4.3 Trouble 2003
 

2003 S-10 Extended ZR2 190000 Miles
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When I got it a year ago it ran just ok and it got 15 MPG. It needed all the maintenance items. Plugs, wires, filters, ect everything was shot. I have had lot of 4.3s ( 10+ ) and this has always made them run great. This made no difference on this truck. The idle is ok but on the lousy side. It almost feels like a miss but has no misfires. Driving feels ok but has poor power. Today I tried to keep up with another S10 4x4 getting on the highway; it was not even close he passed me gained more than 100 feet in 5 seconds. It was just like my truck has the 2.2L. I pulled a 3500# boat with a 2wd 4.3 s10 to the lake and back on about ¾ tank of fuel. This truck burned a whole tank and had to be refueled 30 miles from home. I have made the trip also with a 4.3 2002 Asrto van full of people on much less fuel.
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The Cam Retard is -5 @ 1200 RPM and -4 @ 2000
If you listen very carefully you can hear what I think is the balance shaft rattle at 1800RPM while driving uphill. With a stethoscope on the timing cover it sounds good. The engine sounded fine while pulling the boat.
The distributor aligns with the number 6 mark at TDC as it should
It has no misfires and uses almost no oil.
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I love the truck but this engine trouble is driving me crazy.

I can move the distributor from -6 to -2. It is now at -2
Fuel pressure engine off is 59.5 with 0.5 PSI drop over 5 min.
It is 54 PSI at idle and jumps up as the throttle is cracked.

Adjusting the distributor from -<?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-comhttps://chevroletforum.com/forum/ /><st1:time Hour=5 to -2</st1:time> has helped. It has much better acceleration. 0 to 60 WOT is 14 seconds. I did not time it before however I would estimate 18-20 seconds. Is it a bad sign that I can not adjust it past -2?
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timing chain or gear?

Have the exhaust checked for a bad cat or muffler blockage. Does it store any codes?