308 QV Misfire

Hey folks... not sure what is really going on, but thought I could ask for some advice on what to check. So I washed my 83 308 QV in the same manner I have all other times. I cover the engine with a very thick towel and make sure all electronic components are covered by the towel. I also do my very best to not "drench" the engine cover, but of course the towel is wet when I remove it. But I didn't notice any "standing water" or anything like that.

Now here's the strange part... the car fired up and drove fine. I took it on a long (10 mile) drive after I washed it to make sure it was dried out. Then I parked her and admired her new fresh coat of wax. Then, 2 days later, I took it for a quick spin to the local store and noticed it was not running normally. When I start out and accelerate normally, it is very sluggish and almost sounds like it is mis firing or something. It almost feels like a rev limiter feeling (skipping a beat or two) and sounds sick (low rumbling) until I get the RPMs above ~2K. Then the engine sounds smooth and normal and she pulls as normal. Then shift into the next gear, and the same thing. Rather sick sounding, missing and sputtering until higher RPMs are reached. Then again, same thing in 3rd and 4th and 5th gear.

This was a rather frustrating week. I was driving it back home not far from the house and was accelerating and slowing and accelertating and slowing trying to see what I could hear and feel. While doing this, I was going 44MPH in a 30MPH zone... and yep, got a damn speeding ticket! All of this 2 days after I just put my dog down after 13 years.... He will be missed....

Okay, tears wiped and back to the car. Any ideas on what to look for? Could there have been moisture hiding in there all this time (3 days)? Or does it sound like there is an electrical component failing? What should I check first? I'm hesitant to remove the distributor caps to see if they were wet as I know how expensive they are and how the gasket is not very easy to replace. Why would it run sluggish for the first few 100 RPMs or so and then "smoothen" out after higher RPMs? No warning lights, funny smells or other noticeable things to mention.

Your help is appreciated!
Thanks,
GT

 

Thanks Tcat... mine didn't get any better after it warmed up. I will check it out again tomorrow to see if it's still there. I'm reluctant to drive it however until I figure this out. Good luck!

 

Thanks everyone. I'll take a close look tomorrow. It is just odd to me that it ran fine for the first day moments after the wash, and then acted up 3 days later on the 2nd drive. Maybe has nothing to do with the wash?

I cover it to keep it clean since I have hard water where I live and if I let the engine get wet, it leaves a tough mess to get off. I have had no issues in the past. Maybe it's not related to the wash. I'll check it tomorrow.

Thanks!

 

well, I didn't get the chance today to look at all connections for moisture. I did drive it again and it's still the same. It is sort of bogging until higher RPM still. While poking around I didn't see anything visually wrong with the plug wires and they are fairly new (less than 2 years old) and the rubber caps are firmly seated on the plug holes. Tomorrow I hope to take them off one by one to examine for moisture, but it's doubtful. I removed the rear bank (2,4,6,8) distributor cover and I see no moisture in the cover. I did not pull the distributor as there are other things to check first. I didn't get the time yet to pull the front bank cover.

I did notice that the bracket that holds the two ignition coils to the side of the engine compartment seems very loose to the touch. I'm assuming that bracket should be tight so the coils and connections don't "bounce around" while driving. I will tighten that down tonight, but I think I will pull it first to be sure that all of the small wires below it are connected and clean.

I also visually inspected the two plugs to the control unit that are mounted below coolant expansion tank and toward the front of the car, and I don't see anything out of the norm. But again, I will disconnect them and visually inspect for moisture and spray with electrical cleaner.

I guess I'm still concerned that it has nothing to do with the wash since the car was fine for the drive right after the wash. Is it really possible that moisture "worked it's way" to a point to cause this "misfire" 3 days after the wash? The first drive was fine. Also, I washed the car over a week ago. If moisture got to a trouble point 3 days after the wash, I would assume it would also have time to dry out by now? Anyway, I will take the advice above and run through the checks.

Can someone tell me the procedure for measuring the resistance to the plug wires and extenders? Is it as simple as disconnecting both ends of the wire and putting a multimeter across the ends and measuring the resistance? What should they measure?

Also, the plugs are new (less than a year) and the air filter is dry (no water from the wash). The fuel filter was replaced two years ago, and that seems doubtful to me that it would cause the issue.

