sticky gas pedal/rough idling/accelerating
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Northstar Engines and System Technical Discussion Discussion, sticky gas pedal/rough idling/accelerating in Cadillac Engine Technical Discussion; Hi Everyone. I have a 99 Eldorado (non ETC) that I've owned since it was brand new with 6 miles ...
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    hankk17 is offline Cadillac Owners Fanatic
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    sticky gas pedal/rough idling/accelerating

    Hi Everyone. I have a 99 Eldorado (non ETC) that I've owned since it was brand new with 6 miles on it. It's had its share of little issues here and there including a strange alarm problem I'll post a question about in the appropriate forum, however for this go-around my issue is north* related.

    I've recently gotten a job that's 50 miles away from home, so I'm doing a lot more highway driving than previously. Recently I noticed that my gas pedal was getting sticky, and when I'd accelerate to get into traffic on the highway I'd have some really weird hesitation as it went through the gears.

    Then the problem got worse and extended itself to EXTREMELY rough idling at stop signs or even when the car was in park.

    I read the forum here a few days ago and found that it was most likely a carbon-fouled throttle that was the issue, so last night I carefully took the air-intake apart and sure enough it was BLACK with carbon. I cleaned it with a toothbrush and some carb cleaner and the problem has gotten better but is still there. I looked inside the intake and the entire intake seemed to be black with carbon as well... What's my next step? Top Engine Cleaner?

    I've also read here that this year north* has had issues with the crankshaft sensor. Could it be a culprit as well?

    The engine has 81K on it and up til now has treated me very well.

    Any thoughts are definitely welcome, and thanks to all for the tip on the carbon - I think it's set me on the right path to fixing the issue.

    -Hankk17

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    Re: sticky gas pedal/rough idling/accelerating

    Did you hold the throttle wide open and clean the throttle bore all the way around the perimeter of the bore where the blade contacts it? Also, clean the backside of the throttle blade. Not looking for squeeky clean here, just get the worst of the deposits off.

    The deposits in the manifold are perfectly normal. Dry intake manifolds on PFI engines do not have gasoline sluicing thru them like on carbed or TBI engines so the intakes will tend to get sooty and oily from the EGR introduction and the PCV oil mist.

    Crank sensors were not typically a problem with the 99.... The crank sensors changed design for 2000 and later and there were some quality issues off and on with those...but that doesn't apply to the 99.

    Your onboard diagnostics has an engine misfire detection code logic that is very robust. If the engine were missing it should turn on the SES.

    Have you checked for any codes to see if there is anything in the diagnostics?

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    Re: sticky gas pedal/rough idling/accelerating

    Also, read the following and take heed..... http://www.cadillacforums.com/forums...read.php?t=226

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    Re: sticky gas pedal/rough idling/accelerating

    The other thing that you should check is the fuel pressure regulator. Take the silver top cover off and you will see the small canister shaped device on the fuel rail that has the fuel return line coming out of it and a vacuum line hooked to it. Take the vacuum line off while the engine is idling and watch the vacuum nipple for any signs of fuel...there should be none. If there is any fuel present at the vacuum nipple after idling for several minutes with the hose off then replace the FPR.

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    Re: sticky gas pedal/rough idling/accelerating

    wow - a bobbynski trifecta!

    Thanks for the quick replies.

    OK - I checked the computer - no codes.

    I did indeed clean around the entire throttle opening and made sure that the valve opens and closes smoothly. I also did clean the back of the valve as well.

    I will take your suggestion about the FPR and will investigate.

    While I have your attention - I have a slight oil leak coming from my front valve cover. is this a relatively straightforward job to do?

    Thanks!!

    -Hankk17

    (also an nski..)

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    Re: sticky gas pedal/rough idling/accelerating

    Quote Originally Posted by bbob
    Also, read the following and take heed..... http://www.cadillacforums.com/forums...read.php?t=226
    Oh, and I live in MA. subsequently I have certain bad driving habits.. one of them being that I go 80-85 when I hit the highway. This morning, after I had cleaned the throttle body last night, I opened it up and did about 90 all the way to work, and hit it hard on the hills to help blast out the crud.

