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Discussion Starter · #1 ·
Like the title says I'm looking a the Solstice GXP. I want a roadster and something that puts down some good power so Miata is out. GXP styling is also very appealing to me. But I'm unfamiliar with their reliability.

I've had a n54 335i and that thing had great power. A JB4 tune and it ran 4.5 sec 0-60 while putting down around 350ish hp and tq @ the wheels. Run e85 blend and you're close to a 4 flat 0-60 and 400whp/wtq. Curb weight of 3400-3500lbs.

Unfortunately it had terrible reliability and was expensive to fix.

-Mosfets in the DME(engine management device) would burn out. If you could find someone to solder in new ones it might be a $300 repair otherwise a $1200-1500 replacement for the part.
-HPFP but that's warrantied for 10yr/100k otherwise $800-1000 for the part.
-Injectors. Usually have to replace a bank of 3 injectors if not all 6. $250-300 a piece. $1500-2k just in parts and they need to be coded which is $150 in cables and program if you DIY it.
-Wastegate rattle. 8yr/80k. Mine went out in warranty at 40k. Then those reaplcements went out at 85k. Turbos were $1200(a deal) and 10 hours labor to replace. Gotta drop subframe to access them. $1000 in labor costs.
-Waterpump. A lot seem to fail at 40-80k with no warning signs. $500 part but DIY is easy and maybe 2 hrs.

Even though I could do most repairs myself it was still apt to cost me at least $1k per incident. So while a Z4 sDrive35i is a consideration I'm looking to see if there's more reliable options.

From perusing some forums it seems the GXP could be more reliable and cheaper to own. Problems still persist though.
-HPFP. Mostly due to people running the tank under 1/4 frequently or does this happen randomly like the BMW? Part seems to be $300 and DIY is easy and might take 1hr.
-Waterpump. Prone to random failure like the BMW. Driven by timing chain? Does it require removal of turbo? Seems like a tight fit and a 5-7hr job? $280 for wp and gaskets isn't too bad.
-Engine block cracking/failure. Foam casting or something that leads to catastrophic engine failure. $2k for a short block or $2500 for long block but need to transfer pan and valve cover? How prone is this to happen? On Cobalt forums it seems to be mostly with 2008 models. Would 2007 Solstice be safer or a 2009? From the reposts on various forums it seems to happen at various intervals. Could be 10k, 30k, 70k or even 120k miles. This is obviously my gravest concern since it's a costly repair in both monetarily and time terms.
 

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Looks like you have it covered. The water pump runs under $100 for the pump. You must have a dealer pump priced? I haven't heard of many cracked blocks.
 

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I'll try and answer some of your questions, and hopefully those into engine modding will jump in. Also, check out Kappaperformance.com, as some of those guys are into performance also.

Generally speaking the 2.0 is a solid engine, solid enough that GM offered their own performance tune that kept the warranty intact. The engine's stock output is 260HP/260TQ.

GM Performance Tune (GMPP)
Solstice SKY HP & Torque ratings:
290HP @ 5,200 RPM
MT 340 lb,-ft of torque @ 3,600 RPM
AT 325 lb,-ft of torque @ 3,600 RPM

There's a couple of aftermarket tunes that pushes those figures further, though there has also been talk of a perceived lack of tech support since the platform has turned into an orphan. As far as how far you can safely push the HP (before things start going south), 400HP is often quoted as the farthest you should go. After that it is being recommended to start thinking installing stronger pistons and rods. There's also been discussions on ecotec internal engine changes, but I believe that applies to the 2.4s. I believe it had to do w/the first 2.4s had forged rods, while the latter had sand cast? Hopefully someone will jump in and clarify.

The waterpump is one of the Kappa's achilles heels, and I have read that the WP can be replaced w/o removing the turbo. And your right about WP fails, while some believe there was/is a design flaw there doesn't seem to a rhyme or reason when failure will occur. But if taken to the dealer to replace you're looking at $1200+. Some believe adding water pump lubricant helps prolong the life of WP seals (not the WP itself), so that is seen as cheap insurance to some and a waste of money to others.

The passenger seat airbag sensor is another sore point, avoid placing your knee or foot onto the seat cushion. The bottom pic shows why placing too much stress on the sensor can lead to its failure. For cheap insurance I have bought seat pads to both protect and remind myself not to put pressure on the seat cushions.
Top:


Bottom:


Failure (this is after I tried to delaminate and solder):


The HPFP has been discussed many times, along with not letting your gas go below the 1/4 mark. Some believe it others don't, but as far as I know there's never been any definitive proof low gas has lead to failed HPFPs.

