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Old 12-16-2002, 10:17 PM   #1
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Default Engine Misfire - safe to drive?

Hello,

Right now my engine is misfiring, though I'm at school and don't have the resources to fix it or have it fixed by anyone. I'm going home next week, which is 100 miles away. The car shakes a lot on the highway, so I figure I will keep everything slow until I can figure out what'* causing this miss. Thing is, I was wondering if it will be dangerously harmful to anything if I drive the 100 miles like this? The thing I'm most worried about is the catalytic convertor getting too hot (since there'* a whole cylinder or more not burning the fuel) or maybe the engine mounts breaking if it vibrates more than usual. I wish I could have it checked out, but I've no time (it'* final exams time!) and I don't know any shops around here. Any info would be greatly appreciated. Thanks a lot!

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Old 12-16-2002, 10:50 PM   #2
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Have you looked at the engine. Take a look and make sure the insulation to the injectors has not been burned through exposing bare wires. That could be a possiblity, but without more information from you it'* difficult to tell what is the problem.
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Old 12-17-2002, 06:52 PM   #3
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Thanks for the input, guys!

I've looked around under the hood, but not too extensively since school has been prohibiting the amount of time I get to spend with Bonnie. From what I can see of the forward-facing spark plugs, I don't see any insulation degradation, nor can I see any problems with the ends of the wires at the coils. I can't look any deeper because for the life of me I can't figure out how to get the freakin plastic cover off the engine. Can somebody please detail for me on how to get off the (rather superfluous) Series II engine cover?

But so far, the connector to the coils is in solid, and I can't see any insulation breakdown (at least as far as what is outwardly visible). About a month ago it would randomly start to miss once every say, 70 miles, and the Check Engine light would come on. This would occur whether it was under load or just sitting there idling. If in idling in drive, I could feel the whole car car "pulse" several times a second with the engine. On the highway, whenever it started to misfire, it would make the whole car shake violently, as if running over rumble strips. Just last week it starting misfiring all the time, and the Check Engine light is constantly on. Over Thanksgiving I brought it into a shop to read the codes, and they reported that it was a problem in the ignition circuit (they didn't tell me exactly what code).

Again, I'm 100 miles from home, so if there'* a simple, tool-free method to get it working well again (at least for another couple hundred miles), I'd be indebted to you guys. But so far, I'm just wondering if it'* safe to drive, say at 55mph for an hour at a time without wrecking the cat, the motor mounts, or something else important.

Thanks for all your help guys!

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Old 12-18-2002, 03:16 PM   #4
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I agree with Jr's3800. The most likely ignition parts involved in you problem would be one of more of the following: ECM, Coil pack, Plug Wires, or Spark Plugs. Even if everything looks good on the outside, it is no indication of the internal breakdown that may be occurring. For a "tools free" attempt at a repair, you are limited to the plug wires. Once you remove the engine cover and front plastic wire cover that runs along the front of your front valve cover (this lifts straight up but may require a little prying--up only--with a screw driver), all you need to do is twist and pull off one of the old wires (carefully so that you don't separate the wire from the boot) and replace it with a new one of equal length. Do them one at a time. This will eliminate much of the problem IF it is the wires/ plugs. If you haven't replaced the wires in a while--or don't know when they were last replaced, replace them now. Even if it doesn't fix the problem, they need to be replaced periodically anyway. When you get home, purchase some AC Delco platinum plugs and replace them. That is the second stage of the most common fix for these symptoms. I had similar problems so I replaced my plugs and wires. It totally cleared up the problem. Good luck and keep us informed.
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Old 12-20-2002, 02:23 AM   #5
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I have also had this problem with my series 1 engine the plugs didn't look bad as far as any burn marks but the miss m=got worse in the rain and while i had my hood up rain dripped down where the wire connects to the #1 wire and i heard and saw it arch. After changing the wire the miss was still present but not as bad. after doing all of the wires the next day the miss went away but i'm also thinking about changing my coil packs just to be safe.
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Old 12-20-2002, 03:47 PM   #6
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Default Re: Engine Misfire - safe to drive?

How many miles does your car have?
CHANGE YOUR SPARK PLUG WIRES! My 1997 Bonneville did the same thing, the routing of the wires are not the best in the world. You can actually see with the cover on the engine, how 2-3 wires practically touch each other. Anyhow, you should change your wires because chances are they need to be replaced anyways. II did and it stopped the problem. You can use fuel injection cleaner, cause your engine probably has some carbon buildup due to the running condition.
Dave

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Originally Posted by StoopidSavant
Hello,

Right now my engine is misfiring, though I'm at school and don't have the resources to fix it or have it fixed by anyone. I'm going home next week, which is 100 miles away. The car shakes a lot on the highway, so I figure I will keep everything slow until I can figure out what'* causing this miss. Thing is, I was wondering if it will be dangerously harmful to anything if I drive the 100 miles like this? The thing I'm most worried about is the catalytic convertor getting too hot (since there'* a whole cylinder or more not burning the fuel) or maybe the engine mounts breaking if it vibrates more than usual. I wish I could have it checked out, but I've no time (it'* final exams time!) and I don't know any shops around here. Any info would be greatly appreciated. Thanks a lot!

