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gitsum

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Everything posted by gitsum

  1. As my son pointed out, I've had several coolant overflow bottle issues. The point of failure has been the return coolant hose nipple. It's plastic with a metal inner sheave. It failed on the original bottle around 45k miles. I bought a new one for $25 and it arrived with the nipple already cracked! Reduced the nipple on the original bottle to about 50% length and repaired with JB Weld brand plastic epoxy. It was a temporary fix, it works but still weeps a small amount of coolant. Bought a second overflow bottle and it arrived intact. Cut off about 2" of the return coolant hose to remove t
  2. Let's go ahead and beat this horse some more to make sure it is dead. The oil life algorithm in the Spark measures engine parameters to predict oil life. Is it accurate? It appears to work good enough. But let's make sure and recognize one very important fact. The algorithm is based on a theory, not actual physical oil properties/condition. It is estimating the actual oil life based on how the said engine parameters are affecting the oil. It is not checking the actual oil properties. For the most part this works good enough. But there are a few things that can't be factored in or acco
  3. Yes, you were correct. But you didn't test it yourself, you took GM's word for it. Yes, GM's description was correct. But that doesn't mean one should take every manufacturer's claim as 100% truth. If we could blindly believe all, the Volkswagen diesel wouldn't run dirty and Hyundai's would get better gas mileage than they claimed. Just to mention a few recent manufacturer's false claims among many...
  4. Retired old Gearhead that is an excellent response. Your answer is based on facts and actual experience. You have definitely convinced me the oil life monitor does work on parameters that give it proven functionality. Since it doesn't actually analyze the chemical properties of the oil, I will continue to err on the safe side and change the oil every 5000 miles. I drive the Spark mostly short trips with a lot of stop and go, surely falling into the severe use category. The oil life monitor always says that I am changing the oil earlier then necessary. But there is no doubt that one can he
  5. I really trust GM. The same company that says I need a GM brand oil with a "specific" additive or else risk engine damage.The same people that denied there was an ignition switch/cylinder problem that caused engines to shut down. After enough people got killed or injured they finally decided to do a recall. Must be a really sophisticated algorithm, a little extra rpm and heat will reduce the engine oil life. I'm really gonna trust that! I'm going to put about 150k on this car before I retire it. Not following the "sophisticated" oil change algorithm is going to the best thing I ever di
  6. 72,000 miles and running perfect on my 2013 5-speed LS. SuperTech 5w30 every 5000 miles, Valvoline Synchromesh at 50k. 185/60r14 tires, averaging 42 mpg. Airbox mod, throttle body half shaft mod, removed rear muffler, shortened gearshift.
  7. Well, just because they say it's so I'm going to be stubborn and not believe it. On my next oil change (about 2-3 months) I'll reset the oil change function. I change my oil every 5000 miles with full synthetic 5w30 SuperTech from Walmart (I don't believe the GM additive bull). I'll report back with the percentage left and then reset and go another 5000 miles with a fresh change. I strongly suspect the second percentage is going to match the first exactly. If the parameters really include engine temp and revolutions, the percentage readings are going to have to be different. This is going
  8. Someone mentioned the muffler had some sort of valve to keep back pressure even between low and high rpms. I cut my muffler off and welded on a plain piece of exhaust pipe. The OEM is a generic cheap $30 muffler with baffles, no valve. Several people talked about the oil change meter claiming it can analyze remaining oil life. No, it's simply hooked up to the odometer. It might have a way to adjust for city vs highway miles, but I doubt it. The Chevy Spark is a low end economy car made by Daewoo at a price point, not a Mercedes Benz or Lexus. I don't want to ruffle anybody's feathers, b
  9. I ran the stock tires at 40 lbs front 42 lbs rear for a compromise between fuel mileage and ride quality (tires were still harsh riding). On my 185/60-14" wheels I run 34 lbs front and 36 lbs rear. They are not rock hard fuel efficient tires like the stock tires. Much smoother and better traction. On any all season radial that isn't a rock hard fuel efficient tire, the 2250 pound Spark feels and rides better at tire pressures well under 40 lbs.
  10. Yes, the stock 15" rim with a stock 185/55 tire will fit in the spare tire location. Lay your seat backs flat and the tire fits by dropping in the back first and then the front. It might be the front first, I've had one in there with a tire iron and a bottle jack for over six months. It only drops in there one way, but it's not too hard to figure out how to fit the stock rim and tire size into the spare tire well. By the way, I replaced my stock rims and worn tires with 14" rims and 185/60 H rated tires. It rides way smoother and handles better than the rock hard "fuel economy" stock tir
  11. Could the problem be caused by excess crankcase pressure? I changed the oil on my Spark at 500 miles and then every 5000 up to the current 34,000+ mileage. I always fill the oil up to the second dot on the dipstick, never all the way to the top of the second set of hash marks. I ride small motorcycles and scooters and it is common for them to blow excess oil through the crankcase vent tube if filling all they way to the top level on the dipstick. I also believe that a small high revving auto engine can be prone to cavitation of the crankshaft in the oil pan at high rpm's. This results in
  12. You're right, it could be a risk for negating a warranty claim. But I think it's a small one, and I'm willing to take a chance anyway because the car runs so much better.
