TPI or TBI what way to go?

[morrisammo]

I bought a 1985 GMC Suburban ¾ TON 4x4, , it’s in good shape. Little or NO rust.


The motor, well it starts and Idle’s, but it is rough, I have changed the plugs, distributer, wires, checked the timing. And did a compression check, but it still runs rough. And is not drivable.


This is the twist, someone whom owned it at some point in its life, had a Camaro motor put in it; I don’t know what year motor it is. And it has TPI injection from the now out of business Arizona TPI, at one time I do believe it ran well, but when I bought it, it had been sitting in a garage for 3 years.


So I’m weighting out what to do. Or what to get done to it. Seeing getting it running well, has stepped out of my skill/ knowledge range, and I need to bring it to a shop.


My goal is to have a super dependable vehicle that runs and runs, change the oil, do a tune up now and again and get 150,000 out of the motor, be able to drop in a re-build and run it another 150,000.


So the opinion I’m asking for is?


Should I have the shop fix the TPI and keep it as is?


Or should I have the shop, change it back to factory TBI?


OR another option?

 

[eagle mark]

Keep the TPI and learn all about it so you can fix yourself!

 

[morrisammo]

Keep the TPI and learn all about it so you can fix yourself!

I'll need to work at it,, and keep buying tools, it has a computer, I don't have tools or a way to interface with it.
So I'll have to bring it to a place, to get fixed for now.
It was also all taken apart, and I'm putting it back together.

so much to learn, so little time.

 

[Greg Ducato]

I think I would rather have the TPI but if you want to rid yourself of that bastard system I have a TBI system I can swap you for it

 

[morrisammo]

I think I would rather have the TPI but if you want to rid yourself of that bastard system I have a TBI system I can swap you for it

Their is a Good Mechanic, I would have do the work. I'm going to seriously ask him the TPI, TBI question and see what he says.

Your kind of joking,, but I hear you,, and for the trouble free, system, I'm looking for,,, that might just be something, we might,, talk about,

 

[dyeager535]

I'd be careful about asking someone their opinion of a system if they aren't INTIMATELY familiar with both of them. Realistically for the time vintage, the difference is 8 injectors vs. 2. Yeah yeah, long runners, faster processer than early TBI, MAF, etc., but the amount of wiring, type of sensors used, etc., are pretty much all the same. If you have TPI, leave it IMO. It made decent power, and it makes good torque, which trucks need. Realistically TPI should have been installed in the trucks from the factory.

Potential problems I would look for are aftermarket injectors, (Junk, I think Accel turned our some real stinkers awhile back), failure to wire things up like VSS, failure to properly tune the PROM, etc. Things that would equally be a problem with an improper TBI swap.

 

[morrisammo]

I'd be careful about asking someone their opinion of a system if they aren't INTIMATELY familiar with both of them. Realistically for the time vintage, the difference is 8 injectors vs. 2. Yeah yeah, long runners, faster processer than early TBI, MAF, etc., but the amount of wiring, type of sensors used, etc., are pretty much all the same. If you have TPI, leave it IMO. It made decent power, and it makes good torque, which trucks need. Realistically TPI should have been installed in the trucks from the factory.

Potential problems I would look for are aftermarket injectors, (Junk, I think Accel turned our some real stinkers awhile back), failure to wire things up like VSS, failure to properly tune the PROM, etc. Things that would equally be a problem with an improper TBI swap.

Thank you,,, that is some good feed back,,, I know going back to TBI means, fuel pump, wiring distributor, as well. not just the top side,,

in the past I had a Suburban 2wd that had Tbi and it ran and ran, I liked that. I put in a re-build, and sold it after putting 90,000+ on the re-build,
I saw it around town for a few years after that..

who knows, once I get this one to the shop, he may find some silly thing. and it will tune, up and run fine.

 

[eagle mark]

It's not much harder to work on or learn TPI over TBI. If you have a mechanic that was around during TPI/TBI then I would say let him look and diagnose what you have!

All it takes is one silly little thing on either and you have issues. I've seen both TPI and TBI run well over 200k with no major issues other then maintenance!

Laptop $ ? , cable $50, TunerPro RT software $39. and you have all the tools you need to work on either.

 

[morrisammo]

It's not much harder to work on or learn TPI over TBI. If you have a mechanic that was around during TPI/TBI then I would say let him look and diagnose what you have!

