The most newb question of all

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mineral co
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The most newb question of all

Post by mineral co »

I am planning to go bone yard scrounging this weekend, starting Friday. Besides other stuff, I want to get a complete TBI FI system from a '93 - '95 5.7/auto Chevy truck (7427 ECM).

The problem is that I don't even know what tools I need! I don't even have a comparable vehicle around here to look at! I've got virtually everything metric, and I'm of the impression that a GM product of that period is mostly metric, but I don't know that for a fact. And, what the heck are those things called "Torx" !!?? Okay, I'm kidding a little bit, but I don't have any, regardless.

Is there anything out of the "ordinary" that I'm going to need in order to grab all that stuff? A prior experience years ago makes me want to be sure I don't have to leave half-way through a job to go buy a tool. Somebody else may finish the job for me in my absence!

Thanks for tolerating such a silly question.

Chris
'84 GW, returning to service.
360, 727, Selec-Trac 229, TFI, Hydro-Boost, 4" all-spring BDS lift (what a PITA!), BFG/AT 31x10.5x15, 5125 Bilstiens

AwesomeJ10
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Re: The most newb question of all

Post by AwesomeJ10 »

So you asking what tools you need to pull a TBI from a truck in the yard?

The short answer is not much.

You need a good pair of wire cutters. The type of cutters that can cut several wires at the same time.

A basic metric socket set (maybe some SAE as well). Deep dish work well.

Couple of screw drivers.

A Torx set is not required to remove the assembly from the truck (I don't think..) but a normal set of Torx is required to rebuild the TBI itself (recommend and easy).

You will want to remove the entire wiring assembly as a whole. There really is no need to actually disconnect it from the TBI. The only really 'hard' part (that's not that hard) is removing the coolant tank and pushing back the A/C hoses on the passenger side to expose the firewall plug. The FW plug has the main TBI harness leading to the ECM behind the glovebox.

Don't bother grabbing the O/2 sensor cause it's a PITA to remove and is cheap to buy from the parts store. But you will want the O/2 sensor wiring connector. Just clip it off with the wire cutters.

You will end up having to cut through a really thick wiring loom on the driver side FW before it goes into the FW plug. Just cut that entire assembly and leave it connected to the TBI.

Tip: depending on what air cleaner you are planning to run on the Jeep (stock is fine) you will want to get the correct bolt that hold the air cleaner on. Don't forget the stock TBI spacer. There are several 'styles' of TBI air cleaner bolts and you may need to get several of them to be sure you have the correct one for your air cleaner.

Topic author
mineral co
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Re: The most newb question of all

Post by mineral co »

Thank you, thank you.

It doesn't sound too bad. I'll pay my dues, and take my chances. With any luck I'll have a new toy to start working on this weekend.

It seems that, so long as I stick with it, I should be able to get this all put together in a relatively short period of time and have it running on the truck fairly quickly. The requirement is to have it all buttoned up within 10 weeks (end of October), as that is the latest we can expect acceptable weather for being outside under the hood of a truck. Is that time frame reasonable?

As soon as I have an ECM, I'll get the appropriate stuff from Moates. There is lots of advise out there on what to get if using the 7747. How would that list be modified for the 7427? Assuming the 7427 is capable of being "flashed", does he have hardware to do that? I'm not a big fan of burning and swapping chips if I can possibly help it.
'84 GW, returning to service.
360, 727, Selec-Trac 229, TFI, Hydro-Boost, 4" all-spring BDS lift (what a PITA!), BFG/AT 31x10.5x15, 5125 Bilstiens

AwesomeJ10
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Re: The most newb question of all

Post by AwesomeJ10 »

You should read through Jason's TBI thread on here in the fuel injection section...

I have not yet done a 7427, but I will be this winter using a junkyard system. I *think* that there is no need to solder anything on the 7427. I think you need the G1 adapter and SF512 chip from Moates. Then you will need a burner. I have the APU1 burner and think it works great.

I am still looking for a TEXT based (not a pic of a manual) of the 7427 wiring pin outs. Lemme know if you find one...

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mineral co
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Re: The most newb question of all

Post by mineral co »

Blake wrote:You should read through Jason's TBI thread on here in the fuel injection section...
I have, a couple of times. I'll probaby read it a few more times in the next few days.

What format would you like the 7427 pin list in? I think I can create this without too much trouble, but it will be a few days for that too.

I'm reading the Moates site stuff right now, and the G1 seems to be correct for any unit with the 27xx512 chip. He has a spreadsheet to help identify things. At this point I have gotten the impression that some variants can be flashed, and others cannot. Do you know if there is any way to determine the variant ID of the box without having to power it up (while still at the bone yard?) I think I would prefer to get the $0E variant to support the 4L80E trans. I'm not looking to do a trans swap any time soon, but if the 727 were to start having problems. . .

