20 replies to this topic

[one eye]

So I have a huge problem, I have an 88 XT 4 wheel drive It has the MPFI in it and it won't fire on # 1. Chris (Audio file) and I have gone through the entire wiring harness and check all the Injectors and did everything in the book that tells you what to check for.....And Still it is only running on 3. Has anyone ever had this before, Is it the ECU or should I just through it away? It has me . And I just want it to run. Chris Checked a whole bunch of stuff, and I dove into the Harness thinking that it had a short in one of the wires. I just don't know what to do anymore If any one has any Ideas let me know

The specs on the car are
88 XT
4wd
It has the spider intake on it
MPFI
135.000 miles
If there is anything else anyone needs to know ask me?

Jeff

[GeneralDisorder]

Have you checked for spark with an inline spark tester on the #1 lead?

Have you ran compression on all the cylinders?

GD

[one eye]

Have you checked for spark with an inline spark tester on the #1 lead?

Have you ran compression on all the cylinders?

GD

I checked it with the spark plug on the wire and The wire itself, I have not done an inline check yet.

Compression Check is going to happen tomorrow morning. I was thinking and even said it to Chris right at the end I wonder if there is Bent valve or just a bad cyclnder. It does not have the TOD or anything like that. The worst part is, is that sometimes it runs perfect, It didn't do that today but the last time I drove it was last winter and it was about 30 sum deg. out and it ran great for 5 days and then it started missing again. I have replaced the cap and rotor, plug and wire. so I am pretty sure it is not a spark issue. I think that it is in the wires that tell the injector to shoot the fuel but I don't know where in the car to try to find this "place" to fix it at


Jeff

[Gloyale]

The injector are triggered in pairs by the ECU

injector 1 and 3 are toghether, signal from pin 51 and 52.

The wires come out of the ECU as 2, then a crimp splice toghether until close to the Engine connector. Then there is a crimp connection where the 2 wire seperate again before the main engine connector.

You need to find both of those crimp connection. They should be only a short way into the harness from the ECU and engine connector respectively

Here is a partial diagrahm showing the splits. It i for 88 GL mpfi, but I believe all you're pins and wire color to be the same. The only thing that might be different is pins on the round engine connector. Wires highlighted in red are White w/ Red stripe. Blue is White w/Blue stripe.


After making and posting this I realized I mapped Injectors 3 and 4. 1 and 2 go to pin 49 and 50 of the ECU. Both are white wires until engine connector, through engine connectors at pins 6 and 4. Engine ide, inj #1 wire is White, #2 wire is White w/ Black stripe.

[Skip]

You could also check at the dropping resistors
on the pass side fender well (see below)?

This devise has battery voltage in and four wires
out, one to each injector.

The injectors are fed battery voltage through the dropping
resistors and the ground for them is provided by the ECU
as G points out.

If the resistor for #1 injector was toast
(never seen it happen) only #1 would be effected.

[audio_file]

(i'm reading this while i eat my cocoa puffs)
i put a multimeter to all injectors last night, all were in the acceptable 2.5-3 ohm range of resistance, then i focused on the wires for each injector. #'s 2,3,4 showed a resistance of about 20ohms (like the manual said) but number 1 showed no resistance, 0ohms. we followed the wire all the way up the harness checking for continuity (that cool "beep if you're touching the same wire test) and it #1's two wires had continuity all the way through both of the main connection plugs on the firewall.
with the key on, all pairs of injector wires read just under 12v DC, even the #1 wires.

that's my story from last night . . . does that help diagnose at all?

[audio_file]

we were wondering where in the he-ck they were hiding that, it's in the same spot on the xt?!

You could also check at the dropping resistors
on the pass side fender well (see below)?

This devise has battery voltage in and four wires
out, one to each injector.

The injectors are fed battery voltage through the dropping
resistors and the ground for them is provided by the ECU
as G points out.

If the resistor for #1 injector was toast
(never seen it happen) only #1 would be effected.

[Gloyale]

....then i focused on the wires for each injector. #'s 2,3,4 showed a resistance of about 20ohms (like the manual said) but number 1 showed no resistance, 0ohms.

Reistance to what??? Ground?
What you need to do is disconnect the ECU and the injectors, and test the resistance of the injector ground(white w/stripes, not the red ones) wires end to end.

with the key on, all pairs of injector wires read just under 12v DC, even the #1 wires.

So the power supply is good. I believe the ground is the issue. IF it is an injector issue. Not *firing* and not *parking* are 2 different thing.

Let's clarify. You said earlier it was not sparking on 1? That would not be associated with the injector circuit. Have you tested the resistance of the #1 spark plug wire? or tried swapping it around to see if the no spark follow it?

[Skip]

You could use one of these to check
the spark at #1

[audio_file]

Gloyale, the book says to check resistance in ohms between #1 and the rest of the injector wire pairs, with #1 being the constant variable (to make sure the wires are good). . . i dunno, i was just following the directions

can i pick that up at napa?

