ultimatefighter

Hi all!
I have a 1992 Z28 with a 305 TPI, auto. My car hasn't been starting very good. Kind of a hit and miss thing. So, I took my timing light and disconnected the brown with a black stripe wire. The timing was WAAAYYY off. So i finally set it at 6*BTDC, plug the wire back in...now it won't stay idling at all. Plus, when i have the wire plugged in, it knocks. When i unplug it to set timing, the knock goes away. Is this the knock sensor?

Thanks 4 any replies

bigzeke

isnt the timing controled by the ecm ,the computer advances and retards it if im correct you may have upset it more back up and retract your steps and set it where it was before ,the knock sensor picks up detonaton and ecm adjust timing and fuel accordingly ypu may want to go back and look at map sensor and check for any small unseen vacuum leaks

ultimatefighter

That is why I umplugged the brown and black stripe wire...so it wasn't being "controlled". I think the ECM advances and the knock sensor retards it. But, I could be wrong.

ultimatefighter

Could it be the ECS? Or ECM?

doc221978

Try idexing the crank. Take out the number one plug, and make sure the timing mark is at zero on the top of the compression stroke. The outside of the balancer can slip and give false timing readings

ultimatefighter

Just did that and it reads fine. The car runs and idles just fine when the brown and black striped wire is unplugged, but driving down the road i runs like crap. Plug the wire back in and it won't idle at all. Also, with the wire plugged in it had a knock, with it unplugged the knock went away.?

F-body-fan

How did the syptoms first appear? Was the car runnig fine at some point before the onset, & was it sudden?

ultimatefighter

The knocking has been going on for about 3 months....thought it was an exhaust leak or lifter. The car was running ok until I would drive it and then it wouldn't start back up. Just kept turning over and over. It has a hard start now meaning it hesitates or clunks while cranking. Also, the check engine light just started coming on about a month ago and seems like it's eating more gas and less power over this course.
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Could it be the ECM? Cause i have it pulled out and ready to go to the parts store

ultimatefighter

Also forgot to mention that after I changed the timing to 6* BTDC the thing fires right up! No more cranking over and over.

F-body-fan

So when you set the initial timing, then plug in the bypass wire again, Can you still see the timing mark? Does it jump up & advance as it should? Do you have an ajustable timing light, or fixed?

SpitotRs305

where was the timing before you changed it?

ultimatefighter

I never looked for the timing mark after i plugged it back in. Because it wouldn't even idle and wouldn't stay running even when given gas. I have an adjustable timing light. Thanks
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IDK...it was so far off, I couldn't even see it...LOL

bgood71

I had a similar problem with my 87 T/A. Turned out to be the distributor. Take off the dist cap and check for corrosion in it. Another indication would be the timing mark jumping all over the place.Hpoe this helps and good luck.

doc221978

He has a good point with the cap and rotor. Another thing, with the knocking if you don't get it pinned down a compression test may help. It could also be bearings or a number of other things, depending on the type of sound.... even improperly adjusted tappets, or dirty oil can cause it. It's one of those things that's easier to hear for yourself.

F-body-fan

Can the timing control wire be plugged in whille its running? Or does the ignition have to be turned off first?

I was thinking if you could somehow check the timing once its plugged in, you should be seeing it advance 10-20 degree's right?

Maybe thats not happening at all?

pandin

Some cars are set to 0 and others at 6, has to match the chip.

Idle timing is about 20-40 with est wire hooked depends on the chip.

ultimatefighter

If it was an actual knock, then why would it completly go away with the bypass wire unplugged? I am no longer concerned with the knock since it does go away. The problem is somewhere in a sensor, I think, and I dont' know where that bypass wire goes to or controls.
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I don't know what it is supposed to be set at. I do know that from the factory it came with an SLP chip, for whatever thats worth. I set it at 6 now.
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When the bypass wire is plugged in, I can't read it at all, because it dies. I can't even hold the throttle and gove it gas because it sounds like it is just sucking and dies.

ultimatefighter

I guess the Title of this thread is misleading. The car wasn't running right and wouldn't start all the time. Would just crank over until the battery went dead. Then other times it would fire up, but hard to start. So, I thought it was the timing. Got my timing light out and it was waaayyy off with the bypass wire unplugged. I set it to 6* with the bypass wire unplugged. Shut it off to see if it would fire right up. Sure enough it did, sounded much better. Then I go to plug the bypass wire back in and it won't stay running. Go back and unplug the bypass wire and it purrs like a kitten, so I drive it around the block like that and it runs like crap which tells me I need that bypass wire hooked up and functioning. Hope this clears some things up.

bgood71

If the car idles good with the wire unhooked, but stalls/won't idle plugged in then I would look at the ignition module, pick up, or ECM. The first thing I'ld check would be the ignition module