A9M with Trouble Code 18

[Past_Miner]

Hi everyone. It's been a long time since I posted here. Other life issues have drug me away from my Broncos for a few years. Forgive me if this is in the old threads somewhere, I had a hard time with the search function on the new forum.

I have recently had a random stall/no start problem on my Bronco that has required a tow home. I injected this truck in 2006 and have never had any problems with it except one worn fuel pump and a few random TFI modules burn outs. Otherwise, this EEC and engine arrangement has been bulletproof for 16 years. It stalled driving down the road on the way to a friends house lats week and would no restart. It sat for a few days and started right up. It then ran long enough to back out of their garage and stalled again. It got towed home yesterday and fired right up and ran multiple times. After heating up, it has not started again.

I ran KOEO codes and got the following:

33, 81, 82, 84, 85 - I just ignore these. I am running an old Ryan McCormick harness and these are all emission related.
29 - VSS Problem - I am surprised, since my electronic speedo is registering just fine. This might cause a stall at a stop, but not running down the road and should not keep it from starting.
18 - SPOUT/IDM Circuit Failure - I haven't encountered this before and I suspect that it is the root of the problem. If anyone out there has any experience with this code I would appreciate some feedback.

Here are the basics of my system: A9M EEC, RJM harness, 351W with Explorer upper, ZF5 manual transmission. I spent a lot of time trouble shooting yesterday and know the following:

- I have 12V at the coil with the key on. I have about 9.5V while cranking.
- The coil fires but has a weak spark. I assume the TFI is working (and I have changed out with a new TFI and coil with the same results)
- The plugs wires are sending spark but it is extremely weak - maybe not enough to actually fire a plug
- The no start problem exists with the SPOUT connected or disconnected.
- I have 45 psi of fuel pressure and it does not dip - I do not have a fuel supply problem.

Sorry for the long post, here is my direct question: Will a bad PIP in the distributor cause a bad SPOUT signal and will that in turn cause a low spark intensity? Or should I be chasing a short in the SPOUT wire, or worse yet, am I looking at an EEC failure.

Thanks,
Brad

 

[DirtDonk]

Sorry, no idea. But I’m subscribing to hear what the general thoughts are.
Good luck. I know how frustrating it can be to have it work so good for all these years and then have a mystery problem to solve.

 

[gremlin]

i had the sheild wire that wraps around the igntion wires going to the spout rub thru the insulation. would run with spout removed.

 

[stupidboy]

Is it fixed yet?

 

[lars]

IDM is the Ignition Diagnostic Monitor signal. The EEC monitors the ignition signal on Pin 4. If it's intermittent or nonexistent, it throws a code 18. Pin 4 at the EEC connector goes to the TFI module and the negative terminal of the ignition coil, so you can check continuity there. Note that there is a 22k ohm resistor between Pin 4 and the TFI module.

If the pickup (PIP) in the distributor is bad I believe you'll get a code 14, so likely it's ok.

Could be a bad connection, a bad TFI module or a bad EEC.

Do you have a diagram for Ryan's harness? If not that, a 1993 Mustang diagram? The latter is pretty obscure but it shows all that stuff.

 

[ksagis]

I don't know if this is it the issue, but I know the foxbody ECM have an issue with the capacitors aging out and leaking. And that can cause all sorts of weird issues. Maybe open up the box and have a look. Here's a link with some details:

https://www.allfordmustangs.com/threads/this-is-what-a-bad-ecm-looks-like.1007465/

 

[Broncobowsher]

Anytime I see a wonky EEC-IV code these days, I lean toward aged out caps on the board.
If the EEC can't read a tach signal, it won't fire injectors. Will it run if you bottle feed it? (that is run it on carb/brake cleaner)

Weak spark with TFI is strange. And even swapping the module is the same. Maybe you are loosing a coil? I am grasping at straws at this one. Are you checking for spark at the plug or the coil? I've had issues in the past with the coil lead going bad and that made a weak spark at all spark plugs. But not with EFI.