Stoopid
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Old 12-20-2002, 05:42 PM   #7
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Well so far, everybody seems to be pointing to the plug wires, so I think that'll be the next item on the repair list. The car currently has 126,000 miles on it, but I bought it a few months ago at 123,000 miles (I make no denials about being a poor, poor college student - but I absolutely had to have a Bonnie) , so I have no idea on any prior maintenance, so I suppose it would make sense to change the wires, plugs, and filters.

The last two tanks have had some fuel injector cleaner in them. I'm not sure if the stuff really ever makes any sort of difference (I'm fairly skeptical of any treatments in a bottle). So right now I'd like to change the spark plug wires and the fuel filter. Let'* say that I'm a technically-inclined novice (never worked under the hood, but I'm otherwise really good with machines) - would it be worth my time to attempt to change these items myself or should I just have a shop do them? I've read about the fuel filter process, and I'm not too keen on getting gasoline all over the place, but if the process of changing the wires is a decent weekend project, maybe I'll try to do that. Getting the wires off the spark plugs is obviously a no-brainer, but how do I get them off the coil packs? Are there any other issues with changing the wires that I should know about, and is there a recommended brand?

Thanks again to everybody for answering all my questions. I appreciate all the help that you've been offering me.
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Old 12-20-2002, 06:58 PM   #8
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Sometimes we take it forgranted that everyone knows how to do this stuff already. I apologize for this. I checked in the Techinfo section to see if this was already covered, and I didn't find it--so here goes...

1. Make sure the engine is cold so that you don't burn yourself.

2. Remove your engine cover--as described earlier.

3. The coils are located on the passenger side of the engin (left side of engine when standing in front of the car) and in front of your serpentine belt (the belt that runs the alternator, etc.)

4. Remove the first plug wire from one of the three coils (it doesn't matter which one) by first twisting, then pulling strait up. They are just pressed on at both the coil and plug ends. it should come off fairly easily.

5. Follow that wire (the one you just removed from the coil) to its respective spark plug. There are six plugs, three in the front (the easy ones) and three in the back of the engine (the harder ones). I would suggest doing the back ones first. You must work around the strut bar brace (the black bar that goes from one end of the engine compartment to the other--toward the back of the engine), but once you get your hand beyond that, you should be able to find the wire and cap. Twist and CAREFULLY pull the boot off of the wire--DO NOT PULL ON THE WIRE ITSELF as this will detach it from the boot. If need be, carefully use a pair of plyers to assist you.

6. Match the new wire'* length as much as possible to the old wire that you just removed.

7. Some wires may be covered in a wire loom (a black corregated plastic tube with a slit the entire length). Remove this loom from the old wire and carefully work the new wire into it.

8. With the conductive lubricant provided with your plugs, apply a liberal amount to the inside of both boots on the new wire.

9. Connect the new wire to the coil in the where you removed the old wire (make sure you match the boot of the new wire with the type of boot that was on the coil. The wires have two different boots--one on each end. One boot is for the coil, the other is for the spark plug.) Then rout the new wire in the same place or similar location over the engine and connect the wire to the spark plug

10. Proceed to the next wire and repeat the above proceedure.

11. Remember, DO ONE WIRE AT A TIME. If you take all the wires off before putting the new ones on, you may not remember the sequence and could cause firing order problems. In short your car won't run at all.

As far as wires go, any parts store will carry them. I would recommend Taylor 8mm (from Hector at ADTR) or Accell. But since you don't have time to wait for them to ship in, just go and get some cheap ones at a parts store to get you home.

12. When you get home, change the spark plugs--again, one at a time.

Good luck. If you get in a jam, remember that we are here for you. Just be careful not to break your old ones incase something goes wrong and you can't put the new ones on.
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Old 12-20-2002, 10:56 PM   #9
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Thanks for the writeup, 95Bonn! Very detailed and concise. Hopefully right after my exam tomorrow I can finally get out to her and see what'* up. One last question: is the computer intelligent enough to detect a misfire as a result of a short-circuit due to the wiring (or some other anomaly in the ignition system) and throw the SES light?
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Old 12-23-2002, 02:23 PM   #10
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Well I finally found the answer to my problem! I took everyone'* advice of looking at the spark plug wires (since that'* the only thing you can really do without tools at your disposal) and everything seemed to be fine, so in a way I was a little bummed that the answer wasn't obvious and that I'd have to dig further, but in a way, I'm glad it wasn't the wires since that means I don't have to spend the money to replace them (yet!).

The next thing I could think to do was just inspect each and every connector under the hood, starting with the fuel injector plugs. I pulled out and reinserted each one a few times in order to rub off any oxidation that may have occurred, and to reseat the connectors if they were working loose somehow. Fire up the engine and it purrs like a kitten! I'm so glad that I found the answer to the problem and that I don't have to spend $300 to fix it (like other shops recommended). Of course some more preventive maintenance stuff will be done to make sure something more catastrophic doesn't occur. Luckily, since it meant that an injector wasn't firing, that means the catalytic convertor should be fine since there was no excess fuel being squirted in the first place.

I just wanted to thank everybody again for their quick, enthusiastic, and helpful replies, and cheers to one of the best online automotive communities out there!

Cheers,
Stoopid
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