 

Checked plug wires and extenders today. They seemed fine. I did see a very small amount of "brown" looking residue on 3 of the 8 extenders on the inside. But very little amount and nothing that seemed very bad at all. I also cleaned the plug connectors to the ECU. Still have the misfire or "bogging" under load. The car idles perfectly fine. Only when under initial acceleration and load does it bogg down and then the engine seems to "clean" up and pull strong. I'm still at a loss. It's been over 1 week since I washed it. I really don't think anything is wet.

 

So I did find burns and some small brown and black marks on 3 of my extenders. I replaced them, still the same misfire. I am having a very difficult time finding the problem with this misfire.

I cleaned all electrical connections that were visable. I cleaned with electrical contact cleaner the crank sensors, but only from the outside. I did not remove them, as I didn't have the time just yet to jack the car and get under there to remove them.

I found the double red wire that is screwed to the top of my positive battery cable to be loose. I took it off and cleaned the contact to a nice shiny copper. Replaced and tightened the cables after I charged the batter (1 year old red top) to a full charge. I was hoping that maybe the loose connetion was the culprit, but nope... Still misfire on accelleration. What is that double red wire for anyway? Where does it go?

So far, i have changed the plugs (the ones I removed were less than a year old and looked perfectly fine). Replaced all 8 connectors. Charged battery fully and checked vacuum lines and cleaned electrical connectors in the engine bay as best i could.

Question; I have been reading about the relay with the 10A fuse on the top that should be located under the antenna in the boot compartment. I peeled back my carpet about 1/3 of the way and I do not see a door with bolts to access this relay. Do all of the 308 QV cars have a frequency valve and this relay? Where is the frequency valve? I have read it should buzz when the engine is running if the relay is working correctly. I could listen to it with my stethoscope to see if it's buzzing, but I'm not sure where it is located on the engine.

I am having a tough time believing that my problem might be caused by my dizzy caps or wires for two reasons. One, maybe not such a valid reason, is that the misfire started instantly. It's not something I noticed building up over time, and then one day, bam - misfire. Two, I checked each plug wire while the engine is running with a timing light. Just about every one is misfiring inermittantly. I can't image all wires going bad all at once! And I can't imagine both dizzy caps going bad on the same day either??

Is there anyone out there that has an extra set of digiplex boxes that I could install to see if the problem goes away? I would love to test first before throwing money at them and not have it fix the problem.

Thus, I am thinking it might be the frequency valve relay or the actual digiplex units?? Frustrated in Texas!

Thanks to all of you that have been helping me with this problem. I truly appreciate it!

 

that should read that I replaced all 8 extenders, not connectors.

 

thanks for the photo! It would appear that my car does not have a frequency valve. Maybe the lambda system was removed when the PO removed the smog stuff and airpump. But I don't see that valve or wiring harness/connector near the fuel regulator.

 

Okay, no frequency valve! One item down!

Question. I just pulled on of the distributor caps (front - tailight side of engine) and it appears to be in very good condition, but maybe I'm wrong? Here is a photo. Any opinions? The center carbon button looks very good. I can see a small amount of build up on the contact on the rotor. I'm thinking of lightly sanding it smooth.

Question; I want to measure the wire resistance. I went to remove the coil wire from the "nipple" on the coil and it's rather hard to get out. Do I pull hard and down on the wire or is there a screw through it somewhere like the ends to the plug wires that are screwed into the cap? I don't see anything that is "locking" the coil wire into the nipple. Am I missing something or do i just need to pull it down hard? If so, is it difficult to get back into the nipple on the coil? I don't want to break it just to measure the resistance....

Thanks everyone!
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Well, I finally narrowed the problem down and decided to pull the caps and wires to clean/test as you can see from my previous posting. I was actually bummed out that I didn't find the problem with one of the caps. So today I continued to pull the rear bank cap and wires and looky here!!

This has to be the culprit, obviously! Now, do I buy one wire or a set? They are not cheap and the remaining wires all test fine. What do you guys think? What is a good source for one wire? I have seen sets of 4 + coil wire, but they are quite expensive as you all know.

Any suggested sources is appreciated!

Thanks to all!

1. replaced plugs
2. replaced extenders (3 were bad) - did not fix problem
3. checked/clean all connections and vacuum lines - no problems found
4. pulled caps and rotors and all seemed fine.
5. checked front bank wires and all measured AOK.
6. Pulled front cap and wires and here is what I found!

I'm assuming this is the culprit. Hopefully there is nothing else wrong.
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And yes, I'm embarrased it was this simple... I looked at the wires while on the car and they appeared to be fine. Then I finally decided to tackle the caps and rotors and test the wires. lesson learned - stick with the simple stuff first. "Keep it simple stupid" comes to mind!