Shaking during acceleration

[Anonymous]

I have been having trouble with my 200 and its stock ignition. I have distributor set at about 12 degrees...and idles pretty smooth. But after i drive it for a while...the engine vibrates a lot at stop lights, and shakes a little during smooth acceleration, but under full acceleration it runs really smooth. If you let it sit for a few minutes, it'll start idling smooth again. Its confusing the crap out of me!! At first i thought it was a timing problem, but now im starting to think is a vacuum problem.

I just replaced the plugs this week with AC Delco ones(the only ones they had left).... could this also be a culprit? Because it didnt start doing this until soon after i put them in.

Can you all help me figure out what the heck is wrong with this engine?


Hey guys by the way...thanks for the previous help as well

 

[Anonymous]

what are you using for a carb? have you made sure that your carb (whichever model it may be) is tuned correctly? How are you timing your ignition - via timing light, vacuum guage, or ear?

How about some more details and I'm sure you'll get all the help you need....

 

[JackFish]

What kind of car is it on? Got an EGR valve? Vacuum leak maybe?

 

[CZLN6]

Howdy Back all:

Stangontheway- If the miss started shortly after the plug change, start detecting there. It sounds like an intermitent miss, so likely just a bad connection somewhere between the distributor and the plug itself. It is not likely to be a plug, as long as they are gapped correctly. More likely a bad connection or a break in the plug wire.

If you pull the plugs after an episode, you may be able to see evidence of a misfire on the plug. That will be the electrical lead to follow.

Also check to make sure your automatic choke is not sticking closed in some situations.

Keep us posted on your progresses.

Adios, David

 

[Anonymous]

Well i replaced the plug wires today to try and fix the miss....but didnt help a whole lot. I looked at the number 3 plus and it looked like it had been missfiring, so i think i am going to check out the distributor setup tomorrow.

Its the factory 66 200ci mustang setup ignition setup with the automatic tranny...i forgot the name of it... something-matic, but the ignition has not been modified yet. Thanks

 

[Anonymous]

When was the last time you serviced the ignition--ie -- points, condenser etc.?

 

[Anonymous]

That sounds like a good idea. When i got the car, it had been sitting for a while. So im sure not much work has been done to the ignition system in a while. Where can i go to get a kit or somthing to replace the points and condensor??

 

[Anonymous]

What are the chances of the timing advance diaphragm at the distributor getting stuck? What would be the symtoms of this?

 

[ludwig]

Put in a Pertronix I and a Flamethrower coil. It will really help the ignition and you can run a much wider plug gap into the bargain. You'll have to do some adjusting of the timing and the fuel mix, but you will get a much better idle and better fuel economy. Buy a tune up kit for the glove box in case the PI fails and you have to switch it out.

 

[Anonymous]

I drove it tonight, and it runs great if you go lower speeds. But after to run it hard, it wants to idle rough at stop lights and kind of shake a little when accelerating some. But when you let it idle for a few minutes, it runs smooth again.

 

[addo]

Is it shifting correctly up and down?

The distributors can get sticky as the grease dries or parts wear. You should be able to rotate the breaker plate smoothly towards the advance canister, and when you let it go it should "snap" back. It doesn't rotate far so don't force it.

Condensers can and do dry out also. If you stay with points in the short term, set the dwell with a meter rather than gapping them. Ensure the rubbing pad on the points, and the hexagonal section on the dizzy shaft are both lightly greased with high-temp grease. As to plugs, I never trust the gap as they are sold.

Check your engine grounding strap, and confirm the coil's continuity.

After all this, you can start suspecting the carby!

Regards, Adam.

 

[Anonymous]

Absolutely nothing wrong with AC plugs--but as Aldo says always gap plugs before installing as they are not gapped prior to shipping, have seen .020 and .070 from plugs out of the same 6-pack.

 

[Anonymous]

Well I have replaced the rotor, dizzy cap, capacitor, wires, plugs (gapped), and points. I am still having the problem, so i think that one of the vacuum components are sticking. From reading up on this topic, i found that the 1100 carb has 2 different vacuum system on it. I think the WOT vacuum( manifold vac) is sticking and making the engine timing think that the engine is running wide open( since the manifold vac is alot stronger than the port vac). What do you all think of this conclusion.

 

[Anonymous]

May not be related. But my mustang did the same thing and cause was heat soaking of the carb due to an exhaust leak arond the #3/4 cylinder exhaust.
r/
Steve-O

 

[645blitz]

Yeah! I was having that problem too and found an exaust leak and a rusted out heat riser tube going from the exaust manifold to the carb. Inspect your exaust manifold and that tube!!! Another car I had once had really old gas and didn't run very well, and make sure your fuel pump is working ok. I like the 5$ inline fuel gauge I got a Napa.

 

[CZLN6]

Howdy back SOTW:

The Spark Control Valve in the 1100 carb is the brains behind determining which vacuum gets to the distributor. It is possible that the diaphram inside the SCV is not functioning properly and sending a confused signal to the distributor. A new SCV is included in a rebuild kit for an 1100.

I'm still stuck on when you said that this did not happen until you changed plugs. Think back. What is the connection?

Adios, David

 

[Anonymous]

Alright, we have this problem fixed....it was a stuck valve, causing the cylinder to misfire. After $600 for all new valves and a new head gasket, she runs smooth as silk

 

[MercuryMarc]

Glad you got it running properly. How did you figure out it was the valve?

 

[Anonymous]

When i pulled the plug wire off of the number 4 cylinder, there was no change in the erratic idle....but there was a charge being sent. So i told the mechanic that and he said the valve was really loose in its seat. I think the intake valve was sticking, causing that cylinder to get no fuel.
But it was running as if one of the cylinders was missing, almost like an electrical problem.