Mechanics

CHEVY

2002 Chevrolet Blazer

Engine Performance problem
2002 Chevy Blazer 6 cyl Four Wheel Drive Automatic 103500 miles

my 2002 blazer has engine light on and had it checked out and it came out as p0304 and sometimes p0300 the wires and sparkplugs were changed fuel filter, pvc valve coil, gas cap, and still gives me the same code I was told to do a compression test and I did only on one side though and the numbers came out to be very similar on the side that the #4 cyl is can you help me out I'm going nuts. The car seems to ride pretty smooth the tachometer doesn't fluctuate at least to my eye.
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Guz0181
November 12, 2008.




Try taking out crankshaft position sensor and cleanig .. your getting in intermitent misfire @ 4 cyl

this is 4.3L engine


http://www.2carpros.com/forum/automotive_pictures/266999_GraphicCAS371KE_1.jpg



this is 2.2L engine


http://www.2carpros.com/forum/automotive_pictures/266999_GraphicCAPN82AV_1.jpg


Dave H
Nov 12, 2008.
Dave H; Thanks for the advice on removing the CKP Sensor, I did what you suggested and for a lil while I thought that it got fix but I thought too soon the same p0304 code came back. Now I'm really stunned and not knowing what to expect, anything else comes to mind. I really appreciate your advice any more suggestions : )

Thanks

Rick
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Tiny
Guz0181
Nov 13, 2008.
Because you said you thought it might have worked i looked TSB's for you .. this could be interesting ..

Information on Engine Misfire MIL/SES Light Illuminated or Flashing DTC P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, P0420 or P0430
TECHNICAL SERVICE BULLETIN
Reference Number(s): 06-06-04-046, Date of Issue: September 12, 2006
Affected Model(s):1999-2007 Cadillac, Chevrolet, GMC Full-Size Pickup and/or Utility Trucks; with 4.8L, 5.3L, 5.7L, 6.0L or 6.2L VORTEC GEN III, GEN IV, V-8 Engine (VINs V, C, T, Z, B, 3, M, 0, J, R, U, N, Y, K, 8 - RPOs LR4, LY2, LM7, L59, L33, LC9, LH6, LMG, LY5, L31, LQ4, LQ9, L76, LY6, L92); with Active Fuel Management(tm) and E85 Flex Fuel

Related Ref Number(s): 06-06-04-046
ARTICLE BEGINNING
SERVICE INFORMATION
If you encounter vehicles that exhibit the above conditions, refer to SI for the appropriate DTC(s) set. If no trouble is found, the cause may be due to an ECM ground terminal that has corroded with rust over time. Inspect the main engine wiring harness ground terminal (G103) for this condition.
The wire terminal (G103) attaches either to the front or to the rear of the right side cylinder head, depending on the model year of the Full Size Pickup and/or Utility Trucks. If the ECM ground terminal has been found to be corroded, then follow the service procedure outlined in this bulletin to correct the corrosion issue.
Fig. 1: Engine Wiring Harness Ground Terminal Location (2007 Full-Size Pickup and/or Utility Trucks)
Courtesy of GENERAL MOTORS CORP.
Fig. 2: Engine Wiring Harness Ground Terminal Location (1999-2006 Full Size Pickup and/or Utility Trucks)
Courtesy of GENERAL MOTORS CORP.
Remove either the nut or bolt securing the main engine wiring harness ground terminal (G103) to the right cylinder head. Refer to the above illustration to determine where the ground is located on the vehicle (1).
Remove all rust from the ground terminal, the cylinder head and the retaining nut or bolt.
Position the main engine wiring harness ground terminal and install the nut or bolt.
Tighten:: Tighten the retaining nut or bolt to 16 N.m (12 lb ft).
Apply some type of electrical moisture sealant to protect the harness terminal from further corrosion.


http://www.2carpros.com/forum/automotive_pictures/266999_ground_1.jpg



ENGINE RUNS ROUGH, SERVICE ENGINE SOON LIGHT ON, DTC P0300 OR P0335 SET (SHIM CRANKSHAFT SENSOR)
TECHNICAL SERVICE BULLETIN
Reference Number(s): 02-06-04-059, Date of Issue: December, 2002
CHEVROLET:2002-03 Astro, Blazer, Express, Silverado, S-10 with 4.3L V-6 Engine (VINs W, X - RPOs L35, LU3)
GMC:2002-03 Jimmy, Safari, Savana, Sierra, Sonoma with 4.3L V-6 Engine (VINs W, X - RPOs L35, LU3)
SECTION:06 - Engine/Propulsion System

Related Ref Number(s): 02-06-04-059
ARTICLE BEGINNING
CONDITION
Some owners may comment on a rough running condition or a Service Engine Soon (SES) light being illuminated. Upon investigation, the technician may find a DTC code P0300 or P0335.
CAUSE
The crankshaft sensor may be contacting the reluctor wheel.
CORRECTION
Remove the crankshaft sensor. Refer to the Crankshaft Position Sensor Replacement procedure in the Engine Controls - 4.3L sub-section of the Service Manual. After removing the sensor, inspect the end of it for witness marks that would indicate contact with the crankshaft. If contact with the reluctor ring is indicated, then inspect the front cover for cracking or other signs of alignment concerns. If the inspection indicates that the cover is causing misalignment, replace the cover. If replacing the cover, then the 0.5 mm shim is not needed.
If the inspection of the front cover indicates that the cover is not the cause of mis-alignments, then the sensor should be shimmed. Add one shim between the sensor and the front cover. If the concern still exists, then add the second shim. Unless the sensor has been rubbed through the casing or deformed by contact with the crankshaft, it should not be replaced.
In either case, the crankshaft relearn procedure should be performed after any repairs.

Dave H
Nov 13, 2008.

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