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Thread: tps and/or iac valve...

  1. #1
    Join Date
    Apr 2002
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    Greenville, IN
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    Arrow update: EGR and/or EVS!!!!!!

    alrighty...first i want to ask about the throttle position sensor....what would the car do if that little fart went bad?? my car is acting weird (different anyways...maybe it's running correstly for the first time!) i had similiar symptoms with my standard t-bird awhile back, and after i replaced the iac valve, all was well.....but this time, unless i have TWO bad IAC valves, it's something different. first of all - i replaced the supercharger, inlet plenum, and throttle body off my parts car (in one piece, so i wouldn't have to mess with the gaskets) the only sensor from the parts car is the tps..... today i cleaned the EGR valve because i got a code saying it wasn't opening...i need to scan the comp again now but these symptoms still remain:

    SYMPTOMS:

    car will idle decent (sometimes slight fluctuations) but if i press the clutch in it will idle at about 1500 rpm...it used to idle at 1000 rpm in this case, and 750 at a stopped-car idle

    when coasting...the engine will cut out a little, slowing the car down slighty....it feels like the iac valve is messed up....it's just like the air flow gets cut and then when i press the gas pedal a hair, it snaps open again. (the car either speeds up a litttttttle bit or slows down a littttttle bit when coasting) like i said, on my other tbird, i replaced the iac and it stopped, i did some iac swapping this time....and either neither work now, or it's something else.

    hope someone can help me out, sorry if this post seems jumbly...i'm in a hurry to get back out there to the garage!!! thanks guys, happy easter!!!

    derrktor feesh
    Last edited by DrFishbone; 04-24-2003 at 11:42 AM.
    Matt Haub
    Shootouts: '09 SS 1st | '10 Mod1 2nd | '11 Bracket 3rd | '12 Bracket 1st | 2013 | '14 Bracket 3rd | 2015 | '16 Bracket 1st & Mod2 2nd | 2017 |
    Black '89 5spd - 281K miles, MPx, E85, Alky-Inj RWHP: ? RWTQ: ? Best 1/4mi:12.521, MPH:107.23mph
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  2. #2
    Join Date
    Apr 2002
    Location
    Madison, Ohio
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    I don't know the exact effects of each item failure, but you do need to verify that TPS voltage is around .9 with key on engine off.

    If that is ok, then IAC is the next suspect. It could also be a vacuum leak, so don't overlook that possibility.

    Good luck!

  3. #3
    Join Date
    Nov 2002
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    Syracuse, NY
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    it's probably the tps. my ranger used two rev up and down at idle and i was sure it was the iac but turned out to be the tps.
    good luck doc fish.
    joe

  4. #4
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    heh heh...

    it shouldn't be a vacuum leak, i sealed off about 3 or 4 a few weeks ago however, if i can manage to get teh tps OFF i'll try putting my old one back on. i can't get ANY of the stupid tps screws out of the throttle body!!!! thanks joe..that should help the computer isn't throwing any codes as far as the tps or iac...BUT MAF..however, it still could be either of the afforementioned sensors. anyways, i'll let you guys know what's up when i get back out there! anyone else have input?? i've spent hours researching them on here, but have found limited info that relates to my probs. have a great day everyone!!

    derrktor feesh
    Matt Haub
    Shootouts: '09 SS 1st | '10 Mod1 2nd | '11 Bracket 3rd | '12 Bracket 1st | 2013 | '14 Bracket 3rd | 2015 | '16 Bracket 1st & Mod2 2nd | 2017 |
    Black '89 5spd - 281K miles, MPx, E85, Alky-Inj RWHP: ? RWTQ: ? Best 1/4mi:12.521, MPH:107.23mph
    35th Anniversary Auto 46k miles | Red '93 Auto 186k miles
    My Garage

  5. #5
    Join Date
    Jul 2002
    Location
    Coeur d' Alene, Idaho (God's Country)
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    does it have these symptoms when you first start it up cold in the morning? because i don't think the TPS effects anything until the engine reaches operating temp and the computer goes into "closed loop". The IAC valve , however , would have an effect on a cold engine. did you replace it with a new one or another used one? I had an idle fluctuation on my Bronco and sprayed carb cleaner into the IAC valve and hit helped, but still did it some. So i took it off again, removed the electric motor part, and soaked the valve in Carburetor dip for 3 hours. when it came out it looked brand new, and now the bronco Idles perfectly. Looks like the IAC on my SC is all plastic though so i dont know if you should soak it in carb dip but you could at least clean it thoroughly with spray carb cleaner.

  6. #6
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    Nov 2002
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    Syracuse, NY
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    those screws are stupid. i had had to take them out with vise grips after i broke the tps a little. i put hex head bolts in it after.
    good luck
    joe

  7. #7
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    Apr 2002
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    Madison, Ohio
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    The screws are not phillips, that is why you have trouble. They are actually posidrive and have locktite on them. Which the right screwdriver they come off ok. Before you swap parts you should check the voltage. It wouldn't be the first time there were two bad or misadjusted parts.

