DaveK

For about a year now, I've had occasional hesitation (split second hiccup in power) and when this happens I also get an uneven idle. But it usually clears on the next journey and sometimes won't happen again for weeks or months (although I think it's got a bit worse).

Anyway - I decided to do some basic work myself. First - I chucked some injector cleaner in the fuel tank - I know, it's pointless stuff but figured it couldn't do much harm.

I finally got around to opening up and cleaning the air flow sensor - and it did look to me like there was pitting in one of the tracks. It looks like there are 3 simultaneous tracks though (redundancy?) so I don't think this is my problem - but will probably get hold of a second hand air flow sensor at some point (in fact, if I don't cure my problems other ways I'm sure Christer has a spare I can try before I buy one!).

I also removed one of the distributor caps and was surprised the contacts and rotor arm were quite pitted. These were replaced only 30K miles / 2 years ago - and I'm surprised they are in such a poor state already. I had idle hunting problems once before - which is why they were replaced (and that did cure my problem) - so my question is : why have they pitted so quickly?

I didn't bother taking the other one off since I've decided I need to order new ones anyway. I also ordered coils earlier today before I did this work - and since it's just had a service I know the plugs are new. Hopefully, this will rule out the obvious stuff and I'll see whether this makes a difference once I've got the coils / dist caps / rotor arms fitted.

But obviously, I would rather not need dist. caps every 30K miles - so do I have another problem which is causing this? (I'll be very happy if someone says knackered coils can cause it.....)

By the way - I was surprised this only took me about 1.5 hours. I bet I would have been billed more than 1.5 hours labour if a mechanic had done it!

Wachuko

If I remember correctly the caps and rotors are to be replaced every 15k (at least that is what I do). I do the same with the plugs.

In my case I had a few things needing attention that were contributing to the rpm fluctuation. I can't tell you what did it exactly, only what I have changed so far. Car runs excellent now.

Outside of the stuff that gets replaced every 15k miles (distributor caps, rotors, spark plugs, fuel filter, oil filter, air filter element, etc) I changed the coils, spark plug wires, DME Relay (this one was responsible for low rpm and sometimes the car dying in initial startup when cold).

It is also recommended to keep the battery fully charge. Get an inline charger hooked up if you leave your car sitting for a few weeks. Beats having to take the battery out for a charge.

dkeen

Have you had the distributor update completed. There is a vacume update that is designed to eliminate moisture in the cap, which could be the cause of your problem. It is suppose to be a pretty easy update ($15 in parts and less than hour labor).

DaveK

Yep - ages ago, but my undestanding was that it's to prolong the belt life, not the caps / rotor arms.

springer3

Caps and rotors will last a lot longer if the plugs are changed regularly. Firing voltage increases with plug wear and contamination. Higher voltage stress accelerates aging for all ignition system components.

Are you sure the parts were changed (and not just cleaned)? I am finding invoices in my POs records for work that I suspect was not done. 30 k sounds pretty low miles to have severe pitting, especially if the plugs were changed as well.

DaveK

They were definitely replaced - I saw the old ones. And, I don't believe it would have cured the problem I had if they had just been cleaned.

I get new plugs every service - once a year, about 10K miles.

StevoUK

My 1988 3.2 was very sensitive to clean rotor arm and distributer cap electrical "contacts" - smoother tickover and no hesitations. The major improvement was after finding a stop light fuse crumbling I replaced all fuses on the car with new ones. Transformation. The car requires decent up to spec voltages in the ignition circuits to the computerised ignition. My Carrera fired on 2 to 4 cylinders for the first two miles until the voltages were high enough to properly report engine sensor status to the computer.
Replacing the fuses fixed it. Earth contacts ar as important too.