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Discussion Starter · #1 · (Edited)
I've managed to locate my CPS, I'm about to remove it, figured I'd do some testing first while its still on the car before removal & visual inspection.

I've found where the wire runs up to next to the power steering pump, theres a connector that just sortof floats between the block & the power steering pump, above the main rear hose. Its evidently been subjected to some pretty considerable heat, the connector itself - a tiny piece of it basically fell off on its own when i went touching it to get it apart, & then in the process of trying to figure out how to disconnect the CPS, broke off another big piece with EASE. Sortof looked like the connector was on there sideways too before I started. Anyway. I don't think I've broke off anything that would keep me from disconnecting it or re-connecting it. I also broke off the little plastic bit that keeps the harness to the distrib fixed on top of the distrib the other day -.- old cars, lol.

Is this normal?? I can provide pictures if needed. Also how do I disconnect this? I always struggle with these sorts of "lock style" secure connectors and something youve gotta find or push or compress or stick a screwdriver in etc in order to get it apart. Espec at this rate, I'm scared of busting it up to where I would have to replace the entire connector itself & thats, as far as I know, not possible without a stocked junkyard.

Connector in question - and yes, its always floated around, literally. Freeballing, lol. I see theres some sortof threaded hole there - if theres some piece or holding bracket thats supposed to be there, well, its been missing since I bought it:
Automotive tire Motor vehicle Gas Personal protective equipment Auto part


Automotive fuel system Motor vehicle Automotive exterior Auto part Gas


Piece I broke off the bottom, you can see its melted a bit or something:

Automotive tire Motor vehicle Sleeve Bag Grey


Tire Automotive tire Road surface Tread Wood


And an accidental find, yet curious - makes me wonder if it also scrubbed thru any internal wires inside the loom - my air filter has scrubbed a hole through the harness that goes to my external igniter:

Jaw Sculpture Bone Wood Rim
 

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You press the rectangular tap in the first picture. The problem is the plastic doesn't flex as easily when it was new so you need to press harder. The connecter may also be gummed together a bit, but in principle it should be press the tab hard enough and slide them apart.

The piece that broke off looks like the part that mounts to something, the little circular part.
 

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Discussion Starter · #3 · (Edited)
Well, with some patience I managed to remove the CPS without having to touch anything else. It's got some grease & dirt on it, but god knows how much of that was from the hectic removal process. Ultimately though its fairly dirty, the magnetic pull on it is also not that strong, I guess its not supposed to be tho.

Cold resistance measures 2100 ohms, so thats within spec, annoyingly. Short of general voltage/resistance checks, how can I test this? I ask because in the case of an ignition coil, resistances arent really going to tell you anything. Resistances on both my ignition coils OEM & aftermarket NGK read out the same, and the same at operating temp, but the two run completely differently - since resistance checks don't tell you anything regarding inductance, or if theres a short anywhere etc, I'd like to try some more applicable ways of testing in order to try and diagnose this CPS. I mean I have a number of the symptoms a whacko CPS can cause. I'd like to replace it but, I'm sure its best to test it first instead of throwing money at it.

At said rate of disintegration & given its so bloody brittle, theres somewhat of a chance I'd break off the bracket part if I attempted to put it back in n then I wouldn't be able to secure it anyway.

Would like to add aswell, lol, keeping with the theme of the thread name, somehow, in the disassembly process, this piece also readily broke off the actual mounting bracket for the CPS:

Hand Finger Gas Thumb Bicycle part



The metal ring that overlays it is now also a bit loose from the bracket and can wobble around a bit, so making sure it's lined up proper would also be important.

The big question, erg:

Must I go with OEM on this? Ik theres a favorability for OEM parts on here in general and I respect that, but given my current expense-to-result ratio, I'm not exactly inclined to go throwing twice as much at it to likely just have a different name printed on it - course, in the case of an ignition coil, I now understand the reasoning - if this part is like the ignition coil where anything besides OEM is likely a big mistake, please let me know and I will heed
 

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1994 Corolla DX
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How about go with OEM manufacturer's aftermarket version - Denso 196-1106?

Runs about $70-$80 before any discounts at various stores upon a cursory search.
 

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The other way to test it is using an oscilloscope to look at the waveform while cranking or running.
 
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The redne©k way to test your CPS would be to let it sit in the oven at 180º-200º for a while, and then pull it out and immediately check to see what its resistance is.

Edit: That copyright symbol was intentional because this site won't let you use that word! Silly modern people...
 
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The redne©k way to test your CPS would be to let it sit in the oven at 180º-200º for a while, and then pull it out and immediately check to see what its resistance is.