All it takes is one silly little thing on either and you have issues. I've seen both TPI and TBI run well over 200k with no major issues other then maintenance!

Laptop $ ? , cable $50, TunerPro RT software $39. and you have all the tools you need to work on either.

thanks,,, the guy I'm going to bring it to, is a hot rod, guy that works on all types of stuff, he has his own shop, and is always busy. the good thing is this Burb, is not my daily driver, so I'm in no hurry, but at some point after I get the other stuff all put together, I do want it usable,,

 

[dyeager535]

Like I said, be careful. These trucks had pretty much everything from the factory (1987+) available to properly run either system.

Older stuff that hot rod guys tend to work on don't have the readily available components and interchangeability the trucks do. VSS, high pressure fuel pumps, high pressure fuel lines, proper sending unit, all sorts of extra electrical feeds, tons of space, this stuff makes keeping/using EFI easy, and the trucks have it. Injecting even a mid-70's car is infinitely more difficult, and *some* mechanics that have dealt with the older stuff may be inclined to go with whatever they know to be easier.

I don't know your mechanic, I'm not disparaging him, just what I've seen from a fair number.

 

[morrisammo]

Like I said, be careful. These trucks had pretty much everything from the factory (1987+) available to properly run either system.

Older stuff that hot rod guys tend to work on don't have the readily available components and interchangeability the trucks do. VSS, high pressure fuel pumps, high pressure fuel lines, proper sending unit, all sorts of extra electrical feeds, tons of space, this stuff makes keeping/using EFI easy, and the trucks have it. Injecting even a mid-70's car is infinitely more difficult, and *some* mechanics that have dealt with the older stuff may be inclined to go with whatever they know to be easier.

I don't know your mechanic, I'm not disparaging him, just what I've seen from a fair number.

I have mixed feelings,, seeing someone put a Motor out of a Camaro in it. it still is a 350, but its not stock, I'm keeping a book of what I do to it, so I can go back, when I need to and have the ( memory) to fix it, and remember what it has now,,

 

[dyeager535]

If done right the install should be pretty clean. The problem often seen when trying to do a clean install is removing things people deem to be "unnecessary" (Seen that with o2 sensors even). It may run, it may seem like it runs good, but with injection, in certain situations it is impossible to tell how it's really running without some specific equipment.

Is this MAP or MAF TPI? Cold start injector? I would assume MAP, but you didn't specify.

 

[morrisammo]

If done right the install should be pretty clean. The problem often seen when trying to do a clean install is removing things people deem to be "unnecessary" (Seen that with o2 sensors even). It may run, it may seem like it runs good, but with injection, in certain situations it is impossible to tell how it's really running without some specific equipment.

Is this MAP or MAF TPI? Cold start injector? I would assume MAP, but you didn't specify.

all I know is that it has 9 injectors, so the 9th one should be the cold start one.

I have been doing a bit of reading about tpi but have no experience working on them,, YET,,

 

[eagle mark]

Well if it has a 9th injector it probably also has a MAF sensor in the air intake duct? It's a common upgrade to change these to the later 90-92 MAP Speed Density system and 1227730 ECM. Which would be way more work then just learning a system.

You could still run the MAF system with 1227165 but they are harder to tune if the motor has had any modifications.

By the time you swap everything over to TBI, you may as well swap everything over to the 90-92 MAP system using a 1227730 ECM. It's only been done a bizillion times and well documented on Thirdgen.org $8D is the mask defintion for the chip bin file and it is probably the most documented ECM code there is.

If you haven't found Thirdgen yet here's a link to The Prom Tuning Guide Book and FAQ: Common Questions and Answers.

http://www.thirdgen.org/techboard/diy-prom/288763-prom-tuning-guide-book.html

TPI either way would be my choice! There's no way I would go back to TBI with it already done and all the parts available.

 

[morrisammo]

Well if it has a 9th injector it probably also has a MAF sensor in the air intake duct? It's a common upgrade to change these to the later 90-92 MAP Speed Density system and 1227730 ECM. Which would be way more work then just learning a system.

You could still run the MAF system with 1227165 but they are harder to tune if the motor has had any modifications.

By the time you swap everything over to TBI, you may as well swap everything over to the 90-92 MAP system using a 1227730 ECM. It's only been done a bizillion times and well documented on Thirdgen.org $8D is the mask defintion for the chip bin file and it is probably the most documented ECM code there is.

