Help me create the "Surging Idle Checklist"

87_stang · Feb 9, 2007

OK guys, last night I re-cleaned the IAC and MAF sensor and also took my dremel to the IAC and opened them up together a little bit like mentioned toward the beginning of this thread. I went about 1/8" in so a little air could get between the two holes. I then fired it up and it idled great so I went and picked up my cousin and we just cruised town for about 30 minutes just to hit all the stop signes and stop lights that way I could keep an eye out on the idle. SO far it is working great! Thank you very much to everyone who has helped out by throwing out ideas for me and everyone else with this problem.

WhitePony93 · Feb 26, 2007

I've been through this checklist over and over. My car has a hanging idle problem. With the IAC unplugged, it will idle down to around 800 RPM, but ends up around 1100 (at best) after I drive it. Also, any time I'm rolling with the clutch in or in neutral it's closer to 1500-1800 RPM's(IAC unplugged). My computer throws no codes, everything is cleaned and functioning properly (IAC, EGR, O2's, Baro sensor, TPS, MAF,VSS). I even broke down for the first time in 5 years and took my car to a shop and had them give me a diagnostic. They said sensors checked out ok , there was a vacuum leak, beween the head and lower intake on the passenger side. I had already torn it down to the heads just days before. I tore it down again, being extra careful to follow proper torque procedures. It still runs exactly the same, and I can't even think of any more areas that could even cause a vacuum leak. What should I do? I'm out of ideas.

jrichker · Feb 26, 2007

Did you replace the lower intake gaskets or just re-touque them?

There have been instances where the gaskets have slipped out of place on installation and caused leaks.

My favorite trick that saves time and effort is the stay in place gasket. Be sure that you scrape (don't use a wire brush) all the old gasket material off, then clean all the surfaces with acetone or MEK.

When the surfaces are clean, use weather strip adhesive on the head to manifold surface. Also use the weather strip adhesive on the side of the gasket that mates to the head. When you are done, the head surface and the gasket surface that mate together will have weather strip adhesive on them. Follow the instructions on the tube or can and when it gets tacky, press the gasket down on the head.

Clean the area where the rubber rails mount to the block in front and in the rear with more acetone or MEK and do the same trick with the weather strip adhesive that you did to the heads.

Coat the rubber seals and the gasket area around the water passages with lots of Blue Silicone gasket sealer and put it together. Bingo! no leaks, and no gaskets that shifted out of place.

If you reuse the injectors from your old setup, a repair kit is available from most auto parts stores if needed. Coat the injector body "O" rings with oil before you use them and everything will slide back together. Take the other advice you got here and run with it.

Fuel injector seal kits with 2 O rings and a pintle cap (Borg-Warner P/N 274081) are available at Pep Boys auto parts. Cost is about $2.74 per kit. The following are listed at the Borg-Warner site ( http://www.borg-warner.com ) as being resellers of Borg-Warner parts:

http://www.partsplus.com/ or http://www.autovalue.com/ or http://www.pepboys.com/ or http://www.federatedautoparts.com/

Most of the links above have store locators for find a store in your area.

Use motor oil on the O rings when you re-assemble them & everything will slide into place. The gasoline will wash away any excess oil that gets in the wrong places and it will burn up in the combustion chamber.

BK_CAULEY · Feb 26, 2007

i got one for yall

when i first crank my girlfriends 1989 gt on the first crank it does its normal 12-1400rom start up and when the rpms come down from the start up it dies. try to crank it again and it does fine. we did this like 25 time in a row. we crank it on time drove it around for about 10 minutes shut it off and it did its dying thing again. let me calrify it a little bit. 1st start cranks then dies 2nd start does fine 3rd dies 4th fine agian and it has done it consecutivly and isnt putting out any codes. any idea's?

P.S.- if any body has seen my threads i started i disconnected the battery while the car was still running and it started surging then it just up and quit now i have problem stated above. but hey without careless people where would :SNSign: be?

WhitePony93 · Feb 26, 2007

jrichker said:
Did you replace the lower intake gaskets or just re-touque them?

There have been instances where the gaskets have slipped out of place on installation and caused leaks.

