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Bricky EFI question

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RenoHuskerDu

Bricky EFI question

This post was updated on .

It's a friend's 1990 F150 with the 300 six. It's clearly too rich at idle and low speed, but cleans up at higher RPM. We have one gasser parts truck with a 351. We could swap in parts off that truck.

We're not too familiar with these early EFI systems. I'm scratchin my head trying to remember 30 years ago. One of my sons is a full-time wrench and has never had an EFI vehicle in for service or repair (also never seen points and condenser in his shop, so I had to teach him).

As I recall, on these early EFI systems it's based on a simple airflow sensor, just a flap, with corrections for coolant temp, ambient temp, and atmospheric pressure. I don't recall them having closed loop or O2 sensor.

I guess I'll just start ohm testing the various components for dead shorts or open, once I get info on specs. Also, inspect the air flow sensor visually and put a DMM on its output to see if it's lumpy instead of a nice curve. I have this question out on FTE too, but am doubtful I'll find much help.

Reno in Central Texas, 86 F250 XLT Lariat eclb 2wd 6.9, plus 2 Bricknoses, 1 Aeronose that's getting a Bullnose front clip, and parts trucks. Busy lads, father and sons wrenchers.

RenoHuskerDu

Re: Bricky EFI question, please delete if not allowed

I actually got a few responses on FTE. But there seems to be confusion about OBD on a 1990. Several advised me to read codes. I'll take a closer look under the dash tonight. I didn't think Ford adopted OBD that early.

Another thing that surprised me is that this early EFI has no way of measuring intake mass. No flap, nothing. Just stored maps used to set injection volumes under varying conditions. Live and learn.

Reno in Central Texas, 86 F250 XLT Lariat eclb 2wd 6.9, plus 2 Bricknoses, 1 Aeronose that's getting a Bullnose front clip, and parts trucks. Busy lads, father and sons wrenchers.

Gary Lewis

Re: Bricky EFI question, please delete if not allowed

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If there's no mass air flow sensor then the truck has EEC-IV with what is called speed density. In other words, they know how many cubic inches the engine has, what cam it has, how big the valves are, and what exhaust system is on it. So they know how much air it ingests with any given throttle opening. Assuming, of course, that none of that has been changed.

Most EEC-IV systems don't have an OBD-II port, and I believe the few that do have don't have a fully functional OBD-II interface. But I'm not sure on that.

I'm going to ping Bill Vose as he may know about this.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

grumpin

Re: Bricky EFI question, please delete if not allowed

Here’s what I use on my 92 Bronco. I like it, it works good.

https://www.innova.com/collections/obd1-tools/products/digital-ford-code-reader-1981-1995-3145

Dane
1986 F250HD SC XLT Lariat 4x4 460 C6-Sold
1992 Bronco XLT 4x4 351W E4OD
1998 GMC Sierra SLE K1500 350 4L60E
Arizona

85lebaront2

Re: Bricky EFI question, please delete if not allowed

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In reply to this post by RenoHuskerDu

Since I was tagged (I guess that means I'm IT), 1990 is an EEC-IV system, the diagnostic connector is on the back side of the air filter bracket and is two separate plugs, a large odd shaped multi-pin and a single pin. An OBD-II (parts store) tester will not work on it and if I remember correctly 1990 will not give live data. If the 6 uses the same locations as the V8s the MAP sensor will be on top of the HVAC casing. Make sure the vacuum line isn't cracked or collapsed as it will make it rich, also check the line from the pressure regulator for liquid gas inside which indicates a bad regulator.

Here is a way to retrieve codes without a scan tool on Ford OBD-1 systems:https://www.fordtruckzone.com/threads/how-to-retrieve-trouble-codes-on-your-eec-iv-system-without-using-a-code-scanner.659319/

It gives you a way to get both sets KOEO and KOER (engine off or engine running). ECT can make it pig rich, but it won't usually clear up at higher rpm. Good luck, and ping me if you need more on it.

Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

Gary Lewis

Re: Bricky EFI question, please delete if not allowed

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Thanks, Bill. I knew you'd know.

Gary, AKA "Gary fellow": Profile

85lebaront2

Re: Bricky EFI question, please delete if not allowed

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You might want to save that link as it will work on the 1985/86 EFI 302s, main difference is test connector and MAP sensor are behind the battery.

