My 1987 Mercury Colony Park

[Kodachrome Wolf]

it is, but NP caps in those values will be larger and you might run into fitment issues. No real reason to not use the original type unless you're changing them to film.

Fair enough. I'm just having to scavenge online for some decent ones that meet the criteria. Rather not put some cheapy no-name stuff in there. Figure the originals made it this long, even if their plotted lifespan was likely never expected to stretch this far.


Edit: Just for fun, I cracked open that '97 P71 ECU. It uses the same capacitor values as my Box ones, a 47uF 10v and a 3.3uF 63v unit. Just like the Box units, the 47uF is showing signs of age. Honestly, these are some things I'd just never thing about for longevity in a car, and yet I guess we're steadily moving into that period where inspecting stuff like this might be necessary to keep things in order.

Finding units with the exact voltage in Nichicon brand has been a bit tougher ensuring that they meet the 105C+ standard, so I've been substituting with a higher voltage unit since it appears that'll work just fine as long as the uF rating is the same.

[gadget73]

You can bump the voltage if needed. 10v caps can be replaced up to 50v or so. The 63v one can go to 100v if needed.

[Kodachrome Wolf]

Out of boredom, I decided to check the plugs since I'm still waiting on my capacitors.

All of the plugs looked like the ones on the left. The one on the right came out of cylinder 7.


FWIW, the spark plug wire clip inside the boot broke off on that plug when I went to remove the wire. I'm not sure if this cylinder was firing 100% of the time. I'm curious about the coloring though, since when cylinder 1 didn't have any compression the plug would just come out gas fouled, but clean. I've replaced the broken wire with a spare I had.

[Kodachrome Wolf]

Got the capacitors replaced on both PCMs. Checked the original DD unit to ensure it worked, and it did its business as normal. Checked the replacement DU unit, and it definitely exhibited a different startup strategy. Both start at about 1100 RPM, but the DU unit spiked the idle up to about 1600 for a few moments, then settled it down to 850 RPM. The DD unit usually just sat at 1100 to 1000 RPM.

The DU unit also didn’t exhibit the up/down loping of the IAC after a few seconds of running. It definitely seems to be able to nail down where it wants the idle speed better than the DD unit. I want to see how it performs going down the road and get some drive cycles out of it. I’ll hopefully have it back out on Monday or so for testing.

[gadget73]

The letters do indicate some difference in strategy, but unless someone manages to find a trove of Ford internal programming docs, or has the ability to extract the program we may never know the differences. I doubt anyone is going to make the effort to extract program info from a lopo ECM.

[Kodachrome Wolf]

Got the wagon back out today after installing the DU computer, non-floppy air vents, and installing 1.25" wheel spacers to the rear to eliminate the excessively tucked rear wheels.

Driveablitity on the "new" ECU seems roughly the same, however the engine I believe is running a touch smoother since I don't have a busted spark plug wire anymore. I'm not sure if the computer output to the TripMinder is more optimistic than the previous one, as it seemed it was reporting considerably better than normally reported mileage in local driving at speeds between 50-60 MPH. Typically with consistent speed in that range with overdrive engaged, it was reporting a steady 26-29 MPG in the instant readout. Even being in stop and go traffic, average MPG reported 16.3 MPG.

With a fresh tank of gas a few consistent drive cycles over the next few days, I'll see where it's actually playing and if the TripMinder is too optimistic now (was more pessimistic on the other computer). I always check my mileage each fill up on a tracking app, so I'll be curious. Perhaps this catch code has better fuel management, who knows, I'll just wait for the numbers.

[Kodachrome Wolf]

So I found and fixed a new issue that I really hadn't diagnosed.

A few weeks ago, I had a surging idle issue, noted the TPS voltage was a bit high. Figured maybe it slipped after the ears were indexed out. Dialed it back down to around .96v and forgot about it since it started idling normally again. After that I was noticing if you really got down on the pedal, it didn't feel like all the pickup was there and at WOT or near WOT, you could really smell the exhaust, like a bad converter. Let off and things got back to normal.

Anyway the idle surging came back today and it wanted to idle stupid in gear. Grabbed a new TPS at work, took it home. Checked the old TPS, still at .96v, but oops, at WOT it was reading only 3.21v. Based on everything I'd been seeing, that's below threshold to get it to go to WOT strategy (I think I saw the PCM looks for at least 3v above closed throttle voltage). Tossed the replacement on, closed value was .90v, and WOT it was reading 4.25v. Took it for a drive, certainly seems a lot more awake and no weird smell at WOT. Idle was more settled as it should be.

