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mojosvt
06-10-2007, 08:58 PM
Well, drove to cleveland this weekend (2hrs) got there fine. Drove around with my father a little while, and headed off to a cruise in sat night. While sitting at a light, the car all of a sudden died, and then wouldn't start. So after freaking out for 2 or 3 minutes, and holding all sorts of traffic up, I tried again, and it fired up. It ran fine the rest of the way home, other than the idle is way high, like 1200-1300, when it normally idles around 750. Other than the idle, it drove fine the rest of the night. So I drove it around all day today, and the idle is still high, but the car was driving fine. So my father and I head out to another cruise in tonight before my 2 hr drive home, and right before we pull into the parking lot, once again it died, out of nowhere. This time it only took 2 or three time, and it fired back up, but still wasn't the first try like normal. After it fired up, once again it drove fine, but the idle is still off. After walking around the cruise in for a few minutes, I decided I should head home, just incase something goes wrong, and I have to call AAA, it would be a little earlier in the night. Made the 2 hr drive back to Columbus without a single problem. Car still pulls strong, no smoke, no miss or anything, other than the idle is up, and the 2 times the car died. Any ideas..... I just ran seafoam through the car last week, and changed the plugs. The old plugs were gapped at like .65 (have no idea why), so the new Motorcraft plugs I put in I gapped at .54, but I don't think that could be the problem. Thanks for the long read.

Lumpydogs
06-10-2007, 10:15 PM
I suggest you get your codes scanned. I wonder if the computer shut down the engine due to an engine problem. A friends minivan shut down once on the highway for no reason. Long story but the dealership read the computer and found that a cylinder had failed to ignite three times so the computer shut it down. Just a thought. Good luck on the diagnosis and fix.

97PGCobra
06-10-2007, 10:30 PM
You may want to check your IAC valve. My car was doing the same thing a year ago and it turned out that my IAC was bad. It would idle high like yours and also try to go dead when I pushed the clutch in at a light or stop sign. It went dead a couple times as well. I've seen where some people have pulled the valve off and cleaned it but I chose to have mine replaced. :thumbsup:

mojosvt
06-11-2007, 06:42 AM
Well, ran the codes, nothing out of the norm. I will have to look into the IAC, somebody else mentioned the TPS, Throttle Position sensor????

mojosvt
06-12-2007, 06:58 AM
Well, the car died again on me yesterday as I was driving up to autozone to pull the codes. Finally got it started again, and pulled the codes...nothing.

I was told that with the car idling, even though it is idling at 1200-1300 right now, that if I unplug the IAC, the computer should over ride the sensor, and it should idle at 500-600, just barely running. So I tried that, and the car died right away. So I pulled the IAC off, cleaned it really well with Carb Cleaner, put it back on and tried again. With the car running, I unhooked the IAC, and it choked up, and then idled at 500. I shut the car off, and tried it one more time, and it died again. So I am starting to think that it might be the IAC is bad. I don't know, Might go pick up an IAC tonight, see if that fixes the problem.

blk04cobra1
06-12-2007, 09:09 AM
Well, the car died again on me yesterday as I was driving up to autozone to pull the codes. Finally got it started again, and pulled the codes...nothing.

I was told that with the car idling, even though it is idling at 1200-1300 right now, that if I unplug the IAC, the computer should over ride the sensor, and it should idle at 500-600, just barely running. So I tried that, and the car died right away. So I pulled the IAC off, cleaned it really well with Carb Cleaner, put it back on and tried again. With the car running, I unhooked the IAC, and it choked up, and then idled at 500. I shut the car off, and tried it one more time, and it died again. So I am starting to think that it might be the IAC is bad. I don't know, Might go pick up an IAC tonight, see if that fixes the problem.
IAC is an easy fix and if it doesnt cure your issues, you can always return it :thumbsup:

mojosvt
06-12-2007, 09:46 AM
IAC is an easy fix and if it doesnt cure your issues, you can always return it :thumbsup:
That was my exact though, already ordered one from my local ford guy, throwing a new one in this afternoon

ausie
06-14-2007, 06:21 AM
Almost sounds like a new IAC would be the cure. What I have seen with IAC problems on my 2001 were similar to what you have had. However there were some differeneces:

1. with engine at idle, once the IAC connector was removed, engine RPM climbed to 2500 RPM. If the IAC is functioning properly this is what should happen since the valve should open when there is no current in the solenoid. Following that will be a check engine light and an error code indicating incorrect idle speed or idle high.