Bill AKA "LOBO" Profile

ArdWrknTrk

Re: Bricky EFI question, please delete if not allowed

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In reply to this post by Gary Lewis

Yes, OBD-1 is not only far different than OBD-II, the codes are not standardized across manufacturers, so prior to 1996 it was specialized.

I was going to point out how to pull codes by grounding with a paperclip while counting flashes of the check engine light but I see that's been covered.
One thing I will add to what Bill has said is to address numerically lower codes first, as fixing 3 can resolve 11 but not the other way around.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

85lebaront2

Re: Bricky EFI question, please delete if not allowed

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Very true Jim, and Ford started 3 digit codes on the later OBD-I vehicles.

Bill AKA "LOBO" Profile

RenoHuskerDu

Re: Bricky EFI question, please delete if not allowed

In reply to this post by 85lebaront2

Thank you Sir. The gentleman is bringing his pickup over this evening and we'll have a go at it.

My son did find a Ford-specific OBD1 reader at the repair shop where he works, left by the PO, who retired. We'll see if that plugs in.

Reno in Central Texas, 86 F250 XLT Lariat eclb 2wd 6.9, plus 2 Bricknoses, 1 Aeronose that's getting a Bullnose front clip, and parts trucks. Busy lads, father and sons wrenchers.

85lebaront2

Re: Bricky EFI question, please delete if not allowed

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Good luck with it and let me know if you need any more information on it.

Bill AKA "LOBO" Profile

RenoHuskerDu

Re: Bricky EFI question, please delete if not allowed

We found the conx, pulled codes, got a 41 which is lean O2. Sent our buddy off to NAPA to buy a starter, PS pump, O2 sensor, and 20' of vacuum hose to renew all of that under the hood.

Reno in Central Texas, 86 F250 XLT Lariat eclb 2wd 6.9, plus 2 Bricknoses, 1 Aeronose that's getting a Bullnose front clip, and parts trucks. Busy lads, father and sons wrenchers.

RenoHuskerDu

Re: Bricky EFI question, please delete if not allowed

Based on code 41 we decided to replace the O2 sensor. The one we took out was in miserable shape. We also replaced the starter, PS pump, and 6' of vacuum hose. She smokes less and runs a little better.

But still not right. Idle isn't clean, she acts like she'll stall on throttle opening, and only smooth out above 2000 rpm. Our friend is going to buy a cap and rotor, they look old, time for new ones anyway. And I'll look for carbon tracing under the old cap.

Can anyone confirm ID these components? For each, we would like to test it with a DMM to see if it's in spec.

Idle Air Control AIC:

Coolant temp sensor:

Throttle Position Sensor

Reno in Central Texas, 86 F250 XLT Lariat eclb 2wd 6.9, plus 2 Bricknoses, 1 Aeronose that's getting a Bullnose front clip, and parts trucks. Busy lads, father and sons wrenchers.

85lebaront2

Re: Bricky EFI question, please delete if not allowed

Administrator

You have the correct ID for each, top one is indeed the IAC. Question, what do the plugs look like and what brand are they? I have seen some strange things on Fords with platinum plugs where they weren't originally specified and even with non-Motorcraft ones (friend had an F150 that had AC plugs in it, He changed to Motorcraft and nearly doubled his gas mileage.

Also check that the EGR valve isn't leaking or stuck, that will cause a very rough idle.

Bill AKA "LOBO" Profile

RenoHuskerDu

Bricky EFI question redux

Bringing this thread back to life because the rich, rough running came back.

We had achieved considerable improvement and the 300 six was running pretty well, but still a little rich.

List of work done:
New cap and rotor, plugs, air filter.
Throttle body removed and cleaned.
IAC cleaned (cured stall when put in Park).
EGR valve tested for correct operation.
New O2 sensor.

Thinking we had things under control, we decided to fix the exhaust leak that had been there forever. The second converter was split open, empty. We welded it up tight and installed a new side dump exhaust with a MBRP stainless muffler. She sounded nice and quiet, but right away rough running and black smoke started too.

What the heck??? Could there have been melted converter bits in there, blocking the exhaust? We cut it off and examined closely ... nothing in there. And it still ran like dookey with the exhaust open again. We double checked the cap and rotor, both look normal. We pulled and cleaned the O2 sensor, it was all sooted up. We pulled a couple plugs and they are sooty but look like they'll fire fine (see pic below). We checked that both butterflies in the throttle body are opening on throttle. We checked for objects or nests in the intake tract.

