47 replies to this topic

[john in KY]

XT6 Ohm testing specs since there is no manual available for XT6 and this ECU won't give codes.

Neither is true. The XT6 has a FSM nd the ECU will store/flash DTCs.

[crazyhorse001]

On my 87.5 XT I had a similar issue, after replacing the HG's. I was able to disassemble the disty, and clean the photo-eye. This cleared my problem right up.

It may not be your issue, but clean parts are happy parts.

[RetardedGenius]

Neither is true. The XT6 has a FSM nd the ECU will store/flash DTCs.

In my case it is.
My ECU will not give codes. I've pulled code from at least a dozen OBD1's so I know what to look for, and I've followed the procedure from xt6.net, but this ECU will not blink the light on the ECU.
I have been searching ebay for months for a Subaru XT service manual, but haven't found one and finally drove 40 mins to the nearest Subaru dealer to see one where they told me that they no longer work on XT there at all and they threw out their XT manuals years ago. Then they tried to sell me a new Subaru (which they later would not support either). From there things got unpleasant.
john in KY, since you have a FSM readily available, could you please post the Ohm specifications for the pickup coil (or ignition module) for an XT6 please, and if you have time, Ohm specs for the Idle Air Control valve and Coolant Temp sensor.

[john in KY]

I'll see what I can find. Where in NE Ohio? Originally from the Warren/Youngstown area.

[john in KY]

I'll see what I can find. Where in NE Ohio? Originally from the Warren/Youngstown area.

Found no ohm value for the CAS. Just a LED shining through 360 slots. Guessing it either works or doesn't.

CTS:

Test in water and the first test has me puzzled.

@ 14F---7-11.5 kilo ohms. (How do you get water to 14F?)
@ 68F---2-3 kilo ohms
@ 122F--700-1000 ohms

Edit: Just ralized you have an XT. Specs I provided are for the XT6. Probably the same.

Air valve:

YR wire goes to terminal #1
BW wire goes to terminal #2
YL wire goes to terminal #3

Between terminals 1 and 2---9.5 to 11.5
Between terminals 2 and 3---8.5 to 10.5
Between terminal 2 and the metal housing of the sensor--infinity.

If you need another distributor, ECU and/or have any interest in an incomplete set of 1988 XT6 FSMs, missing chapter 1. PM me.

John

Edit #2. Ignore the above because what I have is for the XT6. A bad airflow meter will cause most of the problems you have described.

[RetardedGenius]

Thank you john in KY.
That's exactly the info that I needed.
I may need a new 1988 XT6 distributor and possibly IAC. I will likely know by tomorrow. Hopefully it would explain why my distributor is only sending spark to 3 of 6 cylinders.
BTW I'm just south of Canton, OH @90 mins from Youngstown.

[RMVR53]

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.

to answer your question .... no. I haven't found a CAS yet to my financial liking. I put another dizzy in the hole and I thought it was cured. Drove it local about 10 miles and had no porblems. My daughter shows up about 10 minutes later and heads off to town in it. She got to the end of the street and it started all over again....so at this point I really have my doubts about it being in the dizzy...

Bill

[Cougar]

If the tach is still going wild after the disty replacement then I suggest you check the alternator as the source of the trouble.

[RMVR53]

If the tach is still going wild after the disty replacement then I suggest you check the alternator as the source of the trouble.

you mean as in output, short or ???

[Cougar]

Excessive ac noise from the output.

[RMVR53]

yeah I know...you'd think after all this time passed it would be fixed. But it ain't. I have narrowed things down a bit however. I borrowed a friends XT and we put my dizzy in his car. He drove on it for a month (it took that long to catch back up to him) so it ain't the dizzy. So now I'm lookng a open loop/closed loop issues. Car runs fine when cold, starts this miss/bouncing tach crap when warmed up. Runs fine if you keep the rpms below 1800, above 1800 and the above miss/bouncing tach problem rears its ugly head. I considered the TPS but can that really have an effect on the tach/firing? Same for the AFM...

ideas gang?

thanks
Bill

[Gloyale]

ideas gang?

thanks
Bill

Put a noid light on the injectors to test that they are all firing. You might want to pull up the carpet and inspect the famous injector wire junction under the carpet.

[Cougar]

You should have the alternator checked out. I suspect it is causing the problem you see with the tach.

[RMVR53]

You should have the alternator checked out. I suspect it is causing the problem you see with the tach.

question...how can the alternator cause the tach to jump wildly and at the same time the cause engine to try and die?

[Cougar]

Excessive noise in the power buss can cause the low level signals from the sensors to be distorted and possibly intefer with the ECU also. If there is a power buss problem you possibly may be able to hear it in the AM radio tuned between stations.

[RMVR53]

Excessive noise in the power buss can cause the low level signals from the sensors to be distorted and possibly intefer with the ECU also. If there is a power buss problem you possibly may be able to hear it in the AM radio tuned between stations.

I had a chance today to work on the XT again. Got it warmed up and when the crap started happening I stopped and removed the alt belt. Problem continued so that is ruled out but thanks for the idea.

next thought anyone?

Bill

[Cougar]

After reading through the posts again I think you might have a faulty ECU. I suggest you try replacing that to see if it will get you going.

[RMVR53]

After reading through the posts again I think you might have a faulty ECU. I suggest you try replacing that to see if it will get you going.

will a replacement have to come out of an 87 MPFI XT or what are my options?

thanks

Bill

[Gloyale]

will a replacement have to come out of an 87 MPFI XT or what are my options?

thanks

Bill

87-91 4 cyl XT.

You might be able to use an ECU from a turbo GL. All the connections are the same, but it may not run quite right.

[RMVR53]

87-91 4 cyl XT.

You might be able to use an ECU from a turbo GL. All the connections are the same, but it may not run quite right.

you sure on the years?..I not doubting you G, just funny how the brain stayed the same but they used a handfull of distributors that aren't interchangeable!!

[Gloyale]

you sure on the years?..I not doubting you G, just funny how the brain stayed the same but they used a handfull of distributors that aren't interchangeable!!

Uhh..... As long as it's an optical style disty, it should be the same distributor for all 87+


Perhaps you have an early 87 xt. Does it have a vacuum advance diaphrahm on it? If so then you have the early style which would be the same as 85,86 MPFI/Turbo GLs. In that case you would need an ECU from one of those cars.

[RMVR53]

Uhh..... As long as it's an optical style disty, it should be the same distributor for all 87+


Perhaps you have an early 87 xt. Does it have a vacuum advance diaphrahm on it? If so then you have the early style which would be the same as 85,86 MPFI/Turbo GLs. In that case you would need an ECU from one of those cars.

June 87 build and no vacuum advance...and I tried to swap in a dist from an 88 and the plugs are different. I then swapped the plug from my 87 onto the 88 dist (same wire count and color) but it would not work. Went to my neighbor who had a 88, put the dist in his car and it ran fine...go figure...

[john in KY]

I still think you have an AFM problem. PM Gary as he knows which ECUs swap.