Upgrade Posted November 4, 2003 Report Share Posted November 4, 2003 My 95 Lumina LS is driving me crazy. The thing eats gas like a fiend. Its not throwing any codes. The thing runs pretty smooth. has anyone else dealt with this? What did it turn out to be? Quote Link to comment Share on other sites More sharing options...
patgizz Posted November 4, 2003 Report Share Posted November 4, 2003 how recent have you done plugs/wires? Quote Link to comment Share on other sites More sharing options...
SmokesGTP Posted November 4, 2003 Report Share Posted November 4, 2003 I hear you, the mileage is terrible. Quote Link to comment Share on other sites More sharing options...
Upgrade Posted November 4, 2003 Author Report Share Posted November 4, 2003 Did a tune up about 2 montsh ago. This is more than bad. Im getting around 10 in the city and barely 15-16 on the highway. Quote Link to comment Share on other sites More sharing options...
DOHCRagtopguy Posted November 4, 2003 Report Share Posted November 4, 2003 Sometimes it's an indication of a bad Oxygen sensor. No code will show most of the time, either. Quote Link to comment Share on other sites More sharing options...
dkorinko Posted November 4, 2003 Report Share Posted November 4, 2003 I am not saying this is it but i am more asking if this could cause it....What about a fuel filter??? I hear people bitching about those all the time because they can do a lot of harm and they are only like 5 bucks to replace, just thought i would ask??? Quote Link to comment Share on other sites More sharing options...
DOHCRagtopguy Posted November 4, 2003 Report Share Posted November 4, 2003 If a fuel filter was going south it would STARVE the engine of fuel, not cause it to use more. I'm thinking it would be either the oxygen sensor if no code is thrown. If the coolant temp sensor was bad, I think that would throw a code, but maybe not. Because if the engine computer thinks it's cold it will enrich the mixture all the time. Or maybe fuel pressure regulator is leaking. Do you smell gas a lot in the engine compartment? Quote Link to comment Share on other sites More sharing options...
DEMonte1997 Posted November 5, 2003 Report Share Posted November 5, 2003 if the 02 sensor was bad, would the car still run smooth? could timing play an issue as well? i get almost 27highway and city mixed. Quote Link to comment Share on other sites More sharing options...
Robby1870 Posted November 5, 2003 Report Share Posted November 5, 2003 if the 02 sensor was bad, would the car still run smooth? could timing play an issue as well? i get almost 27highway and city mixed. Yeah, it'll usually still run smooth, but more than likely it will run rich all the time. I could hear mine running rich, since I have no cat, I could hear the excess gas making a pinging noise where it would partially ignite (I guess) about half way back. Put a new O2 in and now it only does it at start up, when its supposed to run rich Quote Link to comment Share on other sites More sharing options...
Upgrade Posted November 5, 2003 Author Report Share Posted November 5, 2003 There is no fuel smell. Chevy dealership had it for the past three days and they didnt smell any or notice a drip on the floor either. The fuel filter has been replaced recently. As far as the coolant temp sensor, I replaced the t-stat about 2 months ago. I thought it was bad making the car run cool, making it eat gas. Before I replaced it the gauge would barely move. After it moves quite a bit, about a third of the way across and the heater blows warmer. I am going to take it to Cole muffler in the AM because the guy says he can do some sort of back pressure test to see if the cat is clogged. After that Im not sure where to go. Does anyone here know where I can get a set of cheap O2 sensors? Maybe a set from a wreck just to see if there is a difference? Im about to run this bitch off a cliff. I bought this thing thinking it was a great car. I havent seen another one like it since I bought it. After tossing 500 in it in one week I am at my wits end. Quote Link to comment Share on other sites More sharing options...
