1994 Blazer 1500 lean idle miss and surges
 

Hello, I am new here so please let me know if I am in the wrong place. I have a 94 Blazer 1500 in prestine condition. It has currently 292,000 plus miles on it. Close to 3 years ago when it had roughlt 240,000 mile number 3 cyliner went bad. The cost of rebuild compared to replace made me replace it. The dealer replaced it with a new engine, 3 year 100,000 warranty.

Immediately after the engine was replaced the idele would surge and it had a lean idle miss. Dealer could not find the problem. We decide to change the injectors. Did not correct the problem. Replace Fuel Filter, did not correct problem. Decided to go with it for a while. two weeks ago I tuned it up. Immediately on start it had a much more noticable miss-fire. I figured bad or cracked plug, rotor or wires. Bough a plug, gapped it and went one-by-one moving the plugs to a different cylinder and starting after each move. Did not fix the problem. Replace the new cap and rotor with a new set still no luck. Replaced wires still no change. Computer was tested by dealer and they said it was fine.

Brought to dealer and they said the timing was all over the place and that the distributor was the cause. Went to pick it up and the problem is still there. They are saying live with it - my answer is why put a new engine in if there will be issues? This is sooo frustrating. Does anyone have any ideas? I am ready to go to a private mechanic and hope they will find the problem.

have the fuel pressure checked, or check yourself. make sure you can watch the test so you know it's being done. pressure regulator, fuel pump, bad or wrong injectors, clogged fuel line or clog at fuel pump, bad o2 sensors. maybe something worse internal, but usually it's something that got overlooked. good luck. also, could be Idle Air Control valve.

Maxxman04
 

Maxxman04, thank you for your reply. Most of what you suggested was done but I will definitely look at some of what was not looked at. I will post results when I know more. Thank you.

on the 94's, there's a "timing bypass" wire, usually tan in color, that needs to be hooked up for timing to be right. on my '94 silverado, i found it inside the truck, passenger side, near the heater box, just under the carpet. it's a single, tan wire with connector. usually tho, it will throw a code if disconnected. check every sensor connector on motor too, make sure none are loose or broken. vacuum lines too.