Dr. Jekyll... rough running 2.9

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Ed Lijewski
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Re: Dr. Jekyll... rough running 2.9

Post by Ed Lijewski »

Confirmed: S.M. spec pressure is 43.5.

Gotta drop the tank and inspect.

YMMV
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brokencase
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Re: Dr. Jekyll... rough running 2.9

Post by brokencase »

I disagree. The spec is a range and if you have 35 psi then it is sufficient to run the car normally.

Certainly not the cause of the problem described.
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Re: Dr. Jekyll... rough running 2.9

Post by Joe62Tampa »

Brokencase, I posted an update on 11/14/2022 of where the car had been and where it is on 11/14/2022. There's a link to a video of how badly the car was running with the fuel pressure gage attached. It was all over. I get the impression from the mechanic that it's not doing this so wildly now. I also mentioned that the pressure is on the bottom end of nominal ranging from about 33-35 so just below to bare minimum.

It's curious that the car, at least at idle with no load and even blipping the throttle or holding it open somewhat, smooths out after a couple minutes. It's too late in the week for me to do much other than pick up the car and park it in the driveway again with the pending holidays in which I'll be traveling.

What would cause a MAP sensor to affect the initial startup time period of the car? It's not a sensor like the O2 that can heat up for example. It sets on its own on the false firewall. I'd think it'd work or not for intake pressure whether the engine is cold or not. (I'd think the intake temperature wouldn't vary that much.)
A thought occurred as I am writing this. Does the EEC have a fault strategy if the MAP sensor goes out to lunch? I wonder how the car would run when first started with it disconnected. Then, do the same after it has warmed up a little.

Ed - I like your idea of the fuel gage "taped" to the windshield (under a wiper arm -- what have you). Perhaps they can loan me theirs for a short time as I drive the car home which is very close by. Maybe a good opportunity to check the latest coupons at Harbor Freight for one of my own. (I've had good luck with their items for the most part.)

... I came back for another item I don't know if I'd written -- yeah, I don't want to look. The mechanic also pulled some codes and had to do with "low idle". that's it.
1987 XR4Ti with about 62,000 miles, Azure Blue.
T-5, Mustang front brakes, T-bird rear disks
mc2racing: full/new suspension and all bushings.
stock turbo, T-bird VAM and LA2, ~ 15-17 lbs boost, Rapido intercooler
40-Bob log header, full 3" exhaust
Ed Lijewski
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Re: Dr. Jekyll... rough running 2.9

Post by Ed Lijewski »

"43.5" in the S.M. is not a range.

The tech's readings are ~75% of 43.5.

But, the tech/shop should do a flow test.

With engine off and pump running (S.M. shows how to jump it via the test connector) for one minute flow should be 1.5 liter/minute (*). If flow is less, and pressure is less than 43.5, the pump and filter should be inspected.

(*) Just FYI if the pump is to be replaced the Walbro 240 lph is overkill; a smaller lph pump, e.g. 80/100 lph would be a sufficient replacement.

At this point re the MAP, I'd just again look for any other possible vacuum leak and if none are found then move on.

YMMV
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brokencase
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Re: Dr. Jekyll... rough running 2.9

Post by brokencase »

Ed Lijewski wrote: Thu Nov 17, 2022 3:04 pm "43.5" in the S.M. is not a range.

The tech's readings are ~75% of 43.5.

But, the tech/shop should do a flow test.

With engine off and pump running (S.M. shows how to jump it via the test connector) for one minute flow should be 1.5 liter/minute (*). If flow is less, and pressure is less than 43.5, the pump and filter should be inspected.

(*) Just FYI if the pump is to be replaced the Walbro 240 lph is overkill; a smaller lph pump, e.g. 80/100 lph would be a sufficient replacement.

At this point re the MAP, I'd just again look for any other possible vacuum leak and if none are found then move on.

YMMV
Ed, You better be dang certain before you send Joe off on a wild goose fuel pump replacement project and then he ends up back at square one.
I don't think you are certain and I wonder if you have ever measured the pressure on your own Scorpio.

I have, and Joe's pressure is par.

Spec for 2.9L Ranger and same for Scorpio.
"- Key ON Engine OFF (KOEO) = 35-45 psi
- Engine Running @ Idle = 30-45 psi

Pressure should remain within KOEO specs for at least 1 minute after turning the key off."

