sabresfan

Drove my car on an 80 mile trip on Friday. It drove great until I got into town, then it started to stumble and hesitate at idle and acceleration.

Pulled codes. Once in a while I get code 18. I know which injector circuit is giving me trouble, but I tested it with a multimeter and both the injector and the clip tested fine at key on. I've been dealing with this for a while, but usually I'm able to maneuver the wires into a position where it functions fine. But now even with the injector functioning, its giving me trouble when I accelerate. It runs as though the injector isn't working, but when I run the software it doesn't show any codes.

I pulled a few spark plugs and both looked great. I'm thinking I should pull a few more from the side that the injector is giving me trouble. Also at idle there seems to be uneven exhaust pressure.

Right now I'm thinking I might have a backed up cat because it had a slight rattle a few weeks ago. I'm going to try pulling them off to inspect.

Or I'm thinking it could be the opti. I replaced it a few summers ago but I'm just getting a bad feeling about it. On friday I drove through heavy rain, and the top of it looks dirty from oil (from what I could see).

Last week I also used seafoam through the brake booster hose, and I poured a large bottle of injector cleaner into the tank. It drove great all last week and most of my trip but now its running poorly.

Any ideas?
Maybe spray the outside of the opti with WD-40 as best I can?

Injuneer

How do you know the PCM is providing the ground at the connector to fire the injector, by measuring with the key on? How did you measure the exhaust pressure? You can pull the O2 sensor and measure the pressure with a pressure gauge.

sabresfan

I don't have a noid light to test the ground at the connector. It's an odd issue because when I play with the wires when it's throwing a code, I can get it to go away and run smooth. It usually acts up when the engine is hot, so I'm thinking heat soak is one of my problems.

I don't have a pressure gauge to measure the exhaust pressure. It just seems a little inconsistent when I'm standing behind the car but it could just be a symptom of the stumble at idle.

I ran it up and down my street today and it seemed to run okay but the engine was cold. I pulled off my cats to inspect them and the honeycomb in both cats was completely gone and I'm 90% sure when I first installed them they weren't gutted. Is it possible the internals broke loose from the cats? And could that cause back pressure in my exhaust if they were clogged up somewhere?

Also, if my opti was bad would if run poorly all the time?? I'm thinking my issue may just be when the engine is hot in closed loop. I'm going to check for any arching when it gets dark later.

Injuneer

If you have a long term ongoing issue with a specific injector, it would seem that a complete check of the circuit would be a good idea. If jiggling the connector solves the problem, have you changed the pigtail? Since the pins on the injector could also be the cause, have you swapped injectors to see if the problem follows the injector? A few bucks for a set of 'noid lights would seem to be a good investment.

Are you comparing the "feel" of the exhaust from the left side of the muffler to the right side? It would appear you have a Y-pipe and a single cross-flow muffler. Any difference on exhaust flow left to right could be a result of the non-symmetrical layout (single in /dual out), or plugging due to accumulated catalyst substrate pieces. Or do you have a true-dual exhaust?

Cats can disintegrate when they overheat.

A "bad opti" would not necessarily make it run poorly all the time. The optical cam position sensor module is subject to heat soak, like any other electronic component. If you have oil entering the Opti, could be blinding the shutter wheel for the cam position sensor intermittently. Heat soak can adversely affect the ICM, the fuel pump or the PCM. But I don't think I've seen many, if any instances where the PCM was the culprit. But if you have a problem with a specific injector, it could be the injector driver in the PCM.

sabresfan

Ideally I would like to change the pigtail but my experience with wiring & soldering is slim to none. I do not have a soldering iron or any knowledge of how to splice a wire and solder 2 together. I think that I would only make it worse. The wiring harness in general makes me nervous because I wouldn't want to rip anything apart by accident, being 20 years old with brittle plastic connectors and my lack of wiring knowledge.

I wasn't comparing the feel from side to side because I don't have duals. It just seemed weak in general from what I've noticed when it's running better. If there were components of the cat clogged, how could I clear it? and could that cause the symptoms I'm describing?

Also, in the past I've noticed a bit of a stumble at idle. It would stumble and the battery voltage would drop and the lights would flicker if at night. During the colder months it was much worse at idle, and it got to the point where it stalled out a couple times. But upon acceleration it would even out and accelerate smooth.