    I'll know if I did anything tonight on my way home.

    Thanks again!

    -Hankk17

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    Re: sticky gas pedal/rough idling/accelerating

    Quote Originally Posted by hankk17
    Oh, and I live in MA. subsequently I have certain bad driving habits.. one of them being that I go 80-85 when I hit the highway. This morning, after I had cleaned the throttle body last night, I opened it up and did about 90 all the way to work, and hit it hard on the hills to help blast out the crud.

    I'll know if I did anything tonight on my way home.

    Thanks again!

    -Hankk17
    Keep hammering it. Do some of the manual second gear, WOT from 55 to 80 and then allow the vehicle to slow down with the heavy engine overrun/engine braking of manual 2...then do the WOT to 80 again and repeat ... as often as you can until the exhaust is clean and doesn't give you a cloud when you nail it. Driving 80 is great but it is not really stressfull on the engine at all. You need the WOT and high RPM of the upshifts. Always merge from 55 to 80 at WOT and you'll start to clean it out....

    The cam cover is pretty simple to remove and touch up the seal. I would just pull it off and see what is causing the leak. It may be a cut seal or a surface defect (scratch) in the mating suface on the head....just clean the area and patch locally with some good high temp RTV....just a dab will do it. No need to replace the seal generally.

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    Re: sticky gas pedal/rough idling/accelerating

    Quote Originally Posted by bbob
    Keep hammering it. Do some of the manual second gear, WOT from 55 to 80 and then allow the vehicle to slow down with the heavy engine overrun/engine braking of manual 2...then do the WOT to 80 again and repeat ... as often as you can until the exhaust is clean and doesn't give you a cloud when you nail it. Driving 80 is great but it is not really stressfull on the engine at all. You need the WOT and high RPM of the upshifts. Always merge from 55 to 80 at WOT and you'll start to clean it out....

    The cam cover is pretty simple to remove and touch up the seal. I would just pull it off and see what is causing the leak. It may be a cut seal or a surface defect (scratch) in the mating suface on the head....just clean the area and patch locally with some good high temp RTV....just a dab will do it. No need to replace the seal generally.
    OK will do. Thanks!

    Incidentally - I'm still a noob to these forums.. what the heck is WOT?

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    Unhappy Re: sticky gas pedal/rough idling/accelerating

    just an update - after a long HARD drive home on Rt 495, the problem persists and is just about the same as before I cleaned the throttle body. Guess I'll try looking at the FPR next.

    I've also picked up some top engine cleaner as well and will use that just for kicks..

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    Re: sticky gas pedal/rough idling/accelerating

    Quote Originally Posted by hankk17
    OK will do. Thanks!

    Incidentally - I'm still a noob to these forums.. what the heck is WOT?
    Wide Open Throttle...also known as WFO...LOL

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    Re: sticky gas pedal/rough idling/accelerating

    Quote Originally Posted by hankk17
    Hi Everyone. I have a 99 Eldorado (non ETC) that I've owned since it was brand new with 6 miles on it. It's had its share of little issues here and there including a strange alarm problem I'll post a question about in the appropriate forum, however for this go-around my issue is north* related.

    I've recently gotten a job that's 50 miles away from home, so I'm doing a lot more highway driving than previously. Recently I noticed that my gas pedal was getting sticky, and when I'd accelerate to get into traffic on the highway I'd have some really weird hesitation as it went through the gears.

    Then the problem got worse and extended itself to EXTREMELY rough idling at stop signs or even when the car was in park.

    I read the forum here a few days ago and found that it was most likely a carbon-fouled throttle that was the issue, so last night I carefully took the air-intake apart and sure enough it was BLACK with carbon. I cleaned it with a toothbrush and some carb cleaner and the problem has gotten better but is still there. I looked inside the intake and the entire intake seemed to be black with carbon as well... What's my next step? Top Engine Cleaner?

