Microtech LTX-12S AMP Usage
 

Hello, have a question - anyone know how much power Microtech LTX-12S consumes at idle? Amps? Second, how about the Microtech and 6 MSD Blaster SS coils? I have an email into Microtech but have not yet heard from them.

My problem - I have a 45 AMP draw at idle on my car which would indicate to me I have a grounding issue or short somewhere. I have listed all the items which are powered at idle (with no accessories on or fans):

- Microtech ECU
- Ignition
- Dash lights
- (6) MSD Blaster SS coils
- (2) Denso fuel pumps
- (8) PLX Devices gauges

So far, I know the Denso fuel pumps use no more than 7.6 amps max at idle and the PLX gauges use no more than 4 amps, totaling 11.6 of the 45 amp draw. I would think the next biggest power hogs would be the Microtech ECU and the MSD Blaster SS coils.

So, does anyone know who many amps the ECU draws and/or the MSD coils? Thanks for the help.

Its your coils.

ECU DRAWS shit all.

Max including injectors would be 10 amps. Id say more like 3-4 amps.

What do you mean it is the coils? Are you saying the Microtech should draw max 10 amps or the coils and the Microtech should draw 10 amps?

No im saying the majority of your current draw is your coils.

Its not the microtech if thats what your asking

Okay, but what I need to know is:

1) How many amps should the Microtech draw?
2) How many amps should the MSD Blaster SS coils draw at any given time? They won't all fire at once.

So, at idle what can I expect from the Microtech and from the coils?

MSD coils i couldnt tell you. Only thing i do with anything msd is throw it in the bin.

As for the ecu.

MAXIMUM 10amps at any given time.

Thanks for the help. Anyone else out there know anything about this? I heard back from Microtech and they told me to call the main factory:) Tough to do here in the US.

Why dont you test it?

Yes, we are going to do this but it defeats the purpose doesn't it, if we don't have a baseline to compare it to? I was hoping to have an understanding of what it should be and then compare it to what it is on the car to know if I have a problem.

What is your problem to begin with? Maybe better to look at it that way?

My problem is my car is eating alternators and my AMPs at idle (1,000 RPMs) are 45 which I believe is too high. I am now on my third alternator, a 150 amp unit and it is having problems.

When I start the car my volts are fine, in the 13.8 range. Once the car gets hot though, volts start to drop and at idle, they are 11.8 and at 3,000 RPMs, they are in the 12.8 range.

We tested the battery and alternator and they test fine. When we measured the load on the alternator though, it was using 45 amps at idle with no accessories on. Once the fans came on, the load increased to over 80 amps, causing the alternator to begin to fail as 80 amps at idle is too much for the alternator and would be way too much for a stock alternator (most alternators achieve their max AMP rating at 3,000 RPMs or so and at idle, have much less power). As my alt can only produce 80 amps at idle, the car begins to use the battery also and the alternator tries to compensate, which has burnt out two diodes on past units. Now imagine me turning on AC (I live in FL) and having to use my headlights at night, and you see why this is a major issue for me.

This is why I posted the question. I am putting together a baseline of what the amps SHOULD be at idle and a list of the power requirements of the electronics that are on at idle so I know what my baseline should be. I'll then test each unit to see what it is consuming so I know where the abnormal usage is coming from.

The problem is getting the information from Microtech about the exact power consumption of the LTX-12S and the amount of amp draw it requests from each coil. I don't think the consumption is great as the MSD ignition amps only draw 1 amp at 1,000 RMPS and the coils are normally fired thru one of these boxes but I would like to make sure. Thought this would be an easy question but Microtech has responded once by saying I need to contact the main factory. I have asked for an email address as I am in the US, but they have not responded which does not make me happy. The number for the main factory is +61 2 9808 5233 if you'd like to call!

FYI - this is the only issue keeping me from driving my FD 3 rotor:(

To me. It sounds to me like the car has a bad earth. And/OR your alternator is wired incorrectly.

Have you tried adding 2 earth straps. One from battery to chassis. One from engine to chassis.

Complete set of grounds going on the car today. More to come.

hey David ur car looks great,

make sure u run @ least one 0 guage from body to engine & one from battery to body
instead of running few lesser guage wires,

rx72c recomended that and it fixed lots gremlins for me better than running couple lesser
guage parts store cables I was running

Thanks Tony. Hope you are doing well.

