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I have a 1994 Thunderbird LX that won't stay running. It will CRANK and RUN, but for only 30sec - 2min or so, then SHUT off as if someone is hitting a kill switch. I at first thought it was a faulty fuel pump so I replaced it and the fuel filter with no luck. I was told by several people that it could be the crankcase position sensor. I replaced it and have the same issues, runs then shuts off. I was told by a ford tech that it could be the computer module located behind the passenger headlight. I replaced it, same thing. Runs for min or 2 then shuts off. I have checked fuel pressure and it's getting 30-35lbs of pressure. I don't want to sell my tbird because it's too nice of a car and it runs pretty good, WHEN IT'S RUNNING. Can anyone please assist and advise me on where to look next? I am sure it is simple, but I have made it seem so complex.
 

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Not sure, But stop guessing, you're wasting money in the long run!
 

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i would check the fuel pump relay, to see if it is shorting out when it gets hot. Did your car come with any anti-thief system. In the newer cars, the security will kill the fuel pump after 30 sec.
 

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Discussion Starter #4
Where is the fuel pump relay and how do I check it? I am pretty sure it doesnt have anti theft built in. I did however replace ignition switch some time ago, but worked fine up until past few weeks. So I don't think it is anti theft equipped. It is a 1994.
 

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I replaced the small box up front behind the air filter area. It still has the same problems. Runs 30sec-2min or lil more then shuts off. I am stumped and so frustrated. Being as this was my daily driver.
 

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It's about time you broke down and picked up (for cheapness!) one of the USB/OBDII or BlueTooth/OBDII adapters, and run the software to datalog and see what the ECU thinks is happening.

RwP
 

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Discussion Starter #8
I have one. The only code being thrown is for intake air temp sensor voltage. Its been disconnected for over a year. Car been only acting up few weeks. Could it possibly be a faulty idle air control valve?
 

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So that's the code.

Where's the datalog?

RwP
 

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It's about time you broke down and picked up (for cheapness!) one of the USB/OBDII or BlueTooth/OBDII adapters, and run the software to datalog and see what the ECU thinks is happening.

RwP
I'm gonna go slightly off topic here, but since it's an 94, isn't it OBD I still? I'm asking because I since I have a 94 too, and it does have a port under the glove box, but when plugging it in, scan tool doesn't do anything (as in the scan tool doesn't act like it's connected, and we do have OBD II vehicle at the house so I know what it's supposed to do)
 

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1994 4.6's were OBDII, 3.8s were EEC-IV (aka "OBDI").

Well, to push it hard, 1994-1995 4.6's were OBD1.9999999 or so *grins* They lack a couple of the monitors for full OBDII compliance.

So for him, yes, he can (read the thread heading.)

For you, no, you'll need something like a Quarterhorse and BE to datalog.

RwP
 

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I replaced the small box up front behind the air filter area. It still has the same problems. Runs 30sec-2min or lil more then shuts off. I am stumped and so frustrated. Being as this was my daily driver.
The one by the shock tower is the EDIS spark module. The one between the air filter box and the passenger side headlight is the IMRC. It contains many relays, including the fuel pump relay.

It may be the IAC, but unless you check the fuel pressure right when it dies, you won't know if its air or fuel the is being cut off.
 

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Discussion Starter #13
I checked pressure up until it shut off and remained 35lbs. Can you send me a pic of the spark controk module? Thanks. And how can you run a datalog if it wont stay running long enough?
 

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1994 4.6's were OBDII, 3.8s were EEC-IV (aka "OBDI").

Well, to push it hard, 1994-1995 4.6's were OBD1.9999999 or so *grins* They lack a couple of the monitors for full OBDII compliance.

RwP
I still cant convince you they are full OBD 2 .. an OBD 1.9 would suggest its an enhanced version of OBD 1, which OBD1 is only a comprehensive monitor, it checks continuity on the electrical sensors only - which is just one of many monitors on OBD 2 - the additional monitors, freeze frame data, and trouble codes make it a full OBD 2 system. Different manufacturers may have additional monitors, they dont all have exactly the same amount. The only monitor difference between 94/95 and 96/97 Tbirds is the EVAP. I dont want people to get the impression they are anything but OBD 2, it says so right on the VECI - you know the Vehicle Emissions Control Information certification decal. OBD 2 scan tool works great, OBD 1 scan tool .. does not work on this system.
 

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Let's look at a few things.

1) OBDII is an enhancement to OBD, or at least, that's what the EPA claims. Not backwards compatible, true, but still, an enhancement.

2) EVAP is required for full OBDII compliance for EPA regs. 94/95 V8's didn't have that, so by EPA regs, they're not fully OBDII. OTOH, as you point out, you use OBDII readers to read them.

3) The VECI was probably printed before the 1994 ISO standards were finalized for OBDII (!!), especially for an 1993-built 1994 (and through most of 1994 - notes say September 1994 was when ISO finalized the various OBDII standards). So it was OBDII, mostly, and good enough for almost all purposes - but not by the subsequent ISO standards.

