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TBI on a modified Engine, now going to Holley Terminator

Greg Ducato

Greg Ducato

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I have been fighting with my 383 swap for about 8 weeks now and I am thinking about ditching the TBI and going to a Q-jet and HEI and calling it a day. Need someone to talk me down off the ledge or make a case for the swap.

After some engine issues such as no oiling in the top end, two burned up sets of roller tip rockers and push rods, and now a nasty bottom end noise, my builder tells me my pistons are losing their coating and the cylinder walls are being washed out due to over fueling. Engine has been out and apart three times.

I am running a very mild LT-1 stock replacement cam, an Edelbrock TBI intake opened up for a 454 throttle body, 454 injectors, adjustable fuel regulator set at 13lbs , TPI fuel pump, stock EGR and an EBL computer system.

The truck does run pig rich at cold start, there has been zero tuning to the program EBL provided, and let me state for the record that this in no way reflects on Dynamic EFI or its excellent products. The problem is that I am not a tuner and I am not familiar with setting up a tune or even downloading one. (I am typing this with two fingers). Until I bought the EBL software I had never even owned a laptop computer.

I can solve all of my drivability issues and pick up horsepower and maybe even MPG by going with a well built Q-jet on a Good aftermarket spread bore intake and using an HEI distributor.

You guys have lots of experience with this kind of stuff, can you give me some advice? ( yes I know I should have put a 6.0 LS in it)
 
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Greg Ducato said:
I have been fighting with my 383 swap for about 8 weeks now and I am thinking about ditching the TBI and going to a Q-jet and HEI and calling it a day. Need someone to talk me down off the ledge or make a case for the swap.

After some engine issues such as no oiling in the top end, two burned up sets of roller tip rockers and push rods, and now a nasty bottom end noise, my builder tells me my pistons are losing their coating and the cylinder walls are being washed out due to over fueling. Engine has been out and apart three times.

I am running a very mild LT-1 stock replacement cam, an Edelbrock TBI intake opened up for a 454 throttle body, 454 injectors, adjustable fuel regulator set at 13lbs , TPI fuel pump, stock EGR and an EBL computer system.

The truck does run pig rich at cold start, there has been zero tuning to the program EBL provided, and let me state for the record that this in no way reflects on Dynamic EFI or its excellent products. The problem is that I am not a tuner and any local tuner has not been willing to help me set this up further. I am not familiar with setting up a tune or even downloading one. (I am typing this with two fingers). Until I bought the EBL software I had never even owned a laptop computer.

I can solve all of my drivability issues and pick up horsepower and maybe even MPG by going with a well built Q-jet on a Good aftermarket spread bore intake and using an HEI distributor.

You guys have lots of experience with this kind of stuff, can you give me some advice? ( yes I know I should have put a 6.0 LS in it)
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Did the oiling issue get figured out??

Don't ditch the TBI setup, you have all of the parts to make it work and work well. EBL is a good system and a great system to learn with so quit psyching yourself out and just play with it, you can only make it better.

First step is use the EBL utility and enter all if the info for you to figure out the BPC value. This value sets the base pulse width and will fix the pig rich problems from the larger 454 injectors and will likely get the tune in the ballpark. From there make adjustments to the fuel map until your BLM numbers are reasonably close to 128.

From reading many of your posts it is obvious that you are a very intelligent person and know how to figure things out, so go and figure it out.:deal: Post up your questions so we can help you. In the end for the small price of some frustration and head scratching you'll gain a lot of experience and the satisfaction of learning something new.:saweet:
 
Thank you, that is solid advice. The top end oiling issue ended up being a cam bearing problem, it was corrected with a new set of cam bearings. I really would like to make the TBI work and not go "backwards" to the carb but I could easily convince myself that I was safeguarding my vehicle against an EMP attack.
 
Correct me if I'm wrong, but doesn't EBL "self-tune"?

All I've ever done is chip burning, I never got into EBL. I understand as far as EFI goes, chip burning is dinosaur, EBL is at least neanderthal era. :)

Do not get rid of TBI. You spent that much money, make it work. How does it run warmed up?

You've done everything to ensure you have no issues like vacuum leaks, plug wires are done right, proper plugs, no pinched wires, check engine light works properly, etc.? Not implying you are dumb, but if you miss something mechanical, you can end up chasing your tail and cursing the truck for a long time. BTDT. You hear the warnings, don't heed them, and end up like everyone else lol.
 