Installed the Hyper ground kit today (very nice quality 8 gauge wires) along with a 2 aught cable (think double zero gauge for thickness) from the battery to the alternator and wham, amps dropped from 45 at idle to 22! And with the fans on, amps are now 44, instead of 82. That's substantial.

What I need to test, now that amps are correct and the grounds good, is voltage. I am assuming voltage should be no lower than 12.8 or so at idle with accessories on and I will test this tomorrow morning.

It's good to know though, that at least a part of the issue is resolved.

What other issues do you have?

20 amps for fans sounds more like it!

Yes, thought the amp pull from the fans before was too much. Not sure if I have an issue but I need to check voltage at idle as I think volts should not drop below 12.8 or so at idle with accessories on. If they go below this, then I'll need to figure out why.

Well, volts are still too low. At idle, with no accessories on, its' above 13. With the AC on, it drops to 12.8 and when the fans come on, 12.0. Not good.

What have you got your idle set at?

And who built you this 150amp alternator?

Were are you measuring voltage from? Back of alternator or battery?

Alternator was built by IRP on this forum or Ihor from NJ.

I think you may have asked the magic question, where I am measuring volts from. My numbers are from the battery and a device attached called the "battery bug". I am going to let the car warm up and then measure at the alternator also to see what is up.

Okay so I tested voltage at both the battery and at the alternator to ensure there is no drop between the two. There isn't so that's good and checked off.

At idle the car is putting out 14.25 - 14.5 volts at the alternator. I see this building back at the battery as it is a bit low now from all of the work, starting at 13.6 and building to 14.5 over a minute or so. This might also be normal.

When the fans come on the car, volts drop at both the battery and the alternator to 13.4 or so and when the AC comes on, down to 12.4. I know when driving this goes down to 12.0 and I am assuming it's at both the alternator and at the battery.

The fans pull a little under 20 amps as this was tested by the shop. Any thoughts or ideas here? I will leave it to the shop tomorrow and will have two options for them:

- Find the voltage drain issue. I know the fans and the AC are dragging the alt down to this level and I also know there is no voltage drop between the alt and the battery so I am not sure where to go on this. Maybe the fans are wired wrong and pulling too many volts? But I know the amps they pull are within range so I don't think this is an issue. The AC is a problem? Maybe wiring is off somewhere?
- Spin up the alternator to achieve higher volts at idle. I can do this with a smaller pulley, or smaller 20B main pulleys or both. But am I causing a problem by doing this? I know this spins the alt faster throughout the RPM band but I would think this would be okay as I am using know parts and not anything crazy?

Remember, at 2,000 RPMs things go back to normal on the car so maybe the solution is to spin up the alt more at idle.

Thoughts? Ideas?

You have answered your own question right their.

Put a smaller pulley in it.

You never mentioned it was a 3rotor:) Thats 6 coils 6 injectors etc.

A Factory COSMO engine has a 120amp alternator and youve got more gear going.


You need a big alternator and you need to speed it up.

It's a 150 amp alternator which should be plenty. Is speeding it up just a band aid or is that a permanent solution? So, even thought amps are now good, it still needs more juice at idle?

And the 3 rotor is nice BTW:)

Im sure it is you bastard:) Now send that 3 rotor down to me asap:)

Speeding it up is not band aid solution.

Will help your alternator cope with what you need unless your alternator mob can give you an alternator that can produce the right amount of juice on idle.

We do have access to a 220a alternator here that can produce 110a on idle. But its not cheap.

something like 750-800 bucks

:)
My current alternator alternator is rated at 80 amps at idle which is double what I need when the fans come on the car. It seems the big drain is the combo of fans and AC, taking the alt down to 12.4 or less volts. Maybe the issue is with the AC?

Anyway, unless the shop feels otherwise, I am going to swap out the pulleys and see what happens. The current main and alt pulleys are FD ones so I will install the smaller 20B main pulleys and the smaller alt pulley I have.

And son of a b*tch, $750 for an alt? Damn, for that price, I'll get out and hand spin the bastard:)