Quick update - I cleaned out my air filter and my throttle body (had a bit of buildup) and it has oddly helped my double-blip issue but hasn’t fully resolved it. Double blipping now happens 50% of the time vs the 85% of the time it used to. FWIW I had the battery disconnected overnight in hopes of a throttle body “relearn”. I’ve only driven it ~15 miles since, so I’ll provide updates here if there’s any difference.

 

Changing the air filter won't affect the Rev Match feature. The ECM uses the gear position sensor to determine when to blip the throttle. The sensor is mounted to the top of the transmission extension housing. There is a gear position sensor magnet that is mounted on the shift shaft and it has to be in the correct position.

The Rev Match feature seems to be working so you don't have any Rev Match codes set that would inhibit Rev Match so the issue may be more alignment/wear related than anything else. Here is a page out of the FSM that addresses code diagnostics but may be applicable in your case. I have crosse out the areas that I think don't apply:

Several transmission P Codes inhibit Rev Match. They are related to sensor position, sensor voltages and sensor magnet placement. If you find any of these codes listed as history codes they might help point you to the area where the intermittent is occurring. If there are no codes then it is likely the problem is an adjustment issue.

Bill

 

Following up on the same issue mentioned at the beginning of this thread.

I had my clutch replaced due to an issue to what I thought was the pilot throw out bearing.

Before the clutch was replaced, the car had a really loud screeching / metal-on-metal sound when engaging first gear. Any time I’d put the car into gear and start to let the clutch out, it would make this awful noise right as the car began to move.

The shop confirmed they heard it too and said the slave cylinder/throw-out bearing assembly felt extremely tight when they removed it, which explains the binding and the noise I was getting. It was basically not engaging or disengaging smoothly, so the bearing wasn’t releasing correctly against the pressure plate.

That’s the issue that led to the full clutch replacement in the first place.


After getting the car back I’m now dealing with rev match acting up. Instead of the normal single blip on a downshift, it’s doing a double blip and making the shift pretty rough.

I’m starting to wonder if one of the clutch-related position sensors may have been slightly misaligned during the clutch/slave reinstall. Since the shifter has to come apart when installing an MGW, could replacing it and redoing the alignment potentially fix this?


Anyone seen this happen or had rev-match behavior improve after an MGW install?

Appreciate any insight.

 

I installed a MGW shifter in my Grans Sport. Great mod. BUT never had a Rev Match issue. I did have one issue a few months after the MGW install and contacted them for a solution. It occurred AFTER this Doc was made. I should have added, MY BAD
The shifter all of a sudden got sloppy. Turned out they had seen before. The issue is the silly way GM attaches the hollow shift rod to Trans (both OEM and MGW) to the shifter. See Pics on Page 19 and 27. No page # on the page BUT you can see above where it will say Page 19 of 45.

This is a DOC as PDF re my install, it's 45 pages but mostly detailed Pics:
https://netwelding.com/MGW_Shifter.pdf

Rather than a bolt holding the shifter and rod together they slip a bolt though a slot and the edge of the bolt holds the two together. Mine was slipping. Not back and forth but rotationally. I even purchased a new aluminum part in case when I tightened with more toque than recommended the treads stripped. I didn't strip the threads. I used their suggestion or roughen the shaft with rough sand paper. That worked, no problem for several years until I sold the Grand Sport and many aggressive shifts.


Used this product after on a striped screw head. Good stuff that they quote increases friction 800%. Probably would have used.



All shift detents, Hall sensors that define shift folks etc position are back at the Transmission, NOT in the shifter. So nothing bad would happen in the Trans with movement of the two parts, just a sloppy shifter feel! Same with Rev Match. The Hall Sensors that define shift level position are NOT in the Shifter they are back at the transmission. The shifter just moves the rod that goes to the Trans, back an fourth and rotates.

I did find one thing I had to stop doing which I have used for years. If downshifting from 5th to 3rd which I often did for turns I would 1st go to 4th with clutch depressed before moving to 3rd. Spools up the cluster gears. BUT the Rev Match logic assumed I was going to 4th. Worse, if in Neutral and I moved too far in the Neutral gate it way over revved thinking I was going to 2nd NOT 3rd. Others talked about it Over Revving and I suspect they were going to far in the Neutral gate, NOT going to 2nd BUT the Hall position Sensors were apparently anticipating that shift.

Bottom Line I stopped that intermediate move and just went to the gear I planned to use. Just my observations, not sure if any help to your issue.