1988 Ford LTD Country Squire - Cold Idle

X2 on the filter. The pundits say 24K, but I replace mine every year whether it needs it or not. The cheapest of insurance to prevent pump failure. Plus, everyone who does their own work should have a basic scan tool and a basic working knowledge of how the EFI works.

 

Okay - I used Twinkie's method of the test light (which I had to buy another one, think my kid melted the old one... stupid kids)

Key On, Engine Off - 34
Key On, Engine On - 12, 41, 91, 34

So if I'm looking at the right stuff ( http://www.troublecodes.net/ford/eec-iv/ and http://www.straighttalkautomotive.com/OBD1/ford-OBD-I.html )

Key On, Engine off - 34 = EGR Valve Position/EGR Pressure Feedback EGR Circuit Above Maximum Voltage (Others)
Key On, Engine On
12 - Unable to control RPM during Self-Test high RPM check (Makes sense if it won't idle right)
41 - System Indicates Lean (see #12 ?)
91 - Heated Oxygen Sensor (HO2S) indicates system lean (front - HO2S) (See 41 and 12?)
34 - 1. Pressure Feedback (PFE) sensor voltage out of range 2. Exhaust back pressure high / Pressure Feedback (PFE) circuit voltage high / From the other page: EGR Valve Position/Pressure Feedback EGR Voltage Above Closed Limit (Others)

Another page has 91 listed as, "Oxygen sensor problem, fuel pressure out of specified range or injectors out of balance"

 

Did you test engine running at temp ? cycling brake and overdrive switch if applicable for WOT test ?

 

I did. Steering, brake, and WOT (No over drive on mine)

 

Since the KOEO 34 is a hard fault, and because a stuck-open EGR (even just a tiny bit) is a vacuum leak at idle, you need to start with the EVP and the valve first. Remember, exhaust gas at idle leans the mixture out so much, it will idle poorly or not at all.

 

Sorry for asking so many questions. Y'all have been super helpful. I just want to make sure I get this right. This is my first time working on anything like this in depth. The last engine I rebuilt was an inline 200 in my 65 Mustang.... in 1990.

To summarize -

EGR Position sensor

EGR Valve

and then go from there?

 

Yes. The EVP (EGR valve position) sensor piggybacks on the EGR valve to tell the computer when the valve is open, especially if the valve sticks open at idle. Remove the three screws holding the sensor to the valve top. Be careful not to lose them or damage/lose the o-ring. There should be the slightest spring pressure on the sensor pintle as you remove the screws. When the sensor is off, you can use an ohmmeter to check for any spots in the sensor's range that show an open in the sensor when you slowly push the pintle in. If there are any, replace it. The resistance range you can find on Google, and should go from high to low and back to high again as you push in and let out the pintle. Any time the reading drops down to zero ohms before the pintle is fully pushed in, that's a short and it should be replaced.

 

Yes. There's a table that crosses the code and your engine to a pinpoint test procedure which will have you check the sensor electrically and physically, and check the EGR valve physically.

 

Since the 34 was in Continuous Memory as a hard fault, there's one of two possibilities, of which one would affect your idle--if the valve is sticking open.

 

Replaced the EGR, EGR Position Sensor.. still runs like hell. I may just have to cave and take it to the shop.

 

You've done the simple stuff, and it may run like Hell, but does it stall as it did originally?

 

Quick question: did you check the TPS voltage, with the car on KOEO, to verify closed throttle voltage and do a TPS 'sweep' test? This is an aside from the code 34; Just that it popped into my head while I was thinking about my padawan mechanic's Grand Marq.

 

I don't rely on the test light method for it is easy to make a mistake in your flash count and end up tossing money down the toilet. If you take it to a mechanic make sure he has proper equipment to test or more money wasted. If you plan on keeping this vehicle buy a good digital scanner and digital ohm meter and save money in the end.

 

Yes - did the KOEO throttle stuff, didn't get any errors there. I bought a digital scanner that was linked earlier in the post, had help trying to get everything going through - hard to do the KEOE when the damn thing refuses to idle to warm up and even when hot, idles like poop.

The mechanic I dropped it to has one specialist who works on nothing but "older" vehicles... anything Pre-ODBI really. I talked to him at length, he said it's odd how the cars went from fairly simple to work on to rudimentary computers making them a giant pain in the ass, to newer versions where the computer can tell you exactly what is wrong. May not be as easy to get to to fix, but at least you know what it is.

To answer another question - yea, still stalls at cold idle. also getting some hesitation during acceleration, too.

I truly enjoy working on vehicles, I'm just slowly building up all the tools and accessories to help me. A few more things and I should be able to do what most shops can do, at least on this old friend of mine.

I plan on building a kit-car (Cobra from unique motors) in a couple years and will certainly expand my shopness then.

 

I understand your frustration for I've been a an auto and diesel mechanic since the 60's and have seen many changes in the industry. There is no system easy even with new that is easy without knowing how each part works in conjunction with each other. Even the new only points to a direction to start diagnosing and is not foolproof. My last schooling was in spring of 2014 and at my age decided to retire do to constant changes each year.