Hard To Solve 5.0 Problem

XBLCanterX

New Member
Dec 28, 2003
34
0
0
Lexington
i have an 87 LX 4cyl conversion car that now has a 306 with an E cam and some bolt ons...blah blah blah...

anyway...the car starts and drives fine until it warms up or I really start getting on it....it doesnt stall it just has NO throttle response...you can limp it by feathering the throttle, but if you go past about a quarter of the way it wont do anything but sputter a little bit. the car does not stall out when this happens...and the really wierd thing about it...is that you can cut the car off (while still cruising down the road) crank it right back up...and it will drive like nothing ever happened...for a few miles at least) then it repeats the process...i managed to get it back to the house yesterday while it was still doing it...i pulled in the driveway, put it in neutral and nailed the gas and it did absolutely nothing but hunt for an idle...cut it off and restarted, nailed it again and VROOOM.. 5 grand no problem...anyone ever heard anything like this?? first time for me...any help would be GREATLY appreciated. thanks.
 
  • Sponsors (?)


Pull codes....

My initial "GUESS" would be that your car does not want to run when the computer is in closed loop mode for some reason. No telling at this point what that reason might be.
 
First, what's your fuel pressure at throttle. Sounds like a weak fuel pump. Has pressure but can't keep flow. When you start up and it primes and sits on but no demand, it buids pressure, but once it is given a load, it looses pressure. If fuel isn't the issue, then I would check the TPS voltage. It should be around .9V with throttle closed and closer to 4.5V open. Try disconnecting the MAF sensor and see if that changes anything, a bad MAF can cause this. Also check the o2 sensors to make sure they are working.
 
XBLCanterX said:
ok got any good links to wiring diagrams??

i guess that would kinda make since with it going away when restarted...

where would you start?

I'd start by finding a Ford dealership that can test your computer to see if it's working correctly.
 
i just got through setting idle, setting tps, cleaning MAF, etc. no change. what exactly does the PIP sensor do?? ive heard about it but still unsure...seems like besides a computer problem...its the only thing i havent checked
 
Dump the codes and see what the computer says is wrong…

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Walmart.

Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $33.
 
wow...i cant believe what I just found...somebody had ran a jumper wire from the red/lt grn wire out of the ignition switch...to my coil. i cut it off and now i have no power to the coil. heres the thing though....by doing this, he/she bypassed the rest of the circuit and i havent had power to the TFI module, or EEC relay this whole time (4 months)...anyone have a DETAILED wiring diagram of this circuit...or the ignition switch??
 
I experienced pretty much the same problem. At first they told me there was no power to the fuel pump module. Then they said it wasnt that it turned out my Ignition wires were fried have them looked at if you havent already. The best thing to do is take your car to the ford dealer. They find the problem real easy dont trust regular techs they bull**** you because, they dont feel like looking all over
 
The only problem with taking it to a Ford dealership is that - from what I've read - they won't touch any modified cars. If this is a conversion car w/ a 306, e-cam, etc, they probably won't touch it.

Here's a link to the diagram I think might help you:
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif
If you want to browse around at others, here's a link to the website:
http://www.veryuseful.com/mustang/tech/engine
The diagram designer is TMoss and website host is Stang&2Birds, as I'm told. They have helped a lot of us very much by creating and hosting those diagrams :nice:

Good Luck...that's unbelievable.