Check engine light

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Apr 20, 2010 | 12:57 PM

catman900

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Check engine light

Hello guys I have been working on my sons 1993 f150 it has the 5.8l motor. We bought the truck cheap and have been restoring it basicly. The truck runs great there is no rough idle or missing or anything but when you start driving the check engine light comes on

. Again even with the light on I cant feel any kind of running problems. I have taken it to the shop but as soon as you turn the truck off the light goes off. No matter what you do it will not come back on until the truck starts moving so they tell me they cant check it for codes. When it comes on it stays on until you turn the truck off. We have replaced a few things like the TPS and air idle vaule just because it needed new ones not to fix the problem and a complete tune up from wires to plugs ect.

Any help would be great with this Thanks

Apr 20, 2010 | 01:13 PM

ymeski56

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From: Long Beach, Calimexiforia

They're full of crap! I guarantee you have active & stored codes. The easiest way to do it anytime you want is buy an OBD-1 Code reader for Fords. Digital numeric display w/ memory. $22.77 online or you can find them in stores if you call around. No "counting the flashes" involved & denotes if the codes are engine off, continuous memory or engine running codes (engine off codes should be dealt w/ first). Comes w/ manual listing codes specific to trucks only also. Works great! I'll guess one of them will be a Hego sensor lean code. How many miles on your o2 sensor? Equus Innova 3145 OBD-I Ford Scan Tool
Note: the cable is an option to allow doing the tests from the drivers seat. Not a requirement.

Apr 20, 2010 | 01:20 PM

catman900

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Hmm I will have to look into that. As far as the O2 sensor I am not sure that is one thing we have not replaced yet. I guess I should to see if it is bad to be honest I forget about that lol. Thanks for the reply

Apr 20, 2010 | 01:42 PM

ymeski56

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From: Long Beach, Calimexiforia

After 60k, they cost you money in gas & performance to keep em. Their switching speed slows & they become less accurate. They still function, but not optimally. o2's ahead of the cat regulate fuel trim. After the cat are for monitoring Cat function (Not so critical). Not sure how your 93'5.8 is set up, but the rules still apply.

Apr 20, 2010 | 02:15 PM

Lazy K

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Ford Fuel Injection How To Run a Self-Test Here is a link to checking for trouble codes without a code reader.
ymeski is right you will have codes (they will be 3 digit) so you may as well see what they are. He is also right that it is easier with a code reader but costs nothing to have a go with the above link.

Apr 20, 2010 | 03:19 PM

ymeski56

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From: Long Beach, Calimexiforia

Quote:

Originally Posted by Lazy K

This is true! I just don't trust my counting the flashes. So it's kind of a stress reducer for me & I wanted to do the cylinder output balance test w/ it. but found out afterwards it only does that w/ SEFI's not EFI's. Still worth every penny!

Apr 20, 2010 | 03:21 PM

catman900

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Thanks for the help guys I will start by replacing the o2 sensors and probably get the meter as well it never hurts to have one when ya need one I have 2 ford trucks.