I suppose if the ECM was in a truck that had a 4L80E in it, then it would be the $0E variant. I just have to learn what a 4L80E looks like (I know nothing about GM stuff). The Moates site lists an entry for GM trucks named "HD". Is this something that can be identified outwardly on the body somewhere? Or, is anything bigger than a 1500 or 2500 going to automatically be an "HD" truck, and have the 4L80E in it, and therefore be the $0E variant?

Thanks again,

Chris
'84 GW, returning to service.
360, 727, Selec-Trac 229, TFI, Hydro-Boost, 4" all-spring BDS lift (what a PITA!), BFG/AT 31x10.5x15, 5125 Bilstiens
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jaber
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Re: The most newb question of all

Post by jaber »

As for the Torx bits, go to a McParts house. I bought a plastic rack of 1/4 & 3/8 drive, and have used the snot out of them. It even has the right size for seat belts, and when I twist one off, I take the whole thing back in and exchange for a new set for the next job. ;)

It a bitchin feeling to spend countless hours trying to grasp the concept, to finally get behind the wheel and cruse down the street in it. Good luck on it. :-bd
Jeff

'46 cj3a
'51 Willys p/u
'51 Willys Parkway Conversion
'74 CJ5
'75 J-20 Wrecker
'75 J-20 Cummins service truck
'77 J-10 p/u
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'88 Grand Wagoneer
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mineral co
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Re: The most newb question of all

Post by mineral co »

I spent part of the evening going through all my tools just to see if any particular ones have gone AWOL, and made a list of stuff to pickup once I get up to Denver. I think one of those "bit" sets is a darn good idea.

Since I'm still in the anticipation stage, let me pose what might seem to be another silly question. I'm at 9000' in elevation, and would like to use the GW as high as 13,000'+. May there be something to be gained by getting the throttle body and injectors from a 454 (7.whatever liter) since this would have the larger, 2" bores? (I would get the entire setup since it also uses the 7427 ECM).

I haven't thought this all the way through yet and if we were dealing with a carbureted system, then doing this would certainly have negative consequences but I'm wondering if this might provide a small advantage by getting as much thin air into the system as possible. We generally think that manifold vacuum goes to zero at WOT but in reality this isn't 100% true, especially at higher rpm. But the closer I can keep it to zero, the better, I think. I believe I would still run the injectors from a 5.7 if they would fit. Possibly even smaller (lower lbs/hr) as this would mean they had to be "on" longer to pass the same amount of fuel and that would help to minimize the effects of injector latency errors.
'84 GW, returning to service.
360, 727, Selec-Trac 229, TFI, Hydro-Boost, 4" all-spring BDS lift (what a PITA!), BFG/AT 31x10.5x15, 5125 Bilstiens
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jaber
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Re: The most newb question of all

Post by jaber »

All the reading I have done says that the larger bore TB is too hard to tune on anything under about 400 CID engines. The 5.7 should do the best for you.
Jeff

'46 cj3a
'51 Willys p/u
'51 Willys Parkway Conversion
'74 CJ5
'75 J-20 Wrecker
'75 J-20 Cummins service truck
'77 J-10 p/u
'79 Cherokee
'88 Grand Wagoneer
http://s252.photobucket.com/albums/hh14/jeffaber/
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tgreese
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Re: The most newb question of all

Post by tgreese »

mineral co wrote:I spent part of the evening going through all my tools just to see if any particular ones have gone AWOL, and made a list of stuff to pickup once I get up to Denver. I think one of those "bit" sets is a darn good idea.

Since I'm still in the anticipation stage, let me pose what might seem to be another silly question. I'm at 9000' in elevation, and would like to use the GW as high as 13,000'+. May there be something to be gained by getting the throttle body and injectors from a 454 (7.whatever liter) since this would have the larger, 2" bores? (I would get the entire setup since it also uses the 7427 ECM).

I haven't thought this all the way through yet and if we were dealing with a carbureted system, then doing this would certainly have negative consequences but I'm wondering if this might provide a small advantage by getting as much thin air into the system as possible. We generally think that manifold vacuum goes to zero at WOT but in reality this isn't 100% true, especially at higher rpm. But the closer I can keep it to zero, the better, I think. I believe I would still run the injectors from a 5.7 if they would fit. Possibly even smaller (lower lbs/hr) as this would mean they had to be "on" longer to pass the same amount of fuel and that would help to minimize the effects of injector latency errors.
With EFI, the manifold vacuum is only used as a signal to the computer. This is quite different from carburetors, where the vacuum actually does work to meter the fuel in the carburetor. Then, too low a vacuum and you have no fuel control.

If you look at the CFM ratings of popular throttle bodies, they will be huge compared to comparable carburetors for that displacement engine. So you already have a big hole in a TB, compared to a carburetor.

Per Jaber's comment, it sounds like vacuum is just getting too low to reliably measure, with a 454 TB on a smaller displacement engine.

A significant down side with the 454 TBI will be cost of the pieces. I would think if you are running a 360, that's close enough to the 350's displacement that you should not see any advantage from the larger TB.

