Author Topic: unstable RPM's  (Read 6729 times)

August 20, 2011, 04:50:10 pm

wdkingery

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unstable RPM's
« on: August 20, 2011, 04:50:10 pm »
Captain Ignorant put an oil pan gasket only to find out it was the oil pressure sensor!  ::)

C ar is doing a slight surge now.. Put a new fuel filter but it didn't help. It's slightly off idle.it will kinda stop accelerating for a second then kinda take off. If I mash it alittle more it won't do it
« Last Edit: August 21, 2011, 08:01:29 pm by wdkingery »

Reply #1August 21, 2011, 01:29:02 am

nathan_b

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Re: Captain Ignorant
« Reply #1 on: August 21, 2011, 01:29:02 am »
throttle cable too tight?

81 caddy frankentd 02a, 99.9 tdi jetta, 00 golf

Reply #2August 21, 2011, 10:27:02 am

wdkingery

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Re: Captain Ignorant
« Reply #2 on: August 21, 2011, 10:27:02 am »
No plenty of play there

Reply #3August 21, 2011, 11:40:37 am

bajacalal

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Re: Captain Ignorant
« Reply #3 on: August 21, 2011, 11:40:37 am »
To start with, make sure it's not ingesting its own oil, either from the turbo (if so equipped) or your PCV system, the later cars had the upgraded PCV and and valve cover baffle so consider the upgrade if it doesn't have these.

Have any screws on the injection pump been turned?

Mine also does this from time to time, where it sticks at a higher idle than where it should be (but it's nothing near a full blown run away). A dose of diesel fuel system cleaner seems to make it go away for a few months so my guess is that something is getting gummed up in there.

Reply #4August 21, 2011, 01:05:43 pm

wdkingery

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Re: Captain Ignorant
« Reply #4 on: August 21, 2011, 01:05:43 pm »
Yes we must be on the right track. My idle can stick high to.. I've been putting all kinds of crap in the tank so who knows. It does alittle low speed buck at times too, and the diesel cleaner had cleared that up. I'm thinkin its related to the cold start.
Oh, and yes i've done dicked with all the screws on my pump :( i've actually got th. Fuel screw turned down past where it came..

Reply #5August 21, 2011, 02:03:48 pm

ORCoaster

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Re: Captain Ignorant
« Reply #5 on: August 21, 2011, 02:03:48 pm »
Hey all that "crap" you have been throwing in the tank is doing your motor good.  I get that surge at idle after a long run on the highway too.  If I look at the IP gauge it drifts a bit.  A few pounds at most.  If I get out and look I see air in the lines.  Race it a time or two and they go away.  Think it might be time to pull the connections at the fuel filter and smooth them out and heat them up till they turn blue.  That should get rid of my problem.  May do the same for you. 

And turning the screws in and out is considered "tuning" and some people charge 100 an hour for that.  Some charge about the same for the term you used as well. 


Reply #6August 21, 2011, 08:03:16 pm

wdkingery

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Re: unstable RPM's
« Reply #6 on: August 21, 2011, 08:03:16 pm »
i made a video but the sound turned out horrible.

what i found is that i can hold the gas pedal down slightly, and it will act like a obd-1 model honda with a vacuum leak... up and down rpm, very constant, stable, up and down, up and down.. then it will eventually break free and run up a good bit in RPM.

do you think having the fuel screw turned out too far will do this? but it didn't do this for the first 400 miles after i turned my smoke screen back out

EDIT: altho i got 46.7 MPG's last go round, my fuel gauge was reading waay high.. like i had barely used a quarter of a tank, but been 223 miles.. normally i break the 3/4 mark at 165ish miles.. and i heard a bearin squall like hell the other day after i fired it up. alternator?

but it does it a lot worse when it's cold.. it actually becomes a buckin then
« Last Edit: August 21, 2011, 08:28:35 pm by wdkingery »

Reply #7August 22, 2011, 01:32:33 pm

R.O.R-2.0

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Re: unstable RPM's
« Reply #7 on: August 22, 2011, 01:32:33 pm »
i made a video but the sound turned out horrible.

what i found is that i can hold the gas pedal down slightly, and it will act like a obd-1 model honda with a vacuum leak... up and down rpm, very constant, stable, up and down, up and down.. then it will eventually break free and run up a good bit in RPM.

do you think having the fuel screw turned out too far will do this? but it didn't do this for the first 400 miles after i turned my smoke screen back out

EDIT: altho i got 46.7 MPG's last go round, my fuel gauge was reading waay high.. like i had barely used a quarter of a tank, but been 223 miles.. normally i break the 3/4 mark at 165ish miles.. and i heard a bearin squall like hell the other day after i fired it up. alternator?

but it does it a lot worse when it's cold.. it actually becomes a buckin then


bearing could be the alternator, or more likely, the timing belt tensioner..
92 Jetta GLI - Black, 1.6D w/ GT2056V turbo..
86 GTI - 4 Door, Med Twilight Gray, Tow Machine..
86 Audi Coupe GT - Tornado Red, All Stock.. WRECKED.
89 Toyota 4Runner - Dark Grey Metallic, LIFTED!

