No Start aftering replacing Dist Cap and Rotor
 

Just replaced the distributor cap and rotor on my 84 Carrera. Now when I turn the engine over it does not fire. All I get is a few coughs but not near enough to start. So, I screwed some thing up.

Here is what I've checked:

I checked and double-checked the correct spark plug wires were on the correct spot on the cap. Both by they way they originally were on the car and by matching the cylinder number on the top of the cap to the actual cylinder.

I also double-checked to make sure all the spark plug wires were fully seated on both the distributor end and spark plug end.

I made sure the new rotor was installed in the same position as the old one.

I made sure the cap was installed in the same position as the old one.

Here are a few things that don't seem right:

The first time I installed the cap I had to push the retaining screws very hard so the cap was VERY snug. When I removed the cap it looked like the rotor was rubbing on the inside top of the dist cap. I think the rotation of the distributor cap was off slightly when I put it on the first time and not seated properly. I was more careful to re-install the cap and check it so I think it is on correctly now. Not sure if I damaged the rotor or the cap so that it will not start.

I had to pull on the spark plug wires extremely hard to get the wires off the top of the cap. I may have screwed up the wires by pulling on them too hard.

When I checked the spark plug wires on the spark plug side, I could wiggle them back and forth when holding them at the point of the wire were you grab it to push it onto the spark plug. Is this normal?

What is the best way to keep diagnosing this problem? I think it might be to check to see if I am getting spark. What is the easiest way to check to see if I am getting spark in each plug? Or getting juice from the coil? Thanks.

To check for spark, pull a plug out, stick it in the end of the wire, and hold the side against a conductive surface and watch for spark as a buddy cranks the engine. You should be able to see a spark. Did you double check to make sure it is the right rotor? Is it making contact with the cap correctly? You said it was rubbing on the inside top of the cap- where was it rubbing at, it is supposed to touch the small spring-loaded piece in the top center. Is there any chance you knocked your points out of wack when you were doing the install?
It is pretty normal to have to give a good tug on the wires to get the off the cap, and the plug ends do wiggle a bit even when they are on (at least they do on mine).


EDIT- You may want to wear some gloves while checking for spark! (ask me how I know!)

Assuming the car ran with the old parts you are at the point I'd back up and put the old ones on to see what happens. Especially since you've raised some questions about fit. Ken

It sounds like something got screwed up with the cap sitting in the wrong position. There is a cut-out on the edge of the distributor body which mates with the cap. Look closely at the inside center of the cap and check the spring-loaded black contact which is supposed to ride on top of the rotor when the cap is in the right position. Re-check the wires for the correct firing order with the cap in the right position!
You can use dielectric grease, or Vaseline, to make it easier to fit the ignition wires. Make sure that the Beru connectors sit on the spark plug correctly; they kind of "snap" on.

I just checked and I am getting spark from each wire using the technique Slater suggessted. It is a nice blue spark. I assume this means the coil, distribtor cap, rotor and wires seem to be connected OK.

Slater: The rubbing on the inside of the cap was in the center. The red plastic part surrounding the lead from the coil was rubbing on top of the center of the rotor. The top of the outer edge of the rotor was also rubbing on the top of the inside of the dist cap.

Gunter: I found the cut out and made sure it was positioned properly.

Tigerrat: That is a good idea I'll try unless some one else has another suggestion since I verified I am getting spark.

I am still not too comfortable with the plug wires. They do not seem to seat well. They are red Nology wires which the PO installed. I have no idea how old they are. Are those wires any good? They don't seem to have a god reputation on this board. I May just replace them with Clewetts.

Thanks.

Well at least I have it running now. But is is running very rough. I think one of the cylinders is not firing. I think I may have installed the rotor 180 degrees off which is why it was probally rubbing.

You're still not getting the firing order right. Check it again.

All it takes is having one wire swapped and you end up with two plugs missfiring!

I've done that too many times to know how easy it is to do.

-Joe

1-6-2-4-3-5.
Cap fits correctly one way only. Same with rotor.

You may have the wires right on the cap but may have lost track of one as they go over to the right side of the engine behind the fan.

That's where I have been known to get it wrong.

If it turns out to be that the wires are on wrong, there are tiny numbers on the bosch cap that tell you which wire goes where.

Next time you might label the wires as they come off. Or you can sort of leave the wires on the old cap (remove the heater blower intake duct first) move the old cap out of the way a tad, shove on the new cap and then one by one replace the wires from the old cap to the new. And to get the wires off you should twist them a bit and then pull straight out (which ain't so easy) and don't wiggle them around.

Some people even take a picture first so they don't screw up. I don't know what kinda dork needs to do that though.
http://forums.pelicanparts.com/uploa...1105261891.jpg

Ausgezeichnet: From what you describe, the rotor may have been put on wrong; it has to sit deep in the cut-out of the distributor shaft. There is a "nose" inside the rotor which fits into the cut-out. Follow each wire from cap to plug, going with the distr.-rotation and firing order. I found that sometimes, when the plug connector does not sit correctly on the plug, the spark will go to ground instead of going through the plug. Maybe your new cap/rotor got damaged when it was put on wrong?

Thanks guys. It turns out I did not have the plug wires making a good connection on the spark plugs.

I really had to play with them to get them seated properly. Is it typical to need to make several attempts to get the spark plug wire seated properly? I was able to feel the tip of the plug to make sure it was not loose and all the spark plugs seemed snug.

I also reconnected the green wire to the part below that had been knocked off. Any one know what it is?

http://forums.pelicanparts.com/uploa...1105303810.jpg

Oil pressure sending unit

Well, good, you found it!