The EBL doesn't self tune but that would be great if it did! I checked, double checked and re-checked all supporting parts, all new GM sensors etc so I think my electrical and vacuum components are OK , but I have been burned in the past by something simple, so I appreciate that suggestion for sure. Truck runs pretty good warmed up, slight stumble after idling for 30 or more seconds, almost like EGR.
 
Sounds like bigblock knows the system...same process as any of the other 1st gen EFI stuff then. Programming the ECM with proper injector size is crucial to the overall performance of the system...assuming this is a narrowband system, the O2 sensor isn't used for feedback with a cold/open loop condition. So if it's running rich, and everything else is correct/working properly, cold engine operation is relying solely on how it's been programmed, which includes injector size.
 
Greg Ducato said:
That makes good sense
Click to expand...

If you are certain of your fuel pressure, use one of the various online calculators (or even better, if you can find it, the flow numbers with the exact injectors you have) to determine the correct lb/hr for your ECM to use. The VE maps and timing are likely going to be way off as well, but it should get cold idle better.

This is why fudging the numbers by bumping up fuel pressure isn't the proper way to add more fuel with EFI.

The more you know, the more interesting tuning gets. :)

If you can make changes on the fly, which I assume you can, calculate the proper lb/hr rating for your setup. Start the engine, then with it running crummy, before it warms up, update the lb/hr to the correct numbers. If all goes properly, you will instantaneously see/feel the difference. Which is pretty satisfying.
 
I just heard back from the engine builder, he says that the engine suffered from over fueling and washed the coating off the pistons, scuffed the skirts, rings etc and will require replacement of all pistons, rings, bearings etc. ( no warranty) I am sure hoping I can get this dog dialed in before I fire it up and avoid the expense of another engine, I find myself looking at returning to stock, buying a RamJet or even an LS engine to avoid ruining this all again. Engine has been out of the truck four times now, but I'm still trying to stay positive and add this adventure to my list of things I didn't let beat me! Though I may have to re-set the bar for what is considered a win....
 
Go LS Greg. You won't be sorry.

5.3 with a 6.0 cam. @Team208Motorsports

Josh is the most likely candidate to get your tune dialed. He can certainly point you in the right direction
 
I'm already sorry I didn't go that route to begin with, it will be $$ painful to back out of the engine I have now and start from scratch on a $2500 Suburban, but it is a sickness for which I have found no cure. I love this big ugly truck
 
I think you'd be happier with the end product Greg. Don't let a previous poor choice force you into making more poor choices...

For what it'll cost to rebuild that motor again you could have a 5.3 installed and be light years ahead.
 
Greg Ducato said:
I'm already sorry I didn't go that route to begin with, it will be $$ painful to back out of the engine I have now and start from scratch on a $2500 Suburban, but it is a sickness for which I have found no cure. I love this big ugly truck
Click to expand...

I know nothing of coatings, but are they that damaging when they come apart? Ceramic of some sort?

I liked the idea of coatings, but they weren't out when I put mine together. Probably got lucky.

I'd have to agree, if the engine is going to need to be rebuilt, probably better to just go LS.

Hard part is taking it in the shorts on what you've already got into the engine. Hopefully you can find someone that wants what you have. At least you can represent it accurately.
 
I have a lot of thinking to do, I have to keep myself from making a rash decision and think about the end product. Even with no tune/bad tune, the truck had plenty of power with the 383 and great bottom end torque that I would miss with an LS swap. I will keep you guys posted with the final decision, in the mean time do your best to convince me
 
The EBL is a keeper, you just need to do a little work. First do the calculations and get it in the ball park. Then let the EBL do its self tune, yes it does some self tuning. Got to put it in learn mode, it'll make corrections, then load the new tune. Keep doing it till no more changes are made and you are pretty much done.


I'm running a stock engine for now using the EBL. I love it. Haven't touched the tuning much yet, but I keep looking at the manuals and playing with the software so I'll be ready when tuning time comes. Though I have removed a couple things like smog pump and will be using the electric fan control once I get the fans mounted.
 
Central, 45 minutes north of Austin, next to Ft Hood.
 
Practically next door in Texas terms.I appreciate your weighing in on this, I may need your expertise in helping me kick start this thing if you don't mind .
 
Certainly NO expert, but I can piddle some.

Here's what your looking for............................... http://www.dynamicefi.com/Tune_Intro.php scroll down to the VE learn area and start reading. You can get it pretty close with just the stock o2 sensor, if you add the wideband o2 sensor you can do the entire VE just with the learn function.
 
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