91chevyz28

Title sez it all. When I disconnect the tan/black wire the car will not idle at all, so I cannot set the base timing. I had someone hold the idle at 1000 rpm and i set it to 6 degrees, but when I open the throttle the timing retards. When I have the tan/black wire hooked up, I look at the timing and it is firing after top dead center and when I open the throttle the timing retards more. I recently replaced the computer but still used the original prom. Could the prom be affecting this?

norcalz28

iTrader: (13)

Anything is possible, you need to think back to when the issue started and what you did or replaced that may have caused it. Otherwise I would adjust the IAC and TPS first, then try and set timing since it won't idle. Also make sure to disconnect the battery afterwards to clear any codes set in the process. And DO NOT plug the black/brown wire back in with the car running, always shut it down first.

91chevyz28

thanks for the response, but the car will not hold idle for me to adjust the IAC and I know not to plug in the wire while the car is running.I replaced the computer,started the car, the car ran great for about 20 minutes, then it just died and would not start. Went back next morning same thing, no start problem. I checked for spark and no spark, so I changed the module and it started. Went to set the base timing and it will not hold idle. I am so confused. Also now the timing is out of wack!

p8dnful

Ok... So I got the engine running again... The gave me a knock sensor for a 350 instead of a 305. After changing MAP sensor, External Coil, Cap & Rotor, Spark Plugs, Ignition Module, and Fuel Filter, still have no luck on what causes the timing to advance after setting initial timing at 6*. The odd part is that sometimes it'll advance the timing and sometimes it'll retard the timing.... I'm stumped on why the random adjustments. I followed the instructions from the Chilton's Manual on the Timing adjustment procedure but still NO Luck... I grounded the ALDL, disconnected the EST, and set the timing. It ran good for about a mile then advanced and ran like crap. Again I grounded the ALDL, disconnected the EST, and set the timing. It ran good for about a mile then it retarded itself. I then disconnected the EST but left the ALDL alone and set the timing and it still seemed to do either advance or retard. Any Suggestions would be greatly appreciated...

norcalz28

iTrader: (13)

Well, it's hard to say without being able to monitor the system and see what it's doing, but I would try and locate a junkyard ECM and swap them, the fact that it advances and retards makes me think it could be the computer crapping out, also you don't ground the ALDL so much as you jump pins A and B, looping them essentially to put it in the diagnostic mode. I would search this site for more tried and true repair procedures by folks who've actually done it, the chiltons book is ok, but the photos in the book are all of a TBI RS, not sure if they actually looked at any other cars or just gathered information and put it in the book

juanillox8

iTrader: (7)

are you sure its top dead center? since you replaced parts of the distributor... another thing is are you warming the car up before setting timing? do you have a stock cam in the car or its a performance one

juanillox8

iTrader: (7)

hey dude p8dnful threw us off, he's not the OP.......

P8DNFUL please dont do that, the way u posted made us think you are the op and you posted the same think on one of your threads.......