 

[lars]

I don't know if this is it the issue, but I know the foxbody ECM have an issue with the capacitors aging out and leaking. And that can cause all sorts of weird issues. Maybe open up the box and have a look. Here's a link with some details:

https://www.allfordmustangs.com/threads/this-is-what-a-bad-ecm-looks-like.1007465/

Anytime I see a wonky EEC-IV code these days, I lean toward aged out caps on the board.
If the EEC can't read a tach signal, it won't fire injectors. Will it run if you bottle feed it? (that is run it on carb/brake cleaner)

Weak spark with TFI is strange. And even swapping the module is the same. Maybe you are loosing a coil? I am grasping at straws at this one. Are you checking for spark at the plug or the coil? I've had issues in the past with the coil lead going bad and that made a weak spark at all spark plugs. But not with EFI.

Worth noting, easy to check, and I should point out that I dodged a capacitor-shaped bullet on that issue myself. I opened up my A9L for a look last year and found ugly capacitors. Easy to replace, and I now have enough spare capacitors for another 40+ years of driving...

 

[BanditBronco]

I had a similar issue of random stalling, if I cycled the key it would start right back up without any wait time. I could literally stall it, cycle the key, and start it back up while driving down the road. If you can get it started again I would put an O scope on the TFI and see if you are getting signal. I would swap TFI's for fun and see what happens as well. If it helps, I spent a year and threw the whole west coast at mine without finding the issue, so I fixed it with an explorer swap haha I really hope you figure out your issue, I have been in your boat before, good luck.

 

[Past_Miner]

Thanks for all of the replies and input. I thought I would give an update and let you know what I think is the solution. The short story is that the SPOUT wire has a partial short to ground that is causing random stall and no start issues.

I literally chased all of the suggestions listed here and a few more I found on other forums. I have done everything except opening the EEC and checking capacitors. I changed the TFI and coil with known good working units a couple of times with no change. I changed the PIP with no change. I put in new plugs and a new cap and wires. I always had spark from the coil but not enough to get the plugs to fire. The fuel pressure was always good and the injectors were firing. I bought a breakout box and tried every diagnostic test that I could find with all normal readings, including the continuity of the SPOUT wire. A couple of days ago it randomly started and ran so I pulled KOER codes and I got that 18 code again. Then when it warmed up it wouldn't start again.

So I pulled the EEC and harness out from under the dash and opened up the 60 pin connector. I had a few new connector terminals laying around so I ran a new wire directly from the EEC to the SPOUT at the dizzy and it starts and runs every time now. It has strong spark at the plugs and it starts easy, even after it heats up. I haven't had it fail to start since I put the new wire on. My working theory is that the harness has a short in the SPOUT wire somewhere that was not sending enough voltage to the TPI to make the coil fire. I checked that voltage a dozen times and it was in spec but it wouldn't work before.

Since I have the harness and computer 50% removed from its normal position I will probably pull the upper intake and pull the whole harness to look for a short. I might as well check the capacitors too.

 

[Broncobowsher]

This might apply...
The salt and pepper connections where the engine plugs into the body. I bought a used 5.0 that was taken out of a Bronco. As I was stripping it down I found a wire that was worn through the insulation. The position was such that it was rubbing the hood. The wire was for an injector trigger.

I can only guess that the engine (and EFI) were pulled due to some strange EFI issue that could never be found. Runs perfect with the hood open. Sometimes pours fuel through the engine with the hood closed. It was a win for me, I found the issue. It was a really good short block as well.

Don't remember if the SPOUT goes through the salt and pepper connections.

 

[Past_Miner]

This might apply...
The salt and pepper connections where the engine plugs into the body. I bought a used 5.0 that was taken out of a Bronco. As I was stripping it down I found a wire that was worn through the insulation. The position was such that it was rubbing the hood. The wire was for an injector trigger.

