Lumpy Idle 87 Ford Speed Density 5l Swap

[Steve McMahan]

Hello:

I’ve posted this over at VMF, but wondered if I’m missing some valuable eyes on my problem? Anyway, if you’ve follows by build, you know I swapped the drivetrain from an 87 TBird 5l Speed Density system into my 73 Grande. I’m sorting out I believe to be a vacuum leak(s), but after two day, and testing everything I can think of, only finding one leak that gave me 2” more vacuum (10 to 12”), I’m wondering if the condition of the motor is the culprit.

The car is hunting for a steady idle, now has 12” vacuum, is lumpy on the idle, and when I connect the timing light, it’s very close to 12 degrees BTDC, but moves up and down 2 or so degrees each way as it hunts.

Now, to be clear, besides taking the top of the manifold off, change the oil pan, new pump, new pump shaft, new timing chain set, and new harmonic balancer, I do not know the condition of this ~75k motor. For all I know, 12 may be good. If it is, what can I do to smooth out the idle?

Here are two videos of it running, first focused on the vacuum gauge, (it’s hard to see this 1970 Craftsman gauge, the plastic lenses if scuffed) reading 12”, and the second is the tach showing how much it’s hunting, and the second shows how much idle charge it’s experiencing. Any ideas or further questions are welcomed (and I still have no codes using my OBD1 reader). Thanks.

View attachment IMG_2371.mov
View attachment IMG_2372.mov

 

[Sheriff41]

Have you cleaned your idle air bypass and cleaned the throttle body? A hunting idle on SD cars is often a dirty IAB.

 

[Steve McMahan]

Everything from the intake manifold to the air cleaner was thoroughly cleaned, new gaskets, etc. I don’t know if the IAB is malfunctions, but I cleaned it very well. How could I test if that is the culprit? Does 12” of vacuum sound like the root of the problem? I have no feel for engine wear/ vacuum loss.

 

[Steve McMahan]

I have a question I hope someone here has the answer to. On a late 80’s, early 90’d 5.0 Mustang, it uses two solenoid controlled vacuum valves, which control two parts of the Air Injection system. The two parts are called the TAB and TAD. The solenoid that is damaged in my application is used to divert the air into the converters. I don’t have converters, so I have it vented into the engine compartment. It’s this second in line of solenoids that I need. NPD sells both of these, I’m just not sure which one I need. They look exactly alike, but have a slightly different connector for each. If someone more knowledgeable could point out to me which one I need, I would be very thankful.

 

[boilermaster]

Steve,
When you were checking the ignition timing, did you have the ignition timing shunt removed or connected ?.
Base timing should be checked with the shunt removed.
If you are in the 12 degree range with the shunt connected and reading 12 degrees BTDC your timing will be severely retarded.
Typically with the shunt in place and reading timing,, the values will be around 30-36 degrees BTDC.
Do NOT remove or reinstall timing shunt while engine is running.
You can check the air idle bypass valve/solenoid by simply unpluging lt while the engine is at a warm idle.
Boilermaster

 

[Steve McMahan]

Yea, I’ve got to redo it. I ordered a replacement MAP sensor since there isn’t any way to test it. And before I “fixed” the timing, it was well advanced from the 12 degrees, but still a very lumpy idle. So, I’m hoping that part and properly set timing does the trick. Will be a week or so before I know; heading back to Ca tomorrow, returning next week with the MAP in hand.

Something else I’ve got to resolve. When I swapped the ECU harness from the donor TBird 5.0, I tried very hard to not eliminate wiring I didn’t need. Now, I decided, since I purchased an OBD1 tester, that I didn’t need the check engine light function. I didn’t remove the wiring for that feature, I just tucked and stowed it (like all of the other wiring of the main harness I didn’t need). One thing I keep intact was the test port. All of the wiring, from its source to the connector, are as it was. But, try as I may, I now believe, my tester is not working. I’ve gone through the test the tester function, and I don’t believe it’s getting KOEO input. So, I’ve got to think through, ie, spend a few days examining the wiring harness book, my wiring drawings, pics, etc to see if there is something I did wrong. It’s possible, since this is my first EFI transplant rodeo.

