New Guy. TBI questions and help needed.

Hello I'm Andrew live in Middle Tennesee, and enjoy working on vehicles and projects. I have a rock crawler/cab truck I have been working on for a while now, over 10 years. Chevy SWB Frame, 350, sm465, np205, 1 ton axles 4.10gears, and 42in Super Swamper TSLs. 1991 s10 cab from a 4.3 truck. Engine is a freshend up 350 .040over, crank is 10/10, regular truck heads (not TBI heads), high volume oil pump, Lunati High Eff. cam 205/205 @ .050lift .427/.427lift LSA/ICL:110/105 800-4600rpm, Edelbrock Performer intake with TBI adapter, and Headman Street rod headers. When I started the build injection was out of the budget, but since I got the new cab and it was TBI, I thought I would try it before I cut it up. I got it all wired up and it runs minus a few hiccups. I emailed a guy a couple months ago who told me he could burn me a chip, emailed him the other day and now all he wants to do is tell me what I have done wrong and when I try what he says and that's wrong too. I understand my cam may not be exactly TBI friendly. I'm going to get exhaust on it in a week, I've got the Flowmaster y pipe and 3 in Summit welded 2 chamber race muffler for it. O2 sensor is about 1.5in down from Header collector. We set timing at 10deg then plugged the wire in, it is reading 15-16in vacuum with no exhaust. The chip guy told me that was way to low for TBI. I went and checked a friends truck with same cam and TPI, it has 17-18in at idle. The exhaust on that truck is close to what mine will be, he did have Howell burn him a chip years ago. From what I can get out of Chip guy my timing maybe off along with other things so he says. I will report back more after exhaust and I adjust timing and a few other things, before i throw in the towel and have to change the Cam in it. I was hoping someone on here had gone through the same thing. Anybody recommend a few chip people or companies, or some things to try? Not looking for a Monster, just a good running engine for the woods. Thanks, Andrew
:rockon:

What year engine and ECM?

In my 88 (7747 ancient ECM) 350, I have a Lunati Voodoo 10120700 cam, 207/213 @ .050, .466/.484 lift w/1.6 full roller rockers, 112 LSA. It runs ~15" vacuum at idle (-2 @ WOT LOL) according to my data log with 46mm bored out TB. I'm not going to say it runs perfect but I'm still working on tuning it.

There's folks here that can help with your tune and just about everyone will tell you that no 1 chip fits all, you need to data log. I'm using TunerPro RT with ALDL cable to do this while learning and improving the performance and MPG on mine.

Enjoy!

The engine is old 4 bolt main 350 out of a 79 3/4ton truck. When I started it had a 1228062 in it. The guy at TBI chips told me it only had V6 timing and fuel tables in it. I went to the 1227747. I have tried 2 different 7747 computers. One hunted for idle like my 8062 did, and the other one didn't. I went to a pull a part and found one, and it seems to idle ok it's just very rich at idle but I think some of that is open headers. I have 2 reman injectors to rebuild another injector pod for it along with a pod spacer and different TBI adapter from SPR performance. I was gonna play with timing and see how that helps. I also have a new set of Z28 valve springs coming for it. I'm not sure if I could tune myself without a lot of help.

I'm new to this game too and have made my share of mistakes. One was to keep the 7747 ECM, it's 10 times slower than the newer years like '93 up. I still haven't made up my mind to pull the trigger and order the Dynamic EFI - https://www.dynamicefi.com/EBL_Flash.php it takes the guesswork out of this whole thing but, where's the fun in that?

My 2nd mistake was ordering a chip from that guy. Dave w helped me tremendously with a different starter chip and a ZIF socket in my ECM so I can flash my own 27SF512 chips while data logging and tuning.

I'm going to make plenty more mistakes but, with folks like these here, I'll learn while playing with my TBI and tuning it.

