Someone talk me out of ditching my TBI setup

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

letitsnow

I'm Awesome
Joined
May 5, 2018
Messages
1,684
Reaction score
2,460
Location
MN
Long rant but I agree with you... I think?

get a 4-barrel intake and go with an aftermarket 'throttle body' of your choice. Holly, Fitech, Edelbrock, whatever.

Im sorry to a lot of you TBI guys but what you get with todays aftermarket far exceeds anything your could have done in the early 2000s. I still have OEM TBIs but I dont think I would think twice about spending $1000 on a manifold and new FiTech or something to get laptop tunable performance if/when I upgrade to the point of out performing the factory settings.

I would need to hear from several people using those new efi's on a daily basis reliably before I would agree with this.

It seems that most people (at least that post about it) who have a new efi set up, barely drives the vehicle and is always still tuning it...
 

RichLo

E I E I O
Joined
Jan 6, 2015
Messages
3,618
Reaction score
5,540
Location
Wisconsin
I would need to hear from several people using those new efi's on a daily basis reliably before I would agree with this.

It seems that most people (at least that post about it) who have a new efi set up, barely drives the vehicle and is always still tuning it...

Co-worker drives a late 70s ford daily in the summer with a base model (7-8 years ago) FiTech. Almost never miss his car in the parking lot and when I do its not a fuel issue.
 

thinger2

I'm Awesome
Joined
Jul 6, 2019
Messages
1,562
Reaction score
3,935
Location
Tacoma
'90 Suburban, LO5 350.

A couple of months ago, my engine blew a head gasket, and while I had the heads off, I installed some ported small-chamber TPI heads, and an upgraded cam (204/ 214, .420"/ .443", 112 split).
Of course, the factory computer is confused by the strange MAP readings from the lower vacuum signal (15-16" hg @ 750 rpm), so I needed a chip.

I've tried FOUR of them, and none of them worked. Every time, the engine goes into "limp-in" mode and runs worse than it did before.
SES light stays on or blinks like a strobe-light; cannot retrieve any codes.
Reinstalling the factory chip eliminates this.

I've gone through the whole diagnostic procedure for this condition (from an official GM service manual), and every time it comes up being the fault of the PROM chip.
The tuner has tested the chips, and swears that they're good.

For whatever reason, this truck's ECM just doesn't like tuned chips.
At this point, I'm about ready to slap a Quadrajet and big-cap HEI on it and call it good, but that seems like a huge step backwards to me.
And I'm not getting rid of the cam.

Anyone have any arguments to keep the TBI?
Just keep in mind if you have a 700r4 you need pay attention to the throttle linkage/ TV cable geometry when you carb it.
The Tv cable will snap right in place on a Quadrajet but the linkage geometry will be wrong.
They used to sell corrective TV cable brackets but I dont know if those are still available.

The TV cable and its relation and its length of throw controls the line pressure in the tranmission.
That geometry between the throttle lingage and the throttle plates is very important.
The 700r4 shift points and line pressures come from that TV cable to throttle relationship..
Look real deep into that.
Its often ignored.
Its about a 50 buck difference between the right parts and a smoked transmissiom.
Only because I do believe I am the King of stupidly smoked 700r4s
I should probably get a 700r4 tatoo.
 

CrustyJunker

Is STILL Here?
Joined
May 20, 2012
Messages
553
Reaction score
382
Location
Indiana, USA
I would need to hear from several people using those new efi's on a daily basis reliably before I would agree with this.

It seems that most people (at least that post about it) who have a new efi set up, barely drives the vehicle and is always still tuning it...

Agreed on this. Modern aftermarket EFI systems are better now than they were just a few years ago, but still not an end-all solution. I've seen and heard a few reliable setups, but I've also seen people get stranded and want to put their "new," stuff for sale and go back to a carb.

Some of these repairs were covered under manufacturer warranty, but it stinks when stuff goes wrong. When you have your second refurbished ECM that quits responding and won't communicate. A fueling loop so out of whack it won't hot start or you have to go through a laptop/handheld with base tunes to get running again.

Granted some of these things are blamed on the installers wiring, poor tuning, etc. -It's not always the case. For a daily driver, if you're not running a reliable OEM-based control or flagship aftermarket setup (expensive)...Keep an open mind and prepare for some issues. End result is what you want to do with your vehicle and the purpose you use it for. :waytogo:
 

618 Syndicate

You won't...
Supporting Member
Joined
Sep 17, 2020
Messages
6,600
Reaction score
15,447
Location
Southern Illinois
Probably 50/50 - good/bad too. In my experience, if you don't try other avenues, you may not know how much can be improved. On the chip I bought from him, all he did was make the SA tables a little more aggressive, and had me install an 18 LB spring without any VE tables modification from stock. The 18 LB spring gave me more fuel but, when I was tuning, I found the injector DC was going over 106% at WOT and 5200 RPM, meaning they were open all the time.

Just buying a mail order chip and thinking it's good enough, it usually isn't. :33:
Anything even approaching 100% DC is asking for trouble.
 

PlayingWithTBI

2022 Truck of the Year
Supporting Member
Joined
Jan 3, 2019
Messages
9,546
Reaction score
14,667
Location
Tonopah, AZ
Anything even approaching 100% DC is asking for trouble.
Yep, I finally wound up setting my pressure to 20 PSI and it's still a little high at ~90% but works fine. I'd like to go a little higher pressure to get it down to 85% but it's getting close to being spring bound.
 

Texasbob

Newbie
Joined
Jul 6, 2021
Messages
2
Reaction score
6
Location
Texas
I have the Edelbrock Proflo 4 on my 90 GMC along with a mild cam. I drive it daily and it starts and runs like a new vehicle. It's been reliable since it was installed 2 years ago. It wasn't cheap but it is reliable and works great with the other mods. No way i would go back to stock TBI.

Bob
 

RedBurb

OBS Enthusiast
Joined
Apr 1, 2021
Messages
70
Reaction score
60
Location
California
Aftermarket EFI? Don't go there! It's more addicting than ****** (first letter "h", e, r, o,i,n --stupid censors) but without any occasional easy fixes. Get a grip, drop the idea, or risk spending the rest of your waking days tuning everything out. :biggrin:
 
Last edited:

Traveling man

Newbie
Joined
Nov 14, 2021
Messages
16
Reaction score
16
Location
Arkansas
Aftermarket EFI? Don't go there! It's more addicting than ****** (first letter "h", e, r, o,i,n --stupid censors) but without any occasional easy fixes. Get a grip, drop the idea, or risk spending the rest of your waking days tuning everything out. :biggrin:
Weird how people have different experiences, I ditched my 350 TBI dropped in a junkyard 6.0 and 4 L 80 e and aftermarket ECU, have twice the power, drive it everyday, read and follow the instructions, no daily tuning no troubles whatsoever. But I love my kick-start only Harley, with a super B carburetor because who needs that newfangled stuff right! Starters horns blinkers extra tuning circuits in the carburetor or fuel injection, that's for posers not real men! Lol
 

RedBurb

OBS Enthusiast
Joined
Apr 1, 2021
Messages
70
Reaction score
60
Location
California
I was only half kidding about how addicting the new EFI stuff becomes. I constantly interact with the Terminator X running my blown BBC 496. Driving with a cell phone in hand pales in comparison. LOL
 
Top