98 z71 need help guys

[jerry mize]

I have a 98 5.7 vortec 4x4 it's my baby love this truck its developed a strange issue though and I cant seem to pin point it truck still has lots of power no bogging or anything but has miss fire code and bucks and constant rpm or when towing under easy or hard throttle does fine though ? Any suggestions ? Thanks for the help

 

[east302]

What is the code...P0300 or one for a specific cylinder?

One possibility is a restricted catalytic converter (or both of them) but that is usually the result of another issue. Here are the pressure test diagnostics for testing the converters...

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[jerry mize]

Thank you sir its showing random misfire and cam correlation but timing seems to be dead nuts

 

[east302]

Is that P1345?

That usually comes when the distributor is removed and the crank/camshaft offset is not reset. Using a scanner, the CMP Retard is set to zero degrees (plus or minus 2) at 1000-rpm. That is a separate value from the actual timing which is set by the computer.

The distributor hold down bolt is loosened and the distributor rotated until the correct offset is read.

If the distributor hasn’t been touched then the code could come from a worn timing chain/gear, damaged distributor gear or bad CMP or CKP sensor.

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[Mark Gilbert]

Just a head's up, there is a way to use torque pro and a cheap ELM327 scanner to read crank/ cam correlation.

Cheaper than paying someone with a scanner and nice to have the tolls at home for other things..

 

[jerry mize]

Thanks guys I just order a double row timing chain set and a distributor to be safe old trucks got my heart strings bout time it went for the wallet lol

 

[jerry mize]

Thanks for advice on scanner also 15 bucks on Amazon hell that's a no brainer

 

[PlayingWithTBI]

Almost sounds like your ICM but I don't know if it'd throw a misfire code?

 

[east302]

Thanks guys I just order a double row timing chain set and a distributor to be safe old trucks got my heart strings bout time it went for the wallet lol

Save your existing distributor hold down bracket. Some of the new distributors come with a bracket attached which does not allow adjustment for the CMP offset. Pop the new one off in that case.

 

[east302]

Thanks guys I just order a double row timing chain set and a distributor to be safe old trucks got my heart strings bout time it went for the wallet lol

Save your existing distributor hold down bracket. Some of the new distributors come with a bracket attached which does not allow adjustment for the CMP offset. Pop the new one off in that case.