2. If the engine idle speed begins to surge or pulsate that would indicate a vaccum leak is occuring. The pulsation is caused by the IAC since the PCM is attempting to control idle speed. Vaccum hoses may have deteriorated or the EGR valve is not functioning properly and could be stuck open or leaking. A bad PCV valve or seal leak will also do this. Surge can also be cause by a dirty MAF sensor since the sensor response is effected by contaminants, the fuel mixture may become too lean for idle which will increase the RPM

3. Spark plug gap, if too large will result in retarding the timming to some degree (by a few milliseconds), may lead to miss-fire if the spark fails to ignite fuel. Double check spark plug gap if using stock plugs (proper gap will be listed on the emissions system label in the engine bay). If there is a range for the spark plug gap , say 0.045 to 0.052, use the smaller gap. The larger the gap, the higher the voltage needed from the coils to create a spark. The higher the voltage required to spark will increase the time needed from the coil to produce the higher voltage. The time delay for the coil to reach the voltage to spark the gap may seem small, but once at higher RPM, every millisecond counts.

4. Check the condition of the air filter. Since your RPM is dropping below nominal that would make me think that there may be an air flow restriction.

mojosvt
06-14-2007, 08:38 AM
Almost sounds like a new IAC would be the cure. What I have seen with IAC problems on my 2001 were similar to what you have had. However there were some differeneces:

1. with engine at idle, once the IAC connector was removed, engine RPM climbed to 2500 RPM. If the IAC is functioning properly this is what should happen since the valve should open when there is no current in the solenoid. Following that will be a check engine light and an error code indicating incorrect idle speed or idle high.

2. If the engine idle speed begins to surge or pulsate that would indicate a vaccum leak is occuring. The pulsation is caused by the IAC since the PCM is attempting to control idle speed. Vaccum hoses may have deteriorated or the EGR valve is not functioning properly and could be stuck open or leaking. A bad PCV valve or seal leak will also do this. Surge can also be cause by a dirty MAF sensor since the sensor response is effected by contaminants, the fuel mixture may become too lean for idle which will increase the RPM

3. Spark plug gap, if too large will result in retarding the timming to some degree (by a few milliseconds), may lead to miss-fire if the spark fails to ignite fuel. Double check spark plug gap if using stock plugs (proper gap will be listed on the emissions system label in the engine bay). If there is a range for the spark plug gap , say 0.045 to 0.052, use the smaller gap. The larger the gap, the higher the voltage needed from the coils to create a spark. The higher the voltage required to spark will increase the time needed from the coil to produce the higher voltage. The time delay for the coil to reach the voltage to spark the gap may seem small, but once at higher RPM, every millisecond counts.

4. Check the condition of the air filter. Since your RPM is dropping below nominal that would make me think that there may be an air flow restriction.

Well, I have ben playing the the IAC, and it helped a little, the started to act up again, so I ordered a new unit, to see if that solves the problem. I also ordered a new TPS sensor, just to eliminate that from the list of possible problems. I don't think is the plugs, as I changed the plugs 2 days before the problems started. The old plugs were gapped at .64 (which I thought was odd), So i re-gapped the new plugs at .54, which is stock. But a smaller gap wouldn't cause the problem, atleast I don't think so, and I haven't heard or felt a misfire yet, and no codes have been thrown.

dewone
06-14-2007, 04:14 PM
Mike I will be coming to Columbus tomorrow for the Central College Church Car Show right there on Sunbury road maybe 2-3 miles from your house, feel welcome to come if you like. At any rate if you like I could stop in and we can look at your car.

We can't enter our cars it's for 72 and older.
My dads working the event so I thought I'd come up to look at some old hot rods.

mojosvt
06-14-2007, 08:06 PM
I would love to take you up on that. But I am heading down your way! Go figure, Colleen and I are going (well, I have to go) to her cousin's wedding in Cinci this weekend. Hope all is well Dave, we need to get together soon, Mike

ausie
06-15-2007, 06:17 AM
Mike, did you disconnect the battery when you changed the plugs? Since the PCM is self adjusting (but only for a given time once the parameter tables are full and it has reached its capacity it will not re-adjust itself when new or different parts are installed that will effect timming, air/fuel corrections, etc...) If it has been a while since the EPROM memory has been dumped it will be operating on old data. Disconnecting the battery will erase the stored parameters and the PCM will begin to relearn operating conditions.