    I've also read here that this year north* has had issues with the crankshaft sensor. Could it be a culprit as well?

    The engine has 81K on it and up til now has treated me very well.

    Any thoughts are definitely welcome, and thanks to all for the tip on the carbon - I think it's set me on the right path to fixing the issue.

    -Hankk17
    Hi Hank I am not totally sure if this will solve your problem but a similar problem i had. When i was replacing the injector fuel rail before i found these forums, I happened to remove the plastic intake plates to replace gaskets. They were so full of carbon and crap it took me 4 hours to completly clean them. Just a thought as you are going to have to remove beauty cover to check fuel pressure reg anyways. Not sure if mine was a one of a kind problem but i have 167k miles and drive my car real hard i dont beat it to death but WOT is an everyday thing for my eldo. Hope this info is helpfull.

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    hankk17 is offline Cadillac Owners Fanatic
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    Re: sticky gas pedal/rough idling/accelerating

    Quote Originally Posted by bbob
    Wide Open Throttle...also known as WFO...LOL
    duh.. I should've guessed that.

    Thanks for all the advice Mr. nski!

    -Hank

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    Re: sticky gas pedal/rough idling/accelerating

    Quote Originally Posted by Eldobroken
    Hi Hank I am not totally sure if this will solve your problem but a similar problem i had. When i was replacing the injector fuel rail before i found these forums, I happened to remove the plastic intake plates to replace gaskets. They were so full of carbon and crap it took me 4 hours to completly clean them. Just a thought as you are going to have to remove beauty cover to check fuel pressure reg anyways. Not sure if mine was a one of a kind problem but i have 167k miles and drive my car real hard i dont beat it to death but WOT is an everyday thing for my eldo. Hope this info is helpfull.
    I think I'm going to hit it with some top engine cleaner first to see if that will un-gum whatever it is that's causing the problem.

    I sent my dad off to get the chemicals from our local GM dealer and he came back with 4 cans - two liquid and two aerosol.. I didn't know they made it in aerosol.. anyone had any experience with them? I've done the liquid Top Engine Clean before.. you pour some in the carb and keep the car running for 30 seconds or so.. then let it stall and pour the rest in the engine. Then let it sit for 5 minutes or so and then turn it over and revv it to burn off the stuff. I'm assuming that with EFI I just disconnect the fuel lead on the top of the engine somewhere and use a funnel or something to pour it in the injectors.. yes?

    I've recently gotten the manuals from Helm (www.helminc.com) for my car as well. I'll be studying them up.. hopefully the procedure will be in there somewhere.

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    Re: sticky gas pedal/rough idling/accelerating

    Quote Originally Posted by Eldobroken
    Hi Hank I am not totally sure if this will solve your problem but a similar problem i had. When i was replacing the injector fuel rail before i found these forums, I happened to remove the plastic intake plates to replace gaskets. They were so full of carbon and crap it took me 4 hours to completly clean them. Just a thought as you are going to have to remove beauty cover to check fuel pressure reg anyways. Not sure if mine was a one of a kind problem but i have 167k miles and drive my car real hard i dont beat it to death but WOT is an everyday thing for my eldo. Hope this info is helpfull.
    Eldo, your engine must be a 93/94. ONLY the 93/94 Northstars have the phenolic spacer plates between the intake manifold and the cylinder heads. Beginning with the 95 model year Northstar the engine has a completely different design intake manifold. It is a one piece plastic intake manifold and the silver top cover is just a beauty cover/noise shield...not an integral part of the intake like on the 93/94. Your comments apply to 93/94 engines only....hank's 99 Northstar does NOT have the phenolic plates to clean out...just the EGR valve itself.

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    hankk17 is offline Cadillac Owners Fanatic
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    Re: sticky gas pedal/rough idling/accelerating

    I went and picked up a FPR today on my lunch. Such a teeny little thing. It looks pretty straightforward to replace based on the clips they gave me. Gonna give it a whirl tonight.

    I'll post my findings tomorrow!

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