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My Cobra
07-08-2004, 03:38 AM
I have a 99 that is pissing me off. I start the car the guages go all the way across then come back to normal. somebody said that was becuase of the battery stuff that the computer was resetting every time i am not sure. Also it will stick at RPM level every now and then. I will drive and shift gears from 2nd to 1st and the RPMs will stay at around 4k even if i am stoped. It is weird. then i give it gast and it goes up then the RPMs fall to where they are spose to be. :scratch::banghead::scratch:

ausie
08-07-2004, 10:48 AM
There are only two times I ever noticed the guages maxing out and then returning to nominal positions is when either I disconnect the battery for 1/2 hour or when initiating the Diagnostic command with the trip button prior to turning the key on.

I think the Diagnostic mode is refered to as the DTS but not really sure. That mode is pointless really.

If the car has problems starting, then I would suspect it is the battery (look at the battery charge guage when starting, if it drops then the battery is weak).
There is a fuse that is used for engine control memory (I just looked it up) It is a 5A fuse #21, perhaps replacing that first may be the best bet. Sometimes if a fuse tests okay, does not mean that it is good. I have replaced fuses that tested good on my exploder and found that corrected the problem (some may develope cracks that will open up with temperature).

If that does not work, the next step would be to disconnect and reconnect the wire harness connectors as well as the main processor connector (you should disconnect the battery if you do this). Vibration may cause some connections to become loose. In most cases, a loose connection is the cause when solving processor issues. Since checking connections does not cost money (unless you pay someone to do it) is usually the first thing to perform. The Processor is located behind the passenger kick panel below the dash on the right side.
After reconnecting all the connectors, and re-connecting the battery, you will still get the guages to max out at least once. Drive the car for at least 1/2 hour. turn it off and turn the key on (engine off). If the guages max out again, it may be the processor memory or the processor itself. Both of which are housed in the processor enclosure which is non-serviceable. Your best bet would be to replace it (you may have to submit the old one as a core).

It is possible that the processor was re-programmed either by Ford Service or by a previous owner (if you bought it used ). One reason I do not like using Ford service is that they sometimes change things or perform tasks without telling you, especially if there is a service bulletin without your knowledge. There is a way to get the ROM code date by using the DTS function. Press and hold the trip odometer button, put the key in the on position. When the word test appears on the digital odometer display release the button. The guages will max out and return to normal (you already see this). Then press the trip button several times to see the various information. There is one that displays the ROM code date. If the processor has been re-programmed it will not correlate to the manufacture date of the vehicle on the door panel. It is possible that your cobra has different code since the 99's had some HP issues that were to have been corrected by Ford in 2000.

Before ripping out the processor, I would check out some other sites or at least wait and see if you get any other replies. This is not the first thread I have seen with the same problem. There could be another solution or a different cause for the problem you are having. Replacing the processor is costly. That would have to be the last step.

My Cobra
08-14-2004, 01:26 AM
thanks a lot i will give this a try. The peopel at the ford place said that it was normal then i asked him why it only does it some times he says " It is a random computer scan it does it when it feels" I was thinkin man i wonder how they program a computer to check it's self randomly and not get it to screw up and do it never or every time.

ausie
08-14-2004, 07:53 AM
I would expect nothing more from the dealership since many or if not all of them do not understand the workings of the processor. They have limited information provided to them. It makes me wonder why they have excuses for everything. Talk about a non-profit plan. If I was working the service desk, I would say this " That is not very common, lets set you up with an appointment and we will take a look at it - while pointing to the labor charges on the poster behind me".

In some respect they may be correct. When the key is switched on prior to start up, the processor more than likely tests the EEPROM (data storage for fuel curve and other sensory information), and if it detects values outside the norm, too low or high it will purge the memory and start from new data. One would think since the processor is always adjusting the values it would be transparent. Since I write code for microprocessors and at times use EEPROMS for data storage, it is common to check the EEPROM for errors at startup to validate the information stored. Otherwise you may wind up with unexpected operation which is not good for a control system since it may crash resulting in damage or death. In code that is used to operate equipment (machinery, environmental, or in this case fuel management) it may be considered redundant but it is a necessary safety check.

It could be related to any performance chip that is added to the main processor. If that is the case, the fuel curve data within the performance chip is attempting to replace that which is in the EEPROM or just bypassing it all together. The processor may be looking for specific data that is stored in memory such as a key code or similar that will inform the processor that what is stored in memory is good. The performance chips may initiate a memory dump of the on board EEPROM so that it may embed its code (I can only speculate as to how they work without really knowing what is really happening). If you have a performance chip, can it be removed without suffering detonation? I would be catious if you do and have a different MAF and fuel injector set that may be different than stock. If you are not suffering any performance issues, perhaps the guage sweep is livable. If you do have a chip I would ask the maker of it about the guage sweep and see what they say. They may even have your question answered in a FAQ forum.

One thing I have yet to do is to open up the kick panel an see what is in there. I have yet to experience the guages maxing out, but I have an 01 which may have different code than the 99. I have gotten some feedback from ford service (when you go there too many times they sometimes tip their hat and offer information not for public exposure). They have omitted to me that the 99 and 01's suffer from pinging and carbon buildup. At first I used to think it was fords error, but found out through research just about any motor having a 10:1 compression will have this problem including BMW, Audi, Corvettes, Vipers, volvo, SAAB, and not just cars either. The list goes on.

redsnake99
08-14-2004, 11:27 AM
My amateur guess is tht the process is messed up. I had to have mine replaced after some goofy stuff happening to me. In fact, the processor, the entire wiring harness and a new Autologic chip went into my 99 a couple of years ago, problems all solved after many days of tracing what it could be.

I saw gauges being wierd, but the first symptom was the car cutting off when driving it normally (on a ramp in a parking garage). Scary thing for me was when the car cut off twice on the track at VIR at 125 MPH. One time was with Brian Shugg in the passenger seat.

Don't take this as the official diagnosis on your car, just relating my personal experience.
:D

ausie
08-15-2004, 11:32 AM
Just about anything is possible. Computers can be sensitive devices. As for the idle issue that was probably forgotten, more than likely not related, however, if the fuel ratio leans out considerably the engine speed may increase when not under load. One trick I found that sometimes gets the high idle speed down is to push had on the brake (when sitting still of course) which will load the vaccum pressure from the master cylinder booster. If the RPM does not drop it is probable that either the IAC valve is getting stuck open or there is a vaccum leak on the intake plenum. When it involves the EGR valve (which is the means all of that carbon enters the intake) can make things worse. I usually clean the entire intake plenum once every 5k miles (usually when I change the oil).

As for the odd guage issue, it may indeed be a faulty processor or wire harness. The only way to be sure is if you were to replace it and not get the occurance of the guages maxing out every time you start it.

Checking the other things like wire connections, etc. may correct the issue or it may not. I did check out the Diablo Sport supplier to see if there are any issues that may cause this, apparently not. However, there was a thread that indicated some of the 99 processors were missing a jumper so that the two chips would communicate properly.