The latter part of the above is in regard to leaking injectors. Leaking injectors won't generally result in drivability issues but you might smell gas around the car after sitting or when starting the car.
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Ed Lijewski
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Re: Dr. Jekyll... rough running 2.9

Post by Ed Lijewski »

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Quod Erat Demonstrandum
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YMMV
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brokencase
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Re: Dr. Jekyll... rough running 2.9

Post by brokencase »

Quaestiones non responderunt.

1) You are certain that a fuel pump replacement will resolve the issue? I wonder because he claims the car runs fine once warmed up.
2) Have you ever measured the fuel pressure on your own Scorpio?
3) Most importantly, will you hold yourself accountable if Joe goes through all the hoops of replacing the fuel pump and still has the problem?

There is little difference to the behavior of the fuel system with the fuel pressure at 35 vs. 45psi at start up and idle conditions. In addition the numbers I have quoted are well established for the 2.9L and can easily be found online.

While I have never experienced fuel pump failure on the Scorpio, I have experienced it on other Fords and the problem is generally that the fuel pump just stops and the car won't start.

If Joe is seeing 30-38 psi then I would not change the pump. The issue lies elsewhere.
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Re: Dr. Jekyll... rough running 2.9

Post by Ed Lijewski »

Yes, I would drop the tank and remove the pump to at least inspect its filter/screen.

And I still subscribe to the SM FP number as what one wants to see on one's fuel pressure gauge at idle.

YMMV
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Re: Dr. Jekyll... rough running 2.9

Post by Joe62Tampa »

It’s been quite a while since I’ve done anything with this Scorpio. This is the latest & greatest.

- I replaced the fuel pump with a Walbro pump. The fuel pump assembly looked very clean.
- I replaced the MAP sensor (as I found a really good deal on one).
- I was concerned the thermostat was stuck shut or only partly open. Once the car got up to an operating temperature, the top and bottom coolant hoses were hot or warm. I measured the upper and lower hose at 183 F, 158 F respectively, using an infrared thermometer,

The car was towed to the shop I’ve used lately near my home.
- The old fuel was dumped, some fresh fuel, new fuel filter, fresh coolant, oil & filter. They felt the car was running better the more it ran. The thought was the injectors could be fouled up. Of course, their intake-injector service for $300+ was suggested. Nope - no guarantee this is the issue.
- They told me the ignition coil was checked and it was fine.

Things I’ve checked or done since getting the car back.
- I drove the car to station that sells race fuel (which was the alternate suggestion by the shop). I put in 5 gallons of 110 octane, filled the rest with about 2-3 gallons 91. There were several gallons of fresh fuel already in the tank. I drove the car across the nearby highway and it ran as though nothing was wrong. My memory fades as I drove it two different times. I think the issues started up again (on the 1st drive).
- FPR holds vacuum.
- I wondered if the catalytic converter was clogging. (I’d suspect the car would run poorly all the time.) I checked the temperature pre and post the 2nd, farther back from front converter at 300 F, 330 F respectively (using an infrared thermometer). (I realize after seeing the shop diagram, temperatures should have been taken in front of the first, after the second.)
- It’s difficult for me to see the proper timing with the angle this is set up at. The timing with SPOUT out seems correct (within a degree either way). KOER shows the computer changes the timing; but it was difficult to see. To me, this shows the computer is able to control advance, retard.
- The timing cannot be checked properly during KOER on a warm engine because the RPMs drop so low that the timing light doesn’t fire.

I’ve run about 90-100 miles on the car. It’s been frustrating as the poor running is inconsistent. In early posts, it ran poorly when it was cold. It runs poorly when it is cold or when it is warm. It’s like a coin toss what happens. I’m realizing this as I type this out. So far, it runs poorly only when cold or only when warm; but never poorly across the range (from cold to warm). It runs fine before the problems show up. When the car chooses to run poorly when warm, there are initial signs it’s going to happen. As the time approaches, there’ll be a “hiccup”, like a skip in the engine sound.

I’ve run codes (since getting the car back).
- KOEO (not having started the car for the day) has no codes to show
- KOER on a cold engine.
20 - ?
31 - EVR/PFE out of limits (*)
8 - ?
21 - ECT out of range (*)
99 - ISC has not learned yet
(*) Do these make sense on a cold engine?

