New to the board here and I have my fist question. I recently acquired a 1993 S10 Blazer Vin W and have been fixing the things that the PO let go. Thanks to this forum I have saved many $$$.

I drive up a canyon everyday to work and when the Blazer is under load is when I notice this the most. The engine goes from great power to feeling like it is under a load and back and forth. If I had to describe what it felt like I would say kinda like when the AC is kicking on and off. The AC doesn't work so I know that's not it. My feeling is a sensor is starting to fail.

Anyone else experience this before, advice?

Thanks,

Shawn

 

Well I ran the codes and all I get is the 12 code. I did a complete tune up prior to this post also. I can't imagin it, but can the alternator kicking on and off have that much pull on a 4.3?

Kinda wierd.

 

Thanks for all the replies.........[sm=feedback.gif]

I think I will try to clean the injectors.....[sm=happy046.gif]

I know, stupid newbie...[sm=smiley19.gif]

 

I suppose you replaced the spark plugs, spark plug wires,cap and rotor? A general tune up will help. A badignition systemwill cause an engine stumble when under load but not necessarily cause a general loss in power.

Check the O2 sensor and thecatalytic converter. A badcatalytic convertercan cause a general loss in power. However, about the only thing today that can cause a catalytic comnverter to go bad beside excess milage isa over rich condition that will sendunburned fuel into the catalytic converter where it ignites and melts the cataylist.Since catalytic converters were introduced,all the lead had been removedfrom gasoline and motor oil hasless than .150%ZDDP (zinc), except for some off-road racing oils and diesel truck oils.The only effective way you can check a catalytic converter is to replace it with a "test pipe" and see if the performance improves. If you go to that much trouble, you might as wellgo ahead and replace it, especially if the vechicle has high milage.You can also temporarily removethe O2 sensor and see if there is a change in performance. If the catalytic converter proves to be bad, youmust find and address the problem that causedthe catalytic converter to fail.Incorrect air/fuel mixture or anengine that is out of tune can cause a catalytic converter to fail prematurely.

*combining consecutive posts*

Temporarily remove the O2 sensor and the replace the catalytic converter with a test pipe and see if the performance improves. There is no way to visually check a catalytic converter and if it has been stopped up for a out of tune engine, it can cause the problem you describe.

 

Temporarily remove the O2 sensor and the replace the catalytic converter with a test pipe and see if the performance improves. There is no way to visually check a catalytic converter and if it has been stopped up for a out of tune engine, it can cause the problem you describe.

 

 

Sorry about the multiple posts but I keep getting a "Internal Server Error" what ever that means.

 

Thanks for the reply. I have never heard about pulling the O2 sensor to check it. That should be easy enough. I also like the idea of checking the Cat. That also could prove to be simple.

Thanks,

Shawn

 

If you remove the O2 sensor (remove it from the exhaust and disconnect its electrical connection), the exhaust leak will be a functional check on the catalytic converter. If the cat is plugged up, the now empty O2 sensor bung will act as a vent, allowing the exhaust gasses to exit. You do not necessarily need to remove the catalytic converter to diagnose it.

Jerry, dont worry about the multiple posting. I will try to put them back into one post if I can after the fact. Do what you need to now to get the information through, in moderation (i.e. try not to post like 5 posts in a row). One thing you can do is take a screen shot of your post, upload it to an online photo host, then post the image here. Hopefully we will not have to deal with the problems much longer.

 

Don't remove the O2 sensor to check the sensor, remove the O2 sensor andplug the hole and see if engine performance improves. If the catalytic converter is over restricted, the O2 sensor will tell the ECM tolean outthe fuel mixture and that will reduce engine power. Installing a new O2 sensor in front of a pluggedup catalytic converter will do no good.I know of no other way to check the catalytic converter than temporarily replacing it with a test pipe to see if the engine performannce improves. When the engine is down on power, mostpeoplemerely replace the catalytic converter it and hope that improves engine performance.That is just a crap shoot.....sometimes it does and somtimes it dosen't.

You may ask "Why niot just have anexhaust emissions test?" That will not indicate a restricted catalytic converterbecausea restrictedcatalytic converter can pass a exhaust emissions test. The emissionstestis only for oxides of nitrogen, carbon dioxide, and unburnt hydrocarbons.

TheEPA has required that catalytic convertersto beon all1975 and newer vehicles, and also to be functional. No gutted or camouflaged units allowed. Thegovernement also has required that factory originalandfactoryreplacement catalytic converters must be guaranteed for 80,000 miles.The cheaperaftermarket catalyticconverters are required by law to last only26,000 miles onpre-owned vehicles. The OEMcatalytic converters have more expensive materials in them and the cheaper aftermarket catalytic converters that are designed for pre-owned vehicles do not have the more exotic materials in them. That is why the OEM catalytic converters are more expensive.