That wire is for the oil pressure sender. There are two units for oil pressure: One is in the back on top of the engine to activate the oil warning light in the dash, the one in your picture is the sender showing the actual pressure.
Underneath the oil pressure sender in your picture is the oil temperature sender. SmileWavy

It's running pretty good now except for acellerating in the 1400 - 2000 RPM range. The whole back of the car shakes like it is only firing on 5 cylnders. Above 2000 it runs fine. Below 1400 including Idle it runs fine. Runs this way hot or cold no difference. Any thoughts on what might be causing this?

You might still have a plug connector that was not fully seated on the spark plug and has slipped off. Or one of your plugs may have gone bad when it wasn't firing when you found a loose plug connector.

-Joe

You need to find out which cylinder is miss firing.

Could be a bad wire, bad plugs, bad injector or the valves for that cylinder may be too tight.

It sounds like one cyl is still not firing. If you have courage, and be REAL careful, you can pull off each ignition wire with the engine idling and the one that is not firing will show up. But, the Voltage on these things is real high! You would have to wear insulated rubber gloves and don't stand in a puddle! Stand on dry plywood. Also, if you have AC, don't get caught in the AC belt when you get zapped! Also, sometime after dark, open the lid and you might see where the spark is jumping from the wire to ground. Cheers.

Thanks for the feedback. Would any of your suggestion explain why the problem only occurs in a limited RPM range?

I noticed another symptom today. I took it out for spin and all of a sudden the engine died while I was stopped at a street light. All the warning lights came on just like when you turn the key before cranking it over. When I tried to start it again I got the same results as when I had the rotor in backwards, the engine just cranked with out firing. I finally got it started after about 10 minutes. It died the same way a few more times (while idling).

This is a puzzling one. Since I may have damaged the rotor, I am going to replace it. Next I will replace the spark plugs (don't know how old the current ones are), then I will replace the spark plug wires. Hopefully one of those actions will take care of it. We will see.....

You may also have a bad connector; these connectors have a small resistance (1 Ohm?) and it shows up more at low RPMS. Before you take out the plugs, blow out the holes with compressed air to prevent any dirt from falling into the cylinders. Most people go with copper plugs, not platinum. If the ignition wires are old, replace them. New rotor is good but the cap may also be damaged; look closely at the sprig-loaded center which rides on the rotor.

Did the car run okay before you changed anything? If yes, then something you did or changed is the culprit. If this is the case, changing plugs and wires are not what's wrong.

There should be some pelicanites in your area that could lend a hand. Are you able to drive the car?

The car ran fine before I started changing things. The car is driveable, just a little shaky between 1400 and 2000 RPM.

I tried swapping in my old rotor last night and still had the shaking. I wont' be able to rule out the rotor completely until I get a brand new one next week.

In re-reading Gunter's advice it seems to me I remember seeing a blue spark around the spark plug wire of the #2 cylinder. I also seem to remember hearing an electrical spark when I was moving the wires on that side of the engine. Unfortunately I have not been able to reproduce the spark.

I think I am getting close to "needing" a brand new set of wires which is not necessarily a bad thing ;)

Thanks for all the feedback!

You have a Motronic system. could also be a partially bad DME

Could be the DME. But I've already replace the DME Relay which is what usally goes first. Plus the car was running fine before I started changing the dist cap and rotor.

Installed a new rotor and changed all the spark plugs. All the plugs were NKG's gapped to .76mm . Now it runs even worse.

Disconnected spark plug wires one at a time to isolate the cylinders that were not firing and found that all 3 cylinders (#4,5,6) on the right (passenger side) were not firing. I also confirmed by touch. The valve cover on the right side was cold and the valve cover on the left side was warm.

I checked to make sure I was getting spark on the right side by pulling the wire to plug #5 and putting a grounded plug it it. It produced a nice blue spark. As best I can tell, it now does not seemt to be a spark problem (cap, rotor, wires, plugs)

Does any know of a problem that would cause all the cylinders in a bank not to fire? I checked the injector connectors they all seem fine. I checked the fuel supply line to the right side and it looks fine.

I hate making negative progress. Thanks.

So it will fire a plug out of the motor, but not if the plug is screwed into the sparkplug hole? Are your injectors on the right side spraying?

Seems like you still have the right side wires mixed up. Jim

Yes, the plug fires outside the motor so I assume it fires inside the motor. I have checked , rechecked and tripple checked to make sure I have the wires connected corrrecty in the right order.

I just read a little more in my Bentley manual. It has an electrical test for the injectors. Do you think this would be a good next check?

I also noticed pin assignement #15 in the ECM is the injection time signal for cyl 4-6. It looks like you need a pinout test harness to test the ECM so I probally will not be able to test it since a harness is pretty expensive.

Did you get the direction of rotation correct? 1-6-2-4-3-5 counterclockwise around the cap. One is on top of the clip in plain sight that holds the cap on.
Someone please correct me if the Carreras are different from the SC in this regard.

Fortunately I have my old cap that has the same numbers in the same location as the new cap. Starting at the top just to the right of the top clip it is 1-6-2-4-3-5 Clockwise. I double checked my bentley manual and it is correct.

Now THAT'S what my dying ECU did! Try some tapping under the drivers seat next time it happens.

Check the connector(s) to the injector(s). You may have knock something loose while changing plugs.

SC distributors are ccw,
Carrera distr. are cw.
Try a new cap along with your new rotor.

Hey guys, I just wanted to let you know I found the problem after all this time. The plug wires were not seated properly!!!. It's running like a champ now. Thanks for all your help and suggestions. This forum is great!

Mike,
I had many problems getting my plug wires to make a good connection on the plugs until I bought a set of Jacobs wires for $129 and they snap on to the plug in a very distinctive way letting you know they are connected!

Just ordered a set of Magnecor's. Hopefully they will be better than the Nology wires the PO put on.