I have just setup a 2.2 LH system on my BMW 2002, and am now trouble shooting the non-start situation I have. (I haven't had this running on my car, but I got this crazy idea from another '02 head who setup a 2.2LH system on his points fired and pertronix fired system. So I know it will work on my setup with pretronix) I've just come across a stumbling block... I have spark, and the fuel pump tests fine, it's just that I don't have enough volts from my coil to trigger the ECU to get fuel.

Going by the Bentley manual (LH-2.2 System Electrical Tests, p. 241-13 and 14), all components/circuits test out fine EXCEPT the engine rpm signal. (Only other slight variances I'm showing are the AMM readings which will be adjusted and throttle position sensor, which shouldn't affect my rpm signal). Sooo... I'm supposed to get approx 12 volts DC from pin 1 (from the coil negative) with the ignition on. Instead, I'm getting 1.1 volts. (all other components that are supposed to show battery voltage during the test check out fine). My lead from coil negative (red coil w/ resistor) to the harness shows no resistance (haven't checked all the way to the ECU connector). So I don't know what is going on.

Any idea why I'm getting 1.1 volts from my coil? Am I missing something here?

Thanks for any light you can shed to this.

off the top of my head, the stock volvo dist sends a square wave to the ign control unit, which then goes to the fuel ecu-not sure what that signal should be. i'd be inclined to scope your buddie's car and see what he's getting at both ecus. all i got , chuck.

You are right, the V/C ignition module sends LH2.2 the info on a separate wire, apart from the coil, but I'm not sure what it looks like electrically, how its driven and how it is received. I don't know Pertronix, but I suspect the coil would be getting pretty warm if it lingered long with only 1 volt on the negative terminal at some position of the distributor.
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-K (hope springs eternal)

Slightly turn the crank and recheck the voltage at the coil... bet its back up to 12V. Keep in mind that the pertronix module, just like the old points ground the negative terminal of the coil through the resistor, ergo, low voltage. If you turn the crank to the point where the "pertronix silicon points" are open, the voltage will go back up to 12V. The fact that you have spark says that the ignition is all good... but you need to check timing.

jorrell
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92 245 245K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently close to running again!

Sounds like the thing to try, I'll do it tomorrow. But I still can't get the fuel pump to run off the ecu. So something isn't triggering it.

I mistakenly double posted my question, so I'm copying Art's post here, to keep it all in one thread...

Art Benstein said...
"Hi,

If you are getting spark you can't always have 1.1V at terminal 1 on the coil; it must be pulsed by the ignition amp. That is what is needed by the LH2.2 computer to determine fuel relay pull-in and injector timing among other things, not a steady 12V. The Bentley may be assuming it is getting its RPM signal from a Volvo ignition module, which is not, in the case of LH2.2, the same connection as #1 on the coil.

Can't tell you what, in waveform terms, the LH computer expects to see, but it is very possible it needs a lower "low" than Pertronix is giving it, when it is charging the coil. A scope on an LH2.2 car would answer the question, or compare notes with your fellow bimmer enthusiast.

Edit: I just read through your project history. It seems I've just repeated advice you've already received from many others. That makes me that much more certain the ECU's RPM signal input is incompatible with the coil switching voltage, and may even be destroyed by its field collapse excursions. A better route would be the LH2.0 ECU, as I know for a fact it has the buffering to handle input directly from the coil. Then again, have any 2002 friends gone to electronic ignition? I don't mean Pertronix, but computerized with knock sensor? Either Bosch EZK or Volvo/Chrysler would be an improvement or an experiment, driven by a hall effect pickup, and output compatible with your LH2.2 FI.
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Art Benstein near Baltimore

I think we're on to something here. I may be getting 12v at one turn of the distributor (I am getting spark, and ignition system was timed correctly and working fine before), but I may be receiving the improper voltage (I'm still holding onto the idea that the signal wave isn't so relevant). So I'll try to get that my friend's scope values from his car. (forgive my ignorance, but I'm taking it that "Scoped" means his voltage values from a multimeter on his car).

You might be able to compare voltages with a meter, but "scoped" means with an oscilloscope. A meter is to a scope what a still camera is to a videocam. Where rapidly changing voltage occur in a circuit, the motion picture is needed. I agree with Art, the signal input on the LH2.2 computer is not meant to receive the sharp-curve and high voltage seen on the primary side of the ignition coil. Hang around this board and hear the woes of those who've accidentally connected that lead used for the tachometer to their speedometer instead. Crispy circuits.
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-K (hope springs eternal)

"But I still can't get the fuel pump to run off the ecu. So something isn't triggering it."

The fuel pump doesn't run directly off the ECU. It runs off the Fuel Relay, which gets picked by the ECU when it sees ignition pulses on terminal #1.

