I am at a crossroads in my project. I am doing a head and cam swap. I have two main choices as far as induction goes. Stay with my carb or install a FIRST unit I have laying around. I know all the power possibilities so no need to discuss them.
My concern is reliability of tpi. I follow forums all the time and I’m concerned with glitches and goblins that are always popping up on tpi. Idle surging. No start. Car falling flat on its face. Will this be avoided by going to all new sensors and sending units?

 

I’ve had no unexpected problems due to TPI parts, specifically

Have had to replace injectors on every one of them. But given the fuels today. Not unexpected.

 

That’s good to know. It just concerns me all the posts I read on various forums about my car quitting, or it’s surging, or I’m getting a code that I can’t clear. This is a 69 Camaro with a healthy 450+ hp motor. I want the reliability of a carb. Can I get it with tpi?

 

Carbs aren't particularly reliable. Manufacturers went to fuel injection BECAUSE it's more reliable. Reliability depends on how you build it, what parts you use, and how it's tuned. Properly setup and tuned fuel injection will run better, be more reliable, and the engine will last longer due to less fuel dilution and cylinder wall washing.

TPI was one of the best systems and thus why is still in use and has been copied and the basics of it's architecture used for many subsequent and aftermarket systems.

That said - you have to understand it. It you don't have a grasp of fuel injection, closed loop, and all the knowledge on how the sensors work and what they do - you will have problems and you will struggle to solve them. At this point these cars are antique and unless you have a LOT of money to pay shops to work on them then you, as a DIY'er will have to learn about it. If that's not something you want to do or pay for, and you know carbs already - then keep the carb.

GD

 

Its the swap aspect that is the most likely to get into trouble. Something not hooked up correctly, a missing or inadequate ground, etc. These EFI systems depend on the proper electrical inputs otherwise they can run like crap and then the user can't figure out whats wrong, gets frustrated, etc. And it gets even more frustrating having to depend on other people because they may not understand how the system works and end up blindly throwing a ton of money at it to get it to work properly.

Not trying to be discouraging, but offering realism. I should know because I did the swap back in 1996 and I went through a lot of that myself. Now you may have am easier time with it than I did, and certainly more is known today, and these message boards are filled with tons of knowledgeable people who are here to help as much as possible.

The other major thing is tuning. If you have a 450 hp small block, its most likely going to need a lot of tuning. Though if you wire up the system with an aftermarket ECM, one with self tuning capabilities, it may make this aspect of it a little easier.

But all that said once you get it running properly, you'll never want to go back to a carb.

 

Thanks, but I feel you’ve missed my point. I know the guy who posted before you did. Big Three went to EFI for two reasons, emissions and fuel economy.

I have the skills and knowledge to make the swap. I will learn to tune it before it goes on the motor. What I want to know is if the thing is reliable. You can read the threads in this forum. Nothing mechanical is 100% reliable but I can and have set carbs where nothing changes and day in and out they run with no problem. Are the problems that pop up in this forum due to things wearing out (sensors) or is it trying to get another year out of the hacked up harness that was used to swap it onto an engine.

 

I did my TPI swap onto a 87 Monte Carlo SS. The swap was fairly easy due to the similarity in body wiring. In the beginning, my issues were swap related (ie: improper Vats bypass module wiring, I programmed Vats out a couple years ago, screwed up IAC wiring, bad fuel injectors). After my initial problems, I would say that my TPI has been very reliable. Knock on wood. The problem with TPI, and any other electronically controlled fuel injection motor, is that when you do have a problem there is allot of wiring and sensors to check and that takes time. Allot more time than a non-computer controlled carb setup. The shop manual has allot of troubleshooting flow charts to narrow down a problem component. I used a MAF system in my swap. I would suggest you go with a speed density system and get EBL P4 flash or SuperAUJP. The speed density ECM is more reliable than the MAF ECM, especially when it comes to datalogging. Good Luck.

 

Thanks, Fred. That was the kind of answer I’m looking for. I already have the EBL and a MAP system FIRST to put on. Before I go to the trouble of changing my accelerator pedal to cable, before I drop the tank and put a fuel pump in it, before I get a VSS sendor to work with my mechanical speedo, etc I just want to know the reliability is there

 

Mine is very reliable now. Get in it, turn the key and drive.

And with a 700R4 I was getting 27-28 mpg... but with my gear vendor unit on there now and the double overdrve I'm getting about 30 mpg.

Plus the throttle response and overall driveability.

If you're able to do it, I highly recommend it.

