I have a 97 2dr blazer ls.... i have replaced the plugs wires, cap, rotor, distributor, oil pressure sensor, fuel pump,filter, tank, battery, and ignition. The engine was full of bad gas. Allines and tank were rusted and rotted out. The truck hadn't run for a long period. I was able to get it started before the fuel line work but had no acceleration. Codes came back misfire. Ended up replacing the injection unit(whole spider)... the engine still fired first crank but still misfire. I took it to a shop to refine timing. Now i have a popping sound in my upper manifold. And engine struggles to turn over. I had a underqualified mechanic do the tank work and injection. Could there be a problem in the spider or crossed lines off the pump. Timing is 100% on. All pressures are good. Any ideas. Truck was running smoothly before this work. Just didn't accelerate full power.

 

Have proceeded to check egr fpr map and mafs. No progress. Gas in oil but seems to be from bad fpr. Still popping at carb. Random not in sequence. Cylinder 6 is carboned up at plug and injector. ??? Would the ecm have any effect on that? Or do i dive into valves? Also spark good ,fp good, compression good 120-110 all around, engine runs and accelerates but so does popping violently. Someone please help i need my truck bad.

 

if your compression is that good, i wouldnt even worry about the valves. 110 in all 6 is probably as good as new. if you had one low one, like around 35-60 compared to the rest then i would worry about it. so yeah, not the valves for sure.

have you put a set of plugs in it? i just did the head on an Acura and when i got it all put back together, it ran like crap. i put a set of plugs in it and it fixed everything. runs like a champ now.

 

2Sets of plugs, wires, tried 3 caps, distributor brand new all delco. just tried coil, still popping. Slight gas smell in oil but no sign of leakage in plenum. Even went as far as checking timing chain, little slack but on time. Check cam and crank sensor. Even cleaned egr. Now its starting to to become a competition i refuse to let this go unfound. I know these self set timing. ... Could it be ecm? Running out of options avoiding a rip down to valves at all cost. Anymore suggestions? I must be missing something.

 

Got a 98 looking to swap it out but not sure on match up or if i should hold up and keep trying. Only 90000 miles on this engine. Gotta be something going on. What is the deal with this popping?

 

Gotta be something stupid, may just be over thinking it

 

It sounds like you may have a partly plugged exhaust. Consider, you recently got it going after it sat for a long time. Well, we're just beginning to come out of winter. It may have a mouse nest in the exhaust. They like to do this and the engine will run as some exhaust will get past the grass and stuff but not much.

Hook a vacuum gauge to it to see what vacuum you're pulling. A healthy engine should pull 17-20 inches of vacuum when warmed up at idle.

 

Vacuum idea will try. Far fetched but worth a shot. I have no cat and sounds breathable when running. Good pressure coming from pipe. Doesn't stall just a pop from rear valve area. No mice just chacked lol. Seriously though. Could it be a bent valve or burnt? Zero miles since popping only start and stop? Crossed wire?

 

Correction popping not in upper. Its loud from lower end. Also #6plug high carbon. Injector high carbon

 

Broken rod.... snapped. One push rod bent, loose rocker arms. Bent rod locking up movement literally bent almost s shape popping was rocker not being able topass through guide bend was severe rocker slamming against top of rod