nmex

I have just noticed the past few days that when I stomp on the gas from about 65 getting up to 80 it feels like the car is cutting out almost like it is not getting fuel and the bosst seems to drop off? When I ease up on the gas it goes back to normal? Could this be the loose clamps symptoms?

HHR_SS_QC

Definitely not good.. I think you should take the SS in for service, so they can take a look at it, and fix what's wrong.

VanB

I think I have the same issue. I've only had mine a few weeks so I wasn't sure if there was something wrong with the car or it was me. When I drive hard from a stop everything is great, boost stays in there at about 20 through the first couple gears (then it's time to get out of it because you're flying lol), but when I'm on the highway and choose not to down shift the 5sp to pass, just give it some gas and let the turbo spool up, it goes well at first 4-5 seconds, boost builds, accelerating quickly, and then it shuts down completely. It is very abrupt and sudden. Then just let off the gas some and easily accelerate and it's not like nothing happened. Not sure of the RPM-Boost numbers when it does this. I'm getting ready to take a long trip next week so I should be able to have the time and road to give a better description to the dealer when I take it in. I can't see it as a fuel issue as the car is a rocket when flooring it. I'd think it is more likely related to boost control ( BOV/waste gate issue/loose clamps). I'll post when I learn more. Good luck!

hyperv6

Mine is doing this from s dead stop or low speed.

We found the Map sensor on the lower tube hitting the AC compressor and poping the blow off valve.

I would build pressure the gate would pop and back to zero till I lifted off the gas and restepped on it.

Tuesday it goes in and they are going to move the intercooler forward to give me more clearance.

I have the stage kit so the Map is pointed right at the compressor.

Right now I took a old piece of roll bar padding and used it to give me some clearance. It is working but will rub through in time.

RocketBuSS

This could be a number of things. Anywhere from a bad MAP/MAF/VEBC to something stupid like an engineering mishap as hyperv6 experienced. Chances are its going to be something trivial. Without having the scan tool equipment to test voltages and duty cycles however, its probably better to let your friendly neighborhood GM warranty provider have a look-see. Unfortunately turbo motors in the hands of over paid engineers have become quite over engineered as well.

VanB

Okay, I've had some time to get a better feel for what is happening. It is intermittent. When passing on the highway, without downshifting, the car accelerates swiftly but when I slowly roll out of the throttle the boost will sometimes fall immediately to zero, feeling like the ignition cut off or something. Once at zero (and by then your foot is off the gas because you thought the engine died) the engine returns to normal operation. Can this be the BOV spring allowing for an abrupt boost loss? I love the car. It is a blast to drive and this does not happen a lot, but it is a bit unnerving. Any ideas? Thanks.

hyperv6

The two things to look for is the Tmap hitting the AC comprssore if this is happening from a dead stop or a over boost condition if it is going down the road. Some else has found overboost condition that is also doing this drop in pressure.

The engine is not over engineered but is a complex new system that is not fully understood by many mechanics yet as so many have yet to work on one. Once more people work on the mysteries will vanish. The same thing happened when the TPI engines arrived in the 80's and many said this is too complicated. Today it is no issue.

VanB

Thanks for the reply. Yeah, it may take some time for the little things to get worked out. I hope the learning curve does not diminish due to GM ending production of the SS model. This engine is too good to let it go away (in Turbo form). Perhaps it'll turn up in another model like the the Cruze. I'll look for the obvious things (interference and loose clamps). I have a Dejon BOV spring still in it's box. Not sure if I want to start taking things apart yet.

hyperv6

Loose clamps lead to hoses blowing off and no boost is regained.

GM has even better engines coming there is a turbo V6 with Direct injection and other advanced engines that will deliver about the same or a lttle more power but better mileage.

The key now for GM is to maintain power in the 200 HP to about 350 HP in smaler and lighter cars. Performance will be there but the mileage will improve as it has too.