If you haven't found Thirdgen yet here's a link to The Prom Tuning Guide Book and FAQ: Common Questions and Answers.

http://www.thirdgen.org/techboard/diy-prom/288763-prom-tuning-guide-book.html

TPI either way would be my choice! There's no way I would go back to TBI with it already done and all the parts available.

I'm leaning on staying with TPI,,, I just need to learn and get comfortable working on it,,

I'll get reading,, this first time, I'll bring it to a shop,, just to get it running and drivable,, , after doing my reading, I'll try not to be too much of a pain! to the mechanic. having a head full of INFO,,, before buying the cable and whatever else is needed to do the diagnostic stuff.
( I'm the guy who goes to the DR after doing all the research on WebMD. I know what I need,,, I just don't have the tool / Lab work,,, or prescription note pad)

 

[eagle mark]

The cable to hook up to a laptop is the most important tool IMO if you own an EFI vehicle. Robert makes them in small batches for $45 shipped!
http://www.gearhead-efi.com/Fuel-Injection/showthread.php?1592-Support-The-Forum-Buy-ALDL-Cables!

Most people have a laptop available. If not we have been seeing refurbed units from like Best Buy for $143. Pretty goodd deal considering it's got a new batt and a warranty.

The other things that are handy and you may already have is a Digital Volt Meter. For the pins on plugs if you need to change them there is one Green one that does most pin release jobs, that and a small pick or sewing needle, all the way up to a three piece set which is about $60.

Really not a lot of specialty tools other then the cable!. Things like fuel pressure which is very important in EFI can usually be borrowed from the parts store and they are usually set up to test most sensors that we can't do with volts or ohms.

It's really not that bad! Add it to what you already know. I've seen guys scared to death to get involved and just playing around as a hobby they are tuning there own chips in 6 months. It's just the unknown that is scary!

 

[dyeager535]

If it's the really early MAF TPI (I think '85-86 only?) it may be problematic to deal with. No one in their right mind would use the first generation setup, but you'd have to look at your ECM to find out I suppose...there is a piggyback portion to the ECM. No idea if converting to later MAF or MAP is easy with the way those are wired. All of them are relatively easy to modify one way or the other, but I'd agree with Mark, MAP/'7730 ECM is the smart upgrade if there is any problems with yours. At $2-300 (last I saw someone price them) the MAF sensor alone is a good reason to dump it.

Got any pictures of the engine?

 

[morrisammo]

The cable to hook up to a laptop is the most important tool IMO if you own an EFI vehicle. Robert makes them in small batches for $45 shipped!
http://www.gearhead-efi.com/Fuel-Injection/showthread.php?1592-Support-The-Forum-Buy-ALDL-Cables!

Most people have a laptop available. If not we have been seeing refurbed units from like Best Buy for $143. Pretty goodd deal considering it's got a new batt and a warranty.

The other things that are handy and you may already have is a Digital Volt Meter. For the pins on plugs if you need to change them there is one Green one that does most pin release jobs, that and a small pick or sewing needle, all the way up to a three piece set which is about $60.

Really not a lot of specialty tools other then the cable!. Things like fuel pressure which is very important in EFI can usually be borrowed from the parts store and they are usually set up to test most sensors that we can't do with volts or ohms.

It's really not that bad! Add it to what you already know. I've seen guys scared to death to get involved and just playing around as a hobby they are tuning there own chips in 6 months. It's just the unknown that is scary!

YUP,,, you nailed it,, "" the unknown is Scary!"" the electrical stuff has always been a pain,, years ago I had to fix some stuff that was, seemingly never ending, so I don't like Electrical,

but knowledge is power, and I need to get my head in the game.

Thank you for the links,, for cables and such,, I have a good laptop,, so I'm good on that, I will need the program, and all that, in the future.

 

[morrisammo]

this is it,,

I stole it, the prior owner just did not have the want to get it put together and running again.

The air cleaner is on it now,,

 

[dyeager535]

I don't know what the box is up by the coil, but I suspect from what I can see that it's the early MAF. Not good for tuning apparently, but if it were running right, no real issue I suppose.

I don't know why there is a spring on the throttle cable(?) I'd remove it.

Google "set minimum IAC", TPI minimum air, something along those lines. That will affect idle, and it's easy to do. Pretty common for those that don't know better, to try and adjust idle incorrectly.