Fast idle after intake mod

Topic: Fast idle after intake mod (Read 9375 times) previous topic - next topic

Fast idle after intake mod

Reply #60 – February 13, 2014, 08:13:15 AM

Bellow is how i make my modifications so there is no rubber hose or plugs hidden between the upper and lower. I modify the FORD STOCK SYSTEM. In the long run it saves BS time looking for Vacuum leaks. All the other hookups are drilled and tapped for pipe plugs, This eliminates any possibility os a vacuum leak from under the upper. The ford syste sucks as iyt has a nasty habit of leaking.

Fast idle after intake mod

Reply #61 – February 14, 2014, 09:51:01 AM

Quote from: jcassity;428837

how much you want for that mass air meter and adaptor,,LOL, seriously

I just got that thing from ebay. After I fix this crazy air leak, I going to have someone help me put my GT40 heads (after I find some) on, BBK headers and xpipe (I have that already), 19lb injectors and HO cam (which I also have) and then convert to mass air (I also have an A9P and a DA1). Budget is a bit tight (my son is in a private college yikes) so I've been lagging on the heads LOL.

Fast idle after intake mod

Reply #62 – February 14, 2014, 09:52:24 AM

Quote from: TOM Renzo;428846

Bellow is how i make my modifications so there is no rubber hose or plugs hidden between the upper and lower. I modify the FORD STOCK SYSTEM. In the long run it saves BS time looking for Vacuum leaks. All the other hookups are drilled and tapped for pipe plugs, This eliminates any possibility os a vacuum leak from under the upper. The ford syste sucks as iyt has a nasty habit of leaking.

Again, very nice. How do you have time for this stuff?

Fast idle after intake mod

Reply #63 – February 14, 2014, 10:19:46 AM

Quote from: TOM Renzo;428844

OK do this and lets cut to the chase

remove the IAC cut a gasket with only the mounting holes in it. Install it in place of the stock gasket with the 4 holes. start the engine This completely blocks bypass air from that system. If the idle does not change you have totally eliminated the IAC SYSTEM and ECM. Check the TPS as i explained and if ok start spraying carb cleaner. Something i do not recommend but you have no choice. if that fails either rip it down to find the leak or have it SMOKED. Check your EGR for idle flow this would be like a stuck valve ETC messed up gasket or rotted adapter plate ETC. Make sure the throttle plate is completely closed and run the engine. If it idles high you have a vacuum leak somewhere FIND IT!!! Remember there are a few hoses under the upper intake and do not forget the PCV valve and hoses.

Going to work on it this weekend, weather permitting. As you can see, I do have an IAC spacer. if I back out the set screws, the idle does go up -- right now both of them are all the way in. I'll try the gasket thing and the TPS. I just haven't had a chance to work on the car with the short days and working all day.

Thanks for all the advice thunderjet, TheFoe, Haystack, Jcassity and Tom. You guys are really know this stuff.

Fast idle after intake mod

Reply #64 – February 16, 2014, 11:30:09 PM

Here's a quick update. I'm following Tom's 'cut to the chase' instructions. I cut out a gasket with no holes for the IAC and installed it -- removing my IAC spacer as well. The engine started perfectly and the idle was perfect -- just where it should be. I took her out for a run and when I came back the engine was fully warmed up and the idle was high again. So... I think that eliminates the IAC system and ECU as Tom says above. What is confusing is the fact that my vacuum leak only occurs when the engine is hot -- or at least it's worse when the engine is hot. Does that mean that it could be my EGR valve? Doesn't that only start coming into play when the engine is hot?
"Check your EGR for idle flow this would be like a stuck valve ETC messed up gasket or rotted adapter plate ETC. " How do I check for idle flow?

I did the carb spray all around everywhere I could think of and it made no difference in RPM. I pulled off the small vacuum line to the EGR valve and it had a small amount of suction on it -- I don't know if that means anything. Tackling the TPS next but I don't hold out much hope that it is the problem -- I've tried two different TPSs with pretty much the same result.

