0 to +/-2 degrees at the most to prevent crossfire, measured at 1,000rpm.

 

Snap throttle above 2000 RPM and back to idle, (must be done before and after each adjustment) should be zero degrees + or - 2 degrees.

 

Well I haven't been able to get the truck into a garage for the retard check, but something I'm noticing now is that the check engine light will randomly reset itself, shut off the light and clear the computer, just as if you cleared it with a scanner. Any ideas Hook?

 

On some of the older models, the throttle had to be snapped above 1000 rpm and back to idle, but on your 1998 Jimmy, the throttle must be snapped above 2000 rpm for the camshaft retard reading to be accurate. As mentioned, the desired spec is zero degrees, although plus or minus 2 degrees is still considered within spec. Among other things, correct camshaft retard helps prevent crossfire inside the cap, which is a known issue on this engine.

When you take the vehicle in, have them check for distributor shaft bushing wear BEFORE they check/adjust camshaft retard. By far the easiest, fastest and most accurate way to check the bushings is done with a scope, set on primary ignition, in the raster mode. To a trained technician, excessive wear sticks out like a sore thumb.

Most DTC's will clear themselves out, and turn off the SES light after a given number of drive cycles if the problem is not present. Some take longer than others to clear, it just depends how the PCM was programmed for each individual DTC.

 

well ive got some more info, ive got misfires on 1 and 4. and my camshaft retard is off by 15. and the mechanic i brought it to doesnt know exactly how to adjust the retard. so how do you do it.

 

Loosen the distributor hold down bolt and rotate the distributor until camshaft retard reads zero + or - 2 degrees on the scan tool. Snap the throttle each time before checking cam retard. The hold down bracket limits the amount you can turn the distributor, if you can't get it within specs, the distributor must be removed. Then remove and discard the original bracket and install a small block Chevrolet hold down bracket, ($5) and reinstall the distributor. If you're at 15 degrees now, you might be able to get it back into specs without replacing the hold down bracket. As long as P1345 is not in memory, (SES light on) the distributor is meshed properly with the camshaft. If the camshaft retard is off ~27 degrees or more, (one tooth or more off) P1345 will set. Might want to print this out and have the tech look at it.

EDIT: Cylinders 1 and 4 are 180 degrees opposite on the distributor cap, (firing order). This could very well point to worn bushings. Have them check the distributor bushings as outlined in post #44.

 

Alrighty then, I will see if I can have that taken care of, we did a camshaft sensor relearn and such not and ive drivin about 45 mi. a mix of 55mph, 45 and 35. I have not had the light come back on. But ive only been able to get the comp to clear 1 of the 4 not ready codes for nys inspection. so ive got more driving to do. Is it possible to adjust the retard from the scanner?

 

The scan tool tells you where camshaft retard is set, that's all, the adjustment is done by rotating the distributor. When you say you did a relearn, the only relearn is for the crankshaft position sensor, and after it's done, nothing special needs to be done as far as driving. When you clear the DTC's, you need to perform the General Motors Driving Cycle to force all of the monitors to run and complete their tests.

 

Well Captain, the problem is solved. It was something to do with the camshaft position. After I did the relearn, I haven't had a problem with the truck since, no misfire, nothing. I still couldn't get the not ready/incompletes clear for NYS inspection. So what I did was I unplugged the battery for 10 mins. Drove it for about 15mi at 70MPH, stopped and let it idle for a few minutes in the drivethrough so I could get lunch, then drove back to where I came but going 55, 45, 35MPH through town, got to the inspection shop and the codes were set for inspection. What I'm thinking is maybe the firing order for the Safari 4.3 might be different then the Jimmy 4.3? so the ECU had to adjust to the Safari motor in my Jimmy?

 

The Safari 4.3L is the same engine, same firing order, same parts as the Jimmy 4.3L engine.

I didn't realize this was a different engine, maybe I missed that in an earlier post, but it all makes sense now. After the engine was changed, the PCM continued to use crankshaft position sensor sync data from the original crankshaft position sensor relearn. With the new engine, both crankshaft and camshaft position sensor data is now skewed. The PCM "assumed" the crankshaft sync data was correct and made adjustments to ignition timing, injector timing and pulse width, EGR, etc etc according to the data it was receiving. Bottom line... junk in, junk out.