DOHCRagtopguy Posted November 5, 2003 Report Share Posted November 5, 2003 The thermostat is not the sensor. The sensor is located on the driver's side beneath the throttle body. It's one of the connectors hooked up to the wire cluster that runs to the TPS and EGR Valve. I would throw an oxygen sensor in it first and if that doesn't do the trick then replace the coolant temperature sensor. Oxygen sensors aren't that expensive, but a bitch to put in on the 3.4. The CTS is probably a little easier to do if you take off the upper plenum. I sympathize with you, my man. Trying to help you out here the best I can. If the Chevy dealer had it, did they do a scan on the system? That would have told you if either of those two components were bad. Good luck. Love those DOHC engines when they are running good, sometimes when they fuck up it can be a bitch to diagnose, as you have found out for your self. Quote Link to comment Share on other sites More sharing options...
SmokesGTP Posted November 5, 2003 Report Share Posted November 5, 2003 Yeah I need to replace that damn oxygen sensor. I know approximately where its SUPPOSED to be but I can't even see it. Whats the easiest route to changing it. IE removing the least shit Quote Link to comment Share on other sites More sharing options...
boostnawd Posted November 5, 2003 Report Share Posted November 5, 2003 Donno how much this will help you, as I've never done it on a LQ1. But us DSM guys tap into the o2 sensor wire to get a look at what it's feeding the ECU, sort of a cheap mans a/f meter. The o2 sensor gives off a reading in voltage, so hook it up to a voltmeter. Once the car is up to operating temp, it should cycle between 0.0v to about 0.9v.. if it doesn't cycle, or does so very slowly, it's bad. Quote Link to comment Share on other sites More sharing options...
CPSMonteZ34 Posted November 5, 2003 Report Share Posted November 5, 2003 Press your head in a vise until it is about 2 inches thick. Slide your newly shaped head down the rear of the block at the firewall. Navigate around the rear manifold bank and use one eyeball to search for the O2 sensor protruding from the top of the downpipe. Honestly, why the hell didn't they just put it in sideways so one can get at it from the bottom. Engineers should be forced to own the cars they design. Dumbasses. Quote Link to comment Share on other sites More sharing options...
Upgrade Posted November 5, 2003 Author Report Share Posted November 5, 2003 The thermostat is not the sensor. The sensor is located on the driver's side beneath the throttle body. It's one of the connectors hooked up to the wire cluster that runs to the TPS and EGR Valve. I would throw an oxygen sensor in it first and if that doesn't do the trick then replace the coolant temperature sensor. Oxygen sensors aren't that expensive, but a bitch to put in on the 3.4. The CTS is probably a little easier to do if you take off the upper plenum. I sympathize with you, my man. Trying to help you out here the best I can. If the Chevy dealer had it, did they do a scan on the system? That would have told you if either of those two components were bad. Good luck. Love those DOHC engines when they are running good, sometimes when they fuck up it can be a bitch to diagnose, as you have found out for your self. Quote Link to comment Share on other sites More sharing options...
Upgrade Posted November 5, 2003 Author Report Share Posted November 5, 2003 Sorry about that post. Yeah I know where the sensor is, just saying that I replaced the t-stat. 100 bucks isnt cheap for O2 sensors. Thats crazy. Im bringing it to get backpressure tested today and see from there. Quote Link to comment Share on other sites More sharing options...
DOHCRagtopguy Posted November 5, 2003 Report Share Posted November 5, 2003 Wow, I didn't realize that your car takes TWO of those damn things. I checked out prices at Advanced Auto and they are pricey. I got like 43 bucks apiece. You didn't say if they checked the output of the CTS or O-2 sensors while Chevy had your car. I don't know what the hell else it could be, if not those two, I'm stumped. Quote Link to comment Share on other sites More sharing options...
sonyman87 Posted November 5, 2003 Report Share Posted November 5, 2003 have you done a Panservice on your transmisson yet? are you having a bad idle problem? I also have a 95dohc. it was a bitch to get running right when i got it. what are the other symptoms besides just flat out bad gas milage. Once i averaged 10mph in mine. I went 30 miles on 3 gallons 87oct. in city. It was alot of drag style running. So just make sure that a LEAD foot isnt the culprate. normal driving with a nice breathing intake and exaust you should get about 26-29highway and 18-22 city. will vary depending on geographic features. aka Hills. Heavy driving/playing with RPMs will average you at 16-20 or less. really depends on how bad Quote Link to comment Share on other sites More sharing options...
sonyman87 Posted November 5, 2003 Report Share Posted November 5, 2003 1 more thing. check to make sure your MAP sensor is pluged in and the temp sensor behind it is also pluged in. the temp sensor on the intake is easily overlooked. Quote Link to comment Share on other sites More sharing options...
