Can someone tell me a little bit about how the timing chain works? If it breaks, is there a particular noise that it would make? Not sure if this is the problem, but the cars engine light came on the other day, started off at a light and all the sudden it started pinging and knocking, let off the gas and it backfired.

Car, 1991 RS Camaro 305, has approx. 180,000 miles on it. It is up on jacks right now. The only code it throws is the VSS. Will not start. Turns over. Can't figure out what the problem is. If anyone has any clues, please advise.........

 

The timing chain is basically just two sprockets and a chain that drives the cam at &#189 the speed of the crank. You can see if the cams moved in relation to the crank or the dist and/or cam stopped moving all together by brining the engine around to TDC. The rotor in the dist. should be pointing at or just ahead of the #1 or the #6 terminal in the cap and should rotate with the engine. You can also test for slop in the system when you get teh motor running by looking for spark scatter with a timing light.

The pinging and knocking along with the backfire sounds like possible timing problems. The advance will pretty much zero out when detonation like that happens. Have you checked to make sure you have fuel while cranking? Does it have a nice strong spark while cranking? If all looks well so far these would be some things to check if it still wont start.

 

If your chain actually breaks, then your engine isn't going to run anymore.

A good way to find out if it did infact break would be to take off the dissy cap, and lightly bump over the motor. If the crank moves and the dissy doesnt, guess what?

If you try this though, bump it as little as possible because your oil pump won't be turning either if the chain broke.

 

i checked for spark when the old ones were in. was getting good spark. replaced the old ones seeing as the gap had increased to approx. 45. tried cranking and it still wont start. sounds like it wants to. we are checking the timing now...... any other suggestions?

 

timing is at 4 before the TDC.......

 

Then the timing chain is fine.

-Fuel/air
-Compression
-Spark

Those are the 3 things essential to starting an engine. You have spark obviously. Have you verified fuel pressure? The engine is obviously spinning, so there is compression. How fast does it spin, anyway?

What did you gap the new plugs at?

Pinging has to do with what goes in in the chamber. Knocking takes place below the chamber. Knock is a heckuva lot worse than pinging (until the pinging gets so bad that stuff breaks).

What did the plugs look like when they came out? Aka - did you read the plugs?

 

I gapped the plugs at 0.35 and they are wet when I take them out. I've checked to see of the cylinders are getting spark and they are. I also looked inside the throttle body to make sure there is fuel spray and there is. There is also fuel coming out of the exhaust pipe, no liquid, but vapors.

 

just because there is fuel spray, doesn't mean there's enough to start the engine on. Check the fuel pressure.

 

Do you think I might have blown the intake, or is there something else that could be leaning out the mixture bad enough where it wouldn't start. I was thinking that the timing chain might have jumped a link, when I took the distributor cap off and set the engine at TDC, it was pointing towards 1, actually between 1 and 8 but closer to one. So wouldn't that mean the timing would be advanced, and when the chain jumps a link doesn't it retard the timing?

 

It's hard to check the fuel pressure because it's TBI, I'd have to rig up something and tee in the line. Besides that, it smells like it's flooding.

 

Try pressing the gas pedal and starting it.

Edit: it's damn near impossible for the timing chain to jump a link when you pull the distributor, heck it's damn near impossible for it to jump a link period. Once you see the tension on them, and how exactly the teeth mesh into the chain, it's easy to see.

 

You can clear it out by unplugging the injectors and cranking the car several times for around 10-15 seconds at a time. The timing sounds like its where it should be. As for the spark, what does it look like? It should be strong bluish white audable spark. Check the fuel pressure next. Should be around 9-12 psi. After that, it could be a bad CTS. If it underreports the temperature youll never get it to start as itll be way too rich when your cranking.

 

That will also work. If you press it all the way down the air fuel ratio will go to 20:1 to clear the flood. Although on some models its set to a really high throttle opening so it can be hard to engage. Along those same lines try cracking it open. On some cars this can help get it going. This used to be the only way I could get mine to start in the winter.

 

You're right it might be the CTS, if you mean the coolant temp sensor. If I remember correctly, sends out 5 vlts and whatever it gets back is how it measures the temp. right. Well, it there a chart for the temp/ returned volts anywhere. The computer is accessible right now and I could backprobe the return terminal. It's 70 degrees outside and the car is completely cold.

 

also tried starting with the pedal to the floor...... nothing, acts like it wants to crank but nothing happens.

 

nailed er' on the head boys! the spark was kinda weak so i went and bought new wires.... still a little weak. bought a new coil, unhooked the old, hooked the new one up and what do you know..... she started right up. sent about three thousands volts threw my bros arm...... thanks for all your help! guess this chick aint that brazen after all......