Edit: That copyright symbol was intentional because this site won't let you use that word! Silly modern people...
Niacin enriched foods practically eliminated pellagra, so there's that.
 

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Discussion Starter · #8 · (Edited)
ahem I present to the class:

old CPS, note the meltified wire insulation for the ground wire:
Water Liquid Wood Fluid Art


Yeah, tis basically wicked into the naked wire.

Note the new CPS & its ground wire insulation:

Hood Tap Fluid Wood Water


Correct me if I'm wrong but I'm pretty sure wire insulation is supposed to be on the outside, lol. Otherwise thats a big problem, right?

Believe I've found a likely culprit. Installing tomorrow. Tis a Denso CPS.

The new one can also hold its own weight magnetically, with a screwdriver - the old one, same screwdriver, hardly wants to do that at all. Definitely isnt as strong, at the least. If these are ferrite, I wonder if the ferrite has broken down internally from so many heat cycles?
 

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If it's a ground wire it shouldn't matter if it's insulated - the whole engine is essentially an uninsulated "ground lead". New one looks a lot better though!

The magnet issue is interesting - definitely sounds iffy. I knew that magnets (except some that appear to be very heat resistant) lose magnetic force with heat but I'd expect any magnets used on the engine to be of a heat resistant type.

 

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Discussion Starter · #10 · (Edited)
Welp, crap. Lol. Made no difference - starting to look back at ignition stuff again. What I found interesting - the other day I ran the car for 30m on the original coil, until it just about stalled out. I then swapped in the aftermarket coil, believing I would prove my theory about the OG being the one that works proper, but stalls eventually, and the NGK being the one that doesnt work proper, but never stalls. I ran it for 30 minutes, swapped the NGK into it, fired it up, it ran for about exactly 5 minutes and then poof, died. Time from initial complaint to full stall was probably just a few seconds. Resistances for both coils, at cold & hot temps, check out within spec. Given this is a "runs for 30m then" scenario I'm assuming whatever it is is heat related - thus, popping in a room temp ignition coil & it dying after 5 minutes, equals that being the wrong part to look at, imo.

Can I rule out my ignition coil given this? And start lookin at my dizzy / ignitor?

I need to do some more driving tests - I get the feeling that if you just drive it anyway, itll be a little erratic the first 5-10 minutes, but after that, you can just go ham and drive away - after you turn it off tho, who knows what you'll get. I did put thought into it maybe being the fuel pump, but the pressures check out beautifully, & they dont drop at all whenever the car starts to stumble & die when I test it in my driveway. So I assume its not the fuel pump?
 

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Fuel injectors possibly? What's the fuel pressure at the rail?
 

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Discussion Starter · #12 ·
They were just replaced, made no difference. Fuel pressures check out properly, FPR is working right, no vacuum leaks anywhere, new fuel filter, new fuel injectors, new plugs & wires, new ignition coil, cleaned IACV, fuses checked, cooling system bled, ECT sensor checks out good, no codes are being thrown and theres no new exhaust leaks. New CPS didn't help at all.

Whatever the problem is, its electrical, and I'm also strongly assuming it to be heat related, as after about 30m, the car will stumble and stall out. Fuel pressure is not being lost when this happens. So whatever it is, it's got to be the spark going away, which points me to ignition. One morning it took 50m to start misbehaving, but it was about 60F out that morning, so whatever it is took longer to get to failure temp, if I had to guess. Following that I swapped ignition coils to an aftermarket and immediately went to fire it up, and it still stalled within 5 minutes, so whatever part of (what I assume to be) the ignition system is failing, its not the ignition coil.

I consider it must be my "Pickup coil" which, I have no idea what that is, or my dizzy, or my ignitor. Unfortunately, those parts being as they are and short of any pending advice on how to diagnose them, the only diagnosis route that seems feasible atleast with the information I'm currently equipped with is to just throw ignition parts at it until it runs right again. Given people keep stating you hafta go OEM with this, basically I'm left scouring junkyards that are 2 hours out from where I live in the hopes that the part/s I acquire are actually functional - which again, no way to test if they are without just, seeing if it fixes the car. If it doesnt, either I'm looknig in the wrong place, or the part I purchased is bunk. You could put 5 distributors on it before you'd put on the 6th one and then whoom, it'd fire up and run proper... so I'm at a bit of a standstill on this at the moment, unfortunately, until I can get some more information.
 

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There's been a few threads here lately about measuring resistance and air gap on the distributor/ignition coil. Might want to start there.

Also - plugs/wires/cap/rotor up to snuff?
 

