with 6 deg advance. Should I be putting this value into the "main spark bias" constant? Is your cam installed advanced also? It sounds like were experiencing some simular things that maybe we can work thru together.

 

Hi, OK im no expert but- Our initial situation was similar, yours worse than mine. Those heads you have need more spark timing than the relatively fast burning 193 tbi heads you removed. With the timing better you will be able to close the throttle butterflys more at idle and you will have more vacuum and the computer wont be adding a bunch of fuel cause its seeing 60 map right now. Mine idles at 18 or 19 inches vac. Your cam advanced 6 degrees is not the value we are talking about. Its not main spark bias either. Leave that alone for now. It is initial spark advance in the constants/scalers list. That is what is set at 0 degrees on the stock setting to match the 0 degree distributor timing setting. You Disconnect the single wire connector tan and black wire, it is under or near the plastic relay cover on the pass side of the firewall, then you can set the timing with a timing light. Then recconnect the wire. I would try 4 or 6 degrees now and put that in the bin as the initial spark advance. Copy the main spark table for rpm vs map open throttle from a L98 tpi bin, I think it is AUJP code . I bet this will get you drivable. You can copy it to the closed throttle main spark table also. You will have to keep an ear out for detonation and reduce timing in the midrange if you get pinging, datalogging would be a good thing too , to look for knock counts . I run premium in mine and have had no pinging. In the truck bin it has a couple extra columns in the main spark table , I dont remember exactly but you have to interpolate a couple columns at say 45 or 55 map or something where the tpi table went from 40 right to 50 or 60map or whatever it was. Mine wasnt fouling plugs but I could smell it was blowing a lot of gas vapor out the exhaust and ran bad and would shake and shudder when you I tried to drive. I didnt have to mess with my tbi. The stock cylinder volume setting is 712cc or .712 liters per cyl. You changing that to account for .030 overbore shouldnt have much effect on your problem, its a very small change. Good Luck, J

 

I actually think I might have it after reading your last post. You've been a huge help! I'm going to try and get my hands on that code this weekend and see how it goes. I'll let you know how I made out as soon as I get everything together.

Thanks Again, Brandon

 

http://www.moates.net/info_pages.php?pages_id=14 The bin is here on moates site. User = moatesuser
Password = moatespassword The xdf for the bin is also there that works with tunerpro, I dont know if it will work for you with tunercat, you may have to get it from tunercat. Or you can use the free tunerpro program and tunerpro xdf and pull up the table and copy it and transfer it to your tuner cat editor.