check engine light....

[KIDSX]

2 questions....

1...i am the proud owner of a 95 sport...thats acting like a jackass. my check engine light comes and goes as it pleases. then the thing just dies and starts sputtering sometimes even shutting off. i had it hooked to a diagnostic machine in the garage no codes. any ideas?

2...i would like to get an intake kit with a new tube and all, along with an underdrive pulley but everywhere i look the 95 4.0 pushrod model is not there. ahhhhhhh
PLEASE HELP

Luego....KID

 

[mrboyle]

Are you sure there were no codes? Every time the CEL lights up the computer stores a code. If the light comes and goes (like your's) thoes codes are stored in the history file of the ECM. I can't see how they didn't find any codes if your CEL was lit. From the symptoms there could be a number of things wrong. It sounds like you have an electrical component breaking down and failing due to heat. My first guess would be the fuel pump (escpcially if there are any codes for running lean).

 

[aldive]

If the CEL illuminated, you should have code(s).

I would run a scan again.

Good luck......

 

[Robert]

Not always. I know of at least one thing I have done to cause a CEL without setting a code. I disconnected my IAC valve while holding the throttle to keep my engine from dying. The CEL was lit on the dash. I plugged the IAC valve back in and the CEL went off. I then read the codes with my AutoXray scaner and there weren't any codes set. When I read the codes while the CEL was still lit it did have a code for an IAC voltage out of range. I tried this with the IAT sensor but the code stayed in memory even after I plugged the IAT sensor back in however my CEL stayed lit as well until I cleared it with my scanner. Sometimes when the CEL gets lit and then goes out before reading the codes, there won't be any codes to pull.

 

[KIDSX]

well i took it to a ford dealership so i hope they know what they are doing......but not always. my friend said his ranger did the same thing and it was the O2 sensor.
i dunno thats my first option and the first route i shall try.
Luego....KID

 

[mrboyle]

Robret, as I mentioned earlier, every time the CEL is lit there is a code stored. The reason you are not reading them with the scanner you have is likely because it doesn't read history codes (codes stored, but no longer active). There are only a hand full of scanners available that can read these codes and most of them run in the $2500- $3000 range. History codes are not always needed to diagnose a continious problem, but they are invaluable when trying to diagnose intermintent problems.

 

[Robert]

What kind of code did I set when I unplugged my IAT sensor? I plugged it back in and restarted my Explorer. My CEL was still lit and I still had a code in memory even though the problem was fixed. My scanner also recorded several parameters that were stored at the instant I triggered the code by unplugging my IAT (RPM, timing, coolant temperature, intake temperature, vehicle speed, etc).

The only difference between unplugging my IAT and IAC was that when I plugged each back in and restarted, with the IAC the CEL was off and I couldn't read any codes. When I plugged the IAT back in the CEL was still on and there was a code set until I cleared it. Both showed codes while the CEL was on with the engine running.

My scanner lists what it calls "Trouble Codes" and "Pending Codes". When my lower intake manifold o-rings failed a couple of years ago I read a P0171 for a Trouble Code and a P0174 as a Pending Code. I am not sure what the Pending Code means unless it is for the codes that take multiple sets before it throughs out an actual Trouble code. The P0455 that I recently got comes to mind. It takes getting set twice before it will set off the CEL and trip a code. Maybe if I would have read my codes on the morning that I got the P0455, I would have seen the code in the Pending list?