2000SVTC Posted April 29, 2014 Share Posted April 29, 2014 I'm going to write it up once I get it resolved, but "throttle hang" on my car seems to be 100% a result of a bad throttle position sensor signal. I used to have a very bad case of it, and was puzzled by the fact that practically anything I did to fix it worked for a bit and then the problem came back. I replaced the TPS - problem fixed, came back. Replaced the IAC (ISC?) - problem fixed, came back. I used a PC scan tool and saw a slightly odd reading on the TPS, fiddled with the TPS connector - problem went away, came back. For a while I ran the "fix" with the line restrictor but that was mostly masking the problem and felt like too much of a bodge so I took it out. It seems like I need to unplug and replug the connection about once a month to keep the problem at bay. I also think my mpg suffers a bit when it's doing it. All of my fixes worked because they all involved disconnecting the TPS connector. What I think is happening is that a corroded ground (??) connection is making the closed throttle voltage float around a bit, ECU thinks throttle is open a bit and the dashpot function of the ECU / IAC control is affected. The ECU on this car must be super sensitive to the TPS signal in this regard. I've just bought some super electrical contacy corrosion cleaner and will give a good cleaning to the female contacts in that connector. If that doesn't do it I'll try to disassemble the connector or maybe replace it.... I have no idea whether my case is typical but it always seemed weird that these cars had so many IAC problems. Software - it's always software these days!!! (Of course the software people reply that software never breaks, hardware breaks.....) Al Seim 2000 SVTC Link to comment Share on other sites More sharing options...
Shane S. Posted April 30, 2014 Author Share Posted April 30, 2014 Well took it for a long drive today & the gas mileage doesnt seem as good as it use to be. Doesnt seem to accelerate as quick & there is still some pops when decelerating but the stumble is gone after the gasket change & the popping is better. The exhaust sounds more buzzy when accelerating also, sounds strained or something & the idle is just not as smooth as I feel it should be & Im getting frustrated lol. Im wondering if I could have a clogged cat? I was also reading about the dpfe being a problem on these cars. I had that code p0420 back when I first got the car, the mufflers where rotted out so I put new ones on then reset the code & its been a few months & I havent seen it again. Link to comment Share on other sites More sharing options...
Shane S. Posted April 30, 2014 Author Share Posted April 30, 2014 Any ideas? I think I might get a vacuum gauge & see what I can see with that. Might check the fuel pressure too just for the hell of it & do one more vacuum leak check. Might get rid of the duralast plug wires & try standard motorcraft wires. I noticed the gas mileage suffering right before the gasket change so it cant be related to that. Really getting frustrated. Ive spent so much money on this car & I just want to drive it. If I dont see anything with the gauges im gonna take it to a shop cause this is suppose to be a daily driver to free up my other 2 project cars so I can work on them but they're running better & more reliable than the contour (81 toyota celica & an 80 triumph spitfire). Does anyone have any ideas? Link to comment Share on other sites More sharing options...
Shane S. Posted May 1, 2014 Author Share Posted May 1, 2014 did some poking & found the pvc valve is leaking where the hose plugs onto the top of the plastic T & there the plastic T connects to the PCV valve. The hose that connects to the top of the T, the clip is broken so I guess thats why its leaking there. Can you cut the plastic clip off the rubber hose & just hook up the hose to the T with a hose clamp? Link to comment Share on other sites More sharing options...
CrewChiefPro Posted May 1, 2014 Share Posted May 1, 2014 Just fix it anyway you can. Try disconnecting the vacuum plug at the EGR and plug it. Drive it and see if it is any better. If not, there is always the possibility that you have wiring issues. The 98s were known to have bad wiring harnesses. Link to comment Share on other sites More sharing options...
Shane S. Posted May 3, 2014 Author Share Posted May 3, 2014 I did some poking around today, I hooked up a vacuum tester to check for a restricted exhaust & it tested normal so I dont have a plugged cat. I disconnected the EGR line & it had slight vacuum on it at idle which isnt normal right? I tapped on the EGR solenoid & the vacuum would increase & decrease as I tapped on it or even moved it the vacuum would change. Im guessing that solenoid is no good, its cheap enough so I'll replace it. Still waiting on my motorcraft PCV valve to come. Im going to test the PCV system with the vacuum tester this weekend just to see what readings im getting with the duralast PCV valve in there. I also tested my EGR valve & its functioning properly. What do you guys make of this? Link to comment Share on other sites More sharing options...