I went with a whole new intake gasket set.I did use some goo to hold the gaskets in place. I rebuilt all 8 injectors because the little "hats" were brittle and 6 of them had pieces chipped off that went through the motor.The o-rings looked like rubber bands that had sat outside for a month in the sun. Even before I took it in, I could never find a leak with a can of carb clean, so I was a bit skeptical of the mechanics verdict. While I had everything off, I took a straight edge to all the mounting surfaces to check for warpage, none. I checked for cracks, couldn't see any. Not to mention I had just done the intake the week before I finally brought it in. Is there any other way to pinpoint a vacuum leak besides listening and spraying carb clean? I don't think I screwed up the install, I mean the symptoms didn't change in the slightest. Thanks for your quick reply!

WhitePony93 · Feb 26, 2007

I pulled the intake tube and covered the idle air hole and it now idles. The throttle body itself seems a bit worn out, there's a lot of up and down play in the blade. Do you think the throttle blade is allowing too much air to pass, making it impossible to bring the idle down far enough with the screw?

jrichker · Feb 27, 2007

WhitePony93 said:
I pulled the intake tube and covered the idle air hole and it now idles. The throttle body itself seems a bit worn out, there's a lot of up and down play in the blade. Do you think the throttle blade is allowing too much air to pass, making it impossible to bring the idle down far enough with the screw?

That is a possiblity. Check the throttle butterfly for a hole drilled it it. Ford used the hole as a means to allow a calibrated airflow to control idle. They would insert a plastic plug to change the size of the hole if it was too big.

Cougar5.O · Feb 27, 2007

The TPS being below 1V makes no sense from the ECU point of view.

Any setting between 0.8 - 1.1V will be seen as "0" my the ECU.

I don't know where or how this rumor started, but it is not supported by the code in EEC-IV.

Cougar5.O · Feb 27, 2007

jrichker said:
No.

...

Try this... Currently there is some dispute about setting it at .99 volts being worth the effort, but anything less is probably OK. All you need is less than 1.0 volt at idle ...

Sorry, it makes no difference if the TPS is above or below 1V at idle, so long as it is not below 0.5V or above 1.2V within the ECU. This means that a measurement of 0.8V - 1.1V will leave you WAY within the acceptable range. The ECU zeros to whatever voltage it sees at closed throttle, so it doesn't matter where it is. If it is outside of the range I mentioned, it will throw a code and behave badly.

jrichker · Feb 27, 2007

Cougar5.O said:
Sorry, it makes no difference if the TPS is above or below 1V at idle, so long as it is not below 0.5V or above 1.2V within the ECU. This means that a measurement of 0.8V - 1.1V will leave you WAY within the acceptable range. The ECU zeros to whatever voltage it sees at closed throttle, so it doesn't matter where it is. If it is outside of the range I mentioned, it will throw a code and behave badly.

Site me a reliable source for the above information and I will gladly make changes.

My personal observation has been that the idle speed increases slighly as the base TPS voltage increases.

WhitePony93 · Feb 27, 2007

I actually have that hole completely plugged now to give it an idle at or around 800 RPM'S . It's like too much air is able to squeeze around the T.B when it's closed. The blade actually slides up and down revealing a gap below or above it. A new throttle body seems to be in order, now the question is whether or not to get a 65mm from Ford Racing. Will I see any improvement with the minimal mod's I currently have, or will I be wasting my money and time? Keep in mind that I have no planned future modifications of the motor itself(H/C/I, Power adders, etc.)

OonDeanisS · Mar 2, 2007

When i turn my car on, it stalls once or twice and bounces from 1500 to as low as 200rpms before it gets warmed up then it stays at either 1000, or 1500 sometimes. Which of my many sensors do you guys think this is? I put on a new tps, but never calibrated it because i dont know how, but it did this before that anyway.

joel5.0 · Mar 3, 2007

jrichker said:
Site me a reliable source for the above information and I will gladly make changes.

My personal observation has been that the idle speed increases slighly as the base TPS voltage increases.

J.....this is from a write-up I did on the TPS adjusting myth, the quotes within the article are from the Ford GUFB Strategy document and has also been verified with "tests" I've done in SD and MA systems, including SN95's that allow the access to the parameters via the Datastream option......There are 3 parameters:

Throttle Pos ClsdVolt = used to id minimum TP value and is reset every time you turn ignition on
Throttle Pos Mode = CT for Closed Throttle, PT for Part Throttle and WOT
Throttle Pos Volt = real time value of TPS signal

Anytime the system detects an increase of .04vdc over the minimum TPS value recorded initially, the idle will increase because the system id's a part throttle condition and switches to a different IAC control strategy. Reason why you have to reset the system by turning the ignition off and recheck the setting when the throttle stop screw is used, as the base idle procedure calls for.

