Vortec 7.4 rough idle

[Seannn92]

I’ll try it. What should I be looking for? Better idle or worst? Thanks

 

[Supercharged111]

The misfire to be gone.

 

[Seannn92]

Tried it and no difference plugged in or not plugged in.

 

[Seannn92]

Update: tested the egr valve per this website https://easyautodiagnostics.com/gm/4.3L-5.0L-5.7L/egr-valve-tests-2 and it showed below the 0.6-0.9 ohm range it’s supposed to be at, it was around 0.4-0.5 ohm. Every other test on it checked out fine. Truck has always has a little tapping noise around 2000 rpms which I figured was a tiny exhaust leak but I noticed the egr valve is kinda noisy and could be making the engine noise that I hear. I’m leaning towards the rough idle issue not being distributor related and probably airflow related to egr or something else. As I mentioned before, acts like a vacuum leak at idle but runs smooth otherwise.

 

[454cid]

You can unplug the cam sensor and run without it. Truck will batch fire the injectors and run just fine. Good way to eliminate that.

I knew the MAF could be unplugged, but had no idea about the cam sensor.

 

[Seannn92]

The misfire to be gone.

Update: I swapped distributor gears and put the old distributor back in as well as changed the EGR valve. It’s maybe a little better but basically the same rough idle. I’m thinking I need to get the new crank sensor relearned. I’ve read places that 98 and older is set with a driving procedure.. 55mph for a period then 45. Does this sound right?

 

[Supercharged111]

Never heard of any way other than a scan tool.

 

[Seannn92]

Never heard of any way other than a scan tool.

I found the thread on this forum. https://www.gmt400.com/threads/case-learn-or-crank-relearn.6423/ I’ll give it a shot. I definitely need a scanner to set the cam retard. I’m gonna try using car gauge pro or the dashcommand app. Just trying to save a trip to the stealer!

 

[Supercharged111]

Can't blame ya there, let is know how that works out.

 

[Seannn92]

No luck on better idle. I’m thinking I must still be off a tooth. Given that the crank and cam sensor has been disrupted, that maybe why I’m not getting the p1345 code. Also, when I point a timing light at the damper it’s firing several degrees before the mark. I know timing lights are not useful in setting time on these but shouldn’t it be firing on the mark?