I'm just trying to get mine to run good. It doesn't have to be a Monster. I'm looking for a good starter chip for mine, and as long as it performs I will leave it be for a while. Just trying to get my truck to the woods and rock crawling. What all has been done to your motor? How do you get a hold of Dave W? Thanks, Andrew

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What all has been done to your motor? How do you get a hold of Dave W? Thanks, Andrew

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I have the 46mm bored TB with 18# spring from SPR Performance on an Edelbrock 3704 bored to 48mm intake, Ebelbrock 43661 breathable air cleaner, ADO-EP381 fuel pump (used in Vortec systems) Summit Racing (made by Trick Flow) 162108 aluminum heads w/2.02/1.60 valves and angled plugs, the Lunati cam mentioned above with Cloyes double roller timing set, Spectra Premium dizzy with Pertronics Flame Thrower coil, Summit Racing G9015 shorty headers (w/AIR required emissions), heated O2 sensor, JBA mandrel bent "Y" pipe with high flow collector to Thunderbolt 3" high flow Cat, to 3" 3-chamber muffler.

It's not a monster, I was hoping I could still pass smog here in AZ with it de-tuned, EGR turned back on and HyWay Lean Cruise turned back off. Dave is a Moderator here on Gearhead EFI. You can try to PM him.

PlayingwithTBI thanks man. I'm just aggravated with mine at the moment. I'm hoping the exhaust helps it along with other changes. I believe my heads are 1.94/1.50 76cc truck heads. My distributor is a Davis Unified TBI unit and I'm also running the Flame thrower coil with Taylor ThunderVolt 8.2 ign wires. Im running a Walbro GSL393BX pump on the frame rail because I have a 16gal fuel cell on top of the bed. The pump is big enough to up the spring in it if i need to. My truck has no EGR on it at all, and a 180 deg Thermostat. I'm just kinda confused a little on which way to go at the moment. I may try to PM Mr. Dave and see what he says. I put Antique tags on my rock crawler for that reason, its a permanent tag in Tennessee, so i don't have to keep renewing it for a truck that won't see 500 miles a year on the road.

My name is Ty. I live in Utah and have been in the military for 32 years. I have a 1995 GMC with 5.7. L TBI. The engine is starting to burn oil and I plan on replacing it. Trying to decide what path to go. Either 383 or 383 with vortec or aftermarket aluminum heads. I do not know much about tuning, ECM, burning chips and etc. I also have thought about a LS swap.... Looking forward to learning what I can from others who have done these type of projects.....

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I went to a pull a part and found one, and it seems to idle ok it's just very rich at idle but I think some of that is open headers.

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It just dawned on me, do you have a heated O2 sensor? With open headers it may not be getting up to temp so your ECM can adjust your AFR.

No sir it's a regular one. I'm hoping to drop it off for exhaust next Sunday or Monday, and I think that will help some. I'm going to bring timing back to Zero and get that new injector pod built for it also. Thanks for all your help. I will report back after I get that done, and let you know it acts. What's your name? I got a hold of Dave W and he is going to help me with my chip.

You should go with a 4-wire heated O2 sensor. This way you have a guaranteed ground instead of relying on grounding through your headers. With the reduced back pressure you get from headers, mufflers etc you will probably be going in and out of closed loop at lower speeds. With the heated O2 sensor in my truck, I go into closed loop shortly afler I pull out of my driveway and it stays in until I go under 4MPH.

Good to hear Dave's gonna help you, he's a great guy.

Peter

Ive seen 1 to 3 & 1 to 4 wire O2 sensor adapters that plug into the 1 wire harness on Ebay. You would have to run the power for the heated part, but it may be easier than splicing. I have not tried one yet though, new at this myself

Ex - https://www.ebay.com/itm/TPI-TBI-3-W...EAAOxy--NRw91T

I've read the same story as yours multiple times.... He's been around a long time but too bad he can't get a tune for a custom build right.

I ran a TBI setup for a while with more cam than both listed in this thread, and it ran OK once tuned. So, the claim about not enough vacuum is pure BS.

Dave W. can get you a decent starter chip. Then, you should decide if you do some tuning work yourself, or if you get Dave to do more iterations for you.

Definitely switch to a 4-wire heated O2 sensor. The sensor signal ground wire goes to the tan wire that is bolted to the intake. You might need to keep it connected to the engine block for it to work, but try it disconnected first. The heater power is from a switched ignition source and the heater ground can go the engine block or truck frame.

