Idle troubles

Topic: Idle troubles (Read 1741 times) previous topic - next topic

Idle troubles

August 07, 2012, 02:14:19 AM

So, I had this problem before on my '83 TC and now it's happening on my '87 TC, but it's gotten horribly worse over time. Used to be once a day or so I would be driving and I'd try to slow down and brake, but my engine would keep running like the throttle was stuck. So I'd throw my car in Neutral (manual tranny) and my rpm's would spike at different ranging rpm's, appearing to be an rpm from 1800-2900 being my range when I shift. This problem would stop for a while if I shut my car off and turned it back on. Now this problem happens like 5-6 times in a short 10 minute drive. Since pulling over to turn the car off and on is retarded, I just turn my key back enough to kill it, pop the clutch and turn the key back to its regular on place (in neutral while doing this). I could have sworn this was my throttle position sensor last time, but I don't remember. I looked at my throttle while this was happening and it was in the regular position it should be in while idling. I should also mention my computer is failing since it dies before it picks up codes during the KOER test. Possibly an issue on the computer's end too? I already know I got a MAF code before it failed (when I brought it into a shop one day, they said it died before it could perform the scan but it picked up a MAF error, but thought it was nothing since the computer is failing). I was thinking of screwing the testing altogether and just getting a TPS? Not sure how to attack this problem....

Idle troubles

Reply #1 – August 07, 2012, 05:46:52 AM

I'd say tps or tfi module, but tps would make it hard for it to start or it would just die. Check your battery connection and if the battery is secured, something similar was happening to my 3.8 where it would surge and the rpm's would rise or while making a turn it would die.

Idle troubles

Reply #2 – August 07, 2012, 06:26:07 AM

OK here is what we do. First you need a restrictor on the IAC. We normally use 1/4 inch holes and work from their. Then change the CTS IAC and the TPS and adjust it properly. Use MIN IDLE screw and follow the procedure in the ford shop manual.

Warm engine up. Disconnect the IAC plug and set idle to 750-800 RPM. THEN SET THE TPS to .90-.97 volts at closed throttle. This should do it. If not you may have a vacuum leak. So check that also.

Never set the idlr RPM with the min idle setting screw. After adjusting you need to drive the car for a bit!!

Idle troubles

Reply #3 – August 09, 2012, 05:36:35 PM

It's definitely not a vacuum leak, different symptoms and I just had it smoked recently because I thought there was one before. If it was the tfi, my car wouldn't even start. I'll check the battery. Why do the TPS pictures look so different from the one on my car? It's that cylinder type thing on the TB right?

Idle troubles

Reply #4 – August 09, 2012, 05:53:07 PM

The "cylinder type thing" mounted on the TB is the AIC or "Air Idle Controller". The TPS is a small relatively flat black piece of plastic (with wires coming out of it) mounted to the TB on the opposite side of the TB to the throttle linkage.

Idle troubles

Reply #5 – August 09, 2012, 08:24:42 PM

Quote from: TOM Renzo;395483

THEN SET THE TPS to .90-.97 volts at closed throttle.

Don't think there is any need to "set" the TPS. If it doesn't give you a TPS code, you're good to go.

Idle troubles

Reply #6 – August 09, 2012, 09:40:35 PM

Quote from: jeremyb;395671

don't think there is any need to "set" the tps. If it doesn't give you a tps code, you're good to go.

Not True. Any time you do an idle procedure you must set the TPS TO SPECK. The TPS very rarely will set an SES LIGHT.

Idle troubles

Reply #7 – August 10, 2012, 02:47:01 PM

Quote from: TOM Renzo;395677

Not True. Any time you do an idle procedure you must set the TPS TO SPECK. The TPS very rarely will set an SES LIGHT.

I'll have to look up the Powertrain Manual, but the EEC will generally work with anything from .5V to 1.2V, depending on the strategy/calibration. If the TPS is below/above that limit, it'll trigger a code.

Idle troubles

Reply #8 – August 10, 2012, 03:02:34 PM

App 0-.4 on the low side and 1.36 on the high side will normally set an SES light. But getting it closer to my posted numbers is in my view works a bit better. If you have different data i would appreciate if you post it. Thanks!!

NOTE .95 V is optimum for a 2.3 T engine. This is from experience over the years of building the 2.3 T engine!!! Just my $.02

Idle troubles

Reply #9 – August 10, 2012, 03:30:33 PM

Quote from: TOM Renzo;395703

App .6 -1.36 will normally set an SES light.But getting it closer to my posted numbers is in my view works a bit better. But in my experience id is far and in between. If you have different data i would appreciate if you post it. Thanks!!

NOTE .95 V is optimum for a 2.3 T engine. This is from experience over the years of building the 2.3 T engine!!! Just my $.02

The GUFB A9L will control idle if the TPS voltage is between 0.5V and 1.19V. If is at closed throttle and goes above/below those voltages, you'll get a code and idle issues. Part throttle starts 0.04V above the RATCH (minimum recorded during current engine cycle). Full throttle starts 2.71V above ratch. As long as the idle voltages are within min/max, the car will be behave the exact same.
Joel5.0 explains is quite well. [link]

The TC engine will have different but similar values for the min/max voltage, partial throttle, full throttle.

Idle troubles

Reply #10 – August 11, 2012, 07:07:06 AM

BUT!!!!

The setting also controls the mixture as well. With the voltage lower the ECM reduces the mixture to a degree. Everyone that runs a potent 2.3 T always runs at or around ,95V. This is my experience and seems to be the standard with the go to 2.3T guys. This is why the sensor is slotted for proper adjustment. In later model years the sensor is fixed. As the ECM'S were modified to work at various different voltages. As far as an SES light the parameters on an LA3 are very spread out as to when the SES comes on. Telling people to ignore a TPS voltage because a code is not set is in my view incorrect. As noted the sensor is slotted for adjustments ans their is a procedure to do so. Thanks

QUOTE!!!
FORD TSB
ROUGH IDLE

If your low reading is out of range – below 88 or above 1.05, loosen the two screws on the TPS just enough so you can turn it with a little effort. Once you hit the target voltage, tighten the screws and check the WOT range.

So the reading i use is .95 or just about in the middle of fords recommendation. As far as the ses light goes that is another story and is not a proper way to set the sensor. Fair enough!!!

Idle troubles

Reply #11 – August 13, 2012, 02:48:15 AM

I gave up reading on all of that cuz it confused the out of me...well then I have my parts wrong, I think the last time we replaced the IAC on our 83 and it solved the problem

Idle troubles

Reply #12 – August 13, 2012, 02:49:41 AM

I certainly don't remember it being $80 what the hell...

Idle troubles

Reply #13 – August 13, 2012, 02:52:13 AM

Also, I can't run a KEOR test with the OBD1 because every time before it retrieves the codes the car shuts itself off...bad computer, could this possibly cause my idle issues? Cuz all it does is at times the rpm's will stick until I turn the car off and turn it back on

Idle troubles

Reply #14 – August 21, 2012, 06:12:07 PM

Tom, you need to start up a shop specializing in turbo coupes. i would bring my car there.