The only thing that comes to mind that would alter characteristics, spark voltage, MAF sensor voltage, Injector pulse width, fuel pump pressure as well as the throttle positiion sensor and all other sensor voltages is a weak battery. With the engine at idle, the voltage across the battery should be close to 14v. Also if you have a battery guage on the dash, it should not drop to the low when starting the engine.

The other issue could be the plugs. Too cold a plug can swamp out the coils and they will not fire properly. Also, if you accidentially got the wrong type of plug ( depending on resistor type or non resistor type) the coils may also operate improperly. Since the issues occured after replacement of the plugs, it may be the plugs causing the problems and not the other parts. Just a thought...

mojosvt
06-17-2007, 04:16 PM
Well, I am at a loss..... Changed the IAC and the TPS, cleaned the MAF, disconnected the battery for a while, and still to help. Actually, now I can't even get it to start at all. When I changed the IAC and the TPS, car started and drove fine, but the idle was still high. Came back to the house, and with the car running opened the hood, and was looking under the hood, trying to feel an air leak anywhere, make sure to air was getting in the engine un-metered, and the car after about 3 minutes died, and I haven't been able to start it since. SO now the cobra is out in the street, and won't start. It seems like it is going to fire, and after 3-4 seconds it dies right away. Looks like I am going to have to break down and get it towed. I can't play around much longer, with VIR less than 2 weeks away now:mad:

blk04cobra1
06-17-2007, 10:06 PM
Well, I am at a loss..... Changed the IAC and the TPS, cleaned the MAF, disconnected the battery for a while, and still to help. Actually, now I can't even get it to start at all. When I changed the IAC and the TPS, car started and drove fine, but the idle was still high. Came back to the house, and with the car running opened the hood, and was looking under the hood, trying to feel an air leak anywhere, make sure to air was getting in the engine un-metered, and the car after about 3 minutes died, and I haven't been able to start it since. SO now the cobra is out in the street, and won't start. It seems like it is going to fire, and after 3-4 seconds it dies right away. Looks like I am going to have to break down and get it towed. I can't play around much longer, with VIR less than 2 weeks away now:mad:
did it possibly throw it in to PATS mode? does the theft light flash real quick when you try to start it?

blueblazes
06-17-2007, 11:33 PM
keep us updated

ausie
06-18-2007, 07:22 AM
IF you have a scan tool or programmer that can pull codes from the PCM I would start there first. At least that way you may be able to see what the PCM was doing after the reboot. If do not, and the car will not start, you may need to disconnect the battery again and wait for at least 1/2 hour before reconnecting the terminals.

Unmetered air or vacuum leak usually results in surging of the idle speed. The surge is caused by the PCM attempting to regulate idle speed by the IAC valve.
If the idle seems a bit high after disconnecting the battery, that will be normal. Once the battery has been disconnected and then reconnected, do not start the engine right away. Leave the key on for about 15 to 30 seconds before starting. Let it idle for about 15 minutes and then shut it down.

When the battery is disconnected, several things happen:
1. The storage voltage within the PCM will drop slowly, once it falls below 2.7Volts or lower it will allow a reset of the PCM. It will take longer for the EPROM memory to reset. 1/2 hour is typical.

2. Before restarting engine, turn the key on and leave it there for at least 30 seconds to give the PCM time to reboot. The PCM will begin by loading up data stored on the EPROM. You may even see the guages max out and return to normal. Wait for all of the guages and lights on the dash to return to normal before attempting to start engine.

3. It will take some time for the PCM to adjust the idle speed. It may start off a bit high and then drop low and slowly climb up. IT should not surge or pulsate. Once the idle has stabilized shut it down and restart. Idle should be close to normal. At this point you can begin to drive the car. Note: during this point, the idle and air/fuel adjustments will be made by the PCM including building of the load tables. Take it easy for the first road trip to allow the PCM to make some minor adjustments before punching the throttle. Also you will need to cycle on the AC. Note: during the first drive, the A/F ratios are being recalculated or relearned for given engine load. this will not over write any custom software or tune, it is basically fine adjustments the PCM uses to maintain proper A/F ratios. It will begin rich then lean out so take it easy the first few miles.

dewone
06-18-2007, 11:08 AM
Mike
I have a Actron reader now, so sometime give me a call perhaps we can get moving on your car this week before you tow it.
Dave 203-627-2745 cell

mojosvt
06-18-2007, 11:30 AM
Ran the codes, and nothing. I have hit the rev-limiter, but not is a while. And nothing blinks ouit of the normal start up.