 

Well, looks like I’ll be putting the FIRST tpi on later this year. Thanks for the replies.

 

What ECM are you planning to use?

 

Supposed to be a 730 out of a Vette. EBL Flash P4. Not sure of the distributor. Came with the whole FIRST setup I bought about ten years ago.
I only find this part number as obsolete for GM pick ups.

Two inputs to distributor

Part #

 

Haven’t gone thru harness yet. Have an Orange wire coming out of box along with a black and green wire. Purple wire next to Orange wire goes nowhere. Can you tell me what these are for?

 

Those would be for additional sensor inputs for example on mine I have a 2 axis g meter and a wide band. You will have to take the cover off to see what channel they are hooked to.
If you ever have to replace the ignition module in the distributor only use a AC Delco one part D1943A or GM # 19179578 EVERY other brand I have tried has failed in less than a year.

 

I would suggest not using an ECM out of a vette. From what I have heard, the vette ecm has more inputs than F-body and if you do not account for those you will get a check engine light. Get an F-body speed density ecm.

 

The problems you see posted are due to all these TPI systems being OLD in general. Most of these are people that A. Don't drive the car regularly (and again - it's OLD), or B. Are trying to resurrect the car from sitting for a long period of time.

My 86 sat for 11 years. Replaced the fuel system (including injectors), and the ECM (cracked circuit board) and other than those everything else was original as far as I could tell (160k miles) and ran just fine. BTW - carbs generally don't last that long and often the engines have much shorter lives due to fuel washing.

My 91 sat for 10 years. Replaced the fuel tank and pump, blew out the lines (kept the stock injectors with 130k) and threw in a VATS delete chip. Runs excellent.

Yes emissions, economy, and performance were all factors in OEM's switching to fuel injection. But in the specific case of TPI (and most other modern FI systems) it lasts longer than any carb would. Carbs get worn throttle shafts, they get varnished up and the seals and gaskets get eaten up by the fuel. That's not even considering the fuel dilution and cylinder washing of cold start.

I am perfectly at home with either one. I have many of both in my fleet and I do performance for a living every day. I tune fuel injection and carbs on my DynoJet. But given the choice, TPI is much better than a carb if you have the means and the motivation.

GD

 

Yeah its crazy to think about it, but some of the earlier thirdgens are pushing 40 years old... 40 YEARS!!! LOL...

Damn I feel old now...

But you can imagine a lot of the systems and parts are long past their expected life spans...

Even the early 4th gens are nearly 30 years old now.... makes one wonder what "late model" means anymore.

 

ULTM8Z & General Disorder, you both make a good point about old parts and components, including wiring. But if someone were to do a TPI swap today, they should get all new sensors and relays. preferably GM if possible. There are also several sources for new TPI swap wiring harnesses, if you have the bucks. I used an OEM harness and went through it wire by wire and replaced several connectors. I admit I did miss a couple things and that caused many days of frustration.

 

Fred, this is a harness, ECM, distributor, and FIRST unit that has operated as one on a car. I intend on checking every sensor if not just flat out replacing them outright.

Btw, where are you guys coming up with this carbed engines don’t last long due to fuel wash. There’s many a carbed car that’s gone way past 150K miles.

 

Frankly 150k is nothing. I have a fuel injected vehicle as one of my loaners at my shop that has 335k.

The reason is - many engines torn down and inspected - that's the reason. I have seen the cylinder wall wear on engines with carbs and with fuel injection. Fuel injection wins. Period. It has MUCH better control over cold-start enrichment.

GD

 

I'm a little late to this discussion but thought I would throw my .02 cents in anyway since I have both.

I have both carbed (my 1985) and TPI (my wife's 1987). Last year I debated converting mine to TPI. This was because I love the way my wife's TPI runs/feels and I hate the hot start issues that carbs deal with. I ended up abandoning the swap idea for various reasons. My 1985 has 40,000+ miles on it (rebuilt engine with new Edelbrock 1406) with no repairs needed to the carburetor (or engine) and only minor adjustments to compensate for other changes I have made. I love how simple that engine is, and it runs great with my only complaint the minor fuel flooding on hot restarts. The carburetor never malfunctions, and if it ever does for about $350 I can throw another brand new carburetor on. Last year I put new injectors on the TPI, and it cost well over $400 just for those. The TPI has been apart in my shop for the last 6 months because I HATE working on that engine. Everything under the hood is factory original, and there is no room at all to work on anything. I had it stripped down to the block, and I have days upon days of time put into putting that thing back together because putting the TPI back together is like a puzzle. You put one piece in the wrong order you have to take out many other pieces to get back at it. For example, I removed the a/c compressor and power steering pump at least 6 times because every time I got it put together I discovered some bolt or bracket that could not go back on without taking everything back apart. Anyone that tells you different is probably doing a sloppy job and leaving bolts/brackets out or using bolts in the wrong places, stripping threads, or is simply working with a system with some parts removed (like the AIR system, which thoroughly complicates under hood disassembly-reassembly).

