Engine won't reach 2000 RPMs under load

Yeah, I'm going to look at the plugs now, at least. The distributor is pretty new, although I'm mostly hoping it isn't that's because of how hard it is to access.

I did discover that I forgot to reconnect the idle air motor, which probably explains why I had so much trouble starting it yesterday.

Once I plugged that back in, I started the car, put it in reverse, and revved it while holding down the brake pedal. -- maxed at 1500 RPM and was clearly missing (by the sound of the engine). Not that I expected the idle motor to affect the car when it's not at idle.

I guess there's no easy way to tell which cylinder is missing, is there?

Thanks again

-- Joe

Pull the plug wires one at a time while listening to the engine. If you get to one that doesn't change anything, that's probably it.
(probably #4 or #5 ;-) Sometimes a high idle will help you hear the difference.

Here's a picture of the injectors as pulled from the engine. From left to right: 3, 2, 1, 6, 5, 4:

Attachment 20723Attachment 20724Attachment 20725Attachment 20726

The last picture shows just 6, 5 and 4. It's hard to see, but as Ron predicted, 4 and 5 are the worst. :). The debris around the top of 5 seems to be a crushed leaf; apparently I let one get in there when I installed these last year.

The ceramic looks good on all of the plugs.

Is there anything I should do to clean them, or should I replace any? Some are blackened, but I don't know if that means that they're bad or just wearing.

Thanks!

-- Joe

Here's some hopefully better close ups of the injectors. First is 3, 2, 1, then 6, 5, 4.

Attachment 20727
Attachment 20728

Odd how smoothly they transition from grey to black-ish in the order I happened to pull them from the engine.

-- Joe

Based on some YouTube videos, I cleaned the plugs with a wire brush and sand paper and put them back in the engine. I did not put them back in the same ports -- I basically swapped the left and right sides, so that the dirtiest injectors were the easiest to reach.

Fired the car up -- same problem.

I tried pulling some plugs wires while the car was idling, but there was nothing conclusive -- the engine firing always seemed to change a bit. I didn't try all of them, as I think I'm already pressing my luck with doing work in the parking lot, and it's harder to ignore with a loud engine running.

I'm not quite sure what to test next.

-- Joe

You probably should of replaced them (Go BOSCH)...you never know if one is beyond cleaning AND looking at new plugs after a short run can tell you A LOT.

You could of tried a poor mans test by connecting them to the coil wire and looking for a nice hot spark after cleaning them....

To answer previous question, the black is not age, it is unburnt fuel/oil (running rich).

Put some gas in it LOL

The good news is that the car is running JUST well enough that if I can get it towed to the garage, I should be able to back it up the short driveway's incline, at least up to the lip at the edge of the garage. If it won't roll over that, I can just jack it up and put some boards under the wheels to get them above the lip. I should have a lot more freedom to take things apart and do other tests once I'm in the garage.

I'll get it towed down there tomorrow, and see about getting it running properly on Saturday or Sunday. At the very least I hope to narrow down which cylinder isn't working properly. I'll get some gas, too. :) And new plugs.

Although if anyone has simple things to try in the parking lot, I'm willing to give them a go.

Thanks again!

-- Joe

Wait until dark, slide the rubber boots up the spark plug wire (if you can, else you'll need a jumper wire), run the car at higher rpm and look down the spark plug wells to see if any sparking is going on. If so, you've found your problem - micro cracks in insulator arcing to the well wall. A failing coil can have these symptoms too. Do you have access to a spare?

Of course it started raining, but I'll do that test in the garage, which is not only dark but has no electricity (or water, or bathroom -- it's a pretty basic garage, but makes up for it by having two autoparts stores and some fast food a few hundred feet away).

I don't know how normal this is, but when I was pulling the #6 and #5 plugs off with the engine running, I got tiny zaps when the wire got too close to the intake manifold. It's not clear to me if the wire should be insulated enough that that shouldn't happen, or if these are high enough voltage that this is normal. I didn't notice any sparks, but it was bright out and I didn't look too closely.

I don't have access to a spare coil, but plugs and coil aren't too expensive, and I imagine a new coil won't be hard to find locally.

Thanks!

-- Joe

I managed to get the car to the garage today. I just went out early enough in the morning that I wouldn't have to worry about holding too many people up. While I went a bit slow up hills, I made it without incident -- I was even able to drive it into the garage, over the 3" lip (I measured, and attached a picture).

During the trip, if I put the pedal down to the floor the car would clearly miss and it there would be popping sounds coming from the exhaust. Google tells me this popping is unburned gas detonating in the exhaust. When I took my foot off the gas a little the RPMs would go up slightly (say, from 2000 to 2100 or 2200) and the popping would go away.

I attempted to find which cylinder wasn't working, but I couldn't figure it out by pulling spark plug wires while the car was running, or by using a multimeter with a tach feature (the RPM went up when I removed the wire, according to the tach -- I'm guessing it didn't know how to read it properly). I replaced all six plugs (they're cheap, so why not) and the coil (as the old Bosch was reading a bit low on the ohm meter). This had no effect. Since I replaced the plugs, I didn't so Owen's test to see if the plug ceramic was cracked.

The way I'm testing it is putting the car in drive, holding down the brake and revving the engine. RPMs max at 1500 and the engine makes the "missing" sound. I'll be happy to record the sound if it would help anyone with diagnosing the problem.

I'm not sure what to test next. I'm thinking if replacing the remaining injectors, if I though that would help.

Attachment 20781
Attachment 20782

I tries to take some pictures of the distributor cap so that I could avoid removing it, but that failed. I gather I need to take it off to inspect it?

Any other thoughts about what I should test?

Thanks!

-- Joe