How to tell if car has stock programming?
03-09-2010, 06:33 AM
#1
Thread Starter
Join Date: Feb 2010
Location: GA
Posts: 14
How to tell if car has stock programming?
Is there an easy way to find out if my 1998 Mustang GT has a stock computer?
I just bought a 1998 GT auto with 170k miles. The previous owner told me that it won't run 87 octane gas (sign #1) and he's had to use 89 or 93. The other thing is that sometimes it seems like its hard to crank (sign #2). It just turns and turns. It may cough once or twice but never fire on the first or 2nd crank. Yesterday, after being parked overnight, it took seven cranks for it to crank. Once it cranks, the car runs perfectly. Once the car is warm, it will normally crank on the 2nd try, but for a FI car, that sounds out of the norm.
I have a scangauge plugged in the scanner and it doesn't throw any codes so the car thinks it's running ok.
I've read the write ups about cleaning the IAF so i'll try that this weekend. Any other ideas? is there a way to tell if the car has an aftermarket tune?
I just bought a 1998 GT auto with 170k miles. The previous owner told me that it won't run 87 octane gas (sign #1) and he's had to use 89 or 93. The other thing is that sometimes it seems like its hard to crank (sign #2). It just turns and turns. It may cough once or twice but never fire on the first or 2nd crank. Yesterday, after being parked overnight, it took seven cranks for it to crank. Once it cranks, the car runs perfectly. Once the car is warm, it will normally crank on the 2nd try, but for a FI car, that sounds out of the norm.
I have a scangauge plugged in the scanner and it doesn't throw any codes so the car thinks it's running ok.
I've read the write ups about cleaning the IAF so i'll try that this weekend. Any other ideas? is there a way to tell if the car has an aftermarket tune?
03-09-2010, 07:31 AM
#2
5th Gear Member
Join Date: Sep 2009
Location: KY, was MA
Posts: 2,797
you bought a 98 with 170K mi and it takes up to 7 tries sometimes to get it to start?? hope you didnt pay too much lol
hmmmmm
why not ask the previous owner what he had done to it? i dont know exactly how many different tuning software's there are but an option may be to take it to a tuner/dyno shop and have them dive in to check the parameters. im sure they will have a "stock" setup in house and then look at what you have.
hmmmmm
why not ask the previous owner what he had done to it? i dont know exactly how many different tuning software's there are but an option may be to take it to a tuner/dyno shop and have them dive in to check the parameters. im sure they will have a "stock" setup in house and then look at what you have.
03-09-2010, 08:30 AM
#3
Thread Starter
Join Date: Feb 2010
Location: GA
Posts: 14
Personally, I think i got a great deal. It's a 12 yr old car averaging 14k/year. That sounds within reason for the year model.
It took 7 times that day but it's usually the 2nd or 3rd try.
The previous owner told me it was stock. When i test drove it, it cranked ok. Maybe not the first time but the 2nd. I have an 99 Avalon and it doesn't crank the first time all the time. Once the Mustang cranks, it runs beautifully.
Can I tell if the timing has been advanced? Wouldn't that cause rougher starts and the need for higher octane?
It took 7 times that day but it's usually the 2nd or 3rd try.
The previous owner told me it was stock. When i test drove it, it cranked ok. Maybe not the first time but the 2nd. I have an 99 Avalon and it doesn't crank the first time all the time. Once the Mustang cranks, it runs beautifully.
Can I tell if the timing has been advanced? Wouldn't that cause rougher starts and the need for higher octane?
03-09-2010, 10:40 AM
#4
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
One possibility is that there is carbon build-up in the combustion chamber, and on the piston tops, has created hot spots that trigger pre-ignition.
At times carbon build-up can also raise the compression ratio to the point that higher octane fuel is needed. This can also alter the amount of added fuel required during cranking to get the fire going (it will need more). Checking the cranking compression can sometimes reveal compression increases brought about by carbon accumulation.
Sticking (slow to open) fuel injectors can also create starting problems that do not affect normal operation.
A Ford dealer will be able to tell you if it's an OEM tune, also most tuning shops would be able to download the tune and tell if it's stock.
There are a number of tools that will let you datalog timing and other operating parameters through the OBD2 port.