However, probably the biggest complaint I have about the TPI system is the lack of quality aftermarket parts. Unlike a simple carbureted system, the TPI system contains a lot of electronic parts which can cause all kinds of running issues when they malfunction. I am willing to completely strip and replace every wearable part to have an engine that will be reliable for 100,000+ miles, but the problem today is finding decent parts. I fought with various aftermarket items like an IAC that never would quite behave right. I eventually went back to the original and lived with it. Another was the TPS. I even searched online for an actual AC Delco TPS because I was tired of malfunctioning aftermarket TPS's giving me problems. The new AC Delco part was bad out of the box and wouldn't even adjust to the correct voltage range. I ended up having to go with another aftermarket part and will live with it and just warranty it every couple years. I'm crossing my fingers that the MAF never goes bad, because that is a nightmare trying to find a decent aftermarket (had this problem with my first Camaro). Bottom line, I LOVE the TPI system when it runs right but I HATE working on it and because every replacement part is junk these days I have to work on it all the time. This car is a daily driver too, so maybe if I was like a lot of people on this board and only drove it occasionally this would not be an issue.

For simplicity/cost/dependability I just don't think you can beat the carburetor. That being said, there are a lot of advantages to fuel injection like smooth driveability in all conditions and the potential for longer engine life. I weighed the pros/cons and decided a TPI swap was not worth it to me, but I would still be willing to entertain the idea of a simple aftermarket fuel injection system like some of the popular TBI systems. I also would not remove a TPI system and replace it with carb. Both have their distinct advantages/disadvantages to consider.

 

That is exactly what I was looking for. I am ordering a Stage 2 Quadrajet that will be built to my engines specs, bolt on, and give me years of reliable power. The TPI was only for shock value at car shows. The Qjet will be just as responsive, probably nail down the same mpg, and I won’t have to do a dozen things under the car to get it ready. It’s a 69 Camaro, it’s supposed to have a carb.

 

If TPI is setup with a stand-alone you aren't tied to using any of the stock sensors or injectors, etc. It's just a hunk of metal onto which you attach whatever components you choose and control them via your own desires.

I haven't had any problems with my ACDelco IAC, and the TPS has never given me problems. MAF is deleted with a speed density ECU (stock or stand-alone). Troubleshooting is really simple with access to all the raw data, and the ability to calibrate any of the sensors to your liking.

Accessibility and ease of working on it isn't much of a problem if you forgo the emissions crap - especially the air injection. Which wouldn't be used on a swap into a vintage chassis.

GD

 

I also have an '87 Monte SS and really contemplated swapping in a TPI motor from an Fbody...I really like the way it looks in the 4th gen Gbody. I swapped in an LS2/4L65e out of a '06 GTO because it had low mileage and was complete.

 

Well, from what I’ve been reading in the other forums you’re one of the lucky ones. 30 different things to check or reprogram just to start the car the first time.

I also don’t think you’ve read what this project is. It’s taking a FIRST setup a guy sold me that he ran on his car. Why wouldn’t I use stock sensors? GM only put thousands of hours developing the parts so they’d last 50,000 miles or more. Why are you talking about emissions on a 69 restomod ? There’s nothing smog related at all on the car. I mentioned a 7730 ECM in my initial post so why are you talking about a MAF?
Btw, a properly tuned carb won’t “wash the cylinder walls down” any more than a fuelie will.
Doesn’t matter, I’ll take the power up to 6500 rpm and the trouble free operation a Q-jet provides. While knocking down comparable mpg even though that is not a concern.

 

Smart. Tpi is yesterday’s tech. LS is is the easy way to mega power for the least amount of money. If I was starting fresh I’d be going the LS route also

 

I really enjoy driving both cars for different reasons, of course. The Camaro's handling is far superior to the Monte's and the 5.7 TPI is no slouch!

 

My 69 has subframe connectors, solid body mounts,
IrocZ steering box, SPC upper and lower control arms, Howe tall ball joints, is lowered an inch and a half, and has Koni shocks all around. She handles like she’s on rails.

