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91 civic stalls, decrease in mpg
I have a 91 civic dx. The past few months the car will either stall, or
jerk then lose almost all power. The check engine light comes on when this happens. It happens only occasionally, but during all types of driving ( highway, 35 mph, or even just staarting up). If i turn the car off and turn it back on, it resets and the car is fine for awhile. The other symptoms are the mileage went down from ~35mpg or better every tank, to 27-28mpg on the last three tanks. The other thing is when i got an emmisions test my mechanic said it didnt pass the HC at first (234 reading w/ 220 limit). He let it warm up for half an hour, then did it again and it passed. Any suggestions would be helpful. Could it just be the o2 sensor or something else simple? |
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motsco_ _ wrote: > ------------------------- > > You've probably changed your timing belt at least twice by now, based on > age (we don't know your mileage), but have you adjusted your valves? Do > you have stinky exhaust once it warms up? Do your records show a new PCV > along the way? Actually it only has 77k on it, so the timing belt is most likely the original (I bought it with 43k). The exhaust doesnt smell unusually bad. As far as time to change the PCV, I think, well hope, that might me premature. Does anyone know if cleaning it out is easy/practical? |
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#6
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"TeGGer®" > wrote > > As far as time to change the PCV, I think, well hope, that might me > > premature. Does anyone know if cleaning it out is easy/practical? > > > > > > > With the car fully warm, squeeze the PCV valve hose shut with a pair of > pliers. If the idle changes or the valve clicks, the valve is fine. > > The idle will change, then smooth out again as the ECU adjusts the air > mixture. If the idle does not change when the hose is pinched shut, the > valve is plugged. Either way, a blocked PCV valve is not your problem here. > A blocked PCV valve will not cause the sort of decrease in gas mileage that > you are experiencing. An old or blocked PCV valve may very well cause a significant decrease in gas mileage. But I'm doubtful the PCV valve is behind the stalling. Even if it's not plugged, the PCV valve's parts wear over time. Change it with an OEM one. It's not hard to do, like Chopface said. You can do the test that Tegger describes above; you should also hold it for at least 30 seconds and listen for a "click" sound. If there's no click sound, then the valve isn't working. My 1991 Civic was getting poor gas mileage around spring 2003. The PCV valve had never been replaced. I didn't know enough to do the tests above; I just replaced it, for around $20 with a dealer one. The old (and original) one was chock full of waxy buildup. My mileage shot up 10-20%. It was very noticeable. Other reports on the net document that a malfunctioning PCV valve most certainly may affect gas mileage. It messes up the ECU's take on the engine's condition, and the computer sends a signal that results in rich (=excessive fuel) fuel-air mixtures. I now clean out my PCV valve every few months or so. It typically has a few specks of gunk in it. And I do mean little specks--Q-tip pick-able. It would take a long time for this to build up to anything that would block it. I remove the valve completely about once a year and spray it with a little WD-40, too. > You need to get the Check Engine light code. Pull the carpet back from the > passenger footwell until you see the ECU. Turn the ignition to ON (but not > to START), and count the sequence of long and/or short blinks from the > ECU's red LED. Report back here. Ya, really. Start there. Various online manuals describe this. If it's the O2 sensor, the good news is that it's very cheap to replace on the 1991 Civics. I have a 1991 Civic and replaced the O2 sensor last summer, as a pre-emptive measure and because it was so cheap, around $45 total, using an online site that had OEM sensors. And replace that timing belt! |
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I would start by replacing the oxygen sensor and performing a tune up.
Before you replace your o2 sensor, I recommend that you get a bottle of SeaFoam Engine Cleaner. This product can be found at your local Napa Auto Parts store or Carquest. Start off by removing your air intake rubber tubing off from the throttle body assembly. Then open up the bottle of seafoam engine cleaner and pour half of the contents into a spray bottle. Mix the solution with 50 percent water and 50 percent seafoam. Be sure to shake it very well. Now, begin by spraying the mist into the throttle body inlet while manually keeping the engine's rpm above 2500. You will notice that your exhaust pipe will be emitting some white smoke. This is perfectly normal because the solution is cleaning the internals of your engine and decarbonizing all of the baked on carbon deposits. After you finish the bottle turn the engine off and let it sit for 15 minutes. Go ahead now and take the car out for a ride on the freeway and apply heavy throttle to remove all the excess carbon. Next replace all 4 spark plugs and make sure to gap them to 0.44 in. Replace your engine oil and filter along with a brand new o2 sensor. If you perform all these steps correctly, you should notice a difference immediately. I hope this helps. For all your Honda and Acura needs, check out http://www.trackspeedracing.com. We carry a wide selection of dyno proven racing products. Support and excellence in bringing you the horsepower is what we're all about. |
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