Will Code Reader detect elec problems even if check engine light is off?

[takaminegenie]

I am uable to find a complete thread for the "dead" engine prob. Everybody posts questions, answers, but no sloution to the problem. I would like to use this thread to post a complete problem solved with your help.

Engine died and coasted to the roadside. Started fine back after that. Checked fuel relay and it was bad, so i replaced all three of the realys by the blower motor box. Worked fine. But get this, i could tap one of the relays on something while the motor was running and the motor would surge to the point of dying. So i swapped the relays around, and no more problems. All other electrical areas of the EX work fine. Read a couple of threads pointing to the O2 sensor being bad, battery cables, realys, fuel regulator and pumps. But all of these are fine.

So i let it run for hours, shut it off and cranked it back several times, and still no problems. Wife took it out for two hours day after and parked it. Went back to it, and the enging just turns over but no start. Fuel pump is priming and fuel is getting to the rails. Spark is good on all of the plug wires. guys i am stumped and have always done all the work to my ex myself. Going to buy a code reader and was wondering if it might tell me whats wrong with it even though Check Engine light is not on. PLEASE RESPOND CREW.

DAVE

 

[mcgyver ky]

not sure

i do know that it will not show a IAC valve on the scanner i will ask my buddy and see what the book says tomorrow and let you know tomorrow night .

[ps if you are going to buy a scanner is what you are saying, a good scanner will cost you upwards of $2,500.00 to $5,000.00 dont know if thats is what you want to buy but if you do i do suggest the snap-on scanner my buddy has one and the ford dealer has been known to call him for its use.]

 

[Brian1]

Yesterday I used my $35 Wal-mart Ford scanner and with the key on engine off it told me I have an octane advance circuit grounded. My check engine light hasnt been on in months either so yes it should tell you problems with it. Now I have to find out where that circuit is...

 

[mrboyle]

Originally posted by Brian1
Yesterday I used my $35 Wal-mart Ford scanner and with the key on engine off it told me I have an octane advance circuit grounded. My check engine light hasnt been on in months either so yes it should tell you problems with it. Now I have to find out where that circuit is...

Brian, the "octane advance curcuit" is a program in the computer that is designed to recurve the timing advance if the computer detects that the octain of the fuel is too low (allowing preignition). Running cheap gas is the typical cause of this. It will not set a CEL since, technally there isn't anything wrong with the opperation of the engine. You should notice a drop in performance. The factory recomended cure is to run 87 or higher octane fuel.

 

[RiverRat]

EEC IV systems will give you three reslults:

Continuous codes - codes generated during normal engine operations. Stored in Keep Alive Memory.

Key on, engine off - Tests processors, some sensors, switches, etc. Outputs any codes stored in KAM from continous tests.

Key on, engine running - Tests most sensors, fuel system, egr, etc.

So a scanner will display codes even if the check engine light is off if they are present in the EEC IV memory.

EEC V systems are more advanced and do store codes also in memory.

The "octane adjust shorting bar" is used to adjust spark. If disconnected the vehilce will be less likely to knock. In addition, there will be less power.

The octane adjust shorting bar looks like a spout connecter.

 

[takaminegenie]

Ok guys thanks. Well say i dont want to spend $2500 on a scanner and prefer to use the $35 Wal-Mart Special. Or even not that. Is there a way that i can plug a test light somewhere on my EX that will give the "flashes" that i need for the code? And if so , where can i get a code definition book or something like that online?

DAVE

 

[RiverRat]

If you don't want to spend $$$ then the free autozone scan sounds like the way to go.

 

[TPLYNCH]

Cheap scanner should be just fine w/your '91. The 95+ with the OBD-II system requires a more advanced (i.e. Expensive) scanner.

Here's a place to find explanations for codes.... http://www.batauto.com/

 

[Glacier991]

Actually with an older EEC-IV system you do not even need a code reader to obtain a code readout. You can use the check engine light. Here's a link on how.

http://dalidesign.com/hbook/eectest.html

Happy Exploring

Chris