ok anyone who has had idle issues please help

Could be lots of things. You SD or MAF? Cold air intake or under hood? What * t-stat you running? How good are your vac lines? Any splices in those vac lines? Did your buddy hook them all back up correctly? Has anything you've done so far made any difference at all?

buy a voltometer and set your tps voltage to 0.985 a volt
also make sure that the throttle body is closed First Before Setting the voltage
And lastly your ( key should be on with the engine off ) whilst changing voltage of tps sensor

go into more depth with the idle and other issues. EGR for instance could be causing some issues (if it is introducing gasses at idle). the pintle could be hung up in its bore.

good luck.

Hissin is right if the computer is spitting out an EGR code that is where I would look first. I am not convinced adjusting the TPS actually does anything. Last one I replaced I just bolted it on and it has ran fine.

i would seriously suggest you put the fan shroud back on there. it is imperative for proper and full fan efficiency.

i would test more with the EGR (EVR, etc) and to ensure it is working properly. simply repacing parts is not always the answer. the codes just give you an area to test. good luck.

OK dude, DON'T take it to the dealership if you can help it... They will change everything under the hood and the problem still won't get fixed. Who put in the new gaskets for you, and why did you put in new ones? While there are a bunch of things that could affect your idle, I would start with the changing of your gaskets. The gasket may not be seated properly, the intake not seated properly, wrong vacuum lines hooked up. Also, if you didn't change any vacuum lines/hoses when you did the gasket change, I would bet my left testicle (if I'm wrong I still have the right one) that the flexing of the old cruddy lines cracked them. Also, how does the car run, how's the power? Maybe you have a plug loose. Don't get too discouraged, with all the experiences that the members of this board have, the problem will get solved.

blk92stangg said:

OK dude, DON'T take it to the dealership if you can help it... They will change everything under the hood and the problem still won't get fixed. Who put in the new gaskets for you, and why did you put in new ones? While there are a bunch of things that could affect your idle, I would start with the changing of your gaskets. The gasket may not be seated properly, the intake not seated properly, wrong vacuum lines hooked up. Also, if you didn't change any vacuum lines/hoses when you did the gasket change, I would bet my left testicle (if I'm wrong I still have the right one) that the flexing of the old cruddy lines cracked them. Also, how does the car run, how's the power? Maybe you have a plug loose. Don't get too discouraged, with all the experiences that the members of this board have, the problem will get solved.

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YYYyyyyyyyep.

If it can't hold an idle when cold, I'd suggest that you run through the standard set procedure (unplug IAB, set base idle, disconnect battery for 20 mins, plug in IAB, etc.--tech article is floating around here somewhere) because it sounds like the IAB is not working/not plugged in. Good luck!

deftsound said:

well, it runs really really rich, i mean it makes my eyes burn, but the codes i pull (91 and 41 i think) say its running lean....?? which is wierd, i also pulled code 21 and 34, so i replaced the egr valve and egr position sensor, i also replaced the ect sensor, no luck, runs the same as it did before....and im still getting those same codes which is even more wierd. ...

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With an eye to all the problems you are having, I would suspect some wiring problems. Here are the test paths for the codes you posted.

Code 21 – ECT sensor out of range. Broken or damaged wiring, bad ECT sensor. Note that that if the outside air temp is below 50 degrees F that the test for the ECT can be in error.

The ACT & ECT have the same thermistor, so the table values are the same

ACT & ECT test data:

Use Pin 46 on the computer for ground for both ECT & ACT to get most accurate readings.

Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts

Pin 25 on the computer - ACT signal in. at 50 degrees F it should be 3.5 volts. It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower intake manifold, the voltage readings will be lower because of the heat transfer.

Voltages may be measured across the ECT/ACT by probing the connector from the rear. Use care in doing it so that you don't damage the wiring or connector.

Here's the table :

68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61

Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter.

Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.
50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms

If the ECT is out of range, it can send a false cold engine reading to the computer, causing a rich condition.