I also maintain a low priced Sol thread, where I'm seeing cars w/150 plus mileage, however most of those are of the 2.4 variety, while I'm seeing 100K plus for the GXPs. so I'd say that's a fair indication of the 2.0 reliability.

For the most part I'd say the majority of Solstice owners are into cruising and using their cars for pleasure, while the minority are into wringing as much performance out of the 2.0 as possible. Hopefully a few of them will chime in and give you their opinions on how reliable the 2.0 is when pushed to its limit.

BTW, do yourself a favor and read this, especially post #13; http://www.solsticeforum.com/forum/f43/things-look-when-buying-75062/#post1121210
 

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Looks like you have it covered. The water pump runs under $100 for the pump. You must have a dealer pump priced? I haven't heard of many cracked blocks.
Welcome to the club! Don't be afraid of issues with these cars. They are great little cars, but not a Toyota Corolla nor Honda Civic either. I use mine as a 84-mile per day commuter, and it's great for that. Here are some of my observations. I know it will irritate some here, but that won't be anything new:

1. Shortly after I purchased my 07 GXP, I ran the fuel tank down to 1/8 a tank. The High Pressure Fuel Pump died shortly after. Limped the car home and replaced the pump myself having locating a pump from an on-line vendor for much less than the stealership. It's not a hard job to replace, just don't be in a hurry.

2. The day after my car went in for the dreaded ignition switch recall, my airbag warning light came on. I suspect the tech put his knee on my passenger seat, killing the seat sensor. It's an expensive repair, mainly because there are less of these new sensors on the market, combined with firmware differences between model years. Some on this site have tried to purchase the sensors from Europe (Opel), but have not reported any success in doing so.

3. There have been many reports of water pumps failing starting at 30,000 miles. I have used water pump lubricant in my car since shortly after buying the car and again after flushing coolant at 50,000 miles. I now have 78,000 miles on the original water pump. My theory is the lubricant helps save the seal from failure. You'll see massive amounts of anxiety about water pump failure on this forum, mainly because replacement involves a special tool that if not used properly, can cause timing chain noise and much more work (and cost of you pay someone else to do it)

4. If you plan on using the car as a daily driver or reliable commuter, stay away from aftermarket engine firmware tunes. In my view, the little extra power isn't worth the headaches and expense from the damage tunes can cause. If you want to beat on the car and care less about reliability and reduced resale value, then bring on the tunes.

5. Check the rear differential fluid every 20,000 miles or so. The seals on these cars have been known to leak. Early models had known bad seals that caused the differential to completely fail, but they still can seep a little even after the new seals. I changed my differential oil to Mobil1 80-90 at 20,000 miles, which doesn't need friction additive. I've just topped mine off every 40,000 miles in the process.

6. Sign up for AllDataDIY.com. They have all the factory manuals, Technical Service Bulletins and recalls on the car.

If you cull through the typical discussion board forum drama and anxiety from a small group, you'll find many more willing to provide valuable knowledge and good folks here. Just avoid getting sucked into the drama.

Have fun!
 

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Discussion Starter · #5 ·
Thanks for all the advice. This is quite the welcoming community.

It seems water pump failure is also common on the 2.4L. I was wondering if it being so close to the turbo that heat was the potential cause but it appears to perhaps be a design issue. I also wonder if Dexcool plays a part. I've seen it clog up systems badly when left in too long. Also seemed to eat gaskets in some GM v6s. I'd probably flush the coolant system and add some of the newer generic fits all coolant instead.

Passenger seat sensor is a minor concern for me but I wonder if one could just measure the resistance and do away with most of the sensor and trick it to always being on.

Glad to hear block failures are uncommon as that was my biggest concern.

Checking all the fluids is easy enough and I typically do that every oil change.

Power wise I would like around 300 whp/tq and was considering the Trifecta budget tune that I could switch on and off. Like my username indicates I do like to get into the throttle though.

So, model year doesn't really matter? I mostly only see 07 or 08 GXPs. I've heard 09s should be a bit more reliable but it appears not to be by a large enough margin that I should exclude the 07 and 08 MY.

Last is the auto vs manual debate. Looks like the auto is faster and might be able to take more power even though on the GMPP tune it's down on TQ by 30. The manual I drove was pretty notchy and not very impressive. I may favor the auto if its able to hold a gear from a wide rpm range as I'd like to probably leave it in 2nd or 3rd when do some canyon driving.
 

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