I stand by what I said. And I also stand by the fact that only someone who's a real nitpicker (raises hand) or who NEEDS the EVAP monitors would ever notice the difference.

RwP
 

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1. OBD2 is a Standardization for protocols, data, DTC's and connector style for all manufacturers. Not just an enhancement to an existing system. Lets point out a few examples ..
1995 Super Coupe - Ford OBD system, no monitors, comprehensive only. Flashes codes on the dash.
1995 Corvette - GM OBD system, no monitors, comprehensive only - but it has an OBD2 DLC connector, still .. doesnt work on an OBD2 scan tool, the software is all OBD1 based. Flashes codes on the dash.
1995 Mercedes, Mercedes OBD, comprenensive only .. the best youre going to get out of this is a blinking light that translates to codes.
.. not one of these cars is nearly as capable as a 1994 4.6 Tbird with OBD2, it has monitors, it displays generic Pxxx codes, etc ..

2. They are OBD2, they just dont have that particular feature implemented. Even without the EVAP, OBD2 wasnt supposed to be fully implemented until 1996 and still some manufacturers did not fully comply, Toyota was selling cars in the USA without OBD2 in 1996. Todays cars

3. Doesnt matter when the VECI was printed or the vehicle was manufactured, it was ahead of its time, it didnt actually need to be OBD2 until 1996 and they introduced it in 1994, two years ahead of time. Vehicles sold in 1996 wouldnt comply to current 2010 ISO standards. So saying a 1994 vehicle doesnt comply with 1996 standards is pointless, it was legal for sale at its time. None of the cars sold today are going to have the same features as the next generation OBD system, but im sure OBD2 will still be around for a few more years, its been 17 years already, 19 if you count 1994's.

Nobody NEEDS the EVAP monitor, its just there to make the EPA happy. You release more HC's into the atmosphere every time you fill up the gas tank than you do out of the tail pipe. Vacuum leak ? That'll probably show up as a P0171 / P0174 lean code, or the engine runs rough .. dont need a monitor to tell me the EVAP is malfunctioning, especially when your average response to an EVAP Gross leak detected code is to replace the gas cap.

Sorry to get off topic.

Xasbys - you have a wiring problem, probably pin 16 doesnt have power to the DLC connector that powers up the scan tool. Check your wiring.

Marc - Hard to say why your car just dies without testing compoents or monitoring the different systems while the car is running to determine loss of crankshaft position signal, or something else the car relies on for feedback while its running, most likely to be a failed sensor, or a wire that is heating up or losing connection.
 

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Xasbys - you have a wiring problem, probably pin 16 doesnt have power to the DLC connector that powers up the scan tool. Check your wiring.
If by "you have a wiring problem" you mean "no, that connector isn't functional on a 1994 with a V6 because it's still EEC-IV not OBDII", you're right.

Won't do much good to check his wiring - it still isn't connected. On Zasby's 3.8 powered car, that is. On a 4.6 V8, it is.

RwP
 

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SCTbird1994 is correct. There are a collection of SAE documents on OBD-II compliance and you will find that our 1994-95 cars are compliant with these documents.

He is also correct that GM had a number of vehicles with the OBD-II J1962 Connector in place for 1995, but these cars did not have the correct protocols in place and could not be read with OBD-II scanners (also about Toyota not having all protocols in place for 1996).

For those wishing to research OBD-II compliance further (Ralph), you can google all these SAE OBD-II Standards (some of these documents refer to later revisions such as CAN, but still interesting research):

SAE standards documents on OBD-II
J1962 - Defines the physical connector used for the OBD-II interface.
J1850 - Defines a serial data protocol. There are 2 variants- 10.4 kbit/s (single wire, VPW) and 41.6 kbit/s (2 wire, PWM). Mainly used by US manufacturers, also known as PCI (Chrysler, 10.4K), Class 2 (GM, 10.4K), and SCP (Ford, 41.6K)
J1978 - Defines minimal operating standards for OBD-II scan tools
J1979 - Defines standards for diagnostic test modes
J2012 - Defines standards trouble codes and definitions.
J2178-1 - Defines standards for network message header formats and physical address assignments
J2178-2 - Gives data parameter definitions
J2178-3 - Defines standards for network message frame IDs for single byte headers
J2178-4 - Defines standards for network messages with three byte headers*
J2284-3 - Defines 500K CAN Physical and Data Link Layer
J2411 - Describes the GMLAN (Single-Wire CAN) protocol, used in newer GM vehicles. Often accessible on the OBD connector as PIN 1 on newer GM vehicles.
 

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Discussion Starter #20
Ok, so this morning I replaced the above referenced EDIS module located on the strut tower. Same freaking problem. Runs few minutes than dies, just as if someone is mashing a kill switch. I am giving up. Tired of chasing dead end leads. I hate that too because the car is a really nice car and was running good. When it runs. If anyone has any suggestions where to look next place point me in the proper direction. Thanks.
 
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