I'd say a coil went out as well. They are just 20 years old... time to go COPs

 

i just bought a 1996 this morning and im having similar problem.. mine is stock tho....heres a video of mine from 15 min ago.

i thought it would be just the spark plugs and wires so i changed those out and its still doing the same thing =(

 

^ not the same problem as mine

 

OK guys,

I replaced the coil pack and the spark plug wires with ones from a running car. Very little to no change in how it ran. At this same time I put in new spark plugs. Here is how they looked after ~ 1 minute of running (using throttle to keep it running):



Then I took a spare set of NB tan top injectors that I had laying around and put those in. After changing REQ_FUEL appropriately, it started up and after some burbling, it began to hold a steady idle.

It would hold the idle with a decent AFR. When I used the throttle to hold it at 2k rpms, it would hold there pretty well but would have occasional stumbles accompanied by full lean spike on the AFR gauge.
"Trying to hold 2.5k on NB injectors" is the datalog of attempting to hold 2.5k rpms with steady throttle, and shows the stumbles.

BUT, idle was looking really good - smooth with no stumbles and holding a nice AFR. So, I then logged the idle. It started off good, but after a little while it began to have spurts of stumbling - again associated with full lean spikes - until finally it would barely run and read full lean on the gauge. This was all with no input from me. "Idling on NB injectors" is the datalog of that

Here are the plugs after these two datalogs. Keep in mind, these are new plugs as of today with maybe 10 minutes on them total:



Close-ups of 1 and 4 which don't look right:





WTF is going on? Help me out here guys

 

I've never found datalogs to be terribly helpful with these types of problems. Spark and fuel is working great according to MS, it can't tell when there's issues with the igniter, coil, wire, plug, injector, fuel rail, fuel pump, FPR, fuel filter, etc.

I'd say 1&4 look good, 2&3 are the ones that concern me, especially in that first picture, as they look completely unused.

Take all four plugs out, and all clip them into the wires, lay them all on the valve cover and crank it, ideally with the fuel pump disconnected somehow. This trick easily helped my head wrap around my spark issues. I think you'll find a couple of them firing half the time or not at all. Or it could all be fuel related. What's grouped as 1&4 and 2&3, fuel or spark? I forget.

Did you try the working FPR? Or another igniter?

 

Thanks for the suggestions Curly.

To recap, this is what's been replaced to date:

- FPR (from working donor)
- Fuel pump (Walbro 255 - new)
- Injectors (NB - used - working)
- Spark Plugs (new)
- Spark Plug Wires (from working donor)
- Coil Pack (from working donor)

The ignitor is part of the assembly with the coils and the big metal bracket right? I swapped that whole assembly that's attached to the metal bracket that bolts to the VC, so it is now using a known-to-be-good ignitor and coil...

I will go out and do the spark plug on top of the VC visual test right now... I see what you mean about it looking like 2 & 3 are not being used... looks like they are firing but not getting fuel... if I'm thinking straight..?

I'll report back in a few.

 

Hmm, some later models might have igniters built into the coil packs, but you should have one of these:


Just double checked, coils are 1&4 and 2&3, so I'd predict a spark issue, not fuel.

 

1&4 are on the same coil, 2&3 on the other. Not sure about the 1.6L coils.

But he replaced the coilpack, so its probably not that. I don't know, I would think fuel, if there was fuel going in and no spark you would still get some kind of muck on the threads? Those two cylinders look awfully lean on the plugs.

 

Hence my thinking that it's the igniter. I'd expect that before the MS at least, if it's worked fine this long.

 

well, what seems to be for sure is its intermittent, because those plugs fired at some point.

Lets see what he gets with the spark plug test. btw I know on the NB stock ecu, you can floor the throttle when you crank it and it will cut fuel. though not sure about how that works with the MS?

 

I just unplugged the wiring connector that sits on top of the fuel pump, and that worked to to keep it from flowing fuel.

Here's the spark plug test:



The first couple times I did it, it might have been the angle at which I was looking at them from, but sometimes it looked like some were firing more often than others, but on this last one when I looked at them more from the top, where the necks couldn't block my view of the gap, it looks like they are all firing OK...

BUT like I said, I got it to idle OK for a little while earlier, during which obviously all 4 must have been firing alright, and then it got progressively worse...

I didn't know the ignitor was separate from the coils on the 1.6 I do indeed have that little box in that pic, so that is something I will need to pull from a working car and swap over, then see what happens.

It SEEMS like changes to the fuel system make tangible changes to the problem, while none of the changes to the ignition have made a difference. At the beginning when I got it home, it wouldn't start - then after the fuel pump it started but was lopey and acted like it was on 2 cylinders. Changing the FPR got it to run a little smoother on start up but then it quickly became crappy again. Changing the fuel injectors had the biggest improvement yet, it would actually idle smoothly and only stumble when I tried to increase RPMs, but within a matter of minutes it deteriorated back to the point where it read full lean on the AFRs and loped/stumbled like it was on 2 cylinders and barely ran.

I'm going to replace the fuel filter and report back... it just seems weird that it looks like certain cylinders are getting more fuel than others, even after switching injectors...

 

Scratch fuel filter off the list of possibilities. Just replaced it. Won't even hold idle.

Next stop swapping the ignitor with a known-to-work one if I can get ahold of my buddy...

 

Could have called that, you don't loose random cylinders with fuel issues, you loose all or nothing unless it's a injector mechanical/electrical issue.

 

From the burnt tip on the plugs, it seems like you are getting spark.

With it being 2&3 I would pull the cas, but keep it plugged in, and unplug the fuel pump relay under the dash. Then manually spin the cas and see if all of the injectors are clicking or if it is just 1&4. If it is just 1&4, then the problem is either the CAS or wiring going to the injectors.

 

I've seen a bad CAS drop cylinders 2 and 4 before.

 

So you're suggesting to leave the plugs on the VC, where I can see if they fire, make sure the fuel pump is disconnected, unbolt the CAS and hold it in my hand, turn the key to ON, then spin the CAS by hand and watch the plugs to see if they all fire or not?

Just want to be clear, because I don't want to F something up.

If that looks right, let me know and I'll try it tomorrow.

Also to-do tomorrow: swap over a good ignitor, and try to find an in-line fuel pressure gauge just to verify things.

-Ryan

 

With this you are trying the see if all the injectors are working as they should. If all of the injectors are making the clicking sound, then they are getting the correct signal. You may need to get a mechanics stethoscope if you can't make out which one is clicking.

 

ahhh injectors not plugs gotcha
will try today

I just switched to Tuner Studio. When the car is running, the "Fidle/Spark" box is constantly flashing on/off the whole time. Is that normal?

 

If it is a 1.6, injectors 1+3 and 2+4 are paired.
If you blew something in your ECU 2 injectors aren't working.
Now if the engine is running and the spark-plugs aren't getting wet on the cilinders that indicate lean, you have a fueling problem. I don't know why you are looking for a spark problem as 1+4 and 2+3 are paired. If you doubt the "direction" of the spark would matter, just invert the spark leads (keeping them on the same coil, but other output).
Just swap the injector connector from 3 and 4 and see if you can move the problem to another cilinder.

 

Exactly, because it appears that 2+3 are clean, meaning they're not sparking. Yet I agree with you, they're also not wet, indicating they're not getting fuel. That's most likely from the limited run time they had.

Try the new igniter? It's looking less and less likely, but it's an easy thing to swap out.