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'92 2.5 Hall Switch/distributor Pickup


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7 replies to this topic

#1 Evan R

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Posted April 11, 2005 at 07:45 pm

I believe I have a failure of the distributor pickup (AKA Hall switch) in my '92 2.5/5-speed. I am led to believe this is a failure-prone part. My troubleshooting to this point makes me think the pick up has GOT to be the problem.

But that's not a test. I really like to PROVE a part is bad before I replace it.

Does anyone have a valid test?

Thanks

Evan

#2 Tech Man

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Posted April 11, 2005 at 07:52 pm

What kind of equipment do you have for testing? Labscope?

You can start by verifying you have power to it. 8 volts I believe. Does the rotor turn when cranking?

#3 Struts 'N' Stuff Auto

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Posted April 11, 2005 at 08:11 pm

To test for a bad Hall Effect pickup, the easiest way is, to apply 12 volts from the battery positive to the coil positive and crank the engine over with the key while probing the Injector negative wire to see if you have pulses, if you have pulses, then the HEP is working.
This is all of course assuming the engine will not start.
If the engine has intermittent running problems, it could be that the HEP is not working when it gets warm, causing the engine to run rough and quit.
Maybe explain what the symptoms and problems are first.

#4 Evan R

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Posted April 11, 2005 at 08:26 pm

Maybe explain what the symptoms and problems are first.


No start. I'm led to believe the wires on these are fragile. I may have manhandled the sensor while redrilling the distributor base (the last remaining splash cover screw snapped off during removal).

Having handled (and possibly manhandled) the switch, and having spark and fuel pump activity during cranking leads me to strongly suspect a failure of this pickup.

Thanks,

Evan

#5 Struts 'N' Stuff Auto

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Posted April 11, 2005 at 10:40 pm

If you have fuel and spark when cranking then your HEP has to be working and sending pulses, otherwise if no pulses were present, the Auto shutdown relay would shut off power to the fuel pump and coil when cranking.
Check for fuel in the throttle body
Check to make sure the MAP sensor vacuum hose is connected and not cracked.
Check while cranking, with a test light, for Injector pulses at the Injector on the throttle body.
If all is good in regards to fuel and spark, the next thing to check would be the valve timing and timing belt for slippage.

#6 Evan R

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Posted April 12, 2005 at 06:07 am

If you have fuel and spark when cranking then your HEP has to be working and sending pulses, otherwise if no pulses were present, the Auto shutdown relay would shut off power to the fuel pump and coil when cranking.
Check for fuel in the throttle body
Check to make sure the MAP sensor vacuum hose is connected and not cracked.
Check while cranking, with a test light, for Injector pulses at the Injector on the throttle body.
If all is good in regards to fuel and spark, the next thing to check would be the valve timing and timing belt for slippage.

<{POST_SNAPBACK}>


Well, perhaps I wasn't so clear. More info:

The van was suffering a bog/miss from about 1750-2250 rpm. Since it is new to me (160k) and I don't have any maintenance records, I thought I'd see if a tune-up was in order.

I pulled off the cap. Everything was indeed nasty. I cleaned all the contacts with some emery paper. Meantime, I re-drilled the distributor base for a new screw.

I put everything back together for the ride to the parts store. No fire.

Figuring I might have bent the contacts (the ends of the plug wires - dumb) away from the rotor, I jumped in another car for the ride to the parts store.

New cap/rotor/wires did not change the no fire condition.

Nothing else under the hood was touched. I can't imagine how cam timing could have jumped. I will look to see if I may have knocked the MAP sensor vaccum hose off.

Is it possible that the HEP switch is flaky now (as opposed to failed) and is just giving enough pulses to pass the shutdown relay, but not enough to fire the engine?

#7 Chuck_Hawks (converted)

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Posted April 12, 2005 at 06:43 am

I have a stupid question:

Could the distro put itself in backwards?

I ask because I chased my tail for about 3 hours after I removed and replaced the distro after replacing the oil pump. DUH, only thing it could have been and didn't even think about it.

Chuck

#8 shak911

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Posted April 12, 2005 at 10:11 am

I have a stupid question:

Could the distro put itself in backwards?

I ask because I chased my tail for about 3 hours after I removed and replaced the distro after replacing the oil pump. DUH, only thing it could have been and didn't even think about it.

Chuck

<{POST_SNAPBACK}>

good point, if the distrib was actually removed, but also hep can be temperimental, I recently worked on a 92 acclaim 2.5l, was running but not too well, took off the distributor's cover, cleaned all, lifted off the hep and noticed the shutter blade plate (not too sure of the name, it's the notched plate that rotates and enters the hep field to interrupt it thus creating the pre ign.signal)
anyway, this plate sits on a plastic base that is secured to the dist.shaft, the plastic rivets were loose/broken and the plated was swinging every which way, as a temp fix I centered the plate and glued it in place, and when put back together no pre-ign signal, forgot what the code was, got a new one, metered differently than the old one, and it worked right away.

Conclusion: old hep was marginal, and because of the play in the plate, was able to generate some signal, but once plate was repaired, effectively increasing the gap, it stopped working.

When I called the dealer to make sure they had the hep in stock, the guy started telling me about the plate breaking loose, ( I had not mentioned it to him yet), and the whole dist.have to be replaced, I don't think so, I think they're fixable)


ps: yes they can be intermittant, sometimes the only way to know is to replace them, well if you find you didn't need it, I am sure you'll need it sooner or later, they're only like $50.


sam


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