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Discussion Starter · #1 ·
Hey guy's long time no chat!

Okay, so the crawler is 98% done:D Worked last night trying to get the beast to fire and no luck. For those that don't know I'm building a 3.9 based X chassis (parts from my original D90...Motor, ZF, LT230).

Anyway, I've got fuel, injectors appear to have signal, and I'm hot at the coil. However it's not getting the fire signal. Did the obvious and swaped a a coil and HE lead, but no luck. Tomorrow I'll swap out the ECM and see what happens...Little buggers can cause so much greif..

I'm a little concerned though in that when I pulled the engine and harness out of the 90 all was in working order. That was <cough> 3 years ago though.

I'd thought I'd post up and see if there might be something obvious that I'm missing...Like a feed-back loop in the harness that I'm not aware of. Right now I plan on using only that which is absolutley necessary from the factory harness...Ignition, Acc, and start are the 3 wires I'm using now...

Any help would be greatly appreciated!

Hope to see you all on the trail soon!

--D
 

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are there pics of this rig somewhere i can see? it sounds very cool...sorry no tech advice for you.

this is a 95 3.9 vintage? coil rotor etc? is spark coming into the rotor/hei?
 

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Anyway, I've got fuel, injectors appear to have signal, and I'm hot at the coil. However it's not getting the fire signal. Did the obvious and swaped a a coil and HE lead, but no luck.
Do the injectors "appear" to have a signal, or are they actually receiving a signal? The injectors are triggered off the signal from the ignition amplifier, which also fires the coil. If the injectors are receiving a signal then the coil should be, too...and if multiple coils are not firing, then I'd double-check that the output from the ignition amp is connected to the (-) terminal of your coil.
 

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My WAG is that it is the amplifier. PTSchram and DieLucas are your best bet, but if all else fails go get a live chicken.

-Jeff
 

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My WAG is that it is the amplifier.
x2 -- Workshop manual has a fairly detailed test procedure to diagnose the ignition system that will help, though the module wouldn't be a surprise at all. If it is the module, STC 1856 is the p/n you want for the entire kit or make your own for $25.
 

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Discussion Starter · #6 ·
Thanks guy's...Yes it is a 'vintage' 3.9...With a coil and every thing! Tee hee...Never thought of my 94' as vintage.

No hit out of the coil at all.

Now please excuse my ignorance, but what is the 'amplifier'? If my assumptions is correct, then you mean the electronic control module, located on the side of the dist? (I never did the relocation...Meant to though:)) I don't have the new fangled distributor-less ignition.

I jumped on All-data and checked the wiring for the coil. They only showed two wires off/to the coil! Now, I really don't remember ever taking the wires off the coil, but with my ever aging mind, I'm not rulling it out completely!

Lets see if I got it right: ECM lead to (-). Resistor (I think) to (+). Now the other two I have no idea. :(

I always thought All-Data was the king, but sounds like I'll pull open the work-shop manual as well.

Thanks again guy's and I'll post pic's up in a few weeks when I roll her out of the shop. And since she's still Rover based, I'll hit the rally next year too!

--D
 

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Now please excuse my ignorance, but what is the 'amplifier'? If my assumptions is correct, then you mean the electronic control module, located on the side of the dist? (I never did the relocation...Meant to though:)) I don't have the new fangled distributor-less ignition.
That would be it. Your distributor has an 8-toothed reluctor wheel and a pick-up inside of it that generates an electric field when the distributor is spinning; the ignition amplifier simply amplifies that signal so that you can trigger the coil and the fuel injection.

That signal goes to both the coil and the EFI. The EFI is the more sensitive of the two for the quality of that signal. If the signal is triggering the EFI to fire the injectors, then the signal is strong enough to fire the coil. That's why I asked if you knew if the injectors were actually firing...you haven't confirmed this.

Lets see if I got it right: ECM lead to (-). Resistor (I think) to (+). Now the other two I have no idea. :(
I'm not really sure if by "ECM" you're referring to the "electronic control module" as you stated above, or to the "engine control module" (e.g. "ECU").

Regardless, lets focus on the ignition amplifier (please don't use ECM or "electronic control module" to refer to the ignition amplifier). Since you only refer to finding two leads, I'm assuming these are leads connected to the two terminals of your ignition amplifier. One terminal of the ignition amplifier connects to the coil (+) and the other to the coil (-). You also need the switched ignition lead connected to the coil (+) and the ECU trigger lead connected to the coil (-). That's 4 leads right there; are these the 4 you mention above?


What makes you think the injectors are firing? If the injectors are firing, then the ignition amp is working. If you don't know if the injectors are firing or not, unless you have a test light, don't waste your time trying to find out. First, determine whether you've got the ignition amplifier wired to the coil properly (you've got two leads unaccounted for...so make sure your wiring is correct!!!). Once you're sure the coil and ignition amp are wired properly, then determine if you've got a spark. If still no spark, then it's time to consider the GM HEI Ignition Amp swap.
 

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The FSM has a pretty good scheme for diagnosing such issues.

