My grandmother recently gave me her 99 blazer that I've been trying to get for years. It has had a turn up. I keep getting code p0300. It has a light pop at idle and almost stalls after reving it. I look at the fuel trims with my scan tool and it doesn't look right

 

We need short term trims, both banks as well. Get all four values at idle and again at 2500 rpm. Yes those numbers are a problem but lets get all 8 before we proceed but adding fuel usually means:

1. Injector issues
2. vacuum leak
3. Intake leak after the MAF sensor
4. Exhaust leak

Popping/backfiring is usually a timing issue. What is your CMP retard?


George

 

Here are the new fuel trims

 

Also i sprayed starting fluid around the engine when it was cold no change in rpm

 

These fuel trims are a mess. Are red values negative or out of bounds. IOW is every one of these values positive, even the red?

George

 

Yes they are positive. Red means they are way out of bounds. Scanner says normal range is -25 to +25

 

The O2 sensors are telling the engine computer to add fuel to the theoretical value based on sensor inputs, to keep emissions optimal.

1. Check for vacuum leaks
2. Check for intake leaks after the MAF
3. Check for exhaust leaks
4. On a cold engine in the morning grab the live data sensor values for ECT, IAT, Baro/MAP, TPS and the look up your local temp and barometric pressure
5. graph your O2 sensors
6. Perform the fuel pressure leak down test
7. Measure CMP retard

George

 

I change the distributor. New reading also fuel pre jumps to 60 then to 50 and leaks down to 40 within 8 seconds and keeps dropping. Also is the maf supposed to be giving a reading with the key on and engine not running











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How do i check the retard

 

Its back reading lean again