Dave1647545494 Posted February 28, 2011 Report Share Posted February 28, 2011 you could always try another tb.... I've never heard of boost pushing the blade open before even on a stock one on anything, but if the return spring is weak it could be possible Quote Link to comment Share on other sites More sharing options...
rl Posted February 28, 2011 Report Share Posted February 28, 2011 No Cruise Control. I'm tracking an interesting idea concerning the turbo building pressure and forcing the tb blade open, raising the RPM, raising boost, raising RPM, raising boost... No, thats not going to happen or work. You could run that thing at WOT 20+ psi with no BOV and go from WOT to closed and it would spin the turbo backwards and never move the blade. I have seen shitty throttle bodies have the blade flex under vacuum, bit its just enough to cause a mild surge. The TPS is interesting, however I dont know how much air the IAC could move, and the iac should be closed under higher TPS voltage to be able to feed air if it needs to (it wouldnt be wide open). Maybe a short in the IAC wire? A vacuum leak would be unmetered air and odds are it would just sputter and pop and not rev. Any chance something is catching the throttle cable? Not enough slack and maybe a bad motor mount causing the motor to twist in gear pulling the throttle open? Quote Link to comment Share on other sites More sharing options...
nurkvinny Posted February 28, 2011 Author Report Share Posted February 28, 2011 No, thats not going to happen or work. You could run that thing at WOT 20+ psi with no BOV and go from WOT to closed and it would spin the turbo backwards and never move the blade. I have seen shitty throttle bodies have the blade flex under vacuum, bit its just enough to cause a mild surge. The TPS is interesting, however I dont know how much air the IAC could move, and the iac should be closed under higher TPS voltage to be able to feed air if it needs to (it wouldnt be wide open). Maybe a short in the IAC wire? A vacuum leak would be unmetered air and odds are it would just sputter and pop and not rev. Any chance something is catching the throttle cable? Not enough slack and maybe a bad motor mount causing the motor to twist in gear pulling the throttle open? Everything you say makes sense under normal circumstances, and maybe in mine too. I traced the cable from the pedal, through the wall, and to the tb. Everything looks good. I have actual been behind the wheel when a cable stuck because of a bad mount in an old 351 Torino. Very similar to what I experienced except for the part where I wasn't revving it and it stuck, it increased RPM by itself, from an idle. People aren't believing me on that last part, but I promise it's true. Can't get back out to wrench on it until Wednesday. About ready to throw a carb on it... J/K Quote Link to comment Share on other sites More sharing options...
nurkvinny Posted March 5, 2011 Author Report Share Posted March 5, 2011 So... Unbolted the TPS again, realigned and rebolted. Removed IAC, cleaned with TB cleaner, reinstalled. Checked all vacuum lines a third time. Started it up, idled out into driveway, sitting in place shifted between N, R, and 1 repeatedly, revved to all different RPMs while in gear and not. Vacuum showed 13-20 depending on engine speed and held steady when engine speed was constant. Stumped on brakes hard a couple times to rule out bad booster. Car does have a very noticeable stumble while tapping the throttle from an idle. Falls on its face when you floor it. Cap and rotor look shitty, will clean them up. Plugs look good, same for wires. Car idles high, IMO, about 1000-1250, but did not experience WOT issue. Think the TPS could cause the stumble, high idle, etc? Thanks. Quote Link to comment Share on other sites More sharing options...
nurkvinny Posted March 9, 2011 Author Report Share Posted March 9, 2011 New TPS installed Sunday. Things are 75% better. No idle surges. Was able to goose the pedal right after starting it and it responded tons better. Still some hesitation now though after it ran for a minute or so and had to feather throttle to keep running. Found the TPS relearn steps, but haven't had time to do them. Clear the computer's idle memory by disconnecting the battery for 20+ minutes. -Disconnect the Idle Air Bypass solenoid -Reconnect battery -Start engine and set idle speed to desired RPM with idle screw on throttle body -Turn off engine and reconnect the air bypass solenoid -Set TPS voltage between 0.90 - 0.95 volts with a digital volt meter -Start engine and let it idle for 2 minutes with no accessories on. -Turn off engine for two minutes -Start engine again and run for 2 minutes with every accessory turned on. -Turn engine off again. And found this: 10 Pin Connector modification: 1. Take the 10 pin connectors apart (salt and pepper shakers). 2. use a pick like tool to spread the male terminals open more so they make better contact. In the center of each male terminal there is a small seam and seams down the sides of the terminal which allows you to spread them open. 3. Apply some dielectric grease to the terminals 4. Plug the connectors back in. Quote Link to comment Share on other sites More sharing options...