Peter,
I may try one after I get the exhaust on and see how it acts, and I'm going to back timing back to Zero like factory. I would think it is getting hot enough because it isn't but about 1.5in below the collector on the street rod headers, they look like the old ram horn manifolds kinda. My truck will run a lot at slower speed in the woods and rock crawling, so that may help it for sure. Thanks Peter for all you help. It's very cool to find a group of people like ya'll that are willing to help me. Andrew

Lionelhutz,
He seemed like a good guy when I first emailed him about getting one of his chips about six months ago, and then when I emailed him the other day telling him I was getting close to ordering it, he seemed to want to point the finger and tell me what I was doing wrong, and that it wouldn't run right. He did help me diagnosis some of my problems with the V6 only loaded computer, and I'm won't take that away from him. I believe he is a good guy just maybe tired of doing it. I would be happy with OK, it doesn't have to be a Monster just make good power and run and idle right. I will probably let Dave do all the alterations to the chip. Tuning it myself seems a little over my head at the moment. I was very proud after I got it all hooked up and fired it up for the first time and it ran. I have heard of the 3 wire heated O2 sensor, but not a 4. Is a 4 supposed to be better than a 3 wire? I'm still trying to learn all I can about TBI, so I can help others like myself in the woods and rock crawling with there vehicles.

I want to Thank everyone who has helped on my post so far. I will keep reporting back on my progress.

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Originally Posted by GreaseMonkey210

Peter,
I may try one after I get the exhaust on and see how it acts, and I'm going to back timing back to Zero like factory. I would think it is getting hot enough because it isn't but about 1.5in below the collector on the street rod headers, they look like the old ram horn manifolds kinda. My truck will run a lot at slower speed in the woods and rock crawling, so that may help it for sure. Thanks Peter for all you help. It's very cool to find a group of people like ya'll that are willing to help me. Andrew

Lionelhutz,
He seemed like a good guy when I first emailed him about getting one of his chips about six months ago, and then when I emailed him the other day telling him I was getting close to ordering it, he seemed to want to point the finger and tell me what I was doing wrong, and that it wouldn't run right. He did help me diagnosis some of my problems with the V6 only loaded computer, and I'm won't take that away from him. I believe he is a good guy just maybe tired of doing it. I would be happy with OK, it doesn't have to be a Monster just make good power and run and idle right. I will probably let Dave do all the alterations to the chip. Tuning it myself seems a little over my head at the moment. I was very proud after I got it all hooked up and fired it up for the first time and it ran. I have heard of the 3 wire heated O2 sensor, but not a 4. Is a 4 supposed to be better than a 3 wire? I'm still trying to learn all I can about TBI, so I can help others like myself in the woods and rock crawling with there vehicles.

I want to Thank everyone who has helped on my post so far. I will keep reporting back on my progress.

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4 wire is better because it uses an isolated ground back to the ECM rather than relying on the sensor body and exhaust to ground it back to the ECM. The 02 sensor ground usually goes back to the block through the harness on a TBI.

Got the exhaust on it. It pulles 18-19in of vacuum idled up some, or 16-17 at normal idle. It seems to be running ok at the moment.

[QUOTE]16-17 at normal idle.[QUOTE]

That's more than I have so, I wouldn't worry about "not enough vacuum for TBI".

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Originally Posted by Fast355

4 wire is better because it uses an isolated ground back to the ECM rather than relying on the sensor body and exhaust to ground it back to the ECM. The 02 sensor ground usually goes back to the block through the harness on a TBI.

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Out of curiosity, what would be a part number or vehicle to look up for a 4 wire O2 sensor that works with the TBI system?

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Originally Posted by c5wagner

Out of curiosity, what would be a part number or vehicle to look up for a 4 wire O2 sensor that works with the TBI system?

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Just get one for say a 1997 C1500 5.7. Upstream sensor preferably Delco.

Here's the ACDelco 4-wire sensor

https://www.amazon.com/ACDelco-AFS75...gateway&sr=8-1