Howdy HHR Folks,,,, It been a while I've not bugged Ya'll,,,,mainly because my2006 HHR has been performng Many Wonderfuls,,!! About 3-4 weeks ago, I noticed the engine running rough and my Son, who has lots better hearing than me, told me he could hear a vacuum leak around the power brake booster,,,? My Son had a new Zurich ZR13 scanner and it told me the MAP sensor was a "probable" culprit, so I replaced it with a known GOOD one but engine still running rough. I could not hear chit but the brake pedal would sometimes go almost to floor! After a close call, I decided to investigate and with a can of carb cleaner, I finally found a sure enough LEAK in the power brake booster area and Dang if I didn't dread getting to the booster as GM did a dang good job of HIDING that thing WAY back there,,behind all kinds of other parts and pieces,,,,,!! Well, after 4 HOURS of removing what seemed like half the engine electrical parts, I got the brake booster out and replaced it,,,THEN,,the real job began of putting everything back like it was. Well, The engine fired up the very first time and ran like a new sewing machine. I was SO proud of "me"! BUT,,,,on the shake-down test the trans had some very harsh shifts and just seems to be getting worse,!! Does not slip between gears but sure does "jerk" now when shifting in ALL GEARS,,,,
Anyone got any kind words of wisdom,,,?? I tried some youtube videos but most of them say "change oil and filters" but that don't make sense as it was perfect before the booster change-out,,,??

 

Why didn't you suspect the easy place for a leak first? The valve where the vacuum hose connects to the booster.
The obvious thing to suspect is the TCM and/or the ECM got some pins bent or pushed out the back when reassembled. Or, as is typical, the fuse box didn't get fully seated; the bolt need to be tightened until it clicks, way past where you think it is tight.

 

Check the TCM connector for loose or bent pins
Check the MAF sensor is connected firmly.

 

Hey DonBrew,,,you have absolutely NO IDEA how bad I wanted the rubber seal at the power brake booster to be the culprit,,,!!!! LOL,,!!! I sprayed carb cleaner on it and engine never showed to be gulping some of that high test,,ALTHO,,,when I moved the carb sspray around to the rear of the booster,,,MAN,,the engine started to accelerate pretty dramatically,,!!! I let her rest a bit to come down on RPMs and then hit her again and she took off like a striped cat,,,,,,I DID NOT want it to be the booster but thas how you learn,,,,ha., ha

 

Hey OldBlue and DonBrew,,,you Guys are KING FOR A DAY,,,,you see,,I DID have a lot of trouble getting those two wiring harness connectors to the ECM, but they didn't have the center bolt but a kinda of a rube goldburg affair that had a plastic cantilever that "pulled" the connector down onto the ECM connector,,,The plastic pins that pull the connectors together were kinda stripped,and would not pull the connectors together. So, I whittled on the plastic pins with knife and a DRILL BIT till they freed up and would move to lock thw two halves together,,, After that doctorin,,all three of the cconnectors would slide together and lock. Took thwe car out for a test run and is lots better but still has a touch of harshness. Now, I had the battery disconnected for bout three hours and prolly did reset the ECM, so maybe it is just re-learning it's duties,,,drove it around at Stop & Go and gettin better all the time.
Say,,I got a couple of sixers of Black Label in the fridge outside if ya;ll wanna come sip a few,,,!!
Many thanks to both of you,,,,,!!! Joe r

 

Is there a Check Engine Light (CEL) on that you forgot to mention ?
Certain CEL's can cause hard shifting like you have. It's the computer's way of telling you to have the car checked for the cause of the CEL..

 

You’re welcome Joe! Double check those connectors maybe some dielectric grease to free them up.
Keep it clean and drive it often!

 

If all of the pins are engaging the lever shouldn't have any resistance. You should be able to just place the connector and move the lever.