Summarized EEC-IV logic for the TPS......

The EEC-IV will check for the following:

- Minimum voltage at closed throttle over .49 vdc. , less than .49 and codes 23 and 63 will set as failures.

- Max voltage closed throttle should not exceeed 1.2 vdc, or codes 23 & 53 will set as failures.

- TPS voltage between .5vdc and 1.19 = no codes, TPS ...then

- Closed throttle TPS value is reset by the system to the lowest value read when ignition is turned on every time. Or as explained by the EEC-IV RATCH algorithm:

The variable RATCH is the output of a ratchet algorithm which continuously seeks the minimum throttle angle corresponding to a CLOSED THROTTLE position. This alleviates the necessity to set the throttle position sensor at an absolute position and compensates for system changes and differences between vehicles. The ratchet algorithm uses filtered throttle position for the determination of RATCH.

Click to expand...

- A voltage increase of .04 vdc from the minimum registered will id part throttle status.
- Minimum WOT value of 3.21 vdc (.5 + 2.71) and not higher than actual Voltage REFerence (VREF) generated by the ECM to access WOT strategy.

FYI....This does not include the other registers and functions, the system uses to id acceleration, deceleration, cruise...etc, like:

APT = At Part Throttle flag

The value of APT is determined by a logic. Briefly, throttle angle breakpoints, in terms of counts, are used to define the CLOSED/PART_THROTTLE and PART/WIDE_OPEN_THROTTLE transitions.

Click to expand...

- OLDTP = Previous TP sensor value, counts.
- TAR = Throttle Angle Rate of change, deg/sec.
- TP = Throttle position sensor.
- FN331B = A multiplier as a function of the present throttle angle minus the lowest measured throttle angle (TP - RATCH)
- Etc, etc, etc

Adjusting the TPS is a myth....or more proof is needed?

In addition, if such a setting needs to be so precise, it would go against the benefits of having a computer controlling EFI.....or saying
"EFI is better over a carburetor setup because it provides the capability and flexibility to self adjust for changes in temperature, altitude, load, etc, etc......but the throttle position?" or......"they (Ford) provided an EEC system capable of dealing with everything but, the TPS variability normal, and expected, in any 3-wire variable resistor component?"......if that was the case.....what about the other sensors?....

Let us know.......

jrichker · Mar 3, 2007

Joel5.0: Your information on TPS settings has been incorporated into the main post, and I have given you credit as the authoritative source for the information.

Joel5.0 said:
In addition, if such a setting needs to be so precise, it would go against the benefits of having a computer controlling EFI.....or saying
"EFI is better over a carburetor setup because it provides the capability and flexibility to self adjust for changes in temperature, altitude, load, etc, etc......but the throttle position?" or......"they (Ford) provided an EEC system capable of dealing with everything but, the TPS variability normal, and expected, in any 3-wire variable resistor component?"......if that was the case.....what about the other sensors?....

I am not sure about the source of these comments, and I am also not sure about what you were trying to say. All the sensors have production tolerances and so does the computer and its input circuitry. Ford made a best case attempt to compensate for variables in sensor values and computer sensitivity. Most of the time, the variables fall within limits and everything works fine. Sometimes the shift of a sensor towards the limits upsets a computer whose hardware input sensitivities are also at or near the acceptable limits. The result is often a car that runs flaky one day and great the next.

TENGRAM · Mar 3, 2007

jrichker said:
Site me a reliable source for the above information and I will gladly make changes.

My personal observation has been that the idle speed increases slighly as the base TPS voltage increases.

the idle speed is likely to raise when you raise TPS voltage with the engine running. this is because you have just shifted it into part-throttle mode. after turning the car off and restarting, the new "base" value for the TPS is recorded and the idle should be back to normal.

as evidence for the falsity of the TPS ".99999" myth, i offer this excerpt from an internal Ford document that was originally intended for their engineers:

joel5.0 · Mar 3, 2007

jrichker said:
Joel5.0: Your information on TPS settings has been incorporated into the main post, and I have given you credit as the authoritative source for the information.

