Timing chain?

2005 Chevy Classic. 2.2 Dohc 140,000 miles +/-. My daughter in law said this car was making a ticking sound. after a couple weeks it got louder. Then the engine died and would not fire. Towed it to my house. I got very good spark, Got good fuel pressure. Dry compression is 150 - 160. when cranking, will not fire till I even with ether. But when I floor it, it will fire just enough on one or two cylinders to match the starter speed. I’m pretty busy now so would like to know from some more experienced guys if I’m going in the right direction. Although I checked fuel pressure, I didn’t check if fuel was traveling through injectors, nor do I feel a need to.My thinking is that the timing chain tensioner failed and the chain skipped a tooth. should i take the cover off or should I go a different direction?

If the timing chain tensioner/guide has failed, the timing chain will have slack in it.

To check for this, remove the valve cover.

Crank the engine over by hand in the normal direction while someone watches the valve movement.

Now crank the engine over in the opposite direction while someone watches the valve movement.

If the engine can cranked in the opposite direction more than 5 degrees before any valve movement is seen, the timing chain has a lot of slack in it.


Thanks I’ll do that.

Well, I’m not so sure a skipped tooth would be enough to prevent it from firing up on it’s own fuel vs starting spray. Although the ticking noise is something to consider, I would still work on the fuel delivery aspect first. Should be easy to see if an injector is getting a pulse from the ECM. No crank sensor input, no injector pulse…

To clarify: I got same amount of fire with or without ether. But like you said it’s quick to check injector pulse. Can I check for pulses with a LED test light?

You need what’s called a “noid light”

1 Like

Yeah, I’m familiar with them but don’t have one. I am wondering if it’s okay to take a LED Test light from battery + to injector signal wire. Will that produce flashing?

No, Amazon has noid light sets,15 bucks and you can have it tomorrow

Thanks I just looked some up and they are cheaper than I thought. I will hardly use it (hopefully), but in your opinion, would I be sorry buying the cheap ones? Cheap has burnt me before. I’ll do some research to find best one for best price. But will trust the judgements here first.

The 15 dollar set that i looked at had good reviews. For the one time use you’d be giving it, it should be ok.

Thanks everyone. Will let you know when I’m done.

For around $20 you could buy a digital multimeter at Autozone. Far more uses than a noid light for not much more money…

I have 2 high end multimeters already. I didn’t know I could test injector signal with them. Do you put positive to battery plus, negative to signal wire on D.C.?

You can’t.

A multimeter can’t react fast enough to the injector pulse signal. This why it requires a noid light or a scopemeter to measure the pulse signal.


1 Like

Here’s the fuel injector/harness tester I bought many years ago.

It has all the fuel injector connectors, noid light, and can pulse test the injectors.


I found one of these. How does it hook up? I couldn’t find instructions

Of course it can. Mine do. Bear in mind we’re talking about cranking signals. So, between 0-200 RPM and approximately 50ms pulse width. Mine definitely show pulsing during cranking versus solid bus voltage when not being pulsed. Done it many times on my own cars. Just double checked it on a bench using a function generator set to various rates equivalent to a single injector timing for a 4 or 8 cylinder motor cranking at 200 rpm with a 50ms injector pulse width. I can see it plainly enough to know there is pulsing going on. That’s all that’s trying to be established…

I have never tested injectors before other than stethoscope, so I know nothing, but my train of thought is that a voltmeter would register the voltage but not actual voltage. I would think that an LED test light would flash. And a filiment test light would be worthless. Either way I did buy a Noid cause they’re cheap, and you can never have too many toys in the toy box.

What kind of voltage would it read? :wink:
What happens is that it cannot follow the voltage change so you see a sampling of it at various times. When the injectors are not being driven, the voltmeter will show a steady reading (either bus voltage or ground depending on the driven leg). If they are being pulsed at all, the voltage reading (and bar graph, if equipped and many are) will be visibly bouncing between the extremes. The higher the duty cycle, the closer it will hover toward the driven end. This is much easier to see at the lower rpms during engine cranking.

Nothing wrong with Noid lights and I’m all for more tools but I personally have never owned one since I have always had at least one multimeter since a young age fixing various electronics. Even a damped analog meter will show some movement under these conditions.

If you wanted to get fancy, with about 50c in parts (diode, cap and bleed resistor) you could assemble an integrator and derive the pulse width based on the voltage reading and pulse repetition rate (RPM).

Anyway, all it was trying to accomplish was to identify if the ECM was providing injector pulses and rule that out, not qualify the pulse shape. Glad to hear you have the tool coming. Good luck diagnosing- hope you find it quickly!

I received this tool the other day and tried it on the car in question. It is really handy. Can even tell you if fuel is actually being dispersed without removing injector. Cool. I also played with my multimeter, and it showed high and low peak readings when cranking.