Fixing your SURGING IDLE!!! IN HERE!!!

[Knightstallion]

hi

i just bought a 94 GT thats totally stock.got plans to put in a 306 with b cam,edelbrock perf heads etc....after reading all this i think it'll stay STOCK AS A ROCK

i'll just pimp my fairmont instead and just enjoy the 94 as it is

Mine is all but stock and it's doing it

 

[ttocs]

Mine is all but stock and it's doing it

next time it starts doing it do a really dumb electrical test that I learned over 20 yrs ago in tech school and have used it to troubleshoot car audio up to million dollar semiconductor manf equipment. Technical taps... Start with your finger tips and just tap on for example the IAC. Start light and then slowly increase how hard you tap on it, then work up to your knuckles and again increase the force. You don't want to be hitting it hard enough to hurt yourself because often if there is an electrical problem doing this simple test will make some kind of change in how the motor is running and you can see it as you tap on it. I have gone as far as to use the back of a screwdriver if I thought I needed more and it has been helpful at times. It sounds stupid but technical taps is actually a term that goes all the way back to the early days of electronics with vac tubes where they would heat up and the connection at the bottom would expand and sometimes lose contact. When they had problems they would simply go down the line of tubes and tap the top of them till it fixed the problem.

If that doesn't work then get stupid with all the wire connections. Grab them and don't be afraid to give a good tug/pull/jiggle and get a little rough with them. A wire harness should be able to withstand a fairly good pull on it and it should not move AT ALL. Even small movements in the harness for something like the IAC or the MAF can cause resistance and throw off what it is doing/reading.

 

[Knightstallion]

next time it starts doing it do a really dumb electrical test that I learned over 20 yrs ago in tech school and have used it to troubleshoot car audio up to million dollar semiconductor manf equipment. Technical taps... Start with your finger tips and just tap on for example the IAC. Start light and then slowly increase how hard you tap on it, then work up to your knuckles and again increase the force. You don't want to be hitting it hard enough to hurt yourself because often if there is an electrical problem doing this simple test will make some kind of change in how the motor is running and you can see it as you tap on it. I have gone as far as to use the back of a screwdriver if I thought I needed more and it has been helpful at times. It sounds stupid but technical taps is actually a term that goes all the way back to the early days of electronics with vac tubes where they would heat up and the connection at the bottom would expand and sometimes lose contact. When they had problems they would simply go down the line of tubes and tap the top of them till it fixed the problem.

If that doesn't work then get stupid with all the wire connections. Grab them and don't be afraid to give a good tug/pull/jiggle and get a little rough with them. A wire harness should be able to withstand a fairly good pull on it and it should not move AT ALL. Even small movements in the harness for something like the IAC or the MAF can cause resistance and throw off what it is doing/reading.

I have several connections that I feel need changed

 

[Knightstallion]

Ok so the everyone who has modified their 94-95 Mustang has dreaded the idle surge from day one! My own personal stroker motor car has a chip and tune and STILL likes to surge a bit until it warms up. EITHER WAY, the principals are the SAME! I hate to link off of the site to do this but I haven't found a MORE thorough write up on how to solve your problems than this very site...PLUS it features pics of a 94-95 so it makes it MEGA easy, even for noobs!

Click here to solve your idle problems!

http://www.muscularmustangs.com/iac.php

be sure to click through all the pages! the link is at the bottom of each page.

Remember this! It is imparative that you do all of the steps in the above link in order! Setting the TPS Voltage and THEN setting your idle RPM will throw the TPS Voltage right back off!

 

[ttocs]

I have several connections that I feel need changed

do those tests to check them and you should be able to narrow them down. Start with any harnesses that have broken clips.

 

[oilspill]

i've read through this and every other page on the entire internet on surging idles and still have the issue. I am at the point that i don't know next steps. Before i take her to the tuner and have them look at it wanted to run by the big brains on here.

The issue: Surging idle at pretty much all times. Worse at cold start but once you get it running it will calm down some. Idle is fairly rich though jumps around. Starts pig rich then jumps between 12:1 to 13.5:1 once running.

What i have done:
Base idle reset- to many times to count
TPS- Replaced twice. 1st time just to throw parts at it. Second time because new one was reading 1.22 volts. Now sits at .93 volts
Idle Air Control- Replaced, with no change
Mass air flow- Replaced with no change
O2 Sensors- Replaced twice with no change
Vacuum leaks- smoke checked, found two leaks. 1 at TB which is likely normal. 1 at kenne bell where throttle linkage attaches, added gasket maker and smoke stopped.
VSS- Replaced with no change
Grounds- Checked and cleaned all grounds. Added a ground from passenger side motor mount to frame. Tested a ground from alternator to frame as well but removed.
PCV Valve- Replaced with no change
Fuel pressure- tested to find steady 34 psi with vacuum hose hooked up and steady 41 psi with vacuum hose off. Allowed it to sit for 45 minutes with no change in pressure after being turned off to see if leaking injector
ECT Sensor- Replaced with no change
ACT Sensor- have one but have not replaced. when i unplug it does not change idle but code appears for ACT.
Codes- only get 511 and 10
TFI Module- Replaced twice, once to throw parts at it, second time because it left me on the side of the road
Timing- base set right at 10 degrees
Voltage- appears good, varies but typically above 14v

If anyone has any thoughts, i am all ears.

 

[ttocs]

what brand throttle body are you using? I had that issue with a proproducts tb I got. I was able to help it with a gasket made to restrict the air but it didn't go away till I swapped tb's.

 

[oilspill]

what brand throttle body are you using? I had that issue with a proproducts tb I got. I was able to help it with a gasket made to restrict the air but it didn't go away till I swapped tb's.

its a BBK 75mm.

 

[ttocs]

just out of curiosity do you have the stock TB you could throw back on and see if it goes away? It is only a few bolts on top of the motor

 

[oilspill]

Unfortunately I don’t but a stack racing 75mm is only $150 so I’m not above trying it. Wish I could post the video showing the amount it’s leaking, not sure if it’s a lot or not

 

[95opal]

Unfortunately I don’t but a stack racing 75mm is only $150 so I’m not above trying it. Wish I could post the video showing the amount it’s leaking, not sure if it’s a lot or not

Any leak at the TB is gonna mess with your idle. BBK has know issues with their Tbodies. I recommend nothing but Accufab for a tb.

 

[oilspill]

Any leak at the TB is gonna mess with your idle. BBK has know issues with their Tbodies. I recommend nothing but Accufab for a tb.

But do they make one for 94/95? I would love bigger than 75 for the KB

 

[ttocs]

I have an edelbrock 75mm I have had good luck with but I have not seen them for a while

 

[oilspill]

Replaced the throttle body…acting better but need to cold start it tomorrow….I’ve thought I fixed it 12 times!

 

[ttocs]

what brand did you go with?

Replaced the throttle body…acting better but need to cold start it tomorrow….I’ve thought I fixed it 12 times!

what brand did you go with?

 

[oilspill]

Cheap SR from American muscle. Costing me a fortune blindly throwing parts at it (my own fault)

 

[oilspill]

Confirmed throttle body did not fix the surge….the fight continues

 

[Daryl]

This is a GREAT thread! Leads to easy-to-follow steps and additional links that even I feel confident I can do!!