I have 94 GMC Sonoma, 4.3 m/t. Truck starts fine, idles rough. replaced plugs, wires, dist cap, rotor, and it still idles rough and seems to lose power and rattle under hard acceleration. Besides the ignition module, what else do you think could be causing this? Local Autozone folks diagnosed my ignition module and told me it was fine and could not diagnose any other electrical issues. My truck has 296,300 miles on it. The check engine light has been on for about 10 years but it still passes the state inspection every year. Besides the ignition module, what else do you suspect could be causing this?
What makes this problem better or worse?
Under hard acceleration
How long has your 1994 GMC Sonoma had this problem?
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Based on the mileage, the rough idle and rattle on acceleration, it sounds like you could have a base timing issue, such as if the timing chain has stretched and possibly jumped a tooth. This would warrant some focus and attention; but it's just a guess from where I sit at my computer, when someone hands on really should be checking it.
Thanks for your prompt reply Dave. I didn't think of that! I replaced the timing chain at around 100k miles but that's it. I can reach 65-75 mph fine but I think I'll do that next. Thanks, Mike
Remove distributor cap - check for any ‘LATERAL’ movement of the dist. shaft by pushing / pulling rotor side to side..
Not rotating the rotor back and forth - this check is for ‘any’ LATERAL movement.
(Timing component are all steel as opposed to fiber coated camshaft gear)
Failures are rare..
Ignition timing is adjustable - following proper procedures.
Thanks for your prompt reply Dave. I didn't think of that! I replaced the timing chain at around 100k miles but that's it. I can reach 65-75 mph fine but I think I'll do that next. Thanks, Mike