Drew's TBI Q&A/install thread

[tgreese]

I'm wiping an old laptop right now and putting XP on for TunerPro. Just curious, does the ECU need 12v in order to connect to it? Constant 12v ok if so? I know it needs it to read sensors, etc...just didn't know if it needs it for testing.

Also, anyone rigged up an old computer power supply to provide the 12v? I've gone one that says it can provide 34A through the 12v rail. Would just be nice for testing in my office before heading to the garage.

Mmm. I don't think you need to be so cautious that you're only using battery power on the bench. Or rather, I think you can get into just as much trouble with a car battery as you could with a power supply. It's easy to build a little 12V regulated supply if you want to go that way. Some wall warts are regulated too. The internal supplies from PCs won't work stand-alone unless you connect the right pins together, if that's what you have in mind - how to jumper a commodity PC supply is given online - search. I'd add some additional capacitance and a drain resistor across the output, between my ECU and the supply. Or use a Corcom-type mains filter between the supply and the ECU.

Another point - I'd think the main reason you'd use the battery is because it's isolated from the mains circuit. This means that your voltage is floating with respect to true earth. This could be something of a safety issue, so that you can't electrocute yourself by touching something that is at mains potential (ie a shorted appliance) and your ECU under test. You can get around this by plugging the computer supply into an isolation transformer, or by making a small linear supply with an actual transformer. But I think the safety risk of using a ground-referenced switching supply (like a computer power supply) is not very significant.

How many amps do you think the ECU needs? Likely not more than one or two. I'd just connect it to a surplus wall wart - that's how I powered my Megasquirt board for testing. Worked fine.

[TUDrewser]

I only asked because I run a small computer repair shop and have plenty of power supplies laying around (also very familiar with jumping them, esp to test water cooling loops). My first thought was that the PSU should be pretty clean power...way cleaner than a battery charger (which everyone says definitely not to use). However, I suppose if the power was perfect the motherboards wouldn't need as many capacitors. Hm.

Anyway, just thinking out loud...er, whatever.

[tgreese]

I only asked because I run a small computer repair shop and have plenty of power supplies laying around (also very familiar with jumping them, esp to test water cooling loops). My first thought was that the PSU should be pretty clean power...way cleaner than a battery charger (which everyone says definitely not to use). However, I suppose if the power was perfect the motherboards wouldn't need as many capacitors. Hm.

Anyway, just thinking out loud...er, whatever.

The commodity PC power supplies - the brick shaped-supplies - are all switching power supplies nowadays, using small inductors at very high frequencies. They make a lot of rf interference, but they are regulated. If you scoped the output, I'd expect to see a lot of hash. Should work fine though. I expect modern battery chargers are also switchers - heavy iron core transformers are very 20th-century, though they do have some advantages in terms of isolation.

I'd speculate that the caps on the mother boards filter out any rf junk from the system clock, whatever comes down from the PS switching, and provide some protection from power line spikes that might get past the input filters in the power supply. I know it's standard practice to put bypass caps to the ground buss on the power leads to all the chips on printed circuit boards.

[TUDrewser]

Good info.

New question...I can go without the VSS to get things fired up, right? Then just add it later? From what I understand, the only thing I'll miss is my speed on the display if I'm realtime logging.

[babywag]

You'll have idle issues, and tuning issues without running a VSS w/ the 7427.

VSS is integrated pretty heavily into the code.
For one the IAC routines heavily depend on VSS input.
It will work w/o a VSS, but will run a lot better w/ a VSS.

There are also near idle and off idle routines in the pcm code, w/o a VSS the computer will have no idea you're driving.

[FSJ Guy]

It's so easy to hook up, use the VSS. The idle and off idle fuel maps are wonderful. I really like the drivability of the '7427 PCM and I think that has a bit to do with it.

[sgtpoliteness]

I'll also bust your chops to use VSS.

Everyone has a budget, but for the $90 or whatever from JTR, it's fairly inexpensive and very helpful. You could do the install without it but there wouldn't be any point in tuning it because you'd have to start all over once it was installed. AND it's super easy to install too. It just threads onto the speedo output from the t-case and then the cable threads right back onto it. Then, run your two wires.

[TUDrewser]

Cool. .. Good tips. Will do vss. Was just thinking I could delay the cost but will stop thinking about that

Ordered a fuel pump of ebay, and couple of sensors have already arrived. Getting closer!

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[babywag]

If you need hard fuel lines for the TB, Dorman sells some that are easy to work with and bend where needed.
Any parts store should be able to get them if not stocked on shelf.
PN#'s 800-151 & 800-153 they're 16" in length.

If you're doing timing control an old Pentium II heatsink works very well for the ignition module.

[sgtpoliteness]

Ooo, I like the Pentium idea! I ended up cutting out several pieces of aluminum, drilling holes through them, adding the heat sink paste and putting them all together and using that. It's worked really well, so far. I've made it through several 100+ degree days idling around town.

[babywag]

Yep, the pentium heatsinks seem made for the GM module...

[TUDrewser]

Man, I have a bunch of late model heat sinks (like lga1156) but none as old as those. But I can probably make something work.

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[FSJ Guy]

I used a bar of aluminum. 1" wide, 1/4" thick, IIRC.

For my next FSJ, I have some heat sinks out of an old HP 2600 series laser printer.

[tgreese]

Any heat sink with a flat surface large enough for the module will do. Fins are nice ... more surface area can only be better.

I used some scavenged finned heat sink for the HEI module on my CJ-6. Use your ingenuity.

[FSJ Guy]

When I first went to look for a heatsink for my first TBI system, I tried to find a CPU heatsink and couldn't. The "old" Pentium style heatsinks just weren't available. I guess I was 5-10 years too late.

[tgreese]

How about something like this? http://www.electronicsurplus.com/Item/1 ... -%2012Fin/



Lots of heat sinks in electronics surplus.

Or go to a ham fest. Lots of surplus electronics for sale there. Hamfests are electronics swap meets sponsored by the local chapter of the ARRL - http://www.arrl.org/hamfests-and-conventions-calendar - I go to one or two a year, and buy lots of handy stuff.

[jaber]

The set up on my wifes GW (Custom EFIs kit) came with the MAP and Ign mod bolted to a piece of galvanized strap. I am running the same Ign mod that he sent me, over 10 years ago.

[FSJ Guy]

Looks good, too. Remember, in stock Chevy configuration, these things were bolted to the bottom of the distributor that sat on top of the motor. Anything we fab up is bound to do better than OEM!

[TUDrewser]

Ordered my VSS and adapter plate. Other than fuel lines, I think everything is either here or ordered! Oh, and a couple relays. And a fuel filter. But can grab those at O'Reilly's. And based on advice here, am going with no knock sensor.

Question: If I plug everything in and give it power on the bench but DON'T connect a distributor, will everything still register? I just don't have an extra dizzy laying around.

[AwesomeJ10]

Question: If I plug everything in and give it power on the bench but DON'T connect a distributor, will everything still register? I just don't have an extra dizzy laying around.

yes

But if you want the really, really cool factor, hook the dizzy and fuel pump up. Make it so the injectors will spray fuel when you turn the dizzy.