At times carbon build-up can also raise the compression ratio to the point that higher octane fuel is needed. This can also alter the amount of added fuel required during cranking to get the fire going (it will need more). Checking the cranking compression can sometimes reveal compression increases brought about by carbon accumulation.
Sticking (slow to open) fuel injectors can also create starting problems that do not affect normal operation.
A Ford dealer will be able to tell you if it's an OEM tune, also most tuning shops would be able to download the tune and tell if it's stock.
There are a number of tools that will let you datalog timing and other operating parameters through the OBD2 port.
03-09-2010, 10:45 AM
#5
Thread Starter
Join Date: Feb 2010
Location: GA
Posts: 14
One possibility is that there is carbon build-up in the combustion chamber, and on the piston tops, has created hot spots that trigger pre-ignition.
At times carbon build-up can also raise the compression ratio to the point that higher octane fuel is needed. This can also alter the amount of added fuel required during cranking to get the fire going (it will need more). Checking the cranking compression can sometimes reveal compression increases brought about by carbon accumulation.
Sticking (slow to open) fuel injectors can also create starting problems that do not affect normal operation.
A Ford dealer will be able to tell you if it's an OEM tune, also most tuning shops would be able to download the tune and tell if it's stock.
There are a number of tools that will let you datalog timing and other operating parameters through the OBD2 port.
At times carbon build-up can also raise the compression ratio to the point that higher octane fuel is needed. This can also alter the amount of added fuel required during cranking to get the fire going (it will need more). Checking the cranking compression can sometimes reveal compression increases brought about by carbon accumulation.
Sticking (slow to open) fuel injectors can also create starting problems that do not affect normal operation.
A Ford dealer will be able to tell you if it's an OEM tune, also most tuning shops would be able to download the tune and tell if it's stock.
There are a number of tools that will let you datalog timing and other operating parameters through the OBD2 port.
I have a scangauge on the port now. it's just a read only though. I can't modify anything with it. I wonder if there's someway to tell with it?
03-09-2010, 11:27 AM
#6
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
Top engine cleaner won't hurt--however the only real solution (if indeed carbon build-up is the problem) is to pull the heads and clean things out.
The tune will have to be downloaded and inspected with tuning software to determine if it's stock or not. What makes you believe it is not stock?
The tune will have to be downloaded and inspected with tuning software to determine if it's stock or not. What makes you believe it is not stock?
03-09-2010, 12:20 PM
#8
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
Change the plugs and wires first. Then try some top-engine cleaner.
If it were mine I'd take it out on the highway and do several WOT pull-ups from 3500 to 5500 rpm to blow it out, however be aware that doing so could break some crud loose and foul a plug. It could even harm the engine if the internals are loose--however I haven't heard it run so that's going to have to be your call.
If it were mine I'd take it out on the highway and do several WOT pull-ups from 3500 to 5500 rpm to blow it out, however be aware that doing so could break some crud loose and foul a plug. It could even harm the engine if the internals are loose--however I haven't heard it run so that's going to have to be your call.
03-09-2010, 04:58 PM
#9
Thread Starter
Join Date: Feb 2010
Location: GA
Posts: 14
Change the plugs and wires first. Then try some top-engine cleaner.
If it were mine I'd take it out on the highway and do several WOT pull-ups from 3500 to 5500 rpm to blow it out, however be aware that doing so could break some crud loose and foul a plug. It could even harm the engine if the internals are loose--however I haven't heard it run so that's going to have to be your call.
If it were mine I'd take it out on the highway and do several WOT pull-ups from 3500 to 5500 rpm to blow it out, however be aware that doing so could break some crud loose and foul a plug. It could even harm the engine if the internals are loose--however I haven't heard it run so that's going to have to be your call.
I got in the car this afternoon (it had been sitting since yesterday) and it took 5 cranks. The 3rd and 4th crank sounded like it tried but couldn't quite get it. The 5th it finally cranked at a very low RPM, and after 3 or 4 secs, idled up like it should have. It does sound like the idle isn't constant. It doesn't surge, but it definitely changes.
I got in it a few minutes ago to drive home and it cranked on the 2nd try.
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