I‘ve sent an email to the OBD1 company asking them how I know it’s working (ie no codes returned verses not receiving the codes), since I can’t seem to find that in the manual.

Thanks again to you guys for the excellent help. Steve

 

[boilermaster]

Steve,
Back when I worked on these things for a living, I made a test connector for MAP and a bunch of other EEC connectors, with it one could get relevant data from the sensor without connecting a breakout box or piercing the wiring to get a backprobe.
One could then use a handheld vacuum pump with the key on and compare data to what is listed in the service manual.
in the 15 years that I was at the dealership, I only replaced a few map sensors.
air idle bypass a completely different story.
Boilermaster

 

[Steve McMahan]

Well, a new MAP wasn’t an expensive part, so, while I’m not a fan of changing parts, hoping it fixes the problem, this time, I’m hoping!

And if not, no harm, no foul. As I said, I’m a week away from knowing if I fixed anything, so for now, it’s all perfect.

For now, I’ve got to figure out, by the color of the wires, which of my two, TAB or TAD, solenoids I’ve got to replace. LRM, which has them, can only tell me by the ford part number, and that's no help. It’s a problem for next week.

 

[Steve McMahan]

Well, I couldn’t stand it, it’s my TAD solenoid. The current problem, no one makes a replacement, even the same year, same function Ford Mustang part, is different, it appears only in the electrical connector (even the wires are the same colors). Why, why do they do that? Of course, I couldn’t find a connector with pigtails (new). I’ll likely buy the new TAD from LMR, but I’m going to hope a connector pops up. The used stuff I’ve seen on eBay is crusty old.

The solenoid on the left in this picture is the one I need.

 

[secluff]

Hey Steve,
Now you see why some of the parts counter personnel you've encountered appeared to have been on a two-week drinking binge. With emissions laws changing almost daily, keeping abreast of the carlines and engines involved could be a bear. The transition from Speed density (SD) to Mass Air Flow (MAF) not being done simultaneously on all vehicle lines added to the fun factor.
Your '87 T-Bird donor engine did not use the separate TAB and TAD solenoid vacuum valves. The '86-87 Bird used what Ford labeled a "Solenoid Vacuum Valve Assembly." As in your photo, this assembly included both solenoid valves mounted on a bracket. These valves were not serviced separately. The part number for the assembly is F65Z-9D474-A (F65E-9D474-A2A). These were also used from '86-88 on Mustangs. Because of stricter emissions laws, the '88 Mustangs can be tougher to find the correct parts cars. The '88 California Mustangs were MAF with separate TAB and TAD valves. The 49 state vehicles were SD and had the solenoid valve/bracket assembly. As if that wasn't confusing enough, Ford started phasing in the MAF system in later '88 49 state production since they knew it would be mandatory in '89 on all models to pass new federal emissions requirements.

You can check with some of your favorite parts houses and see if they can cross the Ford F65Z-9D474-A part number. The aftermarket may have had some separate valves listed. Those were just not fast movers for us. The previously mentioned IAC valves, EGR valves, and cleaning throttle bodies were the most performed work on the top end of these engines for a long time.

Let me know if you don't find anything on these solenoids, either used, aftermarket, or otherwise. As a last resort, there may be one source that might have a NOS part. But I would try to exhaust the aftermarket searches first.

Good luck with your project.

 

[Steve McMahan]

I’ve already crossed off the local salvage yards because when I looked and actually found two, they were both junk. LMR sells one for the 88 Mustang, but then I would need to find an electrical connector. The search fir that, so far, is a bust. But I suspect I could find one in a salvage yard.

Another interesting source might be the front wheel locks, for 4WD vehicles. Seems Ford employed a very similar solenoid setup, but I’m not sure of the voltage. Complicating this is the OEM Ford parts are a 5 volt device. I’m sure the 4WD valves are 12v.

Fabrice has a stock of these parts, I hope. If he finds it, he’s my new best friend .