You can calculate all this... figure the volume of air needed to maintain your ideal mixture with the volume of fuel the injectors will deliver. There's a good introduction to the math on the Megasquirt site. I'm guessing it's not an issue.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
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mineral co
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Re: The most newb question of all

Post by mineral co »

I understand exactly what you guys are saying, and if I were several thousand feet lower in elevation I wouldn't even consider such a thing.

But at this altitude and higher, starving for air is a real problem. Here, a WOT zero MAP reading is like a 4 or 5 MAP reading at sea level. Based on the math, there is about 70% of the atmospheric pressure at 9000' that there would be at sea level. Obviously, it drops even further at higher altitudes.

This idea came to me while rebuilding the carburetor. The altitude compensator is open about 3/16" of an inch just sitting out here in the back yard. I initially thought something was wrong with it, but decided to leave it alone and see what would happen. As it turns out, the engine runs really well and has a lot more power than I thought it would, and with that altitude compensator open where it is, that is BIG vacuum leak.

Like I say, this is something I am thinking through. Parts availability and cost are not issues yet. Accurately controlling fuel with the larger TB on a smaller engine would be a problem, but that is where the smaller injectors come in. I have no doubt that trying to use the standard injectors on the larger TB would definitely introduce control issues.

It may well turn out that a speed/density system just will not work for this as the MAP sensor is going to report zero pressure at WOT and the fuel tables are going to be set up for this altitude. Without any barometric compensation, the engine is going to go very lean at lower elevations and I don't think the system will be able to make enough compensation to get around that. This is a concern even with the system from the 5.7.

Regardless of anything else, I am going to get a system from a 5.7 and get it running as well as possible before doing anything else. There is no point in introducing any more variables than absolutely necessary in the beginning. Once I have a good tune to use as a baseline, then I may play with the larger TB.

I have to do a lot more reading on systems that use a MAF sensor, rather than a MAP sensor. It may well turn out that this is the only practical way to overcome the problems associated with the massive altitude changes that the engine will see.
'84 GW, returning to service.
360, 727, Selec-Trac 229, TFI, Hydro-Boost, 4" all-spring BDS lift (what a PITA!), BFG/AT 31x10.5x15, 5125 Bilstiens
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tgreese
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Re: The most newb question of all

Post by tgreese »

I would think the first thing to do is see if your MAP sensor has any dynamic range at those low pressures. Maybe there is a replacement MAP sensor available that is more accurate at low pressures.

It might not be an issue of dynamic range, but instead of SNR (signal to noise ratio) at those pressures. The fluctuations in the MAP reading might be as large or larger than the measured pressure.

One way to deal with this would be to restrict the air flow to increase the pressure differential. I understand that's the opposite of what you want to do, but you have to make the engine run before you can try and get more power from it.

I suspect the best solution is ... more cubic inches.

This issue must have been encountered before. Consider Pike's Peak...

Re a MAF system - http://www.ifsja.org/forums/vb/showthread.php?t=165704
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.

Topic author
mineral co
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Re: The most newb question of all

Post by mineral co »

Hey Tim, thank you very much!

I had read some stuff from a couple of guys that had hacked the 7427 code to run a MAF, but judging by Tony's thread on IFSJA, this is more main-stream than I realized. That being the case, it would seem to be pointless to screw around trying to force a MAP sensor to operate at high resolution. Just go straight to a MAF system and skip all the other stuff.

It also means that I should be looking for a $0D variant of the 7427 rather than $0E like I had originally planned.

How did I ever make anything happen in the days before the Internet? This is fantastic!

Thanks again!

Chris
'84 GW, returning to service.
360, 727, Selec-Trac 229, TFI, Hydro-Boost, 4" all-spring BDS lift (what a PITA!), BFG/AT 31x10.5x15, 5125 Bilstiens

Topic author
mineral co
Posts: 229
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Location: Mineral County, Colorado

Re: The most newb question of all

Post by mineral co »

More basic questions:

If I understand things correctly, the 7427 wants to see an input from an O2 sensor. Does it require a narrow band sensor, or does it matter?

Tony's thread states that you still need a wide-band sensor in order to calibrate the MAF sensor, and I would like to have a permanently installed A/F gauge in the truck. There are a number of companies that make these, but I have to lean towards somebody like Auto Meter just so that any other gauges I want/need all look the same:

http://www.autometer.com/cat_gaugedetai ... 4063&sid=4

The Auto Meter gauge does provide an output that can be used by other devices, but the true output range is 0 - 4 volts, not 0 - 5 volts, and the true output ratio is 10:1 through 18:1, not 8:1 through 18:1. Without knowing how the 7427 expects to see data, I don't know if this is compatible, or not.

The Auto Meter A/F gauges use the Bosch LSU4.2 Sensor. I've read various things saying that the Bosch sensor was crap, but I don't know which model of sensor these statements were refering to. Anybody got any insight into this?

As always, thanks!

Chris
'84 GW, returning to service.
360, 727, Selec-Trac 229, TFI, Hydro-Boost, 4" all-spring BDS lift (what a PITA!), BFG/AT 31x10.5x15, 5125 Bilstiens
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