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Discussion Starter · #14 · (Edited)
The plugs & wires are all new, the aftermarket cap & rotor that I had been running for some time are ok aswell - using factory cap & rotor yields same results.

From what I can gather, the "air gap" thing is a possibility for me, I'd reckon. My distributor shaft has JUST A SMIDGE of play. If it moved any less, it wouldnt wiggle at all. Seems insignificant. BUT, this play in the shaft can apparently incrase the air gap, from what I gather, which can reduce/eliminate the pickup coils ability to detect the magnetic field & you'll get either erratic, or no spark at all.

Can I assume that ANY play in the distributor shaft is too much? Given we're working with such tiny fractions here?

This could also sortof explain to me the odd way in which the car is running. Starts up just a little slower than it should, and also is idling lower. No one's really made any comments on that - I believe it could be due to the airgap making one of my cylinders routinely misfire, or want to, at any rate - so it idles lower. I think maybe its possible that, with heat expansion, my airgap is possibly fluctuating to just the precise point of outright failure once it hits a certain temperature?

The air gap is adjustable right? Feeler gauges n all that business? Couple phillips screws? I dont really know how to increase/decrease the gap tho, this AIR GAP ADJUSTMENT
only made so much sense to me
 

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Good question regarding play - when I had mine out it had no play at all that I recall. Makes sense that once you do have some play you have some variation in ignition that could mess things up. And no - the gap is NOT adjustable on these distributors as far as the FSM has it - if it's off it says to replace the distributor. It needs to be between 0.2 and 0.4 mm. And yes - feeler gauges.

Did you also try to measure resistance at the two terminals for the ignition coil?
 

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Discussion Starter · #16 ·
If youre speaking about the terminals on the ignition coil itself yes, resistances for both check out proper at cold & hot temps.

I'm quite interested in this, I'm not sure how this was performed, but these guys managed to adjust the airgap on it, and I have an identical dizzy:


Assuming that all my assembly is the same, I'd love to know how they managed to loosen the pickup coil to adjust it, I'm assuming just a couple phillips screws but I don't know yet - if it ever, ever, stops raining outside, I'm going to go poke around on mine.
 

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Discussion Starter · #18 ·
He also shows a few diagrams in there that are somewhat handy, about around 30m or so I believe - I'm interested in checking out the pickup coil resistances, and from what I gathered you do that by disconnecting the actual distribs lil harness and poking your multimeter into some of those terminals. And correction, the distrib isnt identical to mine, this one is adjustable, so he's got a 6 pin connector. Oddly enough only the 4 "left most" pins are marked with N+ and N- and so forth, so I'm assuming those are likely where I need to poke? Do I need to backprobe and have the car running for that or can I just check it the easy way?
 

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Discussion Starter · #19 ·
Well crap. Lol. Curiously enough, the car still runs the same (weird) even with this thing I just noticed I caused...

That dang blasted wire memory!

I noticed one of the wires that leads to the (positive? can't remember - its got two wires going to it, this is a pic of one of them) terminal on the ignition coil seemed like it was slightly crimped in the middle, and I also noticed it twisted itself as it went up to meet the terminal. So naturally, I straightened it out so it'd not be all twisted up on its way to the ignition coil.

Thanks to wire memory, or perhaps some inattentive torquing on my part, it had positioned itself in the way of the what I believe is called the G pickup - the little peak that comes off the shaft to communicate with the pickup coil, yknow where you measure air gap....so yknow, after I'm assuming just a few minutes of running, this happened:

Human body Finger Thumb Toe Foot


Great. Lol..

Gas Auto part Metal Engineering Machine


Gives you an idea of what was happening. That little peak on the g pickup was whizzing past n chewing through that wire. I'd wager a few more minutes or so n that wire would be chewed through, likely. Somehow, the car is still running the same since this happened. Must not have damaged the wire enough to "cause problems" but eh, add to the list of reasons for purchasing a new dizzy, lol.

Also its hard to tell obviously without the g pickup being lined up, but the air gap does look substantial. I need to get some feeler gauges. I also need to figure out how to check the pickup coils resistances, anybody have any advice on that? Would be mucho appreciado
 

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Two of the wires coming out of the distributor are G+/G-. You probe those with the ohmmeter. It's hard to follow my 1997 wiring diagram, but it looks like those wires should be black and the other white, but there is also a black wire going to the coil.

The air gap should be 0.2-0.4mm.
The reisistance, 185-275 Ohms cold, and 240-325 Ohms hot, but this is from my 1997 repair manual which is the same style as your year with a separate crank position sensor, but your spacs may be different. Or is this the thread where you siad you have the same distributor part number as the one I posted? In which case the specs should be the same.,
 
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