Vroomaster

I'm trying to locate the ECU, Haynse pic looks like it's in the floor, under the carpet. I can't see it under the dash, so is it under the car or what?

ps, I did do a search, but no location hints....

91vert

It is under the carpet where your passenger's feet would be. Just pull the carpet back up by the firewall and you will see it.

Vroomaster

cool, thanks
brown wire, black stripe, here I come.....

Vroomaster

I see a couple of brown wires w/ black stripes, which one do I ground?

Turbo Timmy

Confucious says...

Vroomaster

So, do I ground all brown wires w/ black stripes, or is the one I'm looking for in a peticular bundle?
-tryin to fix 3800 rpm problem

Vroomaster

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Vroomaster

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HAILERS

Try this site by RXSTER http://ourworld-top.cs.com/flrxster/ECU.html

HAILERS

Here's a jpg of the three plugs of the ECU. Its a view looking straight into the ECU. They label things from right to left. Above the plugs is a readout of what the pins do in life. I think I'll scan the other two pages and send them to you also.

HAILERS

Second jpg

HAILERS

And third. You can look at the printout of the control unit and see that the grounds are 3G, 3A, 2R, 2C if that helps any.

HAILERS

Here is a schematic of some of the sensors. You're right to want to ground the brown/black wire(86 and 87 model cars). You can see how its all spliced together to the tps,boost sensor, airflow meter, air intake sensor, water thermo sensor, variable resistor etc. It terminates at pin 2C on the ECU. There is a ground for the ECU under the dynamic chamber. Its a round connector lug with about three ground wires. What your doing seems plenty good fine.

Vroomaster

Thanks HAILERS! I'll update when complete, I'm also changing fuel filter and coolant today so It'l be a bit.

Vroomaster

Ok. in the guide to HAILERS 1st link, it says "The ECU, located in the passenger side footwell, has three gang plugs in it. On the smallest plug there will be four green wires (with various color striping) for the injectors, and a solid black wire (among others). This black wire is crimped (poorly, with no insulation) to three smaller black wires about 2" from the plug. "
When I get into the small bundle, the black wire is not crimped into the 4 green wires. Should I connect them? the scematic (HAILERS last attachment) doesn't show they should be connected. I'm thoroughly confused.

Vroomaster

Ok, looking at it more, I see that the black wire is a ground that goes to the body, and that the injectors are activated by ground pulses, so I think this will be ok, but would like confirmation for peace of mind (and my ECU's) heh. Thanks anyone.

Vroomaster

sorry this is so long, but don't want to blow my ECU. There are 2 black wires 3G & 3A, do I attach them both to the 4 green wires (injectors)? Anyone care to take a shot at this?

HAILERS

No don't do that. He really just observed that there were some green wires with stripes. He shoulda maybe left that remark out. He is just grounding the black wire and mentions how if you follow it from the ECU plug up the harness you will find there is a spliced area with some other ground wires. Yeah, whatever you do don't ground the green wires. The ECU pulses a ground to these wires to turn the injectors on and off. I think you already figured that out though.

HAILERS

VROOMSTER, DONT USE THE RXTER POST TO DO YOUR GROUNDS. ITS FOR A LATER CAR. YOU SHOULD BE GROUNDING THE 3G, 3A,2R,2C GROUNDS. PM ME RIGHT AWAY.

Vroomaster

OK, I see, should I ground both solid black wires on the small bundle?

Thanks for responding btw! Newbies like myself would be fryin our ECU's otherwise!

HAILERS

MY fuckup. RXSTER'S got a good write up but for another series. His breakout plug is really nice too.

Vroomaster

Grounding those 4 wires made my idle rock steady at 750, it was varying about 100-200 prm back and forth slowly, it also make the car run much smoother it seems. Didn't solve my 3800 hesitation though, hmpffff.

HAILERS

Seeing as how this is an electrical weekend for you, why not go ahead and try adding a extra ground to the brown/black stripe wire on the boost/pressure sensor and do like Six Rotors did on his car and even add and extra one at the tps. Worth a try and not much bother. Try checking resistance b/t the brown/black wire on the boost sensor and the negative terminal on the battery. I think it should be .1ohm or less with the key turned off. Might double check the ground wire from the battery to the chassis and where it bolts on the starter bolt.