Go back to square one. Fuel pressure? Spark? How do you know the injectors are doing their thing?

There are two wires from the distributor to the coil and two wires from the ECU to the coil. If you don't have this, you ain't wired correctly.

The D90 had the amp remotely located so at least that is in your favor.

PT
 

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Discussion Starter · #10 · (Edited)
Thanks a million DL and PT...Especially on the wiring of the coil. I'm 99% sure I have it right, but if the new amplifier (thanks!) doesn't do the trick, I'll know I'm wired straight. And for the record, 94 and 95 (mayby 97') had the amp on the dist. Relocation kit's avaliable for mucho'$...DIY cheap. Never did get around to it, but <cough> never had a prob before. I'll dive into it tomorrow and letcha' know.

O'yea, and I'd love to hear about the GM Amp swap. Again, when I was following the LR board closely I remember reading about it. Is that the P/N 1856 ABrooks refered to? I 'might' get the new amp for free, but if not, then I'll be looking for a good cost effective option. Time to start the search function.

Larry, nope. Drove the D90 in the shop, striped it down and put the drive train in the new chassis. That's why I'm still a little nervous that it's not the amplifier...Cross that bridge.

And in the old day's I swear we all called the amplifier the ECM...Main EFI controler ECU...O'well. Keeps it a heck of a lot more clear/less confusing.

BTW, how about the tach feed off the alt? I seem to recall in the recesses of my mind that if I'm not running a tach, that I need to put in a resistor of some sort(?).

Last question. Any uber specifics relative to priming the oil pump? I'm running a remote oil cooler in the rear of the rig (with fan) and need to prime. Way too much volume to fill once she fires before I'm up to pressure. I've got an extra salvaged (trashed) distributor and was going to pull the end off, weld to a extension, and put it down the hole. Any rpm on the drill motor to target?

Thanks again boy's.

--D
 

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There are two wires from the distributor to the coil and two wires from the ECU to the coil. If you don't have this, you ain't wired correctly.PT
(slight variation of subject......just curious)

what is the second wire from the ECU to the coil?
 

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. And for the record, 94 and 95 (mayby 97') had the amp on the dist.


--D
(Perrone Ford and Brian Bonner voice on)You're WRONG-or at the very least, not exactly right.(Perrone and Brian voice off)

"97 did not have distributors, therefor, they cannot have the amplifier on the distributor.

I have never seen a NAS Defender 90 with the amp on the distributor, they have all been located on the left inner fender well.
 

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Many of the D90's had the amp on the dizzy.

I think you left something disconnected myself.
 

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(slight variation of subject......just curious)

what is the second wire from the ECU to the coil?
Perhaps I should have been more clear, there are two wires in the wiring harness that comes from the chassis to the coil. (Cue Pendy) Per the FSM, there is a wire from the ECU to the negative terminal of the coil, this is paralleled to the ignition amplifier. The positive side of the coil similarly has two leads going to it. One goes to the battery and the ignition amplifier, there may also be a radio noise suppression capacitor in this circuit, going to ground (bypassing RF to ground).

Is that better?

PT
 

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The positive side of the coil similarly has two leads going to it. One goes to the battery and the ignition amplifier...
Just to clarify, the "battery" PT refers to is the switched ignition lead. In most applications, the "battery" would be hot...but with Rovers, the battery is dead most of the time, so what's the difference? :flipoff2:

Because you've mentioned that the coil is getting power, I assume you've got the switched ignition lead already connected to the (+) terminal of the coil. Now, just make sure the two leads of your ignition amp is connected to the (+) and (-) terminals of the coil and your ECU trigger lead is connected to the (-) terminal of the coil (or connected to the respective circuits that lead to those terminals of the coil).
 

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+ side of the coil should have a white wire that goes into the harness, this one will be hot with key on. This wire carries power to the coil and the amplifier. There may be another wire attached to this terminal leading to the capacitor to ground.

The - side of the coil will have two white with black stripe wires attached to it. One goes to the ECU, the other to the amplifier.

GM HEI conversion stuff is somewhere on this board. It works.
 

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As for priming the pump, I made my own tool from some re-bar I had laying around. I ground a slot in one end, and chucked the other end up in my drill. Worked great.

-Jeff
 

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Many of the D90's had the amp on the dizzy.

I think you left something disconnected myself.
Hence my disclaimer!

I suspected there might have been some, but so far, I haven't seen it on either a '94, nor a '95.

Most of the '93 110s I've seen have been burned out hulks so I couldn't tell where the amp was, but assume it's on the distributor.
 

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O'yea, and I'd love to hear about the GM Amp swap. Again, when I was following the LR board closely I remember reading about it. Is that the P/N 1856 ABrooks refered to? I 'might' get the new amp for free, but if not, then I'll be looking for a good cost effective option. Time to start the search function.

--D
Can't help you with the other stuff really without being there. But here is a link to the Chevy Amp Module swap from our club page:

http://www.solihullsociety.org/archives/107#more-107
 
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