kkingsrulee

I have a '90 305 TBI that has an engine tick. It doesn't start out immediately upon start-up, but sets in about five minutes after starting the car. The SES light was coming on and it's throwing out a code 42.

My Haynes manual informs me that that's either a bad EST, Ignition Module, or ECM.

Based on the symptoms and the code, where should I go from here? How should I further trouble should to pinpoint what the problem is?

Thanks in advance.

305sbc

iTrader: (3)

The book says to check the EST, ESC, or ignition control.

That said, this may sound strange, but first take a really good look at all of your sparkplug wires, particularly looking to see if one of them is contacting hot metal - like your exhaust manifold in any spot.
There are odd occasions where a burned plug wire will both cause an ignition error code, and a ticking sound. I don't know if that would/could be the case with your model, but it's worth checking out.

kkingsrulee

I've checkedd a few times, but never very thoroughly. Actually, before this tick began, it was ticking even worse, it sounded like a motorcycle because one of the spark plug wires had actually come off a spark plug. I think I'll manually check every wire just to be safe.

305sbc

iTrader: (3)

Sometimes the sparkplugs that have the screw-on tips can cause problems when the tips get loose from vibration.

kkingsrulee

Alright, I checked all the wires and all the tips to each spark plug, some were a little loose.

However, the problem still persists, SES light is still on and the ticking is still present. When you first start the car it is very subtle, almost like a quiet rattle that can be heard near the engine, you can't really even hear it, but when the car is allowed to run for about three minutes it starts to become a lot louder.

Can anyone point me in the right direction as far as diagnosing the problem based on the sound of the tick and the error code (42)?

305sbc

iTrader: (3)

I would try plugging in another ESC. - easy for me since I have spares sitting around.
If you go buy a new one it may not be returnable if it doesn't work.

Have you tried finding the exact location of the tick?
Is it down at the exhaust? under the valve cover? from the TBI unit?
Have you inspected inside your distributor?

kkingsrulee

I haven't inspected inside the distributor.

It's near the top/rear(farthest toward the rear of the engine bay) of the engine.

It's easy to hear when leaning over the engine and when crouching down near the sides of the front wheels.

Like I said, it starts at almost a subtle rattle not necessary in time with the engine, then progresses to a tick, which is in time with the engine(increases in frequency when the engine is revved).

kkingsrulee

Actually, the Haynes Manual says it's bad wiring, a short, a faulty Ignition Module, or a faulty ECM.

A new Ignition Module is only 50 bucks, should I just replace that? Is it likely that this is the problem?

305sbc

iTrader: (3)

No way to tell by guessing, especially from a distance. Check to see if it's returnable. In this economy, part-swapping makes even less sense for the DIYer.

I friend of mine had a tick that bugged him so much he pulled the engine, tore it back down and checked all of the bearings. It ended up being a very small exhaust leak where the manifold meets the head.

You do have that DTC code as a guide, but I would at least check every sparkplug, and especially inside the distributor first before buying an ESC. I'm just saying what I would do. I hope you get this resolved with minimal hassle.