Scanner that will read CMP?

[danielliz]

Hi everyone ive been scratching my head for a while trying to get my truck to run right. I got a 2000 tahoe 5.7 z71 and i got a high idle. I had to move the distributor 180 degree and i havent been able to get it within +/- 2. I also got a P0102 code so ive been trying to figure why as well.

Is there a scanner that can read CMP? wether that be app or a hand held. I got an IOS so something for that would be good, but preferably a hand held would be better to me in my opinion. Thanks in advance!

 

[east302]

I’d resolve the P0102 code as that deals with the MAF sensor. Don’t swap the sensor out just yet, GM published diagnostic tables for all codes so it could be something else. They hiked their prices and their format is worse, but alldatadiy.com has this information and is subscription based. They just copy the GM manual into a digital format so that it’s easier to navigate, but you can still get the original manuals on eBay and the like.

With that in mind, take a look at the later model PDF manuals available here as I doubt that much changed in those last years from 98-00. They’ll have the same charts (and it’s free)…

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

To the CMP Retard question, I used DashCommand and CarGaugePro maybe five years ago with an OBD Bluetooth adapter made by BFX. At the time, neither worked on an Apple so I bought a $30 android tablet from Walmart which sufficed with a few select cuss words and a lot of patience. You had to buy the extra PIDs for either app at the time, so I’m sure it’s the same now. Nothing ever goes down in price.

The adapter and tablet have long since bit the dust, but it got me by at the time. A used Snap-On or GM Tech2 would be a significantly better bet if you’re going to keep the truck for a while.

 

[danielliz]

Thanks for the suggestion! I was hoping i could find a good manual to reference since we have 3 gmt400s in the family.

Yeah i’ve been thinking about just getting an android tablet just for that since it’s the easiest thing to do, but having a snap on scanner wouldn’t be so bad either.

 

[Vanishing Point]

Again depending on your finances and what you want the handheld scanner to do?
May I suggest AUTEL's MS906BT, which also does many things like reads OBDII 1996-2021 Foreign/Domestic Auto/Truck, of which I purchased a year ago, to use on my own OBDII 1996 Chevy C2500! Although a little pricey, ($1300 clams is what I payed from a reputable designated official seller) (but cheaper than a Snap=Off) I think you'll find what you are looking for here in this unit, to do what you need it to do. Good luck on your decision, and do let us know what happens.

 

[Schurkey]

I thought I replied to this thread. Guess I didn't hit the "Post reply" button.

My "Snap-Off" scanner cost $350 shipped to my door. Software capable of Domestic and Asian from 1980 1/2 to 2006. Came with scan tool (Solus Pro) cables, a few OBD-1 connectors, an OBD-2 connector and personality keys, owner's manual on DVDs, power cords, battery, and charger. All in a suitcase to carry it around in.

Depending on vehicles, connects to and communicates with Engine, Trans, Instrument cluster, ABS, Traction control, Air bags, and pretty-much anything else on the vehicle that's computer-controlled. The one thing it won't do that I'd find useful, is chatter the ABS valves for the "ABS Auto-Bleed" on my '97 K2500. It will auto-bleed my '03 Trailblazer. Newer Solus Pro software will auto bleed the '97, however.

God bless eBay.

 

[1998_K1500_Sub]

I checked (or, "tried to check") my CMP today using a scan "tool" that I've had since about 2005, "AutoTap".

AutoTap displayed this:

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Does the value "4091.2 Deg" make any sense to anyone or is this just garbage? I expected a small number... like "1" or "13".

(edit) I seem to have found an answer, here. AutoTap doesn't display CMP Retard properly:

AutoTap - Set timing?

I want to set timing on my 99 383. I have the AutoTap with the GM Enhanced parameters. From what I can tell I need to look at the "CMP Retard" readings but it says "4080". Anyone familiar with this? Thanks

www.tahoeyukonforum.com

My guess is AutoTap is mis-interpreting the binary value read from the ECU and is adding 4096 to it. I'll have to experiment.

 

[1998_K1500_Sub]

I was using AutoTap 3.1 on my laptop today to adjust CMP Retard on my 1998 Suburban L31.

As I mentioned above, AutoTap 3.1 displays the CMP Retard values incorrectly. However, I've discovered how to interpret its values.

For positive values of CMP Retard reported by the ECU, AutoTap 3.1 displays them fine, e.g., "1.2".

For negative values of CMP Retard reported by the ECU, AutoTap 3.1 displays values near 4096, i.e., "4088.2". Odd, right? Read on...

The reason: AutoTap 3.1 software is mis-interpreting the binary values for CMP Retard that are reported by the ECU.

Here's how to make sense of AutoTap 3.1:

If AutoTap 3.1 displays a value less than 2047, the value displayed by AutoTap is correct. Typical values are probably less than 31. If 1.2 is displayed, that value is correct. Adjust the distributor so the value is close to zero.

If AutoTap 3.1 displays value greater than 2048, subtract 4096 from the value displayed to get the actual (negative) value. I.E., if 4088.2 is displayed, the actual CMP Retard is -7.8. Or, don't bother with the math, simply adjust the distributor so the displayed CMP Retard value is very close to 4096 (which means the Retard is negative and close to zero).