Fast idle after intake mod

Reply #65 – February 17, 2014, 09:48:08 AM

do you still have the smog system on>?

there are two solenoids behind the passanger strut tower, there are a couple primary vac lines with jumpers in place.

remove vac line at MAP sensor
remove vac line at far end and plug it off
put suction on the line and see if its holding vac

do the same for the two lines going to your smog actuators,, should be white and black.

do you have manual heat? manual levers?
there is a black vac line that travels across the engine bay that enters the cabin to operate the heat controls.

Fast idle after intake mod

Reply #66 – February 17, 2014, 10:00:20 AM

Those lines are small, and even if his HVAC source vac or his TAB and TAD solenoid vac feeds were open, he wouldn't have a huge idle problem because of it. Being that you're in California, though, it's not a bad idea to make sure that the smog pump solenoids are getting their proper vacuum anyway.

Pull the EGR spacer and throttle body off, clean them and dry install new gaskets (Mustang gaskets, not Thunderbird/Cougar gaskets) while you've got it apart, inspect the gasket surfaces, and pull the EGR valve and check that it's all the way closed and that if you work it by hand it can open and close freely.

Fast idle after intake mod

Reply #67 – February 17, 2014, 10:15:59 AM

Ok that eliminates the IAC as the issue. Reason being the IAC . Can not lower the idle if it is beyond a certain point. In your case your initial idle speed is to high and the IAC can not lower it any more. IT IS OUT OF RANGE!! So here is something to try. Remove the PCV valve and plug it then do your test and see what happens. Then remove the EGR adapter and the valve and plug that with a gasket like what you did with the IAC. This should be dun as a process of elimination. What i do is remove the VACUUM hose from the EGR run the car and drive it and see if the passage or pickup is HOT. This will tell you of the valve is leaking. Also check that the throttle plate closes completely when you back off the min idle screw. Make absolutely sure your throttle plate is closing completely then drive the car to test it again. Good luck!!

Fast idle after intake mod

Reply #68 – February 17, 2014, 03:14:03 PM

Quick update. I replaced the EGR valve and mount with the one I had on my old intake. It moved air much better anyway. New gasket, dry. Same issue. I can't find the PVC valve -- where the heck is it? I took a look at the TB butterfly. It closes all the way, but compared to my 50mm stock TB, the hole is much bigger. I put a screw in the hole (not threaded, just loose) and the engine began to stall but the IAC took over and it idled great (even with the engine hot). Anyone fiddled with making that hole smaller. Is there a safe way to do it?

Fast idle after intake mod

Reply #69 – February 17, 2014, 04:13:04 PM

If I were going to reduce the bleed hole in the throttle plate, I think I would remove the plate, flux it and fill it with solder. I'd then make a smaller one through the solder after smoothing it flat. Having said that, I don't think that's your problem, and I don't think I'd ever actually mess with the plate.
Look for the pcv valve at the back of the lower intake right behind and below the gasket for the upper intake. If you just swapped the upper and DON'T know where the pcv valve is, odds are that it was forgotten and it either laying on the intake, or there's a wide open vacuum port on the bottom of your upper (and that would just about do it for your issue).

Fast idle after intake mod

Reply #70 – February 17, 2014, 04:33:32 PM

Ok that is where i was going. The BYPASS HOLE is a metered hole used to bypass the throttle plate. This sets all the parameters on the idle bypass air. I mess with them all the time when we change cams. It is not necessary other than to get the bypass air in line with IAC parameters and TPS SETTINGS. So you are bypassing just as i thought and you went exactly where i wanted you to go. Now find the PCV make sure it is good and hooked up. Then braze or solder that throttle plate closed reset you min idle and hook up your IAC. I have been modifying those holes for years. Even carbs have them and when big cams are installed i have drilled out many and have brazed up some for RE-DRILLING. Now measure the old throttle body plate hole and compare it to the one on your car and post back. Your old one is most likely much bigger. Those bleed holes are a pain as they get gummed up by the fuel and EGR flow. Once you plug that hole make your adjustments you will be golden. You beat me to the punch as i was going to tell you to plug that hole with my next post. Logically if you did not have a vacuum leak that hole in fact is to BIG!!! Always double check parts for fit size and phisical differences like the size of that bypass hole !

