rough idle and shaking

[lilhenry74]

OK I have a 95 beretta base with a 3.1 it idles rough and when Im on the highway it gets to about 50 and starts shacking real bad when I hold steady on the throttle it quits shaking if I let off or accelerate and at about 70-75 it does it in cycles it hasn't died yet I've looked at the forums and found some things that were kinda close but not right I've changed plugs, wires, oil filter, oil, ect no change any ideas?

[88*Beretta]

(lilhenry74 @ Jan. 13 2008,11:19)QUOTEidles rough
50 mph....shacking real bad
steady on the throttle it quits shaking
Read directions, and try one of these ($7.00)


When you have a drive-ability issue:

1. Code Check
2. Check Fuel Pressures specs
3. Use ether starting spray, and focus upon intake side with it
4. Check system components...wiring...

Rule Number One - Don't assume it is broke cause the Code says so...verify.

I'll check back to see where you're at...any questions?

[yellow3800]

I can't see your post as I type my reply so I can't remember [from a sec. ago] if you had any engine codes.  I think you DO NOT have any.  

Check the ignition coils.  They can form dead spots when they are failing.   While they may check okay in a bench test, their numbers may indicate high, or low impedance off the normal reading expected.   This could be the problem.  If not coil packs, go after testing that ignition module, but I really think it sounds like coils.

I can't remember the resistance reading... is it 5.5ohms each?  

Anybody?

also, those wires to the ign. coil take temperature abuse, and sometimes oil runoff from a leaky valve cover runs on them also.

You may just get by removing the coils, ign. module, cleaning, and replacing.  Test the coils while they are out.


remember, plug wires are 1000ohms resistance per FOOT of wire.  Most people replace wires when its unnecessary and this is the guidline to check wires.

Andy
amckevitz@yahoo.com

[lilhenry74]

Cars all better one of the injectors became unplugged and 2 of the spark plug wires needed fixed the injecter still needs a retaining clip but its in a hard to reach place so I'll just deal with it. but thanks for the input. only thing now is the SES light still comes on when I decelerate on the highway but I think thats a egr valve or O2 sensor. pics to com when the weather warms up. hopfully soon.