95 MTX secondary

[josho]

got it from you lol

 

[josho]

The secondaries are spring loaded in the open position. The only way to close them is by applying vacuum to the vacuum motors on each bank. If the motor is not running and therefor not producing vacuum, the secondaries should be open.

When the motor is started and generates vacuum, that vacuum closes the secondaries. When the RPM's reach about 3950, the PCM sends a ground on the non-red wire to the Intake Runner Control solenoid (on the back plenum) which then opens a valve and gets rid of the vacuum (by letting in air). And what happens when the vacuum motors don't have vacuum anymore? They go back to their spring loaded default position, which is open.

So in your statement above, the secondaries did not do what they were supposed to do, that is open when there is a ground on the non-red wire.

Your next logical step is to see if the PCM is outputting a ground on that non-red wire, at the PCM's wire harness plug, when the rpm's reach 3950.

You can do this with a 12 volt test light. Hook one side to + battery and the other side to the non-red wire at the PCM. When you rev it up in neutral, the test light will light at anything above 3950 and go out when below 3950.

If you get light above 3950 at the PCM, but not at the IRCM plug, you have an open in the non-red wire somewhere between the two.

I hope this helps.

Tom

ok... im thinkin while im typing here... the solenoid i know is good because i took it out of my other car which is running perfect.. but its actuating (closing the secondaries) when i run a ground to it. now i know that you know this stuff like the back of your hand and i'm just learnin, but according to what you posted than it shouldn't be doing that, a ground should OPEN the valve, RELEASING the vacuum, and OPENING the secondaries, instead the ground is CLOSING the valve, pulling a vacuum to the vacuum motors and CLOSING the secondaries........

 

[Off Road SHO]

Then maybe the two vacuum hoses on the little canister on the back plenum are reversed. There are colored dots on the canister but they are probably faded by now.

When the car is off, the secondaries are held open by their springs. When the car is started, even with the two wire plug unplugged, the secondaries will (should) get vacuum from the intake and close down. If the plug is plugged in, AND there is a constant 12 volts + on the red wire AND the RPM's go above 3950 AND the PCM sends the Ground out on the non red wire, the secondaries should open.

Remember, if the secondaries are open, it is because the springs opened them.

I know it's confusing, I think for the most part because people don't understand the "held closed by spring pressure" part.

Have the secondary assemblies been removed from the plenums recently?

Tom

 

[josho]

ok ill check those hoses... i dont think thats the deal because i swapped out the canister and switch all in one piece from a running car and never disconnected the hose between them...

 

[josho]

Then maybe the two vacuum hoses on the little canister on the back plenum are reversed. There are colored dots on the canister but they are probably faded by now.

When the car is off, the secondaries are held open by their springs. When the car is started, even with the two wire plug unplugged, the secondaries will (should) get vacuum from the intake and close down. If the plug is plugged in, AND there is a constant 12 volts + on the red wire AND the RPM's go above 3950 AND the PCM sends the Ground out on the non red wire, the secondaries should open.

Remember, if the secondaries are closed, it is because the springs closed them.

I know it's confusing, I think for the most part because people don't understand the "held closed by spring pressure" part.

Have the secondary assemblies been removed from the plenums recently?

Tom

sorry if I'm being an idiot here but the underlined statements here confuse me...

 

[rubydist]

secondaries are OPEN unless held closed by vacuum on the actuators.

 

[josho]

secondaries are OPEN unless held closed by vacuum on the actuators.

thank you...

 

[Off Road SHO]

sorry if I'm being an idiot here but the underlined statements here confuse me...

You're not, I am getting myself confused. I corrected my last post. Sorry, I've been playin with the grandkids all day and am plum wore out.

Tom

 

[intimdatr]

I may have missed it but have you checked the 2nd arent just suck?

 

[josho]

I may have missed it but have you checked the 2nd arent just suck?

Ya I can move them by hand.

New developments! I swapped the pcm from my other car. Its a X2J. The one I took out was a LOS... and it runs terrible, BUT the secondaries are working right now, so now I know it is a pcm problem.. but what's up with to almost identical cars having different pcms? Only difference is my old one is a 92 while this is a 95 , did they change somethin between those years?

 

[jimtash]

My experience is the X2J has smaller tolerances for sensor ranges and will toss out codes while the other PCM's won't. For example, the X2J installed in my car tossed out a MAF code while the LOS never did. And replacing the MAF made a difference in performance with both PCM's but I still kept the X2J installed.

Run the codes. X2J gives them out in 3 digits. Guarantee you'll find some.

 

[rubydist]

there are reportedly several differences in the base Ford tune between the 2 processor codes - somewhere you will find a thread that shows a pic of the base settings for each.

most people prefer the X2J, so I would recommend keeping that.

 

[josho]

ok, heres the deal, it looks like the car has and aftermarket MAF and it has the airbox removed with a open cone filter,also the port cover is missing from the rear of the PCM , car also has hiflow Y pipe and dynomax exhaust. is it possible the PCM has been purposely programmed to have the butterflies open all the time and if so am i better of performance wise to leave it alone or should change intake setup, MAFand computer? PS car runs pretty good like it is would it run better if butterflies working?

 

[kevinspann]

If it was Zachs old car, it used to have an LPM in it. I wonder if he swapped out the PCM for one from his car, which I think had that issue. Could be wrong. If the slot is empty then it is not programmed for anything, and something is not working properly.

 

[jimtash]

Pull the codes. Also start and idle the engine and disconnect the MAF sensor connector. See if the idle changes.