Hello

My car started stuttering a few weeks ago. It was irregular. I was able to drive to work in the morning with a fine running engine. In the evening I'd start my motor and it would stutter like it didn't run on all cylinders. It also doesn't have power when I accelerate. Then I drive for about 10 miles, fill up gas or just turn off the motor for a minute or so and when I restart the car, it won't stutter anymore. Sometimes it works like this, sometimes it goes on stuttering. But the problem has gotten worse now. It started on an irregular basis. Do you think it's the spark plugs? I've never changed them. I bought the car with 130'000 km and am now just over 250'000 km. But if they put platinum plugs in, they might be okay even at over 100'000 km on them.

I also consider the ignition coil, plug wires or rotor. What brand of ignition coil do you recommend? RA has AC Delco, Airtex/Wells, Standard, United Motor Products and Delphi.

Thanks for your help.

Thomas

 

Is the car carburated or TPI?

 

It's a TBI.

 

OK then, my money is on one or more bad injectors, they are basically leaking down into the cylinder after you shut down the engine causing a really rich condition or even temporarily fouling the plugs.

 

I don't get what you mean. The stuttering engine is an intermittend problem. Sometimes it's stuttering, sometimes not. I drive to work in the morning - no stuttering / stuttering. I drive home in the evening - stuttering / no stuttering. Or while I'm on my way home I stop to fill up gas and shut down the engine. Before I stopped it was stuttering, after that it isn't stuttering anymore. For example. But it's not always... not always when I shut the engine down for some minutes, the stuttering goes away. So I'm not sure what you mean by the leaking injectors. Shouldn't it be the other way round? When I shut down the engine and then restart it, the stuttering would be there? And it's also not like when it's stuttering, it will stop somewhere down the road. It's more like I wait until next morning, then it's not stuttering. But it's gotten worse... so more stuttering than not stuttering in the last few days.

 

Ok, I just saw that you said TBI and not TPI, it could still be a bad injector, but more than likely a spark issue.What do the plug wires, cap and rotor look like? Pull the spark plugs and see if any particular cylinder looks like it's not firing as it should to pin point which cylinder is misfiring, then double check the ignition system to that cylinder. Me personally, I would do a complete tune up, the plugs are a big enough pain, that you may as well change them out while you are in there.

 

I'm a bit afraid of doing the plugs because they're so old. The shop guy once told me, with such old plugs in the worst case they might break in a way that a part is falling inside the engine, that's why I'm hesitating.

I replaced the rotor cap about 6 years ago, didn't replace the rotor though. I was just thinking... why does the stuttering come intermittently? How could it be the plugs? The plug wires are also quite old but they have been replaced sometime (they're not the Delco ones), but that was I don't know how long ago. I've driven the car for almost 15 years now and haven't replaced anything but the rotor cap from the ignition system.

Another problem I've had for some months... I have a very high idle. Checked the vacuum lines but it doesn't seem there's a problem. I think it's the intake manifold leaking air. I can also see cooling fluid showing around the edge, so I think it's getting worse. Could it also be the injectors which make for a high idle? It's around 1600-1800 RPMs. Don't know if all this could have something to do with my stuttering problem as well.

 

Ok, now were're getting somewhere, a leaking intake can cause all the problems you are having. Replace the intake gaskets first, then do a complete tune up on the ignition system; rest assured that you can not break a spark plug in a manner in which it will leave pieces in the cylinder simply by removing and installing it.

 

Ok.

But can you explain what the leaking intake does? Actually it sucks air... too much air. But this has resulted in a high idle (if that's the cause for the high idle). So more air (more leaking) should mean an even higher idle / speed. The stuttering however feels more like less speed / hesitating in power. How does this go together?

 

The leaking intake can cause a high idle by allowing unmetered air into the intake charge, which will cause a lean condition. As the leaky intake gaskets get worse, they allow antifreeze to leak into the intake, which will be drawn into the cylinders as well, causing the intermittent miss you described. The leaky intake gaskets can also allow the antifreeze to leak into the engine crank case, which will dilute your engine oil and reduce it's ability to lubricate the engine; if this is happening, your engine oil will have a milky appearance.

 

Okay, thanks for this explanation. I don't know if I can do the intake manifold myself. Especially because of the difficult part of putting back the distributor and lining it up with the oil pump.

What I wonder is, if there is a leakage... why do the symptoms come only intermittently and not regularly? At least the high idle is always but not the stuttering. I mean... does the leaking situation change all the time?

 

Heat expansion between the intake and iron block occur at a different rate, causing the leak to be worse at certain times than it is at others. One thing for sure is it's time to fix it or risk hurting the engine.