Shane S. Posted May 3, 2014 Author Share Posted May 3, 2014 also where can you find replacement plastic vacuum tube? Link to comment Share on other sites More sharing options...
Shane S. Posted May 5, 2014 Author Share Posted May 5, 2014 I got the pcv valve yesterday so I pulled the duralast piece of crap out & I sucked on the top of it & there was a restriction. I havent had a chance to go on a good drive yet but it seemed to idle better. Im going to get the EGR solenoid today then I can reset my ECU & go for a drive. Also there was oil seeping out of the valve cover cap & seals so I know that duralast crap wasnt working. Had no seeping to issue with the pcv system till I replaced the original with that duralast last month. I will never buy duralast again. Thats most likely the source of the smoke from the back of the engine I was getting occasionally, oil dripping from that rear valve cover onto the exhaust made worse by a stopped up PCV system. I felt back there the other day & there was oil back there. I'll have to tackle the valve cover gaskets & oxygen sensors later on when I have some money. Link to comment Share on other sites More sharing options...
Shane S. Posted May 6, 2014 Author Share Posted May 6, 2014 OK the car is running much much better! Its drive able without being irritating accept for the manual trans being a pain to shift sometimes but I have some of the ford honey ready to go in for that. But I put in that new EGR solenoid & there is still slight vacuum at idle with or without the electrical connector connected. Its not enough to open the valve, its just a little vacuum. I hooked my vacuum gauge up to the hose from the solenoid that goes to the EGR valve & it wasnt even enough vacuum to show anything on the gauge but I left the vacuum gauge hooked up & put on my windshield to go for a test drive to see if it ever got vacuum. I went for a cruise & the gauge showed nothing so my EGR valve isnt ever opening. The solenoid is new & its getting 12 volts to it. Im going to ground it to see if it opens just to make sure I didnt get a bad solenoid but its the more expensive napa brand so I doubt the solenoid is at fault. Could the dpfe sensor be at fault? To test it you back probe one of the wires on the dpfe conector to check for voltage & if its past a certain voltage its toast right? Whats the spec voltage it should be at & which wire do you probe? From what I understand one is 12 volts & you check one of the other wires for the dpfe voltage test but which one? The only other thing it could be is the PCM right? Maybe a dirty connector? Its behind the power steering filler right? Can anyone chime in with some advice? Link to comment Share on other sites More sharing options...
Shane S. Posted May 10, 2014 Author Share Posted May 10, 2014 ....... Link to comment Share on other sites More sharing options...
Shane S. Posted May 11, 2014 Author Share Posted May 11, 2014 DPFE tested 1.2 volts cold & 1.3 volts hot. Normal is .8-1.2 right? The wierd thing is, on a cold start test drive with my vacuum gauge on the EGR vacuum line I was getting a good reading at cruise till the car warmed up then all of the sudden I had no vacuum at all & the DPFE was 1.3 volts. Im assuming the DPFE gets hot inside then stops working? Is anyone here? Link to comment Share on other sites More sharing options...
mondeoman Posted May 11, 2014 Share Posted May 11, 2014 Shane - yes we are here. Terry is our resident expert on your issue - I am Zetec literate. I will research and update, unless Terry pipes in or someone else. Terry has been out of town for a week or so. Link to comment Share on other sites More sharing options...
Shane S. Posted May 11, 2014 Author Share Posted May 11, 2014 (edited) I see lol didn't mean it in any negative way. Thanks! Edited May 11, 2014 by Shane S. Link to comment Share on other sites More sharing options...
mondeoman Posted May 11, 2014 Share Posted May 11, 2014 I see lol didn't mean it in any negative way. Thanks! No worries my friend!! There is so much work posted here that you have done. Trying to come up to speed! Link to comment Share on other sites More sharing options...