mojosvt
06-18-2007, 12:06 PM
Now to add fuel to the fire, I decided to give up, and have the car towed to my local shop. I have to have the car running in 10 days, for my open track event at VIR. Fricken AAA gets there, and then refuses to tow the car because of the aftermarket k-member and subframes. Told me there is nowhere he can "safely" pull the car up onto the flatbed. Told me he had to call a pull behind with a dolley tow truck, and it would be another 2 hrs. Well, I had to go to work, so once again, the car sits!!!!

ausie
06-19-2007, 07:03 AM
In the short time you have before the track event, it sounds like a good idea to have the shop look into it. :(

What I do recall in other threads, similar issues involved with not being able to start the engine, it was found that the crankshaft position sensor (CPS) was at fault. Either a bad connection to the wire harness, damaged wires or just a bad sensor. Once the PCM looses the crankshaft position sensor signal, everything else shuts down (injectors and coils). You can check if there is spark at the coil pack on one of the wire connections, more difficult if you have coil on plug set up. If you do have spark more than likely the crankshaft position sensor is fine. It is extremely difficult to flood a multi port fuel injected engine. Also note, similar to the CPS, a loose connector on the MAF or TPS will also prevent the engine from fireing up as well as prevent the spark from occuring. On the parts that you have unconnected the from the wire harness connectors, unplug one at a time and inspect the pins on both the connector and the part to make sure there is no damage. Reconnect that one part and try to start it. Note: if the TPS or MAF are not connected properly, the PCM should generate a code indicating that component was out of bounds. If the engine fails to turn over, leave the key in the on position without turning it to off, and connect the scan tool and perform a code read and look for pending codes. If no codes are returned, it may be a GEM module that is causing the issue. Exactly what blk04cobra1 suggested, PATS may be inhibiting starting the engine. Since the keys to have a life span of about 10 years. If you have the spare key, try that.

mojosvt
06-19-2007, 07:15 AM
Well, I can add another piece to the puzzle. The car has no problem starting and running when cold. Yesterday when I got home, I tried to start the car, and it fired right up. Ran perfect, even drove it around the block a few times. Pulled in the driveway, and decided to grab my wallet and run to autozone to pull the codes again. No sooner than I walked inside, (running for 5-6 min) and the car died, and wouldn't start again. So this morning, trying to avoid calling AAA again. I told my wife that I was going to start my car, and ahve her follow me. If I made it to the shop, great she could bring me home, if not, lock it up, call AAA, and I am at no more of a loss, then calling them from home. Sure enough, after sitting all night, fired right up, and made the 2.1 mile drive to the shop with no problems. Once I pulled into the shop, I let it idle, and once again, after hitting operating temps, the car died. So at least it is at the shop.

mojosvt
06-19-2007, 04:18 PM
It was what I was thinking in the back of my mind, even though all the symptoms didn't line up right. The shop called, and the fuel pump was showing low voltage, and low pressure. He said they were going to look into the sending unit and the pump itself. Sn-95's only have one pump correct? Do you think this could have effected my a/f ratio during my dyno runs, as my car was running lean, and that would explain it.

ausie
06-23-2007, 01:37 PM
If they cannot find an issue with the sending unit and if the pump and pressure are fine when cold, the issue may be caused by the alternator if the voltage drops off once the engine heats up (just a thought). If it is electrical (drop in voltage due to heat) that would at least explain a few things.

I believe you are correct that the fuel pump is a single unit. Ford did not use dual pumps until the 03 model year (as far as I know).

mojosvt
06-26-2007, 03:42 PM
Well, to wrap up this little situation. It looks like I atually had two problems at the same time, hence the various symptoms that the car had at different times. The IAC was bad, and replacing it solved the idle issue. The fuel pump was also bad, causing the stalling and not re-starting issue. So after $800 a new fuel pump, fuel relay, IAC, Fuel filter, and random other odds and ends, the car is up and running again. Looks like once again the mod and race budget has gone out the window. Looks like my brembo's are going to have to wait another year, oh well.

LT Motorsport
06-27-2007, 02:47 AM
Nevermind....to late.:)

dewone
06-27-2007, 01:53 PM
Good to see your up and running. Sorry about the budget thing though.

Brembos would not be needed if it don't go.......