I bought my 2000 blazer back in October and for the past month I've been having some annoying problems. All of the sudden one day, after filled the tank with gas, it started to hesitate badly for about 30 seconds right after when I would turn it on. I figured it might be a bad tank of gas so when it was about empty I put 93 into and it seemed to be much better. Next time i filled the tank (with regular), I was right back to the same problem. Right after I would turn the car on it would hesitate, but as soon as it got into second, I would be fine for the rest of my time driving. Lately though it's been happening worse. When I first turn it on and give it some gas it will sometimes backfire from somewhere at the engine, and the car will jerk a little, as well as anytime i press down hard on the accelerator (won't backfire, but getting onto the highway is a major pain[:@]).

The check engine light was on before this and was giving code P0420, catalyst system efficiency for bank 1 is below threshold. After it started doing the whole hesitation thing i saw the light flash so i got the codes pulled again. It still threw up P0420, as well as P0300 multiple random misfires, and code p0410 a malfunction exists in the secondary air injection system.

I replaced the spark plugs a few days ago with no change in performance (not a surprise, the ones i pulled out looked fine)

Sorry if the post is kinda long, but i want to make sure I get this right.

Any other info that may help:
The car has 232k miles on it. I don't know if the engine has that many on it but I can't be sure.
Fuel Pump was replaced in 02 @117k miles
The cat was replaced in 04 @147k miles
The coil was replaced in 02 @117k miles, then again in 03 @142k
Getting pretty bad mpg , average about 13

 

Just my 2 cents P0420 might be due to a plugged cat that would also cause hesitation. I dont think it would cause misfires and secondary air issues.

 

While it is possible that this is being caused by a plugged cat, I would first clean the MAF sensor and see what that gets you. If the problem persists, pull one of the upstream O2 sensors out completely and drive it. If the problem is gone or greatly reduced, then the catalytic converter is plugged and will need to be replaced.

 

Backfire/hesitation is often caused by a stuck EGR.

 

Just an update on things. Turns out I have a bad distributer and a bad air pump. Going away this weekend so I won't have time to work on it but I'll let everyone know how it goes next week. Luckily (kinda) I also found out thecause of some other problems I'm having. I filled the coolant when I changed my oil and it was empty after about a week. There is a leak coming out of the lower intake manifold gaskets. Going to take care of that when I do the other work. Also found out my A/C has a leaking Schrader valve, but that will be for another time when my funds build up again[sm=smiley17.gif].

 

Okay, I need some major help. So far I have replaced lower intake gaskets (were leaking, seems to be fixed), the entire distributor , plugs, wires, battery and the pump half of the air pump. After doing all of this I still noticed yesterday morning and this morning the car slightly backfired right after I started to drive it, but there wasn't very much of a loss of power. The check engine light didn't come on yesterday(which was the day after I replaced the wires) until i was on my way home later that morning. The car was running fine but about ten minutes into my drive I was stopped and the car idled rough very quickly, which is when the light came on. Had the codes pulled and it came up as secondary air injection system and catalyst system efficiency for bank 1 is below threshold again.

I have already brought the car to two different shops. The first place told me the distributor and air pump were bad I replaced them both and then had to have them redo the distributor because I didn't put it in correctly. When the engine light came back on while I was driving home they pretty much said they didn't know why. At that point I took it someplace else because I didn't want the first shop working on it anymore and was told the wires were causing the backfires and that i was only getting 50 fuel psi which was causing the loss of power. They wanted about $250 for the wires and a little over $1000 for the fuel pump/filter so i just picked up my car and did the wires myself. As for the fuel pump I can bring it to a dealer to have it done for about $800( which I know is still more then I should pay) but I want to try and do just the filter first myself and measure the psi to see if it is low because the first shop said it was fine. Will any gauge that fits onto a Schrader valve all the way work or does it have to be specifically a fuel pressure gauge?

And as for the codes I'm getting now what's the best way to figure that out? I pulled both upstream O2 sensors before and I'm guessing that was not the right thing to do at all because the car wasn't able to run very well at all when I did.

Any insights will be greatly appreciated, and again sorry for the long post. I just want to get this all fixed so I can start doing fun mods.

 

Have the codes read at your local Autozone or Advanced and post the actual codes (Pxxxx) here. We'll work from there.

You should use a specific purpose fuel gauge as gasoline may harm the seals in a gauge not made to handle it. You need 55-60PSI to run and during operation of the vehicle, the pressure should never drop below 50psi.

Try this stuff and let us know. Good luck!

 

P0420, catalyst system efficiency for bank 1 is below threshold.
p0410 a malfunction exists in the secondary air injection system.

Same as were up before.

 

When the shop so nicely replaced the air pump, did they happen to replace the two check valves in the lines? If the pump was truely replaced, then you should no longer be getting that code. I'm betting that they really didn't do the work that they told you they did.

 

Actually I did the air pump with one of my friends. All we did though was replace the actual pump part of it. The old one was in pretty bad shape, all the fan blades inside were completely melted together. On the other half it was a little melted but we made sure all the airways were clear before putting it back together again. I imagine if we did something completely wrong one of the two shops should have picked up on it.