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Ignition Pulse System


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13 replies to this topic

#1 SubTim

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Posted 24 July 2004 - 09:45 PM

86 Sub GL 4WD 5 speed

120k miles

ECS light comes on after 8-10 miles

runs ok-slightly sluggish

ecs code is #73. That says it is the Ignition Pulse System.

What is that? And how do I fix it?

Thanks.

Tim

#2 SubTim

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Posted 27 July 2004 - 10:48 AM

Ok,
Does no one have the answer to this? Has no one else encountered this? Have I stated it so you don't understand the question? Or is this such a tired, rehashed question that no one wants to go over it again?

I will appreciate all help.

SubTim

#3 Greenley

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Posted 23 May 2008 - 06:08 PM

Bump from the dead for help with this question

Stock '86 Hatch d/r 4wd.


Thank you.

#4 GeneralDisorder

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Posted 23 May 2008 - 09:42 PM

Bump from the dead for help with this question

Stock '86 Hatch d/r 4wd.


'86 could be either EA81 or EA82. So do you have an EA81 hatchback or an EA82 3-door coupe?

Either way an 86 with a D/R is going to be carbed.... so you have a feedback carb.

Best option is to rip it off and install a Weber.

Aside from that, we'll need more info for further diagnosis.

GD

#5 Greenley

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Posted 24 May 2008 - 01:56 AM

Apologies, it is a true Hatchback with the EA81, CA specs $hitachi carb, d/r 4spd.

I understand that the weber is the best option and is on the long list of "to-do's", but i just would like to know what the Ignition Pulse System is all about and why i'm getting the 73 code thrown at me.

Thanks.

#6 GeneralDisorder

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Posted 24 May 2008 - 10:50 AM

I don't beleive that your code list is accurate. I will get back to you with a more accurate code detrmination when I have access to my manual's later today.

GD

#7 Frank B

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Posted 24 May 2008 - 12:14 PM

There isn't much on the EA81 as far as electrical or electronic components. The ECM is there to control and monitor the emissions isn't it? Aside from the distributor, and coil there isn't much else to the ignition like other cars. CPS, MAP, MAF, etc are not there. Does your tach jump around? Have you tuned it up latley? New plugs, wires, cap and rotor? Get a repair manual and test the coil and distributor. I would bet it's the disrtributor. Does it have the NipponDenso or Hitachi distributor? It will say on the unit.

#8 Greenley

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Posted 24 May 2008 - 12:24 PM

Does your tach jump around? Have you tuned it up latley? New plugs, wires, cap and rotor? Get a repair manual


It has been completely tuned in the last 3k miles but has been bucking and running a little rough lately. And, actually, the tach has been jumping around erratically lately. I'd have to agree that the disty is on it's last leg, but assumed that was a separate issue than the code 73.

Really just looking for the answer to:


ecs code is #73. That says it is the Ignition Pulse System.

What is that? And how do I fix it?



#9 GeneralDisorder

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Posted 24 May 2008 - 01:28 PM

Well - the ignition pulse codes are a problem.... :dead:

The codes are specific to the vehicle type - 73 indicates a fualt on a Hitachi carbed, analog gauge cluster, california manual transmission vehicle. Being you are in Nevada that makes sense - your car was sold in CA and as such it's a feedback even though it's 4WD. (49-states 4WD's were not).

The problem with that code is that it's a general fault code - there's about 20 pages of troublshooting that you have to go through to trace that code, and it will probably end up being a corroded connector, faulty splice, or the ECU itself (leaky caps, or something perhaps). It could take DAYS of troubleshooting to find it.

IE: I wouldn't worry about that code. Fix your distributor first, and then if you still have that code.... yard that ECU out of the car and install a normal non-feedback Hitachi or a Weber.

GD

#10 GeneralDisorder

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Posted 24 May 2008 - 01:33 PM

The ECM is there to control and monitor the emissions isn't it?


Actually there are two duty-control solenoids that modify airflow to three metering ports on the carb. The ECU has enough control through these to cause the engine to die at an idle or to run very badly if the O2 or CTS have gone south.

The ECU cannot directly modify the ignition timing, that's true. But it does have lines used to monitor ignition pulses from the coil.

GD

#11 zukiru

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Posted 25 May 2008 - 03:39 AM

wow! I had no idea a jumpy tach meant my disty could be going out!
Thanks I needed to know that!

#12 Gloyale

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Posted 25 May 2008 - 11:06 AM

Well - the ignition pulse codes are a problem.... :dead:

The codes are specific to the vehicle type - 73 indicates a fualt on a Hitachi carbed, analog gauge cluster, california manual transmission vehicle. Being you are in Nevada that makes sense - your car was sold in CA and as such it's a feedback even though it's 4WD. (49-states 4WD's were not).

The problem with that code is that it's a general fault code


Actually, 73 is an Identifier code.

There is no Flow chart or any other troubleshooting info is in the FSM for codes 11,71,72,73 because they are ID codes presented when the key's ON/Eng OFF. (respective to Cali/fed 2wd/4wd)

If the CEL is on while driving and 73 is the only code, then the ECU is not seeing the ignition pulse that should be from the Negative side of the coil, to the ECU. It's not a *fault*, so much as just the ECU thinking the car is not running because it see's no pulse.

Jumpering a wire from the Neg of the Coil to the pin on the ECU should serve to bypass the original wire. Sorry, I don't have the ECU pinout here, but search or PM me for info later.

#13 GeneralDisorder

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Posted 26 May 2008 - 03:40 AM

Actually, 73 is an Identifier code.

There is no Flow chart or any other troubleshooting info is in the FSM for codes 11,71,72,73 because they are ID codes presented when the key's ON/Eng OFF. (respective to Cali/fed 2wd/4wd)


Well - the way I read the FSM it shows it as an identifier, but also says (in the flow matrix) "the subsequent check is continued" - ie: you should continue troubleshooting straight through the lettered tests from where you stopped when it told you to check for codes (and you came up with a 73).

If the CEL is on hile driving and 73 is the only code, then the ECU is not seeing the ignition pulse that should be from the Negative side of the coil, to the ECU. It's not a *fault*, so much as just the ECU thinking the car is not running because it see's no pulse.


Now that I have not seen stated anywhere in my FSM. You may be correct.... and in fact it does sound right maybe..... damn these FSM's are confusing! There's a lot of ways you can interpret it. If you run through all the detailed flow charts starting from the top we might be able to infer what the code is - but half the time the checks themselves are ambiguously worded so that you aren't even sure you passed or failed the check :rolleyes:

Jumpering a wire from the Neg of the Coil to the pin on the ECU should serve to bypass the original wire. Sorry, I don't have the ECU pinout here, but search or PM me for info later.


If he has to do that though..... that's a sign of bigger problems. If that wire isn't connected there's a bad spot in a harness somewhere. Bad juju.

GD

#14 Frank B

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Posted 26 May 2008 - 10:01 AM

wow! I had no idea a jumpy tach meant my disty could be going out!
Thanks I needed to know that!

It's the bushings that go bad and cause that. You can have it redone. At some point, it will start stalling, usually while going around a corner.




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