a while back our 98 blazer w/ 4.3 litre was suffering loss of power. i read on one of the posts that a guy rodded out his converter. ours was rattling so we figured it was bad and peices were blocking the exhast. I rodded mine out and no doubt the exhaust flow is better but we still have a consistent power issue. Gas mileage has consistently been down a bit but not too bad. The only code we have is one that says the catylist is below the level that it should be (no shi$^$^). Run and drives fine, the power loss is perplexing. Seems like the timing is consistelnly retarded. but noother codes.

Any ideas?

 

Replace the cat would fix the light.....

As for the loss of power, if you're thinking it's unrelated to the cat, it could be a fuel issue. A fuel pressure test would be a good start, making sure to watch the pressure for a few minutes and make sure it does not drop considerably.

 

This is a good suggestion. I tried to replace the fuel filter a few timebut it just won't come off. I've been soaking the threads with penetrating oil a few times for the past month and no luck. Any ideas on how to get that sucker off?

 

Have you read this tutorial?

 

Yea this would be helpful but my biggest problem right now is getting those treaded connections loose.

 

Yah the connections are really difficult to get off on your back and you dont really want to force it too much and break that nut off. If you tried numerous times it might be better just to take it to a garage and let them get coated in gas.

 

Personally, I had zero trouble getting the two nuts apart by using two wrenches. My issue came with getting the fuel lines out of the mounting bracket. Not to be insulting, but are you sure you're turning the nut the right direction?

 

WOW! turning right direction, that is pretty funny. Yea I was, finally got a small pipe wrench out and trashed the nut but it came off. I coated the threads with antiseaze compound when i put it back on. Still drives the same way even after the new filter. It runs very smooth and does not sputter even when giving it a lot of gas going up a hill. Just does not have power. Seems like the timing is retarded but still no code.

 

The only thing that I can think of that would cause retarded time, would be corrosion build up on the rotor or distributor cap. When was the last time the cap and/or rotor, wires, and sparkplugs replaced? This could be part of your powerloss and fuel economy situation. But I would think if something in those parts was bad that you would have sputtering or uneven idle.

As far as the fuel pressure testing, I am not sure exactly how to do that, but I believe you can get a gauge from an autoparts store and then hook it up to the test port on the back of the fuel rail (as mentioned in my tutorial listed above). I am not sure what the fuel pressure is supposed to be, but running a search for fuel pressure on the forum should get you some information on that. It could be an issue with the fuel pump, but without it sputtering (not having enough fuel) I would say its not the fuel pump (atleast not yet).

I would run the fuel pressure test and post back on the results of that and the last time you replaced any of the ingition parts (spark plugs, wires, distributor, rotor). Also if you did replace the spark plugs what kind did you use. I have heard from most people that our trucks only like the AcDelco Platinum plugs (thats what I replaced mine with, so far no problems (7k miles on them so far).

 

I would perform throttle body cleaning and a MAF cleaning, and also clean the egr valve. You may need an egr gasket, and a can of combustion cleaner for the egr and throttlebody, and sensor safe cleaner for the Maf sensor. If it doesnt fix the problem, it is still good maintenance. Also dont rule out the Map sensor, the specs for testing are here somewhere, i found it on a search a while back. Good luck.