Fox T-Bird/Cougar Forums

I shaved a whole second off of my 0-60 time but...... 

And I have a bridge in NY I'll sell cheap... If you can knock a second off any intake swap, you can make millions in the porting business....

Stock: 11.9 sec
8.8/3.73 rear axle swap: 10.5 sec
Intake swap: 9.5 sec

Check your EGR plate.  If you're running an HO upper but using a SO EGR plate or using the HO plate with the SO gasket, you're probably leaking unmetered exhaust gas into the intake.  I had this problem when I started mixing parts on mine, and like a moron, I asked parts for an EGR plate gasket for my car instead of for a 96 Explorer.  It took forever to figure out what was happening.  I checked all over for a vacuum leak, I was literally driving myself crazy over it.  Then I happened to look into the intake with the throttle plate open and saw all the gasket hanging into the inlet.  I realized what was happening and wanted to shoot myself in the balls for being so stupid.

I am going to suggest that it's running in fail safe mode.  Is it possible to get codes from it?  This is all just a guess.

Stock:  11.9 sec
8.8/3.73 rear axle swap: 10.5 sec
Intake swap: 9.5 sec

Vacuum leak FIND IT!!! Or tps out of adjustment.  One second gain in 0-60 with an intake swap.

And just for the record those engines do not have a Screw to set base idle!! 

Jebus I just saw that. The completely stock standard 5.0 in my Thunderbird would hit 60mph in about 8.5 seconds or less after a swap to 3.73 gears.

Sorry for these dumb questions -- it's a bit of a learning curve.

REALLY by now you should know that that is a MIN idle screw not a base idle screw. There is a big difference from a base idle and MIN idle screw.Clearly i have mentioned this 20,times or more posting on this site. I did a a thread on this a few years back. Basically no modern EFI engine controls base idle with a set screw!!!!! Why do you think you have IAC Step counts. And i am if correct in saying Fail safe does not control IDLE speed to any great lengths in an OBD1 Engine management system> By the way the link you posted is not totally correct to set base idle. FORD has the correct parameters ans the ones you posted in fact has wrong info!!!

First off the 5.0 does not have an adjustable TPS as far as i can remember. The 2.3 does So messing with MIN idle screw is how you adjust it other than removing the sleeves from THE TPS and adjusting it lower than 1.1 VOLTS. The TPS voltage is not critical as long as it is below or @1.1 Volts. To many people set these sensors like a nuclear watch. It does not have to be close by any means. .5-1.1V  is fine

Note when i CAM UP the little ford motors i have a special procedure to bring in all the settings so it can be tuned properly. Remember It is always best to use a brand new IAC along with a brand new TPS Set properly. Fords do hunt to some extent so s little hunt is normal!!

Changing the TPS sensors is BAD as FOD actually lists 6 different ones for different tunes. So what is the voltage reading at closed throttle and which TPS are you using. That is part number.

You're saying you think the ECU is stuck in fail safe and it needs to be reset/rebooted somehow?  Is this something I can do (capture the codes) or do I need to find some piece of equipment?  sorry I'm new to all of this.

That's 1k rpm according to what?  Just curious what instrumentation you're taking that from.  My digital tach is tough because 800 rpm free idle looks like 1000 and 800 rpm free idle is pretty good.  In gear I was getting about 675, which is just a fuzz high, but it was the best I could do.  My loaded idle on my digital tach looked like 800.  Just saying, can you trust your instrumentation? Are you using an buttstuffog, an add-on, a timing light with a tach display, a SUN scope etc.

If I had an 8.5 0-60 with my SO engine, I would probably be satisfied (at least for a while lol). 

So here's an update,  with the car cold,  I started it up the idle went to 1100 and then back down to 700 where it should be.  I drive it around the block, and then put it in neutral or park and I'm at 1100 idle again.    I sprayed around the intake gasket with carb cleaner and all around the IAC and everywhere else I could find had something to do with vacuum.  Nothing.  In my motorcycle days, I used a propane torch so I tried that everywhere -- nothing. 

So then I changed the TPS out with the original TPS from by SO TB.  I think it's idling about 1000 now.  So maybe it is a matter of adjusting the TPS?  Articles I've read said there is no adjustment or that you have to make the screw hole oval to make it twistable.  Any comments on that? 

Lastly,  someone suggested I measure vacuum.  Where should I plug the gauge into? 

Sorry for these dumb questions -- it's a bit of a learning curve.

i wish i had never thrown my old dwell meter away,, it was buttstuffog.. i thought it was only good for carbs and such.
had adaptors for checking and setting points and such,, to be honest i didnt know how to use the darn thing... now i think i could figure it out and make it useful for something.

That MIN idle screw is not a base idle screw technically speaking,, often the two get confussed and each have major differnces.  I did a a thread on this a few years back but basically no modern EFI engine controls base idle with a set screw.  Actually the IAC uses Step counts. And i am if correct in saying Fail safe does not control IDLE speed to any great lengths in an OBD1 Engine management system> The link you posted is not totally correct to set base idle in my records from ford.