I can only guess that the engine (and EFI) were pulled due to some strange EFI issue that could never be found. Runs perfect with the hood open. Sometimes pours fuel through the engine with the hood closed. It was a win for me, I found the issue. It was a really good short block as well.

Don't remember if the SPOUT goes through the salt and pepper connections.

The SPOUT goes direct from the computer to the dizzy, I know that much. I have an older RJM harness and it looks like the harness has been rubbing on the back of the passenger side valve cover for the last 16 years. I'm pretty confident that the problem is right there. I need to get it reworked today because my son is bringing his over for a transmission R&R tomorrow and this one is blocking the lift. Dad isn't rolling under there on a creeper to pull a transmission. I will post pics of what I find before I close this thread out.

I have reused a stock harness before and those salt and pepper connectors are sometimes painful. I deleted them the last time I reworked a harness just for peace of mind.

 

[BanditBronco]

Nice Job! Seriously, in today's day in age most people would have pulled it all out along with their wallet and bought some shitty aftermarket efi kit by now. I commend that you had the balls to keep digging and find the real issue.

 

[Past_Miner]

I pulled the entire EFI harness and found that the whole bundle of wires along the back side of the intake manifold had gotten so hot that they all melted together. Most of the wires were okay but the insulation on all of them was fused together. It took two of us 2 hours to separate the wires and we found that any splice in the harness that had a factory heat shrink cover was bare wire. The heat had melted the heat shrink off. I also found a break in the shield around the SPOUT wire. There was continuity on the wire but I replaced it with a new one anyway.

It was 8 hours total to strip the harness, repair the bare sections and re wrap. There were three bare sections at splices. I wrapped the section behind the manifold with fire blanket before installing the harness wrap. Hopefully it will keep the heat out of those wires.

The truck starts easy and runs really well now. There was some sort of problem in the SPOUT wire. Interestingly, I still get the 18 code with the new wire but we timed the truck to 10* BTC and confirmed that the SPOUT circuit is managing timing. I don't know why it is still throwing the code but the computer is working properly.

 

[Past_Miner]

Nice Job! Seriously, in today's day in age most people would have pulled it all out along with their wallet and bought some shitty aftermarket efi kit by now. I commend that you had the balls to keep digging and find the real issue.

I have had so many problems helping friends with those aftermarket kits that I have sworn them off in all situations except where a factory setup is nonexistent (like a '36 Buick with 455 project that I have in the queue, that one might end up with a Sniper). I have found that it's the same headaches either way but at least I can get parts for the OEM setups at the local parts store.

 

[Past_Miner]

Well... The success was short lived. The engine ran flawlessly the first night after we got the timing set correctly. Now it has a random miss. It doesn't seem to be tied to acceleration or load changes, it is truly random.

Everything on it is new now, including the SPOUT wire. Anyone have any thoughts here?

 

[Broncobowsher]

Same computer? I didn't see that in the list of things swapped in my quick scroll.

 

[BanditBronco]

Well... The success was short lived. The engine ran flawlessly the first night after we got the timing set correctly. Now it has a random miss. It doesn't seem to be tied to acceleration or load changes, it is truly random.

Everything on it is new now, including the SPOUT wire. Anyone have any thoughts here?

Random as in, when it does it or what cylinder does it? Did it pull any new codes?

 

[Past_Miner]

Same computer? I didn't see that in the list of things swapped in my quick scroll.

Same computer. Thats one item I don't have a spare to swap out.

 

[Past_Miner]

Random as in, when it does it or what cylinder does it? Did it pull any new codes?

No new codes, still just the normal emission codes and the 18 for the SPOUT. Random when it does it but I don't know which cylinder. Maybe it's time to buy a monitor recorder to see which one(s) is/are failing.

I put new plug wires on. The only set I could find were from autozone and they seem very short compared to the others. Maybe they are just junk. I have had that happen before.