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RMVR53

87 XT ignition module

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I'm gonna scream!!!

 

spent forever (OK almost 2 years) putting my 87 XT back together after an engine rebuild. Upon completion, it would start, run till it warmed up then loose all power and cut out with the depressing of the accelerator pedal (only idle - nothing more) and the tach would bounce erratically. Swapped out all kinds of stuff (coil, wires, plugs, etc) and finally swapped in a used distributor and it ran fine!!!... for 10 miles...then it started doin the same crap all over again.

 

Did I replace one bad pickup in the dizzy for another that wasn't quite so bad but still failed? I had no such problems prior to the tear down and the dizzy has sat in the trunk during the entire time of the rebuild. I love this lil car but I can't for the life of me spend another $200 (ignition module in dizzy) on a part that I don't know if its going to fix it!!!

 

point me in a direction guys!!

 

thanks

 

Bill

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Johnson']Grounds? Do youhave adequate grounds?

 

yes...cleaned contact prior to install plus added one (not a big one but a 4 gauge from under the alt to the body)

 

Bill

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Johnson']How familar are you with the EA engine? Did you do the timing belts right?

 

familiar?...this is my 3rd Ru (and newest)

 

timing belts?....this has got to be a warm up/electrical problem. Runs like a bat outta hell right up till it quits...every time!! But yes, TB's are dead on.

 

Could this be a sensor or something else going bad? Say a low (or high) resistance ignition module (just a thought here) that was in the car, the fail happened quicker with the old dizzy. I swap the dizzy, new IM has a different resistance so it takes longer to "fail". I have a 85 Jag that drove me crazy for about a month with an ignition problem as well. Everything pointed to the brain failing. After the 4th brain swap, we started wholesale parts throwing at the thing. Got to the coil and no problems since. With that as a background, the coil is the first thing I swapped out (OEM replacement Hitachi) but to no avail.

 

Bill

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have you tried a different ignition amplifier?

And made sure the bracket is well grounded.

They don't fail frequently, but can fail

in some strange ways.

 

(I will assume you checked for spark after

it quit and had none)

 

igamp.jpg

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have you tried a different ignition amplifier?

And made sure the bracket is well grounded.

They don't fail frequently, but can fail

in some strange ways.

 

(I will assume you checked for spark after

it quit and had none)

 

 

it has spark...just dont touch the pedal and it will idle forever. Try and rev it up and it spits/kicks/sputters/dies. Yeah I cleaned the bracket/ground on the coil when I replaced it. No I have not tried replacing the ignition amp. Does it have to come from the same mid-year XT or can it come from another Ru?

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well I didn't pick up on the idle forever part.

I see it now

"run till it warmed up then loose all power and

cut out with the depressing of the accelerator pedal

(only idle - nothing more)"

 

Don't think it's an amp issue.

(any mid 80's and on SPFI or MPFI cars have them)

 

Fuel filter, fuel pressure regulator, MAF

all could be suspect.

I will also assume you have no CEL when this happens.

 

Have you made sure there are no separations of the

tube from the MAF to the intake?

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well I didn't pick up on the idle forever part.

I see it now

"run till it warmed up then loose all power and

cut out with the depressing of the accelerator pedal

(only idle - nothing more)"

 

Don't think it's an amp issue.

(any mid 80's and on SPFI or MPFI cars have them)

 

Fuel filter, fuel pressure regulator, MAF

all could be suspect.

I will also assume you have no CEL when this happens.

 

Have you made sure there are no separations of the

tube from the MAF to the intake?

 

replaced the filter just as a matter of course after sitting for so long. BUT...unless the MAF has an electical signal that could upset the tach, its somewhere in the ignition circuit. At least that is my thinking since when it does this (spits/sputters/etc) the tach is bouncing wildly.

 

CEL?...if you mean error code then no..it has yet to give any kind of code for this condition.

 

I should add/say that it (dieing) is not always instant. Lets say you hold 2000 rpm. After about 10 seconds, it starts to spit/etc. At the same time, the tach needle is starting to bounce wildly up and down. I have noticed that the tach starts to bounce usually before it starts to spit/etc. This combination is what tells me its electrical and not mechanical since nothing mechanical would cause the tach to bounce. If it were mechanical, the tach would just follow the decline in rpm as it died.

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no check engine light ever?

 

with the tach going bonkers make sure you inspect the distributor, that's where the tach signal is coming from and you already had a problem there. disassemble and clean or just install another used one. there are plenty of those around for a couple dollars.

 

are you sure you have the distributor lined up properly - they are easy to install a tooth off..or worse!

 

if that doesn't do it you need to check the TPS, that is what moves when you press the go pedal - TPS - throttle position sensor. you should also inspect the throttle cables, and the IAC - idle air control valve.

 

you'll also want to check the wiring to the TPS, the first 6"-12" has a tight bend that is prone to having shorts.

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"This combination is what tells me its electrical and not mechanical since nothing mechanical would cause the tach to bounce. If it were mechanical, the tach would just follow the decline in rpm as it died."

 

Good point, this kind of info really helps.

This system used a CAS (Crank Angle Sensor)

distrib. There is no "module" in the distrib.

 

Just an optical sensor and a wheel with holes

Check the plug to the dist, the wires

in and out of this plug have been

known to get knackered and cause issues.

Was the distrib from the same year?

CAStest.jpg

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"This combination is what tells me its electrical and not mechanical since nothing mechanical would cause the tach to bounce. If it were mechanical, the tach would just follow the decline in rpm as it died."

 

Good point, this kind of info really helps.

This system used a CAS (Crank Angle Sensor)

distrib. There is no "module" in the distrib.

 

Just an optical sensor and a wheel with holes

Check the plug to the dist, the wires

in and out of this plug have been

known to get knackered and cause issues.

