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Hi, my RPM needle is slightly moving up and down while on idle, also i'm getting bad gas mileage ( I think) 13-14 on a gallon without any crazy driving in NYC, The needle is moving slightly ( but it's definitelly moving )
is it bad oxygene sensor? also my highway mileage have dropped from over 30 miles per gallon to about 26..it's 99 1.8T with tiptronic transmission with 70K on it
Any ideas?
Thanks :weirdo:
 

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Discussion Starter #3
hoypinoy1234 said:
Maybe it's the throttle body. Have you cleaned it out yet?
throttle body is spotless, i have it checked two weeks ago while changing the oil, took the hose out and looks pretty clean, i'm the second owner somebody before me who owned this b5 must have take care of it 8)
needle goes down preety fast before it reaches "half" tank then it seems to slow down :weirdo: anyway i have refueled the tank two days ago, i put 7 gallons to fill it up while i did 94 miles since the tank was full.
I drive in the city and without crazy stuff and for 4 cylinder it's a bit low ain't it?
 

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my car has the same exact symtoms with the rpms moving up and down it only got worse finally i lost acceleration and the cause was a bad throttle body its an electronic part and i have 69000 miles on a 99 1.8t also i would check there just because its clean doesnt mean its working properly.
 

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If it is truly spotless, then all you need is to fix any vacuum leaks and to re-adapt the TB with a Vag-Com.
 

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Listen to Sharky. :)

Check vacuum hoses. Primarily from the intake manifold to the diverter valve (do a search) and from the intake manifold to the fuel pressure regulator (FPR). You can find info on this site if you search for DV, FPR, vacuum leak, etc.

The thottle body adaptation is critical to fixing this "problem". Find a local in your area with VAG-COM software (or buy it yourself) and set block 60 to basic settings. VAG-COM is worth its weight in gold.

-Mark
 

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dronek75 said:
Hi, my RPM needle is slightly moving up and down while on idle, also i'm getting bad gas mileage ( I think) 13-14 on a gallon without any crazy driving in NYC, The needle is moving slightly ( but it's definitelly moving )
is it bad oxygene sensor? also my highway mileage have dropped from over 30 miles per gallon to about 26..it's 99 1.8T with tiptronic transmission with 70K on it
Any ideas?
Thanks :weirdo:
BEEN THERE! I had that problem for months. Mine was bouncing up and down when in idle or slowly rolling.
Get an air induction service. Clears it right up.
 

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What's an air induction service? Never heard of it. How's you air filter?
 

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My idle as of a few days ago has been dipping low to about 600RPM and then rises up to 800RPM when I am idleing at a stop light. I found it odd, since my car was running fine before it basically sat in my garage for 2 weeks without running.

Then I have been doing ALOT of reading (via CB5 Search) about idleing, and have now planned to get the Boche Platinum 4 Sprak Plugs along with Neuspeed Spark Plug wires and I will be cleaning my throtte body soon. I also take my car out time to time and running it at WOT(Wide Open Throttle) to clean out the carbon. I have the V6 and Boris said that it is good to do that from time to time due to the build up of carbon in the V6's.

I also run 91 octane all the time, even though most of my driving is city maybe, if someone informs me that I shouldnt then I will change. Is it bad to use 91 octane for city driving?

But I hope to get rid of this small problem with the new plugs and plug wires.

Rich :)
 

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I'll repeat again....

Check vacuum hoses and then run a throttle body adaptation (block 60 to basic settings using VAG-COM)

Sometimes the throttle body gets out of whack.

-Mark
 

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wow finally someone with a different answer, ive had that same problem for months and the shop has done everything but mention replacing those vacuum line and or the diverter valve. i was beginning to think i was imagining the problem from sitting in dc traffic for to long :crazy: . and recommendations of particular diverter valves or a stock vw one ok?
 

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If you are not chipped, members say the AUDI TT DV is the best value for the money (~$40.00, works fine lasts a long time).

I am chipped. I run the Forge 007 (www.ecstuning.com). Expensive (~$130.00), but can be rebuilt and customized.
 
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