Hi i am new to blazer forum i have two s10 blazer 94 & 01 have trouble with the 94 it is w code cpi 4.3 it lacks power at 30 to35 mph the rpm drops off to 0. When you let off the gas the rpm picks back up no ruff idle or missing have replace fuel filter & EGR vale have check plugs & cap need help.

 

When you say it lacks power. You mean its bogging down like its going to die when you press the gas?

 

Yes it bogging down but it does not cut off check codes found #44 o2 sensor we are going to replace it this weekend. When it start to act up you can only get up to 35 or 40 mph but you have to slowly give it gas or it will start bogging down & when you com to a hill will drop the rpm down. When we got it home & put in park you could bring the rpm up 2500 & it would do the same thing but let off the gas it idle just fine & rpm come back up. The plugs, cap, button is in good shape talk to the man it got it from he said that the cat had been replace about 8 to 10 years ago do not know how long they should last. The truck has 163,245 miles on it is 4x4 4 door with 4.3 cpi with automatic transmission i hope this helps Just to let you know after we replace the fuel filter & egr vale we drover it to put gas in it ran good about 6 miles away on the way back about 2 miles from the house it start act up hop you can help us.

 

Is this always at a given speed? Is there any dependence on a certain throttle position? or engine RPM?

 

So far it has been when you are trying to get up to speed seems like when you go up hills. Could the o2 sensor cause this problem i did find out it has had a fuel pump put on it about 8 to 10 years ago we are going to check the fuel pressure this weekend.

 

8-10 years ago is an eternity.

Sounds like it is load dependent. You can test the TPS sensor. The sensor return should be ~0.5V at closed throttle and ~4.5V at wide open throttle. The voltage should increase/decrease smoothly as you open/close the throttle.

Another sensor which could cause these symptoms is the MAP sensor. A search for "MAP+altitude" with an author of "swartlkk" should find the post where I detailed the method for testing the MAP sensor.

An O2 sensor may be at fault, but generally will throw a code. But the same can be said about some of the other sensors I mentioned...

 

Thanks i will check the two sensor out & let you know what i turn up.

 

Just to let you all what i found out check the fuel pressure when the key was turn on the pressure would up to 60 psi then you would hear a relay click and the and fuel pressure would drop to 0 psi. So we replace the fuel pump and check the pressure turn the key it went to 60 psi and when the relay click the pressure & it drop to 56 psi. Thanks for all the help on this right now the four wheel drive is not working right going to replace the vacuum actuator & vacuum switch and see if this will fix the problem with it.