Same thing happened to my 97 F150. The first time it was the HEGO. When they replaced that, they supposedly installed a piece of aluminum to deflect the air conditioning condensate from the plugs. From time to time, if I'm on the highway with the a/c on, my check engine light will come on. It always clears in a day or 2.

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97 F150 4X2, 5.4, Tow package,K&N filter, true custom dual exhaust, stock 16" rims and 235 Firestones (waiting for the recall to include these!),Truck constantly mated to a Stratos 201 Pro XL 72 mph bass boat....

 

For everyone's information. I posted earlier about my C.E. light coming on every second start up after resetting computer. It doesn't matter if I idle for a few seconds or drive 30+ miles. The first start up no C.E. light.

Well, I found out that during my instalation of my Airaid (with the help of my 2yr grandson not reccomended) I forgot to install and hook up my IAT.

Why wouldn't the computer see the problem on the first start up?



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F150IslandBoy
1997 F150 Lariat
SuperCab, Toreador Red w/ Gold, Styleside, 4.6L, A/T, A/C, 3.55 3800 Limited Slip, Class 3 Tow Package, Leather Captain Seats, Sliding Rear Window.
Modifications:
Airaid FIPK, Flowmaster Delta Flow 50 Series, Bugflector II, Viper 500ESP Alarm, Pendaliner Bedliner, Cobra Trapshooter 3 Radar Detector, CARR Tubular Nerf Bars, NFA 1400 Compact 55W=>85W Halogen O.E. Lights, Durango 255/70R16, Chrome eyelet tie downs, Smoked front lic. plate cover.

 

Ok, I have had the check engine light coming on the last two days. When the truck is cold, it runs fine. As soon as the temp guage reaches the half way point, the tranny starts to really suck on shifting. It goes slow and engine runs rough. I took it down to autozone for free check engine. They hooked it up but did not get any error codes. Any clue or has anyone had something similar to this problem. F150 1995

Thanks

Eric

 

You can try pulling the vacuum line off EGR valve and plugging the vacuum hose (for diagnostic purposes).

The way I understand it the EGR valve does not start working until the engine is warm and the rpms are high. If the EGR valve is open too wide then the engine may stall/die/quit running which might be the problem.

https://www.f150online.com/forums/sh...engine+warm+up

 

Because the computer requires two consecutive drive cycles to turn the CEL/SES light on for non-critical conditions.

As for all you guys that are throwing out ideas because of your own experiences, thanks, but it really is not at all helpful AT THIS POINT. There are several dozen sensors under the hood with several hundred different possible onboard diagnostic codes that the computer can set. Until the codes are read, guessing is about as effective as farting into a hurricane. Once codes are in hand, a logical diagnostic procedure or an educated guess is posible. FWIW, the most common reasons for a CEL, in no particular order, on these trucks are vacuum leaks, EGR sensors and clogged ports, O2 sensors, and misfires (96-on).

Eric: With nothing more than a paperclip and some time, you can pull your on codes on that 95. The drones at AZ just checked for stored codes but did not run the KOER (Key On Engine Running) tests. That test, or the CBT (Cylinder Balance Test), will be the most likely ones to provide diagnostic clues in your case. Instructions can be found at www.fordfuelinjection.com and elsewhere, perhaps even somewhere in this site. I would try temp1's suggestion about disabling the EGR valve and see if the drivability improves. You will get a CEL during this test, but it can be disregarded. BTW, welcome aboard!

Steve

 

Thanks for all the helpful tips. I did break down and buy me a haynes last night and it shows how to run the Diag test with a Meter. Going to try and do that tonight. I also will go and try out that pulling the line of the EGR valve. Would be nice if that is the fix.

 

Well, I appreciate all the help that all of you have given me.

Just ran my self test finally and got two codes on the engine off.

First test. 11 11 which means Good to go for first test.

second test I got

172 right Hego lean
173 right Hego rich.

I am guessing that the right Hego is bad.

but did a engine run test and the code I have does not show anywhere.

4

So, going to do some searching and see if I can figure out what that stands for, for the engine running test. There is only 2 dig and 3 dig codes listed on http://www.fordfuelinjection.com

 

Well, after finally doing a search, was not doing the Engine running test correctly. Found how to do it on this page:

http://www.corral.net/tech/maintenan...-koeokoer.html

After performing the test, I found that my TPS is showing voltage above the 4.5, which means it must be bad, one reason my transmission is shifting incorrectly, makes total sense. And it also is confirming that my right HEGO is all messed up.

Again, I thankyou, all that have inputted to my problem and soon to be final resolution. Hopefully, next weekend I can replace these two parts when I get paid.

Have a great week.