Timing Problems

Hello,

I have an 88 Chevy 5.7 350 c1500 1/2 ton rear wheel drive truck with electronic fuel injection and a Throttle body injection. I have been working on restoring its youth and have run into a couple of problems. One main problem that I have is the timing. I disconnect the Electronic Spark Control wire to bypass the module, (to set initial timing) and time my truck to 0 degrees, but as soon as I plug back the ESC module wire back in, the timing, checked with my timing gun, goes to about 20-30 degrees before (counterclockwise on my vibration damper) 0 degrees. IS THIS NORMAL? or should it remain the same; at 0 degrees? (this is all done at idle speed in park) The strange thing is that the truck runs smooth for most of the time, only during hard acceleration I hear a fast tapping or clicking, but I'm not sure if it is preignition or if it is valve tarin or some other noise. My question is can any of the sensors relay bad information to the ECM and cause it to change the timing incorrectly? I have been assuming yes, and i have changed several sensors (speed sensor, throttle position sensor, EGR Valve and solenoid, the ESC module itself, idle air control valve, distributor, spark plugs and wires, coil, coolant temperature sensor, and even the computer itself) ( I have also changed the timing chain and gears a long time ago) I have not changed the coolant temperature SWITCH, the MAP sensor and the knock sensor, but I do not want to change these sensors without making sure they are faulty. How can I test these items. Before I changed the distributor (which was the first thing I did) the car would misfire like crazy, and my guess is that it could have damaged the knock sensor causing it to relay bad information; is this possible? There is no carbon in the engine as it has been thoroughly cleaned. I understand there are a lot of questions here, but I am sure somebody knows the answer to some of them....

Thank you,
Matthew

I'm working on a very similar issue with an 88 silverado (350 TBI). The engine ran great when I took off the Electronic Spark Control cable to test the timing. When I replaced the cable it started to bog out and run terribly. I've checked the timing chain, changed the EGR, changed ignition module, ignition coil, wires, rotor, distributor cap, spark plugs etc... I'm getting spark, getting fuel, and the compression seems ok (1, 4 = 120psi, 6, 8 = 150psi, the rest are at 135psi) for such an old engine. It seems like it is flooding. Now I can't get the thing to start. It turns but I think I need to set the timing. I'll try new plugs and retarding the time. (Can you set the timing without being able to start it?).

Hay Matt are you getting any codes and it's normal for the timing to fluculate after connector pluged back in The connector must be apart to properly set the base timming and bolt tighten on dist before you put connector back together To check the knock sensor take a hammer [hate saying it] and then tap block beside the knock sensor and see if timming changes or hear the difference of engine no change check wiring right to computer from knock sensor if good replace Question hows your cooling system and belt ,charging and battery condition One other thing is you are sure your dist is in right and not off a tooth or so
BYPASS= right fender by hood hinge [for base timming]

Any type of knock is able to set off the knock sensor. If you have any valvetrain noise, clicking lifters, etc. it can cause what you both describe. A scan tool that can display the knock sensor status may help your diagnosis. A quick check is to unplug the knock sensor and see if the timing jumps back up and stays there.

Prong, If you can get it started, check vacuum.

Actually after running all of these tests I must have blown a fuse. I think I might've run out of gas -- I know on a mustang that I had once a fuse blew when I ran out of gas. But, I'm going out there today to check it out. When I changed the timing chain I moved the camshaft around and set my timing off by 180 degrees so I turned the distributor 180 degrees to get it back in time. Now I need to figure out this no gas problem. I know the fuse in the engine compartment looks fine.