Then the ECU makes the ground for the Fuel half of the 2-part Fuel relay. The other half should pick as soon as the key is on, for main power to the AMM and ECU.

• How does your pertronix or coil interface to the ECU?

• Do you get that 1st click of the Fuel relay with Key On?

• The ECU also needs the ignition pulses to time the injectors. Do they get pulsed when cranking (get a noid light on one or more).

• If all that's missing is the Fuel Relay ground from the ECU, the ground can be wired thru a K-jet fuel relay, which picks directly off coil #1 (ground side) pulses. This would maintain the safety aspect of "no spark = no fuel".


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Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

Lucid said:
"The fuel pump doesn't run directly off the ECU. It runs off the Fuel Relay, which gets picked by the ECU when it sees ignition pulses on terminal #1."

I gotcha, but for now, I can't test the fuel relay, as it's not getting (I'm assuming it's not) a proper signal from the ECU, cuz the ECU isn't getting the proper signals from the coil/ignition system. So is there a test to see that the Fuel relay is triggering the pump? All other tests in the Bentley are fine, I'm getting the proper voltage from the ignition switch to the ECU power supply. I'm also getting 12v to the AMM power supply.

The coil is interfacing to the ecu (it's the 1 terminal which as has wires to it from the pertronix. And the resister goes to it also, I'm pretty sure).

I do get the click of the fuel/main relay with Key On.

Fuel injectors test ok, at 3.9 ohms with ignition OFF as per the Bentley. I can get a noid light for them, if needed, but I think they are ok, right?

I don't quite understand running the Fuel Relay ground ala K-jet setup, cuz I thought I'm trying to get a proper voltage pulse or signal to the ECU to time the injection sequence. But if I understand you, the K-jet fuel relay would be able to use my signal from the coil/pertonix that is 1.1volts to trigger the ground. But what kind of voltage would the k-jet relay be sending to the ecu. I may be better altering the voltage I'm getting now to match what a "normal" 2.2 setup uses, and skip the k-jet relay alltogether.

"So is there a test to see that the Fuel relay is [will] triggering the pump?"

• Yes, you can pry the cover off and hold the relay so you can so see the two coils. With the relay terminals pointing to your right, the lower coil is the Fuel. With the relay connected and the Key On, the pump should run when you close the lower coil's armature with your finger or anything non-metallic.

"The coil is interfacing to the ecu (it's the 1 terminal which as has wires to it from the pertronix. And the resister goes to it also, I'm pretty sure)."

• That's the mystery part for me. I'm confused by two things "going to" ECU #1:
(1) something "from the pertronix: and (2) "And the resistor goes to it also..."

I'm guessing the "pertronix" (1) is something like the Volvo/Chrysler Ignition Controller box, and "the resistor" (2) refers to something at or connected to the Coil. If so, that 2nd part sounds wrong to me, but I'll leave that to the experts like Art, rather than muddy things up with my guesses.

[EDITED] Never mind the K-jet relay thing. I was thinking about the LH2.4 ECU and how some fail to make the ground for the Fuel relay. But your 2.2 ECU is not known to fail that way. My thought was that if the relay ground path was the only thing failing (i.e., the injectors were clicking OK), a K-jet relay (operating off coil pulses) could safely substitute for the missing ECU's Fuel relay ground. The K-jet relay wouldn't be tied to the ECU at all. It would just be a ground side "switch" for the Fuel relay.
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

The coil is interfacing to the ecu (it's the 1 terminal which as has wires to it from the pertronix. And the resister goes to it also, I'm pretty sure)."

• That's the mystery part for me. I'm confused by two things "going to" ECU #1:
(1) something "from the pertronix: and (2) "And the resistor goes to it also..."

I'm guessing the "pertronix" (1) is something like the Volvo/Chrysler Ignition Controller box, and "the resistor" (2) refers to something at or connected to the Coil. If so, that 2nd part sounds wrong to me, but I'll leave that to the experts like Art, rather than muddy things up with my guesses."


To answer your mystery questions:
(1): The Pertonix is a magnetically triggered ignition system. It has a positive and a negative lead that plugs into the coil positive and negative. Then the negative terminal on the coil has wires that go from it to the pertronix, rpm, and resistor. (There is no condensor on the side of the distributor after converting from points to pertronix.) RPM signal comes off of the negative side of the coil

(2): I mistakenly stated that the extra lead (which was for rpm, was to the resistor). The resistor is connected to the positive side of the coil. The Bosch red coil is just an externally resisted coil, rather than a Bosch blue coil which is internally resisted.

I'm trying to figure out how to attach pics of my coil, and where I plugged my coil negative lead into the EFI wire harness. Thanks for all the help so far guys.