5.0L XR Shiny Engine Bay Pics

[john keefe]

Yeah, not driving it enough to drain a couple tanks and solve this as quickly as I'd like. Plus, it'd be annoying to put on miles, knowing what the car could do, but having to baby it.

[Ed Lijewski]

Sticky injector(s)?

Try a bottle.

https://youtu.be/agAWXnT4-EQ

YMMV

[john keefe]

On my list. Been a big fan of SeaFoam since my days working on marine diesels and outboards, way back when. Don't know if it'll do anything with this, though, as I cleaned and refitted all the injectors (caps, spacers, filters, O-rings) after verifying good resistance values across each. Again, if I only accelerate about 85%, and don't punch it from low throttle, the car runs smooth. So, I'm leaning more towards some low-end glitch in some sensor that bugs out when demand is too quick for the read (or voltage).

[john keefe]

OK, not the fuel pressure either. I hooked up a gauge, it idles at 30-31, and steps up to 38 on throttle.

But, during the test I was able to duplicate the bogging at light, but quick revving between idle and 2200 RPM, no load (i.e., parked). Same nothing reaction, but everything seems to be working. Tach shows RPM's increase, I can hear it trying to pull air, fuel pressure goes up. It's climbs up on RPM, so something's firing/igniting, but it's like there's a dead region in the TPS. Doesn't feel like its NOT getting enough air, or enough fuel, just firing is out of beat. But, if the TPS had a dead zone, wouldn't you just get no RPM increase?

I have two 5.0L TPS's which worked fine on the stock setup, and both tested for good resistance, and even analog sweeping (0.97-> 4.65 v). No dead spots. Seems unlikely both would now be bad. Can't hear any vacuum leaks, but would a small leak be enough to screw with light and hard acceleration?

[thesameguy]

I may have this wrong, but I believe the TPS in EEC IV (and most EFI...) is only there to indicate load so the ECM can provide enrichment. Even without a TPS signal at all, you still have the mechanical throttle letting more air in, and the VAM/MAF will indicate that and the ECM will add more fuel. One of the big improvements of EEC-IV over L(H)-Jetronic is the addition of the TPS .... L(H) only had a 2-position (closed and WOT) TPS so there is no load enrichment, it's all reactive. Motronic and later LH Jetronic added a "modern" TPS in to do what EEC IV already figured out.

I would expect EEC IV with a bad TPS to have issues like poor throttle response, weird idle behavior, and maybe power delivery issues at bigger throttle angles. Poor throttle response because a lack of increasing voltage prevents enrichment, weird idle behavior because it doesn't know throttle has shut and the idle valve needs to react (until rpm has gone quite low...), and problems with WOT because (I assume) at WOT the ECM goes to "special" (maybe fixed) maps and open loop for MAX POWER.

[john keefe]

Thanks for all the help, guys. And the winner/culprit is... dirty MAF sensor. Couple of very small filaments sitting cross-wise to airflow, and the fronts were coated with dirt or such, probably trapped by oil from a K&N filter. Makes me rethink going to a plain filter. IIRC, that's why Ford voided warranties on the MAFs in the 90's if they found you used K&N filters, but in this case a simple cleaning did the trick. Wonder how many MAF sensors Ford replaced that coulda' been revived with a cleaner.

Cleaned it up with carb cleaner, disconnected the batt for 30 min., and tried again. Idled like crap for about a minute, and I thought I had wasted the MAF sensor. But then it cleared up and runs really smooth. Mid-range to high RPM is SOOO much better now than stock.

Thanks Sameguy. Yeah, that's what was confusing, as I thought maybe the TPS signal played a small role in enrichment, or could be part of the feedback that influences timing. But, while it had some of the symptoms of a rheostat glitch, it didn't make a lot of sense when testing, as RPM's would climb, and once it got past the stumble zone it revved fine. And, I tested the ones I have multiple times, in combination with digital and analog, KOEO, and KOER and there appeared to be no glitches in the sweep.

