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1987 Toyota Supra
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You are describing my symptoms exactly.
I had the addition of random check engine light flashes and engine stumbling while driving on road while idling and hot.
Couple times the engine would die and come back to life in 1/2 second or so.
These problems were the reason I started all this in the first place :)
Works great now!
 

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1989 7mgte swapped mk3
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1,017 Posts
Discussion Starter · #22 ·
You are describing my symptoms exactly.
I had the addition of random check engine light flashes and engine stumbling while driving on road while idling and hot.
Couple times the engine would die and come back to life in 1/2 second or so.
These problems were the reason I started all this in the first place :)
Works great now!
I have a feeling your services will be/are badly needed among the 7m community. These cps's being 30+ years old at this point...that's a lot of heat cycles for those old wires.
 

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something to keep in mind is the 7mge distributor uses the exact same sensors / connector as the turbo (same teeth count / wheel configuration and pickups). they are sometimes available for $40 online unlike the cps.

so you can use a 7mge dizzy as a CPS on a turbo --it clears the turbo/intake pipe with the cap and rotor off.
 

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1987 Toyota Supra
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641 Posts
Yeah trying to locate a GTE CPS housing is getting really really expensive these days.
Luckily most are still in good shape and just need a rebuild.
But if you are swapping from N/A to turbo or have a broken or missing CPS is can get expensive.
Good idea on repurposing the distributor style.
 

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1987 MA71 R154 Pearl White, Blue Velour
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630 Posts
That is sort of how mine started. At first it wouldn't start easily when hot. Then it got to where it wouldn't start at all regardless of temp unless i jiggled the cps wires. They were extremely brittle.
Yeah the wires do end up getting cooked over the years. I changed out my injector connectors back in 2019 and they have had no issues since. I changed the CPS connector also, but I think only on the harness side. I'll have to go back and look. :)
 

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1989 7mgte swapped mk3
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Discussion Starter · #26 ·
something to keep in mind is the 7mge distributor uses the exact same sensors / connector as the turbo (same teeth count / wheel configuration and pickups). they are sometimes available for $40 online unlike the cps.

so you can use a 7mge dizzy as a CPS on a turbo --it clears the turbo/intake pipe with the cap and rotor off.
I didn't know that was an option. I have a complete GE sitting in my garage but i guess in my case I'm happy to have had the cps rebuilt.
 

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I can also vouch for Piratetip. While he didn't rebuild mine, he did post a well researched tutorial on SM, both offering the steps complete the rebuild, as well as showing scope data and dramatic proof of rebuild effectiveness.

He also helped me source the parts for mine, though engine is still not running for other reasons.

My car would often times not restart when hot, and had stumbling issues. A CPS rewire helped a little for a while, but I am certain this is what my CPS ultimately needed.
 

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1987 Toyota Supra
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641 Posts
Thanks!
I enjoy helping others with their projects, I do what I can for the Supra community.
Reverse engineering is part of my work so I bring some unique skill sets. :)
 
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1989 7mgte swapped mk3
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Discussion Starter · #29 ·
I can also vouch for Piratetip. While he didn't rebuild mine, he did post a well researched tutorial on SM, both offering the steps complete the rebuild, as well as showing scope data and dramatic proof of rebuild effectiveness.

He also helped me source the parts for mine, though engine is still not running for other reasons.

My car would often times not restart when hot, and had stumbling issues. A CPS rewire helped a little for a while, but I am certain this is what my CPS ultimately needed.
Those were my same symptoms. I would have loved to rebuild myself but i just haven't had time lately. So i am super stoked that @Piratetip got it done for me so quickly.

Not to change subjects but is SM still down? I know it got hacked awhile ago and i haven't checked back.
 

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1987 Toyota Supra
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Yeah it's still down.
 

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1989 7mgte swapped mk3
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Discussion Starter · #33 ·
Got the CPS installed. Fired up great! I killed the engine to put the timing light on it. Connected the e1 and te1 connectors and fired it right back up. It was at about 7* so i turned it off, made a cps adjustment and now it won't start.

Maybe i need to get the engine at tdc and check the cps.

I also noticed my cold start injector sensor is busted. I wonder if that has something to do with the no start?
 

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1987 Toyota Supra
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641 Posts
Pull the CPS and verify it's not 1 tooth off.
Yes I would check on the cold start switch/connector/pins.

Prior to replacing mine and the connector I had a very hard time with cold starts.
It was not firing the cold start injector like it should have.
 

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1987 MA71 R154 Pearl White, Blue Velour
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630 Posts
Did you turn the CPS back to where it was before you moved it to change the timing? Still didn't start?
 

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1989 7mgte swapped mk3
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Discussion Starter · #37 ·
Yep i had the cps set back to where it was. About to put the motor in tdc just to verify everything is set correctly
 

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1987 MA71 R154 Pearl White, Blue Velour
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Yep i had the cps set back to where it was. About to put the motor in tdc just to verify everything is set correctly
Ok, also unplug and replug a couple of times the connector. I replaced my connectors last summer and all was well, but then I started having starting issues this summer that I tracked down to that. But of course, make sure TDC and tooth alignment is correct.

When I set my timing, I set the CPS bolt just loose enough to where I could put steady pressure on it enough to advance the timing so I could see it in real-time, but tight enough where it would hold the setting until I could lock it down.
 

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1989 7mgte swapped mk3
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Discussion Starter · #39 ·
Automotive tire Motor vehicle Vehicle brake Automotive design Steering part


Is this roughly where the cps should be at tdc? You can see that i have the housing maxed out to get it lined up.
 

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1987 Toyota Supra
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The rotor position looks correct after inserting. (It will spin slightly clockwise)
But the adjustment slot should be more or less centered.

You are positive the diag block terminals are connected and setting base timing?

Though it's hard to check until you get the engine to fire up again.
I would focus on the cold start switch and injector first.
 
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