You could use one of these to check
the spark at #1

[Gloyale]

Gloyale, the book says to check resistance in ohms between #1 and the rest of the injector wire pairs, with #1 being the constant variable (to make sure the wires are good). . . i dunno, i was just following the directions

What book? Chiltons? Haynes? Probably wrong or addressing a different model. I don't ever trust them. I don't see that in the subaru FSM. Here i the flow chart for teting injector circuit.

[one eye]

Wow, this is becoming more and more confusing to me. I hate trying to play the what wire to check game:-\ . Chris are you getting all of this? I know the average person would be able to understand all this But I know nothing about Electrical stuff. If I can't run it straight off the Batt. I'm going to have a hard time.



Jeff

[one eye]

this is what I've done so far is look for a strpped wire somewhere in the harness thus is what it looks like. I think I've been looking in the wrong place:rolleyes:



Jeff

[audio_file]

The FSM for 89 lists the test procedures i mentioned on FSM's section 2-7, page 94 (pdf linkey's page #100) right above the diagram you scanned . . . check it out.

http://www.ch601.org...ManualPart2.pdf

What book? Chiltons? Haynes? Probably wrong or addressing a different model. I don't ever trust them. I don't see that in the subaru FSM. Here i the flow chart for teting injector circuit.

[Gloyale]

The FSM for 89 lists the test procedures i mentioned on FSM's section 2-7, page 94 (pdf linkey's page #100) right above the diagram you scanned . . . check it out.

http://www.ch601.org...ManualPart2.pdf

The FSM in this link does not include that page in the Fuel Injection section. It ends at pg. 102. Notice the page # in my scan is page 133. There is a similar diagrahm and some other check proceedures earlier in the FSM on page 94 of section 2-7.

But I am still thinking you are confused about the proceedures. You stated:

["the book says to check resistance in ohms between #1 and the rest of the injector wire pairs, with #1 being the constant variable (to make sure the wires are good)."

I can't find that anywhere. You've determined that each of the positive wires(red ones) to the injectors has 12v. And the resistance of the injectors themsleves are fine.

So that leaves the ground signal from the ECU. The scan I posted describes testing for ground at the ecu pins. use a test light with it's clipped wire hooked to a +12V. The touch the tip to pins carefully onto pins49,50,51,52 on the ECU. Each one should light the testlight, showing there is ground. If that works then you have isolated it to a break in the wire from the ECU to the Harness.

You are basically looking for a break in the wire from end to end. The wires from 49,50 and 51,52 pair toghther after a short bit, close to the ECU connector. This creates a redundant connection to the ECU, so a break here would not affect just one injector, a complete severance would affect both, and one wire loose would be compensated by the remaining. The problem likely is at the split again before the Engine connector. My bet is that at this point, the splice is corroded and one wire has come loose. It's all there in the diagrahms

Basically I think it'll boil down to tracing the White wire and the White w/Blue stripe wire back from the engine connector to where they join.

[Gloyale]

Check out the end of this thread.

http://www.ultimates...=injector trunk

Under you're carpet, you will find the culprit.

Joost, I'm surprised you didn't post this here already?

Oh and I'd like to submit it to the USRM???

[one eye]

That link you sent us was very helpful, mine was just as bad as the pics that other fella had, we are right in the middle of putting all back together.

Jeff

[one eye]

We got it all back together, But ........... the power steering pump was bad on it, so since we where there we figured we would just fix it too.
come to find out that power steering pump on the XT is a lot different than on a regular gen 3 wagon so We changed overthing over to the bracket so it would work right. Well some where in the change over things didn't work out so good cause we were able to shread a belt in about 30 sec. the pully seems to kinda be bent in some way or another. not a big deal yet just making more work for tomorrow. :-\

Jeff

[audio_file]

That link you sent us was very helpfull

those exact same connections were the problem, very poor design to just splice two wires together "somewhere" in the line!!!
so +1 thank you, we could've searched for that problem for eons . . . :-\
chris

[Gloyale]

those exact same connections were the problem, very poor design to just splice two wires together "somewhere" in the line!!!
so +1 thank you, we could've searched for that problem for eons . . . :-\
chris

Glad you found it.

but yeah, well, that's how it is:lol:

Any time you see one of those joints in a wiring diagrahm, it will likely be one of those types of connections. The one thing it doesn't show is excactly where in the harness the splice is.

The big one with five wires for the Power Windows +12v is a nightmare.

[one eye]

This is kinda a bad pic but you can see the Green where the wires where toasted bad. Not only that it looked live someone drove this thing across the Skagit River during Flood season......without using the bridge. That kills is what kills the wires.

I'll post a better pic later, I left my camera in the shop and I have not put my shoes on yet. :-)



Jeff