Was the distrib from the same year?

 

OK...so we will refer to it as a CAS instead of an IM...good to know the correct terminology!! I used contact cleaner on it to make everything as clean as I could prior to plugging it in. Is there a plug anywhere other than in the harness between the dizzy and sidewall (under coil area)? Dizzy was from same month GL. I had to make 3 different trips to the yard (over a 2 month period) to find this one with even the same plug on it. Just got lucky it was from the same month. I did try to swap in a later unit - made a harness adapter for it (4 wires were the same color from both units) - but must be different enough as it didn't work.

 

any who...

 

BTW..thanks for your responses Skip. You are quite knowledgeable!

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swap in another distributor or try to trouble shoot yours.

 

here's the funny thing. twice i've torn down a motor and it took a few months. when i got it back together it wouldn't run right at all and no check engine light. was loosing my noggin trouble shooting and it ended up being the distributor both times. the irony is that both were perfectly fine running vehicles before with no disty issues. after the second time happening i suspect something about the disty may get corrupted if it sets for awhile. outside of that i've never seen a distributor fail while running.

 

the second time i think i even tested the disty via the FSM and i don't recall it testing "out of spec".

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swap in another distributor or try to trouble shoot yours.

 

here's the funny thing. twice I've torn down a motor and it took a few months. when i got it back together it wouldn't run right at all and no check engine light. was loosing my noggin trouble shooting and it ended up being the distributor both times. the irony is that both were perfectly fine running vehicles before with no disty issues. after the second time happening i suspect something about the disty may get corrupted if it sets for awhile. outside of that I've never seen a distributor fail while running.

 

the second time i think i even tested the disty via the FSM and i don't recall it testing "out of spec".

 

Unfortunately, I don't have another one to drop in. I was at the yard Tuesday and there were no new prospects to scavenge from. Is there another plug on or in the dizzy I am missing or is the optical unit a part of this total harness coming out of the head?

 

Based on your (extensive) experience, I don't feel so bad right now...not that that helps the situation!!!

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it has spark...just dont touch the pedal and it will idle forever. Try and rev it up and it spits/kicks/sputters/dies. ?

 

This is exactly what a bad airflow meter will do.

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Can't think of any connection between a bouncing tach and a bad AFM but your description of "can idle all day but dies when the pedal is depressed" has bad AFM written all over it. Or bad electrical connections somewhere.

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One other thing you might check out is is there is any AC ripple coming from the alternator that may be causing the tach to bounce. Place a digital meter in the AC voltage mode and measure across the battery. While reving the engine slightly, see if there is any AC being measured. The level should be less than 0.25 volts.

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RMVR, being this is an XT

they do have problems with wiring under the carpet.

 

Don't know why this would cause this but

might be worth looking at

seeings how

it does happen.

Here

http://www.ultimatesubaru.org/forum/showthread.php?t=85671

 

and here

 

http://www.ultimatesubaru.org/forum/showthread.php?t=67331&page=4&highlight=injector+trunk

 

Good reading for XT owners at any rate

 

ugly!! indeed

IMG223.JPG

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RMVR, being this is an XT

they do have problems with wiring under the carpet.

 

Don't know why this would cause this but

might be worth looking at

seeings how

it does happen.

Here

http://www.ultimatesubaru.org/forum/showthread.php?t=85671

 

and here

 

http://www.ultimatesubaru.org/forum/showthread.php?t=67331&page=4&highlight=injector+trunk

 

Good reading for XT owners at any rate

 

ugly!! indeed

 

I'll check it this afternoon. Thanks!!

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A late update but better than never.....

 

Finally had time to do some diagnosic work (called cleaning every frikin contact on the engine). I was able to get the problem to surface in a controled manner...I think. When the engine warms up, if you keep the rpms under 2k you can control when/if it fails. Stable rpm's over 3k and you can "feel" it going south...engine starts to stumble/load up, then start to backfire etc. then die. BUT if you get out of the rpms (back under 2k) it will continue to run for about 5 minutes under 2k before that starts to load up.

 

Now the not so funny part...

 

Shut it off, restart it, and you can drive away...about 30 seconds later it starts to fail again. Shut it off, let it sit for about 2 minutes, and you can drive it for 5 minutes or so.

 

So... I assume Im replacing the CAS at this point unless someone offers another solution...

 

Bill

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I believe there are 2 main harness connections for the engine, down along side the drivers side frame rail or on top of the tranny. Its been a while since I worked on a XT. But to pull the engine, these needed to be disconnected. I had a problem like this once when I was doing multiple swaps on my RX and I finally discovered that I didnt have the plugs tightly connected.

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I believe there are 2 main harness connections for the engine, down along side the drivers side frame rail or on top of the tranny. Its been a while since I worked on a XT. But to pull the engine, these needed to be disconnected. I had a problem like this once when I was doing multiple swaps on my RX and I finally discovered that I didnt have the plugs tightly connected.

 

The two big harness'/plugs I worked with were above the tranny - but in a plug clip of sorts. And yes I unplugged/cleaned/plugged those as well. Anything I moved or disconnected I cleaned....which in doing all this I did find a bad ground wire (chassis to Alt bracket) but installing a new wire did nothing for the condition...unless this wire being bad caused the CAS to go bad from bad/no ground.

 

Bill

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RMVR53, were you able to find a solution to this problem or able to find a replacement distributor (or CAS) or pickup coil?

 

I ask because I'm trying to diagnose an XT6 that had all of the same symptoms but with a much more rapid decline. It will no longer run at all.

 

I had a Toyota that had some similar issues until I replaced the pickup coil in the distributor and it's been running fine since so I've been searching for XT6 Ohm testing specs since there is no manual available for XT6 and this ECU won't give codes.

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