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  #1  
Old 11-11-2010, 11:59 AM
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Location: Chapel Hill NC
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Question Bad TPS????

Will it affect the gas milage? Sometimes when I let off the gas the rpm's will dip about 500 under where they are going to rest and then popup to where it should be. Does not do it all the time. My gas milage is sucking 17.5 or so and I used to get 21. I removed the exhaust system and ran 2" straight pipe from the cat back. The turbo whistle is loud now at high rpm. Is that where the mpg is going, the turbo spinnin faster? The fuel filter is new. The rpm's dipping and then coming up, is that an exhaust leak???
All input is appreciated.

I have to say I think it is burning rich, my new crome tip is a sooted.
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91 940 Turbo Wagon
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  #2  
Old 11-11-2010, 12:46 PM
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1973 Volvo 142
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How old is the O2 sensor?
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Old 11-11-2010, 02:39 PM
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I have no idea Swift. Would that make the RPM's do their little dance?
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91 940 Turbo Wagon
2000 STS
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Old 11-11-2010, 04:19 PM
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Not in and of itself, no. But LH2.4 normally can learn around any number of causes of rich mixture as long as the O2 sensor is functioning. When coming to a stop from highway speeds, the ecu uses the input signal from the seedometer sensor. So...the dip could be a intermittent short in the speedo signal, but you'd probably notice the speedo bounce. Have you adjusted the tps? In 91, the tps was still just an on/off switch. I think in 93 or 94 it actually has variable resistance throughout the travel. So, your tps should click just as the butterfly begins to move. Other than that adjustment, you could check the resistance of the unit. Don't have those figures in front of me right now...any manual should have them. I've had this issue before but as I recall, it can be a variety of things. On my turbo, hard boost followed by immediate hard stops would actually kill my motor as it could not control the idle fast enough. I believe cleaning the idle air control valve helped a bit.
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Old 11-11-2010, 05:39 PM
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The spedo does not bounce. I had previously adjusted the TPS months ago. It was good where I left it. Since it got colder the car seemed to idle a little low and since the rpm was doing the bounce I adjusted it again and had it right as tight to a minor throttle move it could be. I mean if I touched the throttle from under the hood it clicked. After that it seemed to idle even lower. So I need to move it again. I noticed adjusting the TPS when cold vs hot has effect both ways. Example adjust it cold and the idle is great. When it warms up it idles high.
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Life is full of sharp turns, you better have good tires.

Its a turbo, its suppossed to sound like that!


91 940 Turbo Wagon
2000 STS
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  #6  
Old 11-15-2010, 12:09 PM
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Ok turns out NC wants you to have a muffler. I took the entire exhaust down and re did it all, welded all the joints. The down pipe was a little loose off the turbo. Tightened it up but I think I will loosen all of the bolts this weekend and reattach evenly. Most of the whistle I had from the turbo went away. I am guessing the whistle was boost leak, although I still have a little whistle. I readjusted the TPS and I still have the RPM dip and when you start it the rpms start low >500, and then build up to normal 7-800 in just a few seconds. Maybe I have it too close (the adjustment). Also is the cable the only place to adjust idle?
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Life is full of sharp turns, you better have good tires.

Its a turbo, its suppossed to sound like that!


91 940 Turbo Wagon
2000 STS
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  #7  
Old 11-17-2010, 03:20 AM
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Pull codes and adjust the TPS according to the manual. Just guessing isn't the way to do it.
The TPS may not even be an issue.

Regards, Andrew.
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Old 11-17-2010, 05:59 AM
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1-1-1 No codes present. Also I always heard adjust it just before it clicks.
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Life is full of sharp turns, you better have good tires.

Its a turbo, its suppossed to sound like that!


91 940 Turbo Wagon
2000 STS
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Old 11-17-2010, 05:59 AM
 
 
 
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1990, 240, 740, 940, adjust, bad, position, recall, resistance, s70, sensor, throttle, tps, turbo, volvo, whistle


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