 

The guy who's post seemingly swayed your decision was talking about how difficult his wife's car is to work on with the TPI. That's because of the emissions is my point. Without that ease of working on it is much improved which would be what YOU would have on the Camaro. THAT is my point. And the comment about the MAF was directed at the same post about how the MAF is unobtainable and expensive - you wouldn't be using one and thus it's not a concern for you.

And yes I fully understand what you are doing. I daily drive a FIRST manifold Trans Am. I also own a performance shop with an AWD DynoJet. I've built and dynoed and seen all of this many times over. I own two TPI cars and regularly drive them. My daily as mentioned was TPI from the factory and now has a FIRST manifold and is 325 HP at the wheels. I also have two GM trucks in my driveway with carbs, and a 56 Buick with a carb...... I have plenty of experience with both.

And as for fuel washing - Carbs are THE major reason for cylinder wall wear on factory carb equipped engines. When fuel injection came on the scene, cylinder wall wear basically disappeared. Ring ridge reamers exist because carbs sucked at cold start control. Very primitive and crude control - a valve that blocks airflow and increases the idle circuit vacuum signal with various crude devices to attempt to correlate flap position with engine temperature...... it's an extreme approximation to actual engine enrichment needs and as the carb wears and things drift out of calibration it just gets worse as it ages.

GD

 

A carb is not going to wear out like you’re talking for a long time. The ONLY thing that makes EFI what it is the E. Injectors wear out. Electronic relays burn out or corrode preventing them from sending out the signals the ECM needs to run the system. I, like millions of rodders, will run a carb. Easy to set up, easy to tune, doesn’t have a million things that can go wrong. I don’t feel the need to make sure my engine is running at stoich at every rpm. You’re beating a dead horse.

 

I've never seen an injector wear out. They can get dirty (no faster than a carb in this respect - usually takes much longer due to better fitration), and some of the older one's had problems with coil drive insulation..... hasn't been an issue for 30 years or so.

What relays are you talking about exactly? For one thing relay's don't "send signals"...... that would be a sensor, not a relay. And honestly the just don't fail. It's much more likely to have a problem with power supply or grounding. Both are relatively simple for anyone that understands basic 12v low voltage and Ohms law.

it's clear you really have no idea how any of this works and wouldn't be able to cope with any small failure so I agree you need to stick with the carb. But that's not the FI's fault nor is it in any way a reflection of the FI's reliability. That's just a result of not wanting to learn anything new (not really new anymore though). Folks had the same arguments about horses vs. cars, and chalk boards vs. calculators.

TPI is much more reliable than a carb - despite your resistance to it. Neither of my cars would have run after 10 years without replacing or rebuilding the carb if they had one. My 91 fired right up and idled happily with only a fuel tank, pump, and filter. 125k on the TPI. I'll post a video here of it's first start in 10 years:

Notice the rust on the tensioner pulley.......


GD

 

You’re indeed a special guy. You go ahead and play with your tpi. I’ll dust you if we should ever meet on the street with my Stone Age carbed engine. Now you go ahead and post the last word. Bless your heart.

 

It's really not a pissing match about who can dust who. Argumentum ad hominem.

You might want to look that up. It's the internet hallmark of an argument lost.

GD

 

In the end, it is your choice. If you feel comfortable enough with carbs, (and more importantly, can tune a carb to perform under varying temperature ranges, elevation changes, part throttle cruising, and hot restarts), then I would stick to a carbs. There is very little learning curve for you, as you probably understand the importance of transfer slot transition for the idle circuit, primary vs secondary jet staggering, and power valves/ metering rod and springs. TPI (or any electronic fuel injection) has the same concepts, but are vastly different in terms of lingo and Jargon, tuning procedure, can have a very steep/ espensive learning curve.

I have found that making a fuel system work in multiple situations, either carb or EFI, tends to be the most frustrating part of tuning for most people. Sure, the average person can tune a carb or EFI system to idle and keep the engine safe at WOT, but can they tune the engine to knock down high MPGs at light throttle cruising? Both systems have their advantages, and disadvantages. The FIRST intake will make a TON of low speed torque, but might not produce the same power levels in the upper RPM range as a duel plane or single plane carb intakes. Can you tune the EFI on your own? Odds are, the Vette had different fueling requirements, thus the tune needs to be updated. Also, if you can't perform this on your own, you probably will not find a shop that will touch it. Anymore, it is either factory LS/Hemi/Coyote ECMs or standalone aftermarket offerings from Holley, FAST, AEM, Megasquirt, Ect for tuning shops. Anything else might as well be a carb to them.

