I am greateful for the lecture, I feel like I'm learning quite a bit here! I did find a vacuum leak last night and after I capped it off (line to reservoir) took some more scans and the values (stft) are between 0 and like 3 now, I can post them if you want, but like you said, it wont mean much until I can disqualify ignition/ fuel systems. It was an interesting lab, so to speak. The truck is running better, but I can't stop until I've checked the other things this weekend. Once again, I thank you, this is much more fun with some experience handed to ya!

 

I will check to see if I can use my scanner for Cam retard adjustment, but I'm gonna get the aformentioned set-up as well. I'll post results as soon as I get'em!

 

One thing about Car Gauge Pro you need to know is that in this software the PID and module list is not filtered at all by year and vehicle and option, so if you buy it don't be surprised or peeved when you run across things listed that it will not do. Just accept it for what it can do on our Blazers, which is a LOT (but pretty much mostly limited to Powertrain things). It does a lot more on Fords and this is illustrated by showing live data in systems like ABS and airbags on my 2008 Ford Ranger pickup. It even is reported to do injector buzz testing on Ford Diesels. It's kind of a try and see app and there is pretty much zero documentation/instructions so you need to be a bit tech savvy. Remember this app is only $8! I can personally guarantee that it works well for powertrain on OBD2 Vortec V6 and V8 engines at least through 2004 and that it does Cam Retard. In Car Gauge Pro You need to select the Cam Retard PID with the single asterick - that is the PID selection that matches Cam Retard on my Scan XL Pro and HP Tuners softwares when reading the same vehicle.

Torque Pro is a much slicker app and less confusing, and displays most Powertrain PIDs for the Blazers - but it does not display Cam Sensor Retard.

Good luck! if you have any trouble using Car Gauge Pro just ask.

 

I'm going to take a few steps back on this, but wouldn't a worn distributor gear cause the PCM to increase timing? The slop should remove mechanical advance timing and cause the rotor to be farther behind where it would have been. This wear would just cause a small power loss that the PCM would either acount for with a timing advance or else just leave it alone. I guess I'm looking for a reason why it would be of major concern besides erratic timing.
I only ask because I'm starting to wonder if I'm having some sort of symptoms of a distributor gear and I just want to understand the reason why it is such an issue with these engines and I have not seen it mentioned anywhere but here. The amount of slop seems to be the same as the other engines I have that use a distributor. If there was no slop at all, it would be very difficult to get the distributor and cam to engauge eachother without some amount of clearance.

 

On an OBD2 Blazer (not necessarily limited to) the crank sensor sends signal to the PCM. PCM determines the timing of when to activate the coil. Distributor and distributor gears and rotor position have zero to do with ignition timing here, but if rotor is not correctly positioned to complete the circuit when the coil does fire then you get a misfire. A worn distributor gear can cause the rotor to not be in the correct position, since the distributor position is locked in place by the factory hold down. The only way to check correct rotor position is by checking cam sensor retard.

Other engines have a distributor where an internal pickup coil is involved in generating base timing. In this case, if the gear wears some you turn the distributor to set timing to correct for the wear. The other case is if a late model engine has multiple coils (one for every 2 cylinders) a distributor is not needed at all and this issue goes completely away.

I just helped a guy in another forum fix his Vortec V8 - distributor gear wear was a problem for him, plus he had put a regular hold down on and was trying to depend on lining up the mark on the housing with the rotor visibly.

 

Just a small update here. The truck has ran well since my last post. I plan on replacing the vacuum lines mentioned earlier on Sunday. I have ordered the BAFX adapter and installed Car Guage on my phone, as the adapter arrives Sunday, I should be able to play with it then. I do still feel a shudder as if buffeted by high winds still, but it doesn't seem as severe. can't wait to get the cam adjusted and watch some live data. Science, baby! lol.

 

use the CMP Retard labeled with the single asterick. You will see it after scanning PIDS for your vehicle.

 

Ok, got the scanner and adapter, found the correct pid. found out it's running -5.6 degrees. went to turn distributor and......how do I turn this distributor? Lmao,just when you think it,s gonna be easy. I'll search on here and find out whats happening, but damn......lol. I did get my door fixed and the vacuum lines replaced; so not a totally wasted weekend. What a cool app the Garage Pro is, glad I have it.

 

Did you mean Car Gauge Pro?

One of two ways....

1) modify stock hold down to give rotation
2) put an old-style hold-down on it.

You won't need much rotation at all to correct from -5.6° so I would spread and remove the original hold down from the distributor and take a file or grinder to the sharp corners that lock the distributor from turning in it. Distributor removal will be necessary in any case. Don't forget to inspect the gear, but with -5.6 I would not expect it to be worn much if at all. You can also take a little off the sharp corners in the distributor housing if you like. Just a smidge of distributor rotation will get you there. You will be surprised how little. If not enough, file or grind some more (next time you don't have to remove the distributor to get the clamp off). FYI I recently did mine while switching to the all-aluminum Skip White distributor and seemed to notice felt improvement (elimination of a part throttle lag in power that I always seemed to have after shift into second) just going from -3.0 or so to +0.5 during the change. Only reason I replaced entire distributor was because a distributor cap screw hole was stripped.

 

Yes, I did mean car gauge pro, lol. I'm impressed with it. Thanks for explaining the distributor hold down for me, sounds easy enough, but it'll have to wait until next weekend. I will post some pics of the gear when I do it, just for a second opinion....Thanks again!