I am not sure about the source of these comments, and I am also not sure about what you were trying to say. All the sensors have production tolerances and so does the computer and its input circuitry. Ford made a best case attempt to compensate for variables in sensor values and computer sensitivity. Most of the time, the variables fall within limits and everything works fine. Sometimes the shift of a sensor towards the limits upsets a computer whose hardware input sensitivities are also at or near the acceptable limits. The result is often a car that runs flaky one day and great the next.

And appreciated indeed.......the point I'm trying to make, and the source for the comments, is that the TPS is a non-adjustable device, it's a pass/fail, or G-NG (Go-NoGo) variable the system is capable to provide for w/out problems, as long as the operating window (no failure codes) is complied with otherwise, the problem usually lays elsewhere.

If you look at the strategy, the systems identifies TP state as -1, 0 or 1....-1 being the CT state (minimum reading within .5vdc to 1.19vdc) now, base idle could be set mechanically to 700 rpms and a TPS value of .7 vdc, which would be the same as 700 rpms and a TPS value of 1.09 vdc....anything less would make a carburetor setup gain the upper hand.

My apologies if it was interpreted negatively, that was not my intention...you have provided details regarding the EEC-IV system, and the proper procedure to eliminate the guesswork out of solving problems, that it should be duly acknowledged......I do.....

vristang · Mar 8, 2007

Man, these last couple of posts have been great!

I have seen my car run differently after setting the tps, but that was because the tps was originally out of range, over 1.2v

While the GUFB can be found on many tuning sites, I have posted it on my site to make it more accessible.
http://www.freewebs.com/vristang/GUFB.pdf

It is long, and can be a tough read sometimes...

jason

leathernotch · Mar 13, 2007

High Idle

After head install, of iron gt 40's. Car idles at 800 cold once she warms up the car doesn't go below 1400, revving causes the idle to stick and it takes awhile to come back down. Vacuum when the car is cold (800to1000) is about 10 or below. Went through top-end and replaced all gaskets. No change. Why would the car idle correctly when cold?

The car idled at 1400 before we went through and replaced all of the intake gaskets and adjusted valves when we finished she idled the same no change same rpm at 1400 when she is warm. So it has to be another issue

jrichker · Mar 13, 2007

You definitely have a vacuum leak with 10" of vacuum at idle. I have seen cases where the lower intake manifold gaskets have slipped out of place. This creates a vacuum leak in the lifter valley that is almost undetectable by most normal means.

Check up the fuel injector seals when you replace the gaskets. If the injector plastic pintle cap is missing, the O ring can slide down into the intake manifold.

My favorite trick that saves time and effort is the stay in place gasket. Be sure that you scrape (don't use a wire brush) all the old gasket material off, then clean all the surfaces with acetone or MEK.

When the surfaces are clean, use weather strip adhesive on the head to manifold surface, and on the side of the gasket that mates to the head. Follow the instructions on the tube or can and when it gets tacky, press the gasket down on the head.

Clean the area where the rubber rails mount to the block in front and in the rear with more acetone or MEK and do the same trick with the weather strip adhesive that you did to the heads.

Coat the rubber seals and the gasket area around the water passages with lots of Blue Silicone gasket sealer and put it together. Yea! no leaks, and no gaskets that shifted out of place.

If you reuse the injectors from your old setup, a repair kit is available from most auto parts stores if needed. Coat the injector body "O" rings with oil before you use them and everything will slide back together. Take the other advice you got here and run with it.

Fuel injector seal kits with 2 O rings and a pintle cap (Borg-Warner P/N 274081) are available at Pep Boys auto parts. Cost is about $2.74 per kit. The following are listed at the Borg-Warner site ( http://www.borg-warner.com ) as being resellers of Borg-Warner parts:

http://www.partsplus.com/ or http://www.autovalue.com/ or http://www.pepboys.com/ or http://www.federatedautoparts.com/

Most of the links above have store locators for find a store in your area.

leathernotch · Mar 13, 2007

Tell me more about what the O-rings could be causeing. Could they cause the Vac leak w/ out a gas leak? Could I not see a rise in idle w/ the brake cleaner?

I also rechecked the F/P and it was at 50 w/ vac off so I broght it down to 40 and did not see any change. Is that odd.

Could this be the IAC causeing everyting. Because the idle does stick when reved for at least a few seconds at 2000 before droping down to 1400.

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