Something is making the EEC run way too rich. First thing in the morning, it runs fine for about 30 seconds, then black smoke and rough running.

Possible clue: Noted on pulling throttle body that the intake manifold is lined with black gunk. Could that be caused by EGR valve malfunction? (but it tested OK). Could it be caused by a faulty PCV valve? It looks dirty as sin but they are simple devices. I think we'll pull and clean it anyway. Right now we've unplugged the EGR as a test. And we're welding back up the exhaust.

What if the TPS were faulty? Would that possibly cause all this drama? Is unplugging it an option for debugging?

This is a friend's truck. He lets his daughters drive it. I'm afraid the rich mixture will cause premature cylinder wall wear. We are not good at this EEC stuff, we drive diesels. Hopefully one of y'all has the magic tip.

Reno in Central Texas, 86 F250 XLT Lariat eclb 2wd 6.9, plus 2 Bricknoses, 1 Aeronose that's getting a Bullnose front clip, and parts trucks. Busy lads, father and sons wrenchers.

grumpin

Re: Bricky EFI question redux

I don’t know this system well. But, what popped into my head was engine temp sensor, because it runs well for awhile.

Dane
1986 F250HD SC XLT Lariat 4x4 460 C6-Sold
1992 Bronco XLT 4x4 351W E4OD
1998 GMC Sierra SLE K1500 350 4L60E
Arizona

red1980F150

Re: Bricky EFI question redux

A few years ago on my '93 I changed the spark plugs... and the exact moment I started the engine after changing the plugs the diaphragm on my fuel pressure regular ruptured, leading down a rabbit hole similar to this one, I read the engine code with the morse-code engine light and everything. I ended up changing plug wires, 02 sensor, probably 1 or 2 other things, until I figured it out. The timing of the failure couldn't have been worse because it made me think I did something wrong.

If the fuel pressure regulator has failed it'll make it run extremely rich and idle very poorly. It'll smooth out at high RPM, probably because the engine needs more fuel then anyway, but it's still running rich. My MPG went from 16-17 to 9. I guess the only way it would be intermittent is if the regulator is okay and you have a collapsing vacuum line or something (as someone mentioned above)?

Anyway, might be worth checking. On my truck it was a cylindrical can about 1-inch in diameter up near the firewall.

John

Red 1980 F150 Custom - Standard cab, long bed, 4WD
302 v8, Auto transmission
Almost completely stock, quite clean but not perfect.

RenoHuskerDu

Re: Bricky EFI question redux

This post was updated on .

That's a great tip. We searched and found it on the injection rail.

However, the tank and in-tank fuel pump were replaced about a year ago, because the truck had been sitting in a farmer's field for 7 years.

I wonder if that mechanic (guy I don't know, GM fanboy judging by his yard) put in the wrong pump? The truck has always run rich since, as far as we know. But previously it did not run at all.

If someone has a diagram indicating what components should be in the 1990 fuel system, 300cid six, and approximate location, that would be very helpful.

Here is what RockAuto says the fuel pressure regulator looks like. It's $42 at NAPA so I ordered one.

Reno in Central Texas, 86 F250 XLT Lariat eclb 2wd 6.9, plus 2 Bricknoses, 1 Aeronose that's getting a Bullnose front clip, and parts trucks. Busy lads, father and sons wrenchers.

red1980F150

Re: Bricky EFI question redux

Yep, that's exactly the part I had to replace.

Mine was a 302 with MAF, however.

John

Red 1980 F150 Custom - Standard cab, long bed, 4WD
302 v8, Auto transmission
Almost completely stock, quite clean but not perfect.

85lebaront2

Re: Bricky EFI question redux

Administrator

In reply to this post by RenoHuskerDu

I was hoping AllData had some good diagrams or pictures of the EFI fuel rail etc. Does that truck have the small cooling blower in the right front of the engine compartment? If it does then that is the earlier system, and runs around 35 psi fuel pressure. Ford changed to a higher pressure system on the 4.9L to eliminate vapor lock under hot soak conditions, these engines run around 60 psi fuel pressure. If the wrong pressure regulator was used, ie, one for 60 psi on a system designed for 35 psi, it will run rich enough the O2 sensor can't compensate for it. If the emission label is still on the underside of the hood, it may show the fuel pressure spec.

Bill AKA "LOBO" Profile