autojumbled ST185 narrow body

grip-addict

Active member
OZ's do look great!
map does air fuel mixture in gen 3. it's only for boost cut in gen2.

It also sounds ignition related to me. Assuming the spark plug gap isn't all wonky (please check this first), you've already tried all of the normal stuff which unfortunately leaves the less-fun options.

Can you verify the coil is getting 12v? It should get a constant feed.

Do you have access to an oscilloscope? I think you might need to start with checking what the wave length looks like @ 4k from the distributor triggering signals. NE is crank, G1 and G2 are cam sensors. G- is ground. It's an AC signal so you won't get very far with just a multimeter unfortunately.

Also, did you add any grounds right around when this started happening, or does your car have any extra grounds ? Sometimes adding and changing grounds can have unintended side effects.
This is a good read that might be relevant: https://www.hpacademy.com/technical-art ... -grounded/

Hopefully one of the old-timer forum members/electrical engineers from alltrac years gone by has a better idea because my first thought is to see what the VR sensors in the distributor are doing, and that'll probably take some time to work through.

best of luck
 

Tippo

Well-known member
This is like reading de-ja-vu all over again lol. Nice job! How on earth did you get those nicopp lines to line up so well? mine are a mess under the car haha!
 

autojumbled

New member
Tippo":1cozl5sd said:
This is like reading de-ja-vu all over again lol. Nice job! How on earth did you get those nicopp lines to line up so well? mine are a mess under the car haha!
Have you had similar issues then?

The lines are a bit disorganized to be honest but they get hidden well!

Sent from my Pixel 3 using Tapatalk
 

Tippo

Well-known member
autojumbled":3nm9fna1 said:
Tippo":3nm9fna1 said:
This is like reading de-ja-vu all over again lol. Nice job! How on earth did you get those nicopp lines to line up so well? mine are a mess under the car haha!
Have you had similar issues then?

The lines are a bit disorganized to be honest but they get hidden well!

Sent from my Pixel 3 using Tapatalk


Same issues, tank removal, all lines under the car redone... My lines look like an absolute mess under the car though!
 

autojumbled

New member
Can't believe my 185 hasn't worked since March 2021. Well, at least that's how long I've been chasing (on and off) the backfire issue occurring at 4K rpm.
Inspired by RORERI I had a little poke around again under the bonnet to see if I could check off another thing that could be an issue.

I wanted to try whether the issue was caused by the fuel pump switchover from low power to full power - maybe the relay wasn't working or the resistor was faulty.

Test 1: Remove the fuel pump relay and jump the wires to bypass the resistor pack, forcing the fuel to run with full voltage permanently.
Result: no change in behaviour. Backfire still occurs.

Test 2: Confirm relay and associated wiring is sound.
Result: The wiring for the fuel pump relay into the fuse box is damaged! I've repaired and retested both with and without the jumper but no change in result. Backfire still occurs.

PXL_20220924_130609386.MP.jpg
PXL_20220924_114453384.MP.jpg

Blue with orange stripe is the feed to the relay - this is burnt with sleeve melted and connector corroded
Blue with white stripe is the wire to the fuel pump resistor - this shows a little damage and the sleeve is solid

Long story short - the damaged wires don't appear to have been damaged enough to affect the fuel pump operation and I've since repaired them. But now I need to add another worry to the pile - why were they damaged? what caused the wire from the circuit opening relay (blue/orange) to burn up?!
Could the connector have become corroded and raised resistance, therefore causing heat build up and charring the sleeve?

Anyway.....the hunts continues for wtf this thing backfires :doh:
 

alltracman78

Active member
That misfire is probably your distributor. Internal, not the cap/rotor. Especially since code 12 is for your distributor (RPM signal). You can check the signals with an oscilloscope like someone mentioned. If you can find a spare known good distributor it will be easier to swap that in and see if it helps.

The heat in that wire is from the corrosion in the connector and on the wire strands and the fact the wire is partially unwound. Corrosion between the strands of wire and lack of connection (wire unwound) causes resistance. Which means heat. Would be interesting to see how much of a voltage drop that chunk is. Probably nothing crazy, but not good. And it will only (slowly) get worse.

You can bypass all that crap if you want. Going off US wiring but should be same/similar for you. IE2 connector in the LH foot well carries the wire from the Circuit Opening Relay (should be attached to your ECU) to the engine bay and the fuel pump relay/resistor. Then wire comes back through the same connector to go to the fuel pump. If you splice the 2 wires inside the car you bypass all the wires in the engine bay.
The connector is square, white? and at the top/front of that collection of connectors under there.
The wires are pin 18 and 19. On the bottom of the connector.
One is the blue/orange wire (same wire that is corroded at the relay), the other is blue/black.

This connector set is joining the dash wiring harness with the fender wiring harness. One connector in the set is for one harness, the other for the other harness. The connector with the male pins is the dash harness. The connector with the female pins is the fender harness.
One will be clipped into the car, the other will come loose when you disconnect it. I don't know which one is which, and depending which one comes loose determines the easiest way to do this.

The easiest way is to cut the 2 wires and join them.
If the dash harness connector is the one that comes loose you want to cut and join the wires in the harness.
If the fender connector is the one that comes loose (I have a feeling this is the one it will be) you want to cut the wires and leave a few inches of wire on the pins because you're going to connect the 2 pins together, not the wires in the harness. Effectively you're making a jumper for the other connector.

You can also just disconnect the 2 pins and make a jumper out of new pins and wires. This keeps you from damaging the harness at all and makes this easily reversible.


I left this kind of technical because you seem to know your way around the car. If something doesn't make sense let me know and I'll try to explain in more detail. :)
 

autojumbled

New member
Thanks for the indepth explanation :)

I'm in denial about the distributor as it's a brand new (refurbished) unit but as you say....I need to test it.
 

alltracman78

Active member
Is it a Denso reman? Lower quality reman would obviously be suspect.

You can test it but easiest way to check that is swap in a known good one.
If it isn't take a look at the igniter and ECU.

I forgot to mention, that facelift ECU you picked up, it takes a little wiring modification to make it work, but it has a better diagnostic ability than the pre facelift.
You need to jump TE2 (You may not have that wire in your harness, if not you can just bridge the TE2 terminal at the ECU to ground, that's all E1 (and E2) is.) and E1 in the DIAG box and it will run a more sensitive diagnostic program. May give you a code you can narrow down with.
 
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