Shane S. Posted May 11, 2014 Author Share Posted May 11, 2014 Yea I know lol its improving little by little! Its drivable now but I know the egr doesn't work right and it bugs me lol. Link to comment Share on other sites More sharing options...
mondeoman Posted May 11, 2014 Share Posted May 11, 2014 I understand EGR basics, and am versed on the EGR delete on the Duratec, but your issue......not so much. Terry should be back in tomorrow (my best guess). Aussie also has some experience with the Duratec. He i sout there, just extremely busy. Link to comment Share on other sites More sharing options...
Shane S. Posted May 13, 2014 Author Share Posted May 13, 2014 Thanks Mondeoman! Link to comment Share on other sites More sharing options...
Shane S. Posted May 14, 2014 Author Share Posted May 14, 2014 Guess I'll start a new thread on the dpfe? Link to comment Share on other sites More sharing options...
Terry Haines Posted May 14, 2014 Share Posted May 14, 2014 ..not too sure of the issue but the basics are this..When the EEC 'calls' for egr it triggers the vac sol which in turn sends vac to the large EGR valve on the intake manifold. 'If' the DPFE sensor does not sense 'flow' then it will trigger a CEL. main issues with the DPFE are 1)blocked passages on the intake manifold behind the t/body to the EGR valve, carbon build up is usually the cause here or 2) the DPFE sensing lines, 2 small tubes connected to the main EGR tube from the exhaust manifold to the EGR valve..3)EGR valve itself is not operating..this can be checked by disconnecting the vac line to the egr valve and block the vac feed tube then start the engine and use a vac pump to open the egr valve..if the engine stumbles then the egr valve is working... Other faults can be ..egr elect sol not opening, vac tubes broken, dpfe sensor not operating. All electrical connections on dpfe, vac sol should be checked ...Don't jump tests ...get to the root cause before fitting any parts.. Link to comment Share on other sites More sharing options...
Shane S. Posted May 14, 2014 Author Share Posted May 14, 2014 (edited) Ive replaced the EGR solenoid, cleaned the entire intake manifold, tested the EGR valve & all the wiring is good.All the vacuum lines are connected & not broken. The EGR solenoid is getting manifold vacuum. The DPFE voltage was 1.2 volts at cold start & 1.3 after a drive both at idle. On a ride on a cold start I had vacuum on my vacuum tester to the EGR valve till the car warmed up then I had nothing. What do you make of that? Thanks Terry Edited May 14, 2014 by Shane S. Link to comment Share on other sites More sharing options...
Terry Haines Posted May 14, 2014 Share Posted May 14, 2014 ...the EEC only 'calls' for egr in a light cruse and decal modes..it does not feed egr all the time.. Link to comment Share on other sites More sharing options...
Shane S. Posted May 14, 2014 Author Share Posted May 14, 2014 After the car warms up my vacuum gauge shows nothing when cruising but on a cold start it shows vacuum when accelerating & cruising till the car warms up then I have no vacuum at any speed but I only drove around for maybe 5-10 min with the gauge in my window. Does this sound normal? Link to comment Share on other sites More sharing options...
2000SVTC Posted May 15, 2014 Share Posted May 15, 2014 (edited) I think you are monitoring the vacuum line which normally controls the EGR valve? I did the same thing (on my Taurus I think...) and definitely saw activity in normal driving. If you've disconnected vacuum from the EGR as opposed to just teeing in to it I wonder if maybe the ECU is ceasing to call for EGR when it does not see any feedback from the DPFE? This stuff can be hard to diagnose. On my SVT, I had a DPFE failure, replaced with a NAPA DPFE - which was itself no good. That sent me spiraling off looking at other things, finally got a good OBD2 scantool and realized DPFE was bad. Put a Ford one on and all was good finally. Looking at the DPFE readings on a good system, it is fairly dynamic in normal driving IIRC. Definitely EGR happens during much of what I'd call crusing. A good scantool (ie live readings not just codes) is almost a must IMO trying to chase some of this stuff.... Edited May 15, 2014 by 2000SVTC Link to comment Share on other sites More sharing options...
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