Chevrolet Blazer 4.3 Misfire Under Light Load 2000 – 2500 RPM

27 May 2015 | Author: | Comments Off on Chevrolet Blazer 4.3 Misfire Under Light Load 2000 – 2500 RPM
Chevrolet Blazer

Misfire Under Light 2000 #8211; 2500 1996 Chevrolet Blazer | 4.3

Chevy Blazer

This study is on a 1996 Chevrolet with a 4.3 V6. The complaint on this was that it had a misfire that was bad to make the tach jerk. I this SUV for a few miles with no Fuel trims at idle and at were in a fairly normal range of -5 to +9.

The truck actually ran good. Idle was as smooth as I expect. It didn#8217;t miss a even while power the engine. A P0300 was stored in codes.

The freeze frame did not show any that was out of normal range. history showed misfires on all cylinders with the majority on 3 and the next large chunk on 4.

A visual inspection showed new spark plugs, spark wires, ignition cap, and have been installed. information from the customer that the truck misfired the in drive, not overdrive, at light to cruise around 2000 rpm to rpm. The next test indicated that he was right and it was repeatable. Anything outside range and the misfire went

 During the misfiring event 3 was the worse followed by cylinder 4 a few misfires on the other cylinders. order on this engine is You can see that #3 is right after #4.

the misfire event, all the data was normal. Even the fuel were on the money. The only pid that was a little off was the cam retard.

Typically on the 4.3 liter engine I see a cam around -11 to -12. This was at -14 with an occasional drop to I graphed this pid on the Tech 2 the misfire even and it stayed steady at -14.

Now most of the when I have a worn gear or cam sensor that is problems, I will also see the cam jumping all over the place. the cam retard hold steady and no DTC Cam/Crank Correlation code, I to move on but none of the other gave me any reason too.

Chevrolet Blazer

Tech Tip: If your cam is off to far you will set trouble code DTC Crank/Cam Correlation. The 5.7 and other V8 have an adjustable distributor.

you move the distributor you do not effect timing on this platform but how far the spark has to jump from rotor to distributor cap cylinder The 4.3 engine#8217;s distributor is not adjustable and is in place. On the V8 engine, you should try to the cam retard as close to 0 as possible.

You can watch the scan tool cam pid as you move the distributor. The engine has to be 1000 rpm for the cam retard pid to update and be

1996 4.3 Worn Distributor

I decided to research these before I moved on. My research that a cam retard outside -12 caused misfire on cylinders 3 and 4. I the cap and check the rotor play. wasn#8217;t much rotational but there was a lot of back and forth

With the distributor out and disassembled you see the wear on the upper seal, top or bearing, and also on the shaft. The gear only had slight With the new distributor lock in I checked the cam retard which was at -12.

Chevrolet Blazer
Chevrolet Blazer
Chevrolet Blazer
Chevrolet Blazer
Chevrolet Blazer
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