Upgrade Posted November 5, 2003 Author Report Share Posted November 5, 2003 I looked it all over and everything is plugged in. The backpressure test didnt result in anything, it checked out fine. The car idles fine. Its slightly choppy but steady. When I start it up warm or cold its like it stumbles and clacks quite a bit. I didnt have GM test it because my bill was already 500 plus and at 61 bucks an hour I didnt want those monkeys playing with it. Does anyone know where I can get a set of used O2 sensors to test that theory out? Quote Link to comment Share on other sites More sharing options...
Redfox340 Posted November 6, 2003 Report Share Posted November 6, 2003 My 95 Lumina LS is driving me crazy. The thing eats gas like a fiend. Its not throwing any codes. The thing runs pretty smooth. has anyone else dealt with this? What did it turn out to be? When did this start happening? Did it start when the weather got cold? Because if so, gas companies have already added in ethanol to help with freezing / emission over the winter months. Ethanol greatly reduces the gas mileage of any vehicle. Change it up and hit a different pump and watch your mileage. - Erik Quote Link to comment Share on other sites More sharing options...
sonyman87 Posted November 6, 2003 Report Share Posted November 6, 2003 something i noticed when i do tuneups. The gap on the plugs i buy "ACdelco" is more then what the factory spec call for. they should be at .45 not .55 or however they come. Easily overlooked at a tuneup. I have done 4 tuneups on my car and EVERY time the ACdelco plugs were not gaped correctly. Quote Link to comment Share on other sites More sharing options...
Upgrade Posted November 6, 2003 Author Report Share Posted November 6, 2003 It has done this in the cold and in the summer months too. Whenever I do tune-ups I always recheck the gap. I am going to recheck the timing on the motor. I bought a hold down tool a while ago so Im gonna check the front bank and see if it is correct. Quote Link to comment Share on other sites More sharing options...
topless94style Posted November 8, 2003 Report Share Posted November 8, 2003 I am having the same problem. When the weather gets below 40 degrees i run about 11mpg. When its warmer than that i get about 16. And now, my car will not start by itself on teh first 3 tries! I use a remote starter and it takes taht thing about 3 times to start teh car sometimes 5 or 6. And then teh RPMS rev WAY high to 3 grand and then fumble around 200-1200 for ten minutes. Then, the car gets warm and the check engine light comes on. I start driving, the light goes away and when i stop at a stop sign the engine continues to idle like shit. I changed the O2 sensor and i did an idle relearn. I think i will have to try the CTS and also the IAC and after that a good ole fashioned tune up, if the cts and iac dont help because i dont have the cash to spend on a tune up right now. And finally i will go to the EGR valve. i have to stop someplace tomorrow to see if i can get my codes red that have came up. That is my situation on my LQ1 oh yea almost forgot i have an oil leak and seems taht a coolant leak has made its way as of this morning. Quote Link to comment Share on other sites More sharing options...
DOHCRagtopguy Posted November 8, 2003 Report Share Posted November 8, 2003 Topless94, check your intake gaskets for a vacuum leak. You are describing the symptoms. Get some Clean-R-Carb and spray around the gaskets with it running, if the idle changes, you found your problem. You would burn a lot more gas because the ECM is trying to make up for the excessive lean condition caused by the leakage. Chekc it out, gaskets are cheaper than all the other bullshit. Quote Link to comment Share on other sites More sharing options...
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