Fast idle after intake mod

Reply #71 – February 17, 2014, 04:46:05 PM

Quote from: TheFoeYouKnow;429039

If I were going to reduce the bleed hole in the throttle plate, I think I would remove the plate, flux it and fill it with solder. I'd then make a smaller one through the solder after smoothing it flat. Having said that, I don't think that's your problem, and I don't think I'd ever actually mess with the plate.
Look for the pcv valve at the back of the lower intake right behind and below the gasket for the upper intake. If you just swapped the upper and DON'T know where the pcv valve is, odds are that it was forgotten and it either laying on the intake, or there's a wide open vacuum port on the bottom of your upper (and that would just about do it for your issue).

That would be good indeed, but I did find the PVC valve just now. The reason i didn't notice it when I changed the upper is because possibly the PO had installed a metal tube from the PVC to the upper and I disconnected at the upper, not at the PVC because it was easier to get to. Having said that, I took the PVC out as Tom suggested, plugged the upper hose and got the engine hot. No change to the idle problem. I can blow the tube and shut the PVC with my mouth pressure i.e. it seems to work just fine and is not stuck.

Fast idle after intake mod

Reply #72 – February 17, 2014, 04:54:01 PM

Two thoughts:

1. Is the throttle being held open slightly by the cruise control cable? I've had that cable catch on my Thunderbird and not allow the throttle to return to closed. I was able to remove the cruise cable and re-adjust it so the throttle closed all the way.

2. Have you or anyone else moved the throttle stop screw under the throttle body? If so it's possible that it's holding the throttle too far open.

Also replace all the gaskets between the throttle body, EGR plate, and intake manifold. With all that RTV it may be keeping them from sealing properly.

Fast idle after intake mod

Reply #73 – February 17, 2014, 06:33:25 PM

Quote from: thunderjet302;429046

Two thoughts:

1. Is the throttle being held open slightly by the cruise control cable? I've had that cable catch on my Thunderbird and not allow the throttle to return to closed. I was able to remove the cruise cable and re-adjust it so the throttle closed all the way.

2. Have you or anyone else moved the throttle stop screw under the throttle body? If so it's possible that it's holding the throttle too far open.

Also replace all the gaskets between the throttle body, EGR plate, and intake manifold. With all that RTV it may be keeping them from sealing properly.

Good thoughts Jet. It's closed. If the IAC is unplugged and I stick something over the bypass hole, the car stalls. But I can't say I understand cruise control at all. When I had the TB off, that black plastic domed end just moves freely up and down the cable -- feels like the cable is broken or something. Cruise control has never worked since I bought the car -- haven't had a chance to look into it.

RE: the gaskets, I haven't changed those two gaskets yet, but I have run carb cleaner and propane gas all around there and detected nothing.

Fast idle after intake mod

Reply #74 – February 17, 2014, 06:42:13 PM

Quote from: TOM Renzo;429040

Ok that is where i was going. The BYPASS HOLE is a metered hole used to bypass the throttle plate. This sets all the parameters on the idle bypass air. I mess with them all the time when we change cams. It is not necessary other than to get the bypass air in line with IAC parameters and TPS SETTINGS. So you are bypassing just as i thought and you went exactly where i wanted you to go. Now find the PCV make sure it is good and hooked up. Then braze or solder that throttle plate closed reset you min idle and hook up your IAC. I have been modifying those holes for years. Even carbs have them and when big cams are installed i have drilled out many and have brazed up some for RE-DRILLING. Now measure the old throttle body plate hole and compare it to the one on your car and post back. Your old one is most likely much bigger. Those bleed holes are a pain as they get gummed up by the fuel and EGR flow. Once you plug that hole make your adjustments you will be golden. You beat me to the punch as i was going to tell you to plug that hole with my next post. Logically if you did not have a vacuum leak that hole in fact is to BIG!!! Always double check parts for fit size and phisical differences like the size of that bypass hole !

I was trying to think of how I could braze that hole closed without having to take the TB off again. My soldering gun just wasn't getting that plate hot enough for solder to stick (I was trying it with a spare TB I had). I found a small metal tube with a 90 degree flair at the end (about 3/4 cm long) that just fits in the hole. I think it came off my old weed eater carburetor. I stuck it in the hole flair on the outside and JB welded it. It's inside diameter is just about the size of my original hole. When it dries I'll update the post. (probably tomorrow). Hopefully it doesn't start whistling or something.