Turbo: exhaust gasses go into the turbocharger and spin it, witchcraft happens and you go faster.

Reply #8August 30, 2011, 02:00:05 pm

wdkingery

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Re: unstable RPM's
« Reply #8 on: August 30, 2011, 02:00:05 pm »
it appears my timin had slid retarded a tad

Reply #9August 30, 2011, 09:08:13 pm

ORCoaster

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Re: unstable RPM's
« Reply #9 on: August 30, 2011, 09:08:13 pm »
And you paid the price of 45.3 mpg for it.  How did that happen?  Or was it the rebuild and reinstall that caught you?

Reply #10August 31, 2011, 06:37:10 am

wdkingery

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Re: unstable RPM's
« Reply #10 on: August 31, 2011, 06:37:10 am »
You know I don't know what happened! I don't think it was the reinstall. I don't know what it was.. Just don't know. Have to wait another 300 miles to see if it's better :(

Reply #11August 31, 2011, 04:34:35 pm

wdkingery

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Re: unstable RPM's
« Reply #11 on: August 31, 2011, 04:34:35 pm »
yeah it must have been where things weren't right under the hood, cause me and wifey went to the beach today.. tooled around for a little while then drove home, 280 miles.. got'er done in 5.22 gallons; 52.4 mpg! so i think i got it back right. and that was on straight diesel; wish i had added some wax/2 stroke to it.. coulda got like 54

and we had some traffic waitin to go thru the tunnel; 20 minutes of stop and go.. I HATE STOP AND GO. makes me nervous cause my car gets right hot before the fan kicks in, and that only helps but so much.

idle still aint' right tho

Reply #12August 31, 2011, 07:32:55 pm

ORCoaster

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Re: unstable RPM's
« Reply #12 on: August 31, 2011, 07:32:55 pm »
My idle is messing with me too.  I tried to set it different with a tweak, and I mean 1/16th of a turn of the fuel screw and I lost my extra power needed for the extended hills that seem to rob my car of momentum.  Once it got down to 63 I had no more pedal and was force to do a lot of dropping to 4th.  So my mileage suffered for it.  52?  now I am really going to have to think on the increase the mileage game.  You are again ahead of me.  Maybe the new paint I plan for this weekend will give me the coefficient of friction I need.  The body kit may as well.   8)

Reply #13August 31, 2011, 10:03:10 pm

R.O.R-2.0

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Re: unstable RPM's
« Reply #13 on: August 31, 2011, 10:03:10 pm »
i doubt the body kit will even affect the mileage, or if it does, be very minimal..

its not like you are making it any easier for the engine to get air in, or out of it, and thats where the efficiency comes from..

getting rid of that horrid toilet bowl, and getting a better intake setup.. that 1.25" snorkel is pretty much a joke air intake..

i have a mk1 header that i had on my diesel, helped mileage a bit.. i have no use for it.. pm me if you have any interest in it..

(its the header, and flex joint, just take your stock stuff off, and weld this stuff on.. i may even be persuaded to install it for you if you come to me)
« Last Edit: August 31, 2011, 10:05:08 pm by R.O.R-2.0 »
92 Jetta GLI - Black, 1.6D w/ GT2056V turbo..
86 GTI - 4 Door, Med Twilight Gray, Tow Machine..
86 Audi Coupe GT - Tornado Red, All Stock.. WRECKED.
89 Toyota 4Runner - Dark Grey Metallic, LIFTED!

Turbo: exhaust gasses go into the turbocharger and spin it, witchcraft happens and you go faster.

Reply #14September 01, 2011, 05:07:09 am

wdkingery

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Re: unstable RPM's
« Reply #14 on: September 01, 2011, 05:07:09 am »
Well you gotta remember I'm 3% high too, so you are probably actually higher

Plus I never ever downshift, so you must have some hills I dont
« Last Edit: September 01, 2011, 05:15:59 am by wdkingery »