  13. I think the dealer's diagnosis of a clogged fuel injector is a load of crap. Any newer fuel injected vehicle that is driven on a regular basis just doesn't get a clogged injector all by itself. It's possible bad gas can screw with the fuel system, but usually that is caused by water in the fuel. If it was bad/dirty gas, the fuel filter, fuel pump and possibly the tank itself would need to be cleaned. The fuel filter should do it's job and trap any particles before they reach the fuel injectors. Larger particles would clog up the fuel pick up in the pump, unlikely anything would reach the
  14. Your assuming the mechanic would need to remove the throttle body, and if he did he would recognize it was modified. It still looks close to stock and was polished up with fine grit sandpaper. Don't make the mistake of thinking a certified factory mechanic knows anything other than what a computer diagnostic code or a tech manual tells them the next step should be. Good ole common sense and mechanical aptitude aren't a requirement for the job anymore.
  15. I forgot to ask, why is this mod only good for "racing purposes"? The screws are using the same amount of threads as stock. If the stock screws were backing out the extra threads would serve no purpose except to extend the length of time until the screw actually falls out. I don't know of anyone or any dealership that checks those on a regular basis. I applied locktite and put some paint marks on the two screws. It takes less than a minute to remove the rubber intake at the throttle body and eyeball the paint marks. I'll check them after a few hundred miles and then again after a few tho
  16. The car has gone 32,000 miles with no check engine light. I don't think it's a coincidence that after modifying the throttle body it came on. 30 second ECU reset and problem solved. No need to make it more complicated. However, we did check the codes when my son's Spark that started hesitating, having hard starting and lacking performance. The codes indicated a misfire in one of the cylinders. This is very similar to a problem someone else was having in another thread. No dealer visit necessary. The simplest reason for a misfire is a screwed up spark plug. Cleaned and regapped the plu
  17. Update! After a successful preliminary test drive of a few miles, during a second drive the check engine light came on. Nothing that concerned me too much, I knew the car was running smoother and better than ever. Did an ECU reset procedure and the light stayed off and did not come back on. What does this mean? It means the throttle body mod was working so well that the ECU compared the new operating parameters with the old and thought something was wrong. Resetting the parameters allowed the computer to "relearn" and the ECU happily adjusted with no problems.
  18. The shaft has two sides, the back has the threads for the two screws. The mod is called "half shafting" the throttle body. It's been around a long time and successfully used on many different vehicles without issues. The back of the throttle plate/blade is stilled fastened directly to the rest of the shaft, nothing is "cut in half". You have just removed one side for more and cleaner air flow. The throttle plate/blade is still in the exact same position relative to the shaft, the TPS isn't going to know or do jack. I tested the mod successfully and it works with no issues. Before not
  19. OK, enough questions, time for action. Pulled off the throttle body which is about a 5 minute task, about two minutes the second time. Removed the extra screw length from the back of both screws, dremeled off a little material from the front of the throttle body shaft between the two screw heads, polished everything with some 400-grit sandpaper. The two screws attaching the throttle plate/blade to the shaft didn't want to budge, so stopped there and put it back together. A short test drive revealed a slight increase in power, mostly at WOT above 5000 rpm's, but still detectable in the low
  20. My son has a similar issue with his manual transmission 2013 Spark at 19,000 miles. Same codes, hesitation and lack of performance. Simplest things first, checked the spark plugs. They were somewhat dirty and a little worn, the gap was way off on one of them. While there is certainly nothing special about the plugs, the part number was hard to cross reference for a match. Cleaned and regapped the plugs, issue fixed. Several thousand miles later the engine is still running perfectly. As soon as I find a decent iridium replacement, I plan to switch them out on both my Spark and his. The s
  21. I had another thought... I started the original thread on the airbox mod just over a year ago. I could see the airbox snorkel was a definite bottle neck seeing how it was much smaller than the throttle body. I expected a slight improvement, but was surprised by the significant boost in performance compared to stock. Looking at the size of the throttle body and stock exhaust manifold, they seem to be adequately if not generously sized for a 1.25 liter engine. I'm wondering if the majority of the extra performance from your mods are from the airbox mod exclusively? Did you get an opportuni
  22. If you make the extra effort to go under the fender guard to remove the resonator box, the tube can be left in place to draw cooler air from underneath by the wheel well. Same effect as a cold air intake. Been driving it this way for 30,000 miles, the car runs perfect with no issues. The engine really loosened up around 15k and I average 42-44 mpg in the city, no hypermiling.
  23. OK, I think I'll give it a try. Nice job on experimenting and finding the bottleneck allowing the possibility of a free mod to increase performance. Still a little concerned about getting metal particles down in the engine. Your picture is a bit small to see details. So the stock exhaust port splits into two separate passages after 3/4" ? Are the paper towels stuffed into each of the two inner passages past the split? Is there plenty of room for the dremel bit without too much risk of pulling or pushing the paper towels loose and dropping metal shavings into the head?
  24. When you beveled out the last 3/4" of the exhaust port to 23mm, was there still a 20mm bottleneck further in? Or did this increase the diameter of the opening all the way into the head?
  25. Remember, the Spark is made in South Korea by Daewoo...
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