Miller Posted March 9, 2011 Report Share Posted March 9, 2011 Isn't that car on a SCT flip bank with with an a9l? Is EFI learning on? I had the same problem with mine and it was the IAC. It randomly shot to like 4k and wouldn't come down. After replacing it I had to adjust the throttle position to get the rpm in the right range. Is that motor cammed? Quote Link to comment Share on other sites More sharing options...
nurkvinny Posted March 9, 2011 Author Report Share Posted March 9, 2011 Isn't that car on a SCT flip bank with with an a9l? Is EFI learning on? I do not know. I had the same problem with mine and it was the IAC. It randomly shot to like 4k and wouldn't come down. After replacing it I had to adjust the throttle position to get the rpm in the right range. Is that motor cammed? No. Quote Link to comment Share on other sites More sharing options...
hpfiend Posted March 9, 2011 Report Share Posted March 9, 2011 (edited) have you seen the tb butterfly? Maybe somebody drilled a honking big hole in it to "help" with idle issues and somehow the turbo/bov/wastegate/ is forcing a @#%@ ton of air in there... btw a faulty tps should have set a code, my old 5.0 did when it had a crazy surging rpm issue- have you checked it for codes? I sold my obd1 ford scan tool to a guy on here but they are pretty cheap... IIRC the iac can add air reading tps input so it could allow more air to raise the rpm but I don't know if it is enough air for 5000rpm... maybe with a turbo pushing it it could... you can also get the codes with an LED, a resistor and some alligator clips IIRC 19 means all is ok for some reason If you want my honest opinion I would check all of the mechanical things you can first and then have Don LaSota and Rob (RL) if you can get him away from his snapon truck ;-) to take a look at the tune (if it is SCT)... it was money well spent by me! My car after adding the blower ran like absolute @%%@ and they did some brilliant tuning work combined with great mechanical advice ... check your MAF voltage at idle that was one of the things that was off on mine.... mine had a bad MAF ground we think and a lower intake manifold vacuum leak combined with an IAC adjuster I had put on (sold by ford btw so it is very common for the 5.0 to have surge and idle issues, a non-factory chinese oversize TB, too small of an airfilter, no blowoff valve on a restrictive intake system, etc... when they finally got it squared away on all but the coldest days it ran better than when it was bone stock when I bought it (and even then not that bad)- they told me they would take a look and adjust tune if necessary on a really cold day (we tuned it in the summer) for free but I sold the car before we got around to it... their website is really informative as well- lasotaracing.com I think... fwiw I had a pretty lopey cam, moderate heads, supercharger, a soldered lightning truck MAF, and big injectors and pump so it was no easy feat- it had mild issues before but with the boost they were magnified... Edited March 9, 2011 by hpfiend Quote Link to comment Share on other sites More sharing options...
nurkvinny Posted March 9, 2011 Author Report Share Posted March 9, 2011 have you seen the tb butterfly? Maybe somebody drilled a honking big hole in it to "help" with idle issues and somehow the turbo/bov/wastegate/ is forcing a @#%@ ton of air in there... Yes. No holes. Here's the history as I know. - I heard the car idle for 2-3 minutes in Sam's garage late last year. Never revved it. No WOT, no dieing. - Car went to IPS for a few months. I have no idea what they looked at, pulled apart, tested, if anything. - Car brought to me. - Car goes WOT while idling from attached garage to detached garage. Assumed a fluke. - I replace harmonic balancer, pull plugs for compression test, put back together - Car idles long enough to refill antifreeze, 7-8 minutes? Car revs poorly. - Pull car into driveway, runs 3-4 minutes, WOT by itself again. - Cleaned IAC. Not much change if any. - Replaced TPS. Set to .98v. - Car starts and revs MUCH better, but now won't hold an idle after a minute or two. Vacuum showing ~15-18. I have not had time to follow that relearning procedure yet. At this point, I believe setting the idle screw and a relearning will do wonders. It's also sitting with old gas, and the thing has been cranked and started a shit ton now without being driven. A couple miles might help things too.? I am going back to carbs. Quote Link to comment Share on other sites More sharing options...
hpfiend Posted March 9, 2011 Report Share Posted March 9, 2011 (edited) hey maybe its a fuel issue instead of air... what about a sticking injector(s)/tune issue with that super duty fuel system filling a cylinder with fuel and it running superlean when it does its rev tricks? when u heard it idling fine and before it went to ips was it also late winter early spring? Edited March 9, 2011 by hpfiend Quote Link to comment Share on other sites More sharing options...
nurkvinny Posted March 9, 2011 Author Report Share Posted March 9, 2011 hey maybe its a fuel issue instead of air... what about a sticking injector(s)/tune issue with that super duty fuel system filling a cylinder with fuel and it running superlean when it does its rev tricks? when u heard it idling fine and before it went to ips was it also late winter early spring? It was November. I think the TPS cured the revving. It's keeping it running that is the real issue now. I might head out and take a video later. Quote Link to comment Share on other sites More sharing options...
Miller Posted March 9, 2011 Report Share Posted March 9, 2011 hey maybe its a fuel issue instead of air... what about a sticking injector(s)/tune issue with that super duty fuel system filling a cylinder with fuel and it running superlean when it does its rev tricks? when u heard it idling fine and before it went to ips was it also late winter early spring? You might be on to something. I think the car would likely start and run better in the cold. It's hot starts they don't seem to like. Quote Link to comment Share on other sites More sharing options...
Dave1647545494 Posted March 9, 2011 Report Share Posted March 9, 2011 if it had the idle map set with a bad tps you might need to adjust the tune.... Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.