Rough Running - Grrrrrrrr
 

This all may have been asked and answered in previous threads (I haven't checked yet) but my 87 is beginning to irritate me and perhaps someone else has had similar experiences.

It had a full 60k service at 49,000 miles and it now has 53,000 on the clock. Everything tune up was replaced, valves were done, filters replaced, the works.

Lately, it won't start cleanly. It used to start right up and purr away, now it starts right up but drops to a rough shakey idle for 30 seconds or so before clearing out and running smoothly again. Sometimes when cold it won't now pull away from a stop without bucking and going nowhere for a few seconds. Sometimes when slowly accelerating through 3500 or so RPM the revs will just stop building for a few seconds then suddenly kick back in, almost like the key had been turned off for a second. Driving under a load such as when up a hill and trying to maintain a steady speed below 4000 rpm results in a "chugging" feel, not smooth at all.

Above 4000 rpm while accelerating, it is nice and smooth. Below 4000 it feels to me like it's too rich (hence the perceived loading up and roughness at idle) or like a car that has its timing retarded too much. I know I can't adjust the timing of my car but that's what it feels like to me.

This is driving me nuts and of course won't duplicate itself when shown to mechanical types who might know what to do about it if only they could duplicate it.

Is any of this at all familiar to anyone and is there a cure?

Thanks

Kurt

Sounds like a spark condition. I would check all sparkplug wires at the cap and the plugs. Reseat each one and double-check that your Beru connectors are snug. I would also check the cap and rotor. Did you replace these or the shop?

Try the easy and obvious first.
Take a look if your plugleads and distributor wiring are all properly connected. Have a look if your distributor cap ok.
Make sure water isn't getting to any electrical components.

typical problem with the old style cylinder head temperature sensor. pull off the white plug, which is located above two black plugs on a bracket above #3 cylinder, and see if the part that remains on the bracket has one or two pins inside. the old, unreliable ones had one pin. that's the first thing i would do. the second is to put in a new DME relay, which is the black plastic thing right next to the computer under your seat.

I recently had similar problems. Eventually mine got bad enough that it would not run at all, which is nice if you are trying to diagnose but not if you have to get to work! Anyway, a new coil got me back on the road.

Unfortunately there are a hundred different things that will cause similar symptoms, there is no substitute for a comprehensive diagnostic starting at determining if it is spark or fuel related.

Oh yeah, a $10 bottle of 44k is not a bad investment either.

My '87 had some similar symptoms. I first though I had a batch of dirty gas, then, as it got worse I looked for another answer.
JW suggested the DME and Cyl. Head. Sensor. Replacing both cured the problems.
I think anyone with an older Carrera w/ the orginal DME and old style C.H.S should conisder replacing them both. It's an easy fix and will ensure that the car is running at peak performance.