Another story from the service bay

[Timmastertech]

Have seen that before. I use the lisle tool to pull the pushrods. If you buy reman heads for a 3.1/3.4 there is a sheet in the box stating to make sure the rocker arms are torqued with no load on them. I torque the arms and then install the pushrods with the lisle tool when installing reman heads. As far as diag goes, I start every misfire diag with a relative compression test, use either voltage or current on the scope. I do this because it takes 30 seconds before doing any other testing. I would then either hook a pressure transducer to a central vacuum port and take a cranking vacuum reading, or go right to in cylinder with a transducer to see whats going on. On cylinder 5 on an aztek I would look for a reason not to pull the plug so I would use a pulse sensor with an ignition sync and you would have seen the missing vacuum pull and with the sync be able to identify which cylinder (helpful for double checking that the misfire monitor is accurate). At that point, you are 10 minutes into diag and know that we are looking at cam/lifter/pushrod/rocker so you know what you will find when you take the engine apart

 

[P10crew]

CLine and rest of the shop!

 

[clinebarger]

Originally Posted by Timmastertech

Have seen that before. I use the lisle tool to pull the pushrods. If you buy reman heads for a 3.1/3.4 there is a sheet in the box stating to make sure the rocker arms are torqued with no load on them. I torque the arms and then install the pushrods with the lisle tool when installing reman heads. As far as diag goes, I start every misfire diag with a relative compression test, use either voltage or current on the scope. I do this because it takes 30 seconds before doing any other testing. I would then either hook a pressure transducer to a central vacuum port and take a cranking vacuum reading, or go right to in cylinder with a transducer to see whats going on. On cylinder 5 on an aztek I would look for a reason not to pull the plug so I would use a pulse sensor with an ignition sync and you would have seen the missing vacuum pull and with the sync be able to identify which cylinder (helpful for double checking that the misfire monitor is accurate). At that point, you are 10 minutes into diag and know that we are looking at cam/lifter/pushrod/rocker so you know what you will find when you take the engine apart

I just bar the engine over & torque the rockers with the lifters on the cam base circle. I don't work on enough 3.1/3.4 to buy specialty tools. I need to start using my Amp Clamp more, But still caught the uneven cranking compression by ear. I haven't invested in pressure transducers yet & don't really want to for the Snap-on Vantage Pro that I currently have. Looking seriously at a Pico Scope as we all know the resolution of a Vantage Pro is very poor compared to a Pico. I appreciate different diagnostic approaches & the first to admit I need to use technology more, But, It only took about 15 minutes to make sure #5 was in fact the low contributing cylinder by pulling the plug wire off the coil tower with a test light near by to catch the secondary, Which I like to see good arc at the same time. Then balance test the injectors which also checks fuel pressure & for a possible leaky FPR. An analog Vacuum Gauge is one of those tools I'll always use, It was a foundational tool when I first got into this field. It could be construed that it didn't tell me anything....But it did! A healthy 3.4L should produce at least 18 inches of vacuum, 18/6=3, 3-18=15. I was getting 14. The steady reading meant (to me) that the #5 Intake valve was sealing. To be honest....I thought I would find a broken exhaust valve spring! What scope do you use? And how do you like it?

 

[CKN]

The real story here is that somebody <span style="font-weight: bold">still drives an Aztec.....................</span>

 

[dishdude]

Originally Posted by CKN

The real story here is that somebody still drives an Aztec.....................

 

[bbhero]

That ain't you is it ???? ^^^^^^^^^^^^^^â„¢

 

[Timmastertech]

Originally Posted by clinebarger

What scope do you use? And how do you like it?

I have 2 original Snapon modises (Modi?) a Snapon Verus Pro, Pico 4425, Autel Maxiscope, original vantage plus a bunch of 1 and 2 channel scopes built into factory scan tools. I am a diag and electrical specialist. My go-to for quick grab and go is one of the original modises. For working with pressure transducers and anything that requires analysis the pico is THE tool. I use a WPS500x for in cylinder and general pressure testing and a firstlook sensor for pulse testing like looking at manifold vacuum waveforms. The only scope that never gets used is the Autel scope. I have that because I have to teach it for a company I teach for but its not one of my favorites.

 

[Number_35]

Excellent work, Cline. (Not unexpected from you, though.) Thanks so much for posting this - very interesting write-up.