I honestly don't think oil is seeping into the opti, but it's very hard to tell with its location. The engine bay is just dirty in general. Would it be worth it to spray WD-40 on it to clear any possible moisture?

Also, could the build up of ozone in the opti cause the electrical components to go bad because it is a '94? The opti was replaced last summer and has ran fine since.

sabresfan

Ok the problem is definitely when the car is warm. On a cold start it seems normal and seems to run ok from when I drove it earlier. Just now I let it warm up and drove it around the block and its stumbling like it has been. when you step on the gas it hesitates and stumbles with a bad vibration. At idle there's a bad vibration as well, like its missing.

To recap, it all started happening after an hour 80 mile drive of highway driving through heavy rain. It drove great until I got off the highway.

The opti, o2 sensor, plugs, & wires were all replaced last summer. The coil is newer as well and I used the washer method to space the ICM & coil bracket.

sabresfan

Update: Checked for arching tonight. I sprayed them with water and noticed a little arcing near the boots on a couple of the wires.

My current wires are MSD street fire wires. I know they aren't great, but I covered them with heat boots and they've been fine until now (or at least I thought). I could barely see the arcing with the heat boots on the wires but I noticed a little bit.

So I 100% need new wires, correct? And with new wires I should probably do plugs as well. The last time I replaced the plugs I ended up taking both headers off to finish the job.

I'm thinking OTVC wires.

Injuneer

Was it an actual "spark" that you saw? Or was it simply a high voltage "glow" (corona)?

sabresfan

That's a good question. I assumed it was arcing because it was intermittent and I could only see it on a few wires. It looked like an arc from wire to the head. From the symptoms I'm having, arcing spark plug wires makes sense. Stumble at idle every now and then.. driving through heavy rain made it worse.. And the main issue seems to be when the engine heats up, and the weather has been warming up significantly causing it to run hotter

sabresfan

I can really only see the "arcing" when I spray a mist on the boots. I tried again tonight and got the same result.

So I'm leaning towards the OTVC wires to start with. I'm tired of having ignition problems ever since installing headers, and too be honest I don't think the headers were worth it with all the trouble I've had

Question: When I intstall the wires with new heat sleeves, can I zip tie the end of the sleeve tight to the exposed part of the spark plug so the boot is completely protected? Good idea or no?

Also, would the arcing be causing the lights to flicker when there's a stumble at idle? Could a bad ground be causing issues? because I've had arcing issues in the past

sabresfan

quick update: I replaced the wires and that helped tremendously. It ran great until yesterday. Same thing happened, I drove it through a rain storm on an 80 mile trip and now I'm having similar trouble.

This time it's not running as bad but it seems to be all the time (not just warmed up). It's best characterized as a low RPM stumble and lacking power at the high end. I'm really starting to get sick of this car...

Injuneer

Distributor or plug wires got wet. Check for corrosion on the wire ends and Opti teminals.

sabresfan

I checked the wires but I didn't see any corrosion. I found one wire that was slightly loose, and another that was burned (but not burned through). I've finally had enough of the #5 wire burning so I routed a longer wire over the valve cover.

After correcting these 2 issues I drove it. It definitely seemed better but still a slight stumble. And it still seems to be the same problem when the engine is warm or cold. It's most noticeable at lower RPMs in second gear and also when you give it some gas while coasting. It vibrates more at idle but the rpms don't jump around.

I think it could still be a moisture issue & it might just need to fully dry out? Or possibly some carbon build-up on the spark plugs? It was weird because it randomly started after about 50 minutes of driving through rain. And when it did there was a noticeable gas odor.

Also there are no codes thrown, but would it be possible to look at the O2 sensor readings and decipher which side of the engine the problem is coming from? I'm going to try some lucas fuel system cleaner & look for any arcing tonight.

Injuneer

A misfire will cause the long term fuel trim on that bank of the engine to elevate above 128 (0%). That's where you would look in a data log.

sabresfan

I drove it more this evening . The stumbling is most noticeable between 2,000-3,000 rpms. It's not awful but it's still there. It evens out closer to WOT but lacking power.

I noticed some arcing tonight after looking under the hood in the dark It looks like the OTVC wires I was going to return are going on after all. I'm praying this takes care of my problems. That's the only thing I can think of at this point...