I'd be inclined to believe I was running lean when under heavy throttle considering the range issue. The TPS did a steady sweep, but obviously it was no longer performing properly.

[gadget73]

thats odd. usually those work fine or have obvious dead spots or jerks in the throttle sweep.

[Kodachrome Wolf]

thats odd. usually those work fine or have obvious dead spots or jerks in the throttle sweep.

The old one was steady, but just would not engage higher than 3.21v at WOT when properly adjusted for closed throttle. No misalignment of the little tabs either, it rotated fine on the shaft.

New one works like a charm. I want to say Nick stuck a nice Motorcraft one one it during his ownership, but I guess it went stupid at some point. I might check the resistance values to see how those look, just for kicks. Replacement was a Standard unit since it was readily available.

[gadget73]

NFG is NFG, but thats just not the way I'd expect for it to fail. Meh, whatever. Either way its nice you found the problem.

[DerekTheGreat]

After swapping in an older PCM in Ashley's '92 F150, I can say that there are indeed differences. The older one wants to start up and idle about 400rpm higher and then it holds that for a while before it wants to settle into a low idle. The old one started high but then settled right to 1000 rpm until it started to warm up where it then settled into 800 or so.

[Kodachrome Wolf]

Decided to start on some plans I've had for a while and did a minor fix. Already removed the upper intake for the work.

Minor fix: Noticed with the HVAC set to A/C or Vent, any time you touched the accelerator and let off, there was an audible click clack behind the dash, like a vacuum selector. Air always came out of the correct vents, but I noticed it would just lose all vacuum within moments of shutting the engine off and you could hear all the vacuum actuators release. The other day I was climbing a long hill while on the pedal and the vents switched back to defrost. Found the HVAC feed line from the check valve at the firewall vacuum tree had cracked again. Decided to trim it back a bit more and repaired a good section of it with standard vacuum hose. Hopefully that'll keep it placated.

Plans: Toss on aluminum Mustang valve covers I've been kicking around for a while, delete the heater core return pipe and replace with a standard hose, and install a restrictor in the inlet to the heater core.

I've already done the install of the restrictor in the inlet heater hose. Four Seasons/Murray 74796 is for 3/4" line and fits good. I did that since I saw some older posts about running the car hard and ballooning the heater core. I can't say I'm running at max RPM all day, but every once in a while I like to go WOT for fun and I'd rather not kill that thing. Job doesn't look super fun, so I'll do a little preventative work instead.

The return pipe job is on the table since the primary job it used to help with doesn't exist anymore. The pipe has a nipple coming off of it that fed the EGR spacer antifreeze. My EGR spacer has been unhooked forever and the hose is just looped back into the intake. It's not doing much, and I figure I could either just stick a plug in that back hole, or I can move the temperature gauge's probe back there and put the OE switch sensor for the instrument cluster back in the front port. That way all the factory stuff works and I still have my gauge too. From there, I could remove the metal pipe and just run some bulk 3/4" hose from the water pump to the heater core and route it along with the inlet heater hose. All the pre-SEFI cars were done like that, so I figure it'll be fine.

Valve covers are merely aesthetics. I just want to toss a little extra something in there.

[gadget73]

If the gauge is in the rear, it responds oddly. Might be better putting the idiot light switch back there. I had mine in the back corner for a while.

[Kodachrome Wolf]

If the gauge is in the rear, it responds oddly. Might be better putting the idiot light switch back there. I had mine in the back corner for a while.

Interesting to note. Was it reading hotter back there or was it slower to respond? Just curious before I start buttoning things up tomorrow or Sunday.


Regarding the work:

-HO Valve Covers:


-Return Pipe Delete:



I found something worth noting, and that was the little fitting that would have served as the EGR warmer return port was 100% clogged solid. Just full of what looked like mud. I know Nick took good care of fixing the cooling system on this car after it overheated on him once, but something tells me it probably had problems well before he had it. Anyway, the heater core return tube was looking really sad and was rusty inside, and since I didn't need the feed for the EGR warmer, it was simple enough to just toss in some bulk silicone heater hose and call it a day. The earlier cars survived that way just fine, so here we are, even if it isn't as pretty as the factory return tube.

I forgot I tossed the original temperature sender for the light, so I ordered a new one at the store. I'll have that tomorrow, and I'll be done with this little side project once I decide to put it all back together.

[gadget73]

read slower, but it also swung hot to cold somewhat randomly. Up front its rock solid. Not much water circulation there in the back, so I suspect thats the real reason.


Its not actually an EGR cooler. Its a throttle body heater to keep the thing from icing up. I monitored the air temp sensor in mine with it connected vs disconnected and got roughly 10F hotter air with it plumbed in.