[thesameguy]

Do be cautious cleaning MAFs with carb cleaner as it can leave an oily residue behind that can cause debris in the air to stick and cause issues. Also, it can potentially attack the plastic housing or seals. Should really use dedicated MAF cleaner ... which is unfortunately damned expensive.

[john keefe]

OK, important safety tip. Thanks Egon. Next stop at the parts store, I'll pick up some and spray again to make sure there's no residue.

[andyofcolumbusmerkur]

They have those dry K&N filters now.

[thesameguy]

I'm pretty sure I wrecked the MAF in my Alfa with carb cleaner, which is why I mention it.

I use an oil-less filter in my XR and my SPG, both I think are AEM. Been very happy with them both!

[john keefe]

Turns out it was electric parts cleaner, so maybe I'm got a little lucky...

AEM filters? Dry K&N filters? New on me. I'd need one a cone-style, 6" long filter with a base circle of 6" to fit in my airbox. Knowing how expensive K&N's can get, it's in the want/need/can't-afford category right next to Motorcraft parts.

[brokencase]

John, Hope you don't mind me asking...After swapping the motor - how do you manage registration in your state?
Is the car registered as a Classic?

[thesameguy]

You go to the smog referee, give them $8, and they put a sticker on your car.

There are only two classes of registration in California, regular and historic. To get the latter, the vehicle must be of historic interest.

[john keefe]

Out here, you only get to classify as classic, antique, etc. for your different insurance rates. CA only has just the two classes, and I think the "historic" has to be 65+ years, or actually be of some historic value?

They do have in effect a "classic" period by virtue of a rolling smog-exempt status for 40+ year old vehicles. So, a 1981 vehicle would be smog-exempt today, but CA paused it at 1975 and older. CARB is definitely not car-people. They put a lock on that to pre-1975 cars, and initiated a car-crush program to get all those old, battered, poorly-tuned cars off the road, regardless that at the time those old cars only amounted to < 2% of all vehicles on CA roads, and I'd bet 90% of those were classic muscle cars or such which had been restored or very well taken care of by their owners. Go figure.

Sameguy is probably the king of swaps and smog-certifications process, and it seems he has an easy time. Probably in cahoots with his smog referee, big bar tabs, etc. Mine was not as easy as a visual check and slap a sticker. 2+ hours for the complete inspection, roller testing, etc. When I did the swap, I made sure that everything smog-related was in the exact place it was (and number) in the donor Mustang, and replaced if needed with all OEM or CARB-Exempt aftermarket stuff. And the smog ref checked everything, including matching all of the engine, and smog component numbers for exact year and production date of the Mustang donor.

All went well, until he failed me at the very end for not having labeled the CEL. He actually sat in the car and watched the CEL light I had installed blink all his test codes. Not like I was going to sell it, and I know what my new idiot light on the instrument panel was for. I told him I just happened to have a label-maker in the hatch, and could I just roll it out, put on a label, roll it back in and have him pass it... No. Had to schedule another appointment (2+ hours each time) for a week later. I figured he wouldn't allow just the label, so I painted Check Engine in white-out. When it passed, he put a label on the strut tower, which you can probably see in the photos (passenger side). Reminds me, I've got to come up with something to cover it, without tearing it up if I ever have to peel it off.

[thesameguy]

My *theory* is that anything involving a small block Ford or Chevy will get increased scrutiny, because there is such a huge aftermarket for them and every Tom, Dick, and Harry is trying to scam a hotted up small block swap through smog. The trick is to show up with something obscure that you've put something even more obscure in.

That's an interesting thing about the CEL... on 1985 Saabs they "repurposed" the choke light as the CEL, since no US-bound Saab had a carb. So my SPG had the choke light.... Right before I took it in I freaked out and replaced the cluster with one that said CHECK ENGINE. In retrospect, I'm glad I did it! (I don't have a label maker in the trunk! )