Also your IAC just simply might be bad. Also the diameter of the throttle plate hole and bypass screw on some TB units also has to be adjusted. I included this procedure to tune the IAC MOTOR in the old thread, I need to dig that up have it ready for posts like this. Throttle plate hole is also critical as it also bypassed air past the throttle plate.

you lost me but.. if its running great, thats all that matters

I didn't realize the EGR plate is liquid cooled,  i thought those hoses would be vacuum.  It surprised me when I unhooked one hose, hooked up the vacuum gauge and started the car and coolant started pouring all over the place out of my EGR spacer.  I hope that's what it's supposed to do otherwise I have a serious problem.

ok,, so you didnt lose me after all becaue thats all i could think of but ,,,, for some reason ,,, i couldnt think it was possible.
I am still laughing at your expense!,, yet i to am not the brightest crayon in the box so i should stop now before carma finds a convient corner of my world to lurk in.

Got it.  I didn't think about doing a sweep (meaning move the TB open slowly looking at voltage rise) but it makes sense.  If it's not pouring down rain again tomorrow,  I'll try to get to that.  Thanks!

Carb cleaner. With the engine running, spray it around the intake gaskets and vacuum lines.  When you find your vacuum leak, engine rpm will increase.

you really need to read and answer questions,, post 27,,

so do you have a vac line coming out of the front of the intake?

you did not list all the parts you brought over to this upgrade but i do see where you say you added the upper intake and the egr spacer...
comment on this also as in, you did or did not pull the lower.

you also mentioned you installed a ported out upper,, and you wanted to know what he s shaped part was on the rear of the motor to upper.
it is a support, most do not put it back on.

see post 5 & 19

Hmm the vacuum lines in the second picture don't look quite right. Did you re-connect everything as per the emissions diagram on the fan shroud?

What's with all the RTV around the throttle body/EGR spacer/IAC gaskets? Those should go on dry with no RTV.

It appears your car has a idle air adjuster between the IAC and the throttle body. Make sure both the bypasses are shut (allen screws turned all the way in) and see if the idle drops.

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

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.

(http://i740.photobucket.com/albums/xx46/proguns/001-63.jpg) (http://s740.photobucket.com/user/proguns/media/001-63.jpg.html)

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.

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).

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.

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 !

If you can kill it by plugging the iac hole, you should be golden. I'm leaning to a bad iac. is it possible you installed it upside down?

Unplug the iac with it running. lower idle until the car lugs and then plug it back in. if it idle fine after, your fine. it might be possible the iac is bad or getting stuck high. id be willing to bet your problem lies with your iac as long as your not throwing any other codes.

Just wondering but have you hooked up a tach/dwell meter to see what the engine is really idling at? The reason I ask is that if your Thunderbird has a full digital dash the tach display could be waaay off. For example at hot idle my Thunderbird idles right at 750rpm in park and 65rpm in drive with the parking brake on (both settings are within factory specs). Now those rpm readings are from a tach/dwell meter. The tach on the digital dash displays 5 bars at idle (800-1000rpm) when the actual rpm is about 250rpm lower. The factory buttstuffog tachs aren't much better. The tach in my Mark VII shows about 900rpm at hot idle. It's really at 700rpm according to a tach/dwell meter. The only way to know what rpm your Thunderbird's engine is actually idling at is to hook up a tach/dwell meter and find out. Once you've got a tach/dwell meter hooked up do a base idle reset: http://sbftech.com/index.php/topic,1031.0.html
Take a look at page two in the link. It describes the exact situation I'm talking about.

He already established that the bleed hole is LARGER!!! on the new TB. As far as the EGR holding vacuum that does nothing because if the diaphragm is blown the EGR wont open. And there is no VACUUM at the valve when the engine is at closed THROTTLE !!! The mounting gaskets and cooler adapter should be checked for corrosion and proper gaskets sealing correctly. He also posted that the throttle blade was in fact closing all the way.

I find it fascinating how installing an IAC UPSIDE DOWN would cause this as that is beyond comprehension as he totally blocked it off with a blank gasket!!!!! Just wondering how many IAC troubles you have addressed in your career STACKS. Better think over what you just posted!!!!!@

Stacks your post is fascinating because he clearly can not drop his idle with the IAC DISCONNECTED. HELLO if he could do this he would not be having a problem !!

QUESTION what would an upside down IAC motor DO as we sometimes mount them differently on different applications and also remotely. Guess you did not read my post on BLUEPRINTING THE IAC you should take the time and read it it is quite informative stacks!!


Here you go one of my IAC motors being broken down for blueprinting!!!


(http://i740.photobucket.com/albums/xx46/proguns/001-58.jpg) (http://s740.photobucket.com/user/proguns/media/001-58.jpg.html)

Normally i use the MIG to tack those holes closed. Once you close that hole off all your idle parameters will fall in to place. Those holes control the bypass air and there size is critical as you found out. A slight difference in diameter is very critical when it brings the idle circuit parameters out of speck. Remember once the IAC removes all the bypass air and the idle is to high the ECM and IAC are out of the equation. Some people use a steel rivet then tap out the center. But remember if it gets loose the part goes right in the engine. AND THAT IS NOT GOOD!!!