    The TPS is part of cold start up. The EEC always uses TPS.

    Good luck.

  8. #8
    Join Date
    Apr 2002
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    Greenville, IN
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    Thumbs up okay, change of subject...

    i THINK i'm getting closer. i finally found some useful sources online, and learned a bit more about the egr valve and egr valve sensor as well. being that my evs WAS NOT hooked up for about 6 months (with no check engine lights and fairly smooth idle!) and i just hooked it up, AND that the symptoms i've seen are almost exactly what i have.....i think it's probably the stupid little sensor! if not that, the egr valve itself. i cleaned the egr tube, and tried to careful clean the egr valve. computer still gives code 33 which concerns the egr valve. problems are better, but still not solved. so here's my questions : does anybody have an egr valve sensor they'll sell me for a few bucks?

    does anybody know where the best place to get an egr valve and/or sensor would be? there has to be some around that are cheap autozone is like 100 bucks for both! thanks for any and all help!

    Derrktor feesh
    Matt Haub
    Shootouts: '09 SS 1st | '10 Mod1 2nd | '11 Bracket 3rd | '12 Bracket 1st | 2013 | '14 Bracket 3rd | 2015 | '16 Bracket 1st & Mod2 2nd | 2017 |
    Black '89 5spd - 281K miles, MPx, E85, Alky-Inj RWHP: ? RWTQ: ? Best 1/4mi:12.521, MPH:107.23mph
    35th Anniversary Auto 46k miles | Red '93 Auto 186k miles
    My Garage

  9. #9
    Join Date
    Nov 2002
    Location
    Syracuse, NY
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    504
    there is also a vacumm control selonoid for the egr valve. follow the vacumm line from the egr and you will see it on the fire wall. the other one (little gray one) is the pressure feedback sensor, you can get one from napa for about 25-30 bucks. i have an extra control selonoid i thought it was bad but my wiring was bad. if you e mail your adress to me you can have it, no charge.
    joe
    rkurpie1@twcny.rr.com

  10. #10
    Join Date
    Apr 2002
    Location
    Greenville, IN
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    Thumbs up update...

    okay, things are back to where i was earlier (had a few worsening hours there for awhile!) anyhow, i checked the control solenoid like thry5thsc pointed out, and indeed it needed attention (thanks again bud!) the cap on the bottom had popped off somehow...so now i'm wondering if there's something wrong with the little solenoid that would MAKE the cap pop off. (apparently the same thing happened to my parts car before it became a parts car go figure!) i now have the problem narrowed down to the EGR valve, egrvalve solenoid, and/or egr position sensor. hopefully i won't have to buy all new...that'd be around $100 i believe anyhow, WHEN should i feel vacuum going TO the EGR valve FROM this little solenoid anyway? for some reason i have a feeling the answer may be when the car is gently "bucking" when i'm coasting BUT however i'm unsure...any further help will be greatly appreciated, thanks for everything so far guys!
    Matt Haub
    Shootouts: '09 SS 1st | '10 Mod1 2nd | '11 Bracket 3rd | '12 Bracket 1st | 2013 | '14 Bracket 3rd | 2015 | '16 Bracket 1st & Mod2 2nd | 2017 |
    Black '89 5spd - 281K miles, MPx, E85, Alky-Inj RWHP: ? RWTQ: ? Best 1/4mi:12.521, MPH:107.23mph
    35th Anniversary Auto 46k miles | Red '93 Auto 186k miles
    My Garage

  11. #11
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    Apr 2002
    Location
    Imperial, MO (near St. Louis)
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    4,330
    When the car is idling, the EGR transducer (black sensor that controls vacuum to EGR valve) should be supplying the EGR valve with vacuum. If you need any parts, email me at rodsv6cougar@cs.com, I should have whatever you need.

    -Rod

  12. #12
    Join Date
    Nov 2002
    Location
    Syracuse, NY
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    504
    you should feel vacuum at idle. kinda like it's gently pulsing. don't forget to give me your mailing adress and i'll send it to ya. i thought it was bad so i baught another one only to find out it was the little brown wire that had a break in it. the one that i'll send you is only used for maybe a month. i don't remember what i paid but it is a ford part. i think they are dealer item. the egr transducer or pressure feedback sensor (pfe, little square gray one), you can get at napa for about 20 bucks i think. if it's more let me know, i got an excellent hook up at napa and i'll hook ya up. the black one with round grey top and two vac. lines is the egr control solenoid. another thing, make sure you use the factory hose that goes from egr tube to pfe sensor, it's sillicone, most rubber hoses will dry up and crack from the high temps and the pfe will get an incorrect reading. 25 bucks at ford if you don't have one.
    joe
    Last edited by Thrty5thSC; 04-28-2003 at 01:27 AM.

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