I have a 1989 suburban with TBI The timing is severly retarted, and I cannot adjust it by turning thte distributer. I changed the timing chain, and it is still the same. I have been told I can place a jumper on a set of wires and put the ignition in a "performance" mode to bypass the computer controling the timing. Is this possible?
Theres a plug to disconnect (ESC?) before setting it at dead 0...YES must stop computer from interferingmhile u set timing usually a brown wire with a white stripe near firewall under master brake cyl. set at dead ZERO.......if it still stayz totally retarded ya got ESC problems..... ifits too advanced and pings ...AFTER YA ZERO IT...then ya got knock sensor problem. or bad ground at ESC electronic spark control advances and retaRDS IGNITION TIMING for best performance
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First you need to retrace your steps...before you changed the timing chain and gears did It run ok ? what was initial problem, next put a fuel pressure gauge on your fuel line and cycle your key on to run pos, dont have to try start, just run and see if you have fuel press during the 3 sec or so pump cycles, should be around i think 35-45 roughly for tbi. so if you have good fuel pressure , then you say you have good spark, then your problem is either ingition or valve timing, did your dist.come loose, did you properly install chain & gears and align timing marks. did you have somethine else a part on it too like intake, dist, ? get back with me I'll try to help you.
note if it overheats on the freeway or in city driving. If it overheats soon after you leave the house then in has to be the thermostat. If it overheats at city driving where there are lots of stop and go driving or while you are parked with the motor running, then check the radiator fan function properly. If it takes a while to overheat and tend to do it when driving on the freeway, it is a clogged/dirty radiator. If it looses coolant due to a leak, then it will also overheat. The least likely cause which don't even pertain to newer car is a retarted timing. A retarted timing causes a car to loose noticable loose of power accompanied by overheating. A retartded timing is usually common in older car where timing is adjustable by turning the distributor. Your car is exempt from this.
you need a timing light and you have to take the cover off the electrical junction on the passanger side of the firewall once the cover is off you can disconnect the timing advance wire theres onle two wires you can disconnect so you cant mess it up the other one has a fuse in it for the lamp under the hood. then under the distributer theres a 9/16 bolt that holds a clamp on the distributer to keep it in place loosen it up just enough so you can turn the distributer but it still stays in place. then take some clalk of a yellow or white crayon from your kids and look at the crank shaft there will be a notch in it use the chalk to highlight it. then hook up the timing light pos-pos neg-neg and the clamp on the no 1 cylinders plug wire the the no 1 cylinder is the closest cylinder to the radiator on the drivers side. then fire it up and hit the button on the light you will see it light up as that cylinder fires and that notch should line up with the timing tab on the front of the block to adjust the timing just rotate the distributer until the notch lines up with the tab. let me know if that helped.
This Engine uses a Direct Ignition System (DIS) or Distributorless Ignition to control engine timing advance/******. The Electronic Control Module combined with Electronic Spark Timing (ECM/EST) controls the ignition timing. The ignition timing is preset by the manufacture, and no provisions for adjustments are provided.
Sounds like the knock sensor has failed. It's on the passenger side at the bottom of the engine block, in front of the starter. One wire going to it. Have you checked the timing lately, maybe it has moved?
Check the timing chain..Take the belt of and turn the crank by hand and see how much slop there is when you turn it back and forth..If theres not much then there could be a cam problem.But most of the time its the timing chain..Hope this helps you and have a great night....