Code 34 EGR voltage above closed limit - Failed sensor, carbon between EGR pintle valve and seat holding the valve off its seat. Remove the EGR valve and clean it with carbon remover. Prior to re-installing see if you can blow air through the flange side of the EGR by mouth. If it leaks, there is carbon stuck on the pintle valve seat, replace the EGR valve ($85-$95).

If the blow by test passes, and you have replaced the sensor, then you have electrical ground problems. Check the resistance between the black/white wire on the MAP/BARO sensor and then the black/white wire on the EGR and the same wire on the TPS. It should be less than 1 ohm. Next check the resistance between the black/white wire and the negative battery post. It should be less than 1 ohm.

Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter.

This will affect idle quality by diluting the intake air charge

Code 41 or 91 - O2 indicates system lean. Look for a vacuum leak or failing O2 sensor.
The computer sees a lean mixture signal coming from the O2 sensors and tries to compensate by adding more fuel.

Measuring the O2 sensor voltage at the computer will give you a good idea of how well they are working. The computer pins are 29 (LH O2 with a dark green/pink wire) and 43 (RH O2 with a dark blue/pink wire). Use the ground next to the computer to ground the voltmeter.
The O2 sensor ground is in the wiring harness for the fuel injection wiring. I grounded mine to one of the intake manifold bolts

"When the mixture is lean, the exhaust gas has oxygen, about the same amount as the ambient air. So the sensor will generate less than .4 volt. Remember lean = less voltage.

" When the mixture is rich, there's less oxygen in the exhaust than in the ambient air , so voltage is generated between the two sides of the tip. The voltage is greater than .6 volt. Remember rich = more voltage.

Here's a tip: the newer the sensor, the more the voltage changes, swinging from as low as 0.1 volt to as much as 0.9 volt. As an oxygen sensor ages, the voltage changes get smaller and slower - the voltage change lags behind the change in exhaust gas oxygen.

Because the oxygen sensor generates its own voltage, never apply voltage and never measure resistance of the sensor circuit. To measure voltage signals, use an analog voltmeter with a high input impedance, at least 10 megohms. Remember, a digital voltmeter will average a changing voltage."
Charles O. Probst, Ford fuel Injection & Electronic Engine control

The O2 sensors have a ground wire that come out of the harness near the throttle body. Make sure that it is connected. If it isn't grounded to the manifold or head, it will affect O2 sensor performance.

Since you pulled the manifold, it is possible that the 10 pin salt & pepper shaker electrical connectors may have some dirty or bad connections. Open up the connectors & look for dirty or damaged pins. Use electrical contact cleaner or non-flammable brake parts cleaner (same stuff as the contact cleaner in a bigger can, & cheaper too) to clean the contacts.

deftsound said:

ok this sounds newb, but i gotta ask what the iab is, is that the idler adjuster?

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to clarify. IAC (or IAB, both are interchangable) is the acronym for Idle Air Controller (or Idle Air Bypass). it is the cylinder lookin deal on the front of the TB (throttle body).

also, someone said something about how they were gonna torque the upper intake (plenum) down - i would be very careful. torque it to spec and check it. it cracks easily. if proper torquing does not get it, you have other issues. i would check surfaces with a machinist's edge, etc to ensure it is plumb.

JR is right on. sounds like you have an issue with the EGR and some other stuff. EGR can mess with the idle and other operation, depending upon what is malfunctioning and how. go through his post and check stuff.
good luck.

Should be easy enough to rule it out. Swap out the gasket set and clean and inspect your intake before you toss it back on. Mark all of your vac lines as you remove them (I use file folder labels) and you should be able to complete the job in around 4 hours. lower intake torque is 25 ft/lbs. MAX in 3 stages. Get a chilton or haynes manual for the torque sequence. Use thread lock and new bolts. This is all supposing that you've completed the checks is jrick's checklist.

Edit: For the front and rear lower intake gaskets; I like the sealant that comes in the cheese wiz can.

I take it your engine is stock. I would hook a simple vacuum guage to it first and see if there are obvious leaks. You can get one for 10-15 bucks and it should read 18-21 in. hg. at idle. It will also come with instructions to do many tests. Its a great tool to have, allows you to check simple stuff before you start taking stuff apart.

How about timing? Was it set correctly after the manifold install?