The real question is, do you have the time, money, and patience to dedicate 10's or even over 100 hours learning ,understanding, and perfecting a fuel tune with fuel injection? If the answer is no, utilize the knowledge you already accumulated and go with a carb.

 

Well said!

 

I don't quite understand what you're getting at. Don't get me wrong, I am all for running carburetor's (time, place and application of course), but what makes you think a carbureted engine doesn't rely on electronics? Are you running an HEI ignition system? Think those parts will last forever? Alas, the reason why this doesn't worry you is because you're not afraid of HEI, it is easy to fix and diagnose when something is wrong or wears out, If only you realized EFI is just as easy to diagnose once you understand it. It is a cop out to state that carbs are easier to work on, or are better, as if they did everything all on their own. But they don't. Not to mention mechanical fuel pumps are garbage, yes they work, but electronic pumps make carbs feel entirely different for a reason. EFI is precision. You don't need that to run on the road of course, yes you can run very fast with a carburetor, but with what we have available to us, why not take advantage of the technology. Also, from your very first post your position was carburetor all the way, you were only waiting for someone to back you up on that notion. So why bother posting this thread if you are not willing to listen to the contrary...

Either way, keep it on the road...

- Rob

 

I put 200,000 miles on my EFI 88Forumula. No major repairs, just maintenance. (and some mods.....) FIRST thing I did was toss as much of the emissions stuff as I could. Made the engine compartment MUCH cleaner, and the engine easier to work on. Never ran into a problem I could solve in a couple hours. Only time it ever left me on the side of the road was when the radiator died..... or when the new parts I got were crap. (distributor caps from Autozone....) Learned my lesson there, and bought better quality parts, somewhere else.

I will take EFI over carb every day. Easier starts, better fuel economy, and just as reliable.

 

Its 2020 and we're still arguing about whether a carburetor or EFI is better?

 

Just catching up. You guys all make good points. This is a weekend cruiser that won’t see 5000 miles a year if even that. I’m still on the fence. I’m going to talk to my local FI guru, Norm, over at Affordable Fuel Injection. I don’t think the TBI systems are worth a damn from the stuff I’ve read, Edelbrock Tech and customer service is an absolute joke (if I am to believe their tech line, the whiz bang ECM on the pro Flo 4 XT will not provide TCC!). Nothing beats the looks of the tpi based systems. I will admit I get overwhelmed when reading how to tune using EBL and Tunerpro with all the abbreviations and acronyms.

 

My OEM TPI never failed except the famous Multec Injectors after just over 20 years. I did install the FIRST TPI intake on my old LB9 305 as a pilot project. I wanted to learn how to tune. Again everything was reliable with the FIRST. So, I installed it on my new SP383 Deluxe and it has been reliable since then... using all OEM original sensors except for 02 sensor. The reliability is not the issue, it's the tuning you need to do, to have the engine run correctly. TPI systems and their program logics are very sensitive. You also may want to consult with Ken at FIRST Performance on the limitation of the FIRST when it comes down to cam and head combination. There is a limitation on the intake duration.

Tuning with these old EFI systems is NOT EASY to learn by all means. It's not for everyone. It's basically hacking into GM's program which was not designed to be modified. It took me countless hours (over 1000) of datalogging, experimenting, reading, calculating, etc. I now have a giant Excel spreadsheet that can calculate the Spark Advance (SA), Injector Based Pulse Width (INJ BPW), Final Pulse Width (INJ FPW), Commanded AFR at start-up, open loop (OL), and Power Enrichment (PE). This is just to name a few. This really helps me now to correct things up when I am tuning. Yes I am still tuning after one year with the new engine in (and 10 years of learning!). The reason being: it's @#$#% time consuming, you need the right weather condition and it's sometimes hard to be accurate with the old EFI system.

My latest lesson was with SA Latency. Good luck with that one lol. Took about 20 hours of research and testing. Read that thread and you'll see. I'm near the end https://www.thirdgen.org/forums/diy-...ncy-table.html

Reading the forum will make your head spin because there are different systems out there. Mainly Speed Density and MAF. Also, there are the AUJP & TunerPro language vs the EBL and What's Up Display (WUD). It can be very confusing.

If I had to do it all over again, I would most likely go carburetor or invest in a modern EFI system to run with the FIRST.

That was my two cents worth

Good Luck!