exployer/mustang throttle bodies

gorgo · Post by **gorgo** » Thu Jun 19, 2008 7:39 am

will a 88-93 mustang tb fit on a 98 exployer intake.

cee21 · Post by **cee21** » Thu Jun 19, 2008 10:06 am

Yes it will. I used the intake elbow off a v8 explorer and used the stock mustang intake and tb.

gorgo · Post by **gorgo** » Thu Jun 19, 2008 12:43 pm

thanks. i just cant get the tps to work with the a9l and putting a mustang tps on the explorer tb is just to mickey mouse.

MalcolmV8 · Post by **MalcolmV8** » Thu Jun 19, 2008 2:11 pm

gorgo wrote: i just cant get the tps to work with the a9l

Why's that? I'm using one with my a9p in my blue truck. Works great.

gorgo · Post by **gorgo** » Thu Jun 19, 2008 3:41 pm

it keeps throwing a code 23 which is tps out of range. if i plug the mustang tps in it doesnt give a code 23. i tried another exployer tps and it did the same thing, code 23. so im stumped why mine doesnt work with the a9l.

cgrey8 · Post by **cgrey8** » Fri Jun 20, 2008 4:07 am

gorgo wrote:thanks. i just cant get the tps to work with the a9l and putting a mustang tps on the explorer tb is just to mickey mouse.

That's exactly what I did. In the earlier year Explorer TBs, the Mustang TPS bolts right on. So to get the right connector, I just replaced the Explorer TPS with the Mustang TPS and have had no problems with that setup.

Here's a side-by-side of Mustang and 97 Explorer TPS:

Mustang TPS on Left

Explorer connector on Left. Here you can see the incompatibility of the connector. Although the sensor itself seem to have the same resistance range from CT to WOT. Call it Mickey Mouse if you want, but it works great for me.

Later on, the Explorer TPS was redesigned to have an integrated connector instead of the dongle connector and the mounting surface of both TPS and TB changed making the Mustang style TPS not an option anymore which pretty much requires the reuse of the Explorer TPS or replacement of the Explorer TB for a Mustang TB. But even the redesigned Explorer TPS maintained the same resistance from CT to WOT allowing it to be used with the older computers if wired correctly. Here's a pic of the redesigned Explorer TPS with integrated connector:

gorgo · Post by **gorgo** » Fri Jun 20, 2008 7:49 am

i have the newer style tps. so that im hearing is that the tps should work. im not sure where i read it but it said that the new computers on start up starts the tps at ov and goes from there to wot. which would mean that the return volts to the a9l would be 0 when it expects around .98v. which would throw up a code 23.

cgrey8 · Post by **cgrey8** » Fri Jun 20, 2008 9:33 am

There is a TPS Ratchet concept in the EEC. What this does is take the lowest voltage the EEC ever sees and locks that in as the voltage for Closed Throttle. As long as that voltage is below 1.75v, the EEC will ratchet it in and use that voltage as the Closed Throttle (CT) voltage. If at any time the voltage of the TPS goes lower, that lower value will get locked in.

This parameter is important to the EEC because there are a number of things that TPS voltage triggers to happen. For instance, there's a scalar value that defines what voltage the TPS has reach to force OL/WOT mode in the 89-93 Mustang EECs (et al). That voltage value in the tune is 2.78v. But that's not when the TPS hits 2.78v, that's when the voltage is 2.78v above the ratchetted CT voltage.

After analyzing the tune code, it turns out its also ricer myth about having to set the TPS voltage to .94-.99v or whatever that range is quoted as. The EEC could care less what the voltage of the TPS is as long as it doesn't exceed 1.75v when it expects a closed throttle condition (i.e. when the ignition is turned on). Once it sees a voltage below this level or lower, it will allow higher voltages without fussing.

The relevant limits on TPS voltage for an A9L are as follows:

Normal operation TPS must be between 0.4-4.95v to prevent a Check Engine Light
For KOER testing, voltage must be 0.72-1.32v when it expects a closed throttle condition

The A9P will have similar limits, but may not be exact (I didn't bother to load it up in my tune editor software).

My gut feeling is this is what's causing the Code 23. So where to proceed from here? Well either the TPS is bad OR its simply wired wrong. This is where you'll just need to sit down with a volt meter and figure out what wires are what in the wiring harness and what voltage is doing on the TPS sensor itself. There is an old thread where Malcolm asked what the wiring for the newer style Explorer TPS was and he found that info good. So I would start there.

Dave · Post by **Dave** » Sun Jun 22, 2008 9:46 am

Just wondering what the HP limit is on the stock 65mm Explorer TB? The Ford Racing Catalog goes into a four page discussion on proper sizing of the injectors and a page on the MAF but no mention of sizing the TB. The intake is said to be good to 350 hp also.
Dave in raining again Wisconsin, like we need it.

cgrey8 · Post by **cgrey8** » Sun Jun 22, 2008 7:35 pm

I got the following from the AccuFab's Flow Page:
FORD 1996 - 2004 4.6L 2V STOCK 65MM
TESTED @ 5" - 248 CFM
CORR @ 20" - 496 CFM
CORR @ 25" - 556 CFM
CORR @ 28" - 588 CFM

I THINK this is the same TB as the Explorer 65mm TB. If these values are to be believed/trusted, then 588cfm@28" is what you can expect from a stock 65mm TB which is in the 1100-1200kg/hr range. Doing some guesstimating based on what other vehicles from the EECTuning.org website produce with their flowrates, 1100kg/hr is just a bit over 350hp. So the stock 65mm TB is well matched to the Cobra/Explorer intake system.

Interestingly, the Accufab's 65mm TB flows considerably more:
ACCUFAB 65MM
TESTED @ 5" - 280 CFM
CORR @ 20" - 560 CFM
CORR @ 25" - 627 CFM
CORR @ 28" - 664 CFM

This is in the 1250-1300kg/hr range which should support a 400hp motor without increasing the differential pressure over 28".

For max power, you want as little differential pressure as possible @WOT which is why you increase the TB size. The best for WOT performance is the largest possible TB. But in street applications, TBs are also used extensively at non-WOT conditions which means it needs to control low-flow conditions. So picking the largest TB blindly will have unintended driveability side-effects. The larger the diameter of the TB, generally the harder it is to make small changes in airflow as is the case when taking off at a light in traffic or just cruising. So you never want to oversize the TB on a street machine or you'll have a very touchy motor that is hard to keep from over-revving at the slightest touch of the pedal...not fun in the rain. In contrast to max power@WOT, the best option for driveability is a small TB. So to get good driveability and close to best possible WOT performance means a compromise...or at least a rule of thumb to help guide you in a TB selection. So here it is...size a TB that is the smallest without producing more than 28"wc of DP with your motor's estimated max CFM potential. That should get you the best trade-off of driveability and power...assuming driveability is a concern.

So as you can see, a sub-400hp motor can do quite well with most aftermarket 65mm TBs, although most people will sacrifice a little driveability for a little more hp so they oversize the TB to 70-75mm. After all 28"wc is 1 PSI. You only have ~14PSI to work with in a naturally aspirated motor. So oversizing to get the differential lower can mean another 5-15hp depending on the setup. Like I said, it's all about compromise.