- KOER on a warm engine
97 - ?
8 - ?

I’ve copied the video clip of the car running poorly with the fuel pressure gauge connected to the Schrader valve. I’ve not re-checked the fuel pressure since changing the pump. If it shows too low, then there is a more basic, fundamental problem.

https://www.dropbox.com/s/aqdti2gf5ylc7 ... 0.mov?dl=0

I’ve about tapped my knowledge at this point. Summary thoughts:
- I need to go through the Scorpio shop manual into additional diagnostic information likely provided for additional insights.
- I glanced through the emissions supplement, section 5, inputs. The oxygen sensor is ignored on a cold engine. This is the only computer input sensor that hasn’t been changed.
- Could bad/missing grounds cause such erratic conditions?
- Could an old, worn, contaminated oxygen sensor cause these issues whether in open or closed loop?
1987 XR4Ti with about 62,000 miles, Azure Blue.
T-5, Mustang front brakes, T-bird rear disks
mc2racing: full/new suspension and all bushings.
stock turbo, T-bird VAM and LA2, ~ 15-17 lbs boost, Rapido intercooler
40-Bob log header, full 3" exhaust
Ed Lijewski
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Re: Dr. Jekyll... rough running 2.9

Post by Ed Lijewski »

A new ECT, cold/hot, should be within range. So there's an issue either with the unit or wiring to/from it.

EVR/PFE, cold, should not throw a code. So there's an issue either with the sensor or vacuum hose and wiring to/from it.

Re FPR, I noticed on installing a new unit (because I had one handy😁) that the base of the unit I removed was uneven (not perfectly flat). So something to check.

Re FP, let's see the reading now with new pump installed.

Re grounds, the small black wire at the negative post is one I'd clean/check.

YMMV
Last edited by Ed Lijewski on Mon Feb 12, 2024 4:29 pm, edited 1 time in total.
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brokencase
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Re: Dr. Jekyll... rough running 2.9

Post by brokencase »

Ed Lijewski wrote: Thu Feb 08, 2024 5:29 pm
Re FP, let's see the reading now with new pump installed.
Oh yea, lets see the pressure. Gotta see that.
Hopefully Ed, it is just a psi or two above what it was before so you can proclaim "all was not in vain".

Told you it wasn't the pump.

I'd like Ed to measure the fuel pressure on his own Scorpio.
Last edited by brokencase on Tue Feb 13, 2024 12:44 am, edited 1 time in total.
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Bob Weir
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Re: Dr. Jekyll... rough running 2.9

Post by Bob Weir »

I’m posting this in MCA Scorpio forum because I know our more knowledgeable members will respond with corrections to my comments.

I’ve had a “few” electrical issues with one of my Scorpios and the group has helped me find the correct path.

I read your comments and the members’ responses.
Here are my comments & suggestions…

VACUUM HOSES
Disconnect one at a time, using a separate vac source, test everyone!

WIRING CONDITION
You mention turning on some components affects run performance. Turn on all items in sequence, what works vs not working? Voltage drain = short &/or open!

FUSIBLE LINK WIRES
If bumpy, they’ve been under stress. If not smooth, replace them with correct gauge fusible link wires.

OBD CODES & DIZZY PIP
8 doesn’t show up for Ford OBD 1, but it does show for Honda. Are you using the correct code reader?
“8” for Honda mentions wires to dizzy.
Scorpios are notorious for PIP sensor in dizzy. You need an oscilloscope to check wave form. MM won’t help. If your parts car has one, give it a try.

EEC DISCONNECT AND OPEN IT UP. Check for any suspect bad soldering and / or components. I suspect it due to all the run problems you’re having. A4LD required, not 5 spd manual.

FUEL INJECTION HARNESS. One half connecting to the injectors, other half goes into firewall. Completely open up the half to the injectors and inspect every wire especially insulation. To see how bad yours could be and mine was, Search MCA / Scorpio / "FI / Sensors Harness vs Sensors".

viewtopic.php?p=318632&hilit=FI+harness#p318632

CRITTERS FEASTING ON WIRING
Using the Elec & Vac Book diagrams, seriously inspect and test every wire that affects run condition. A LoadPro or PowerProbe are best to use.
Almost every circuit requires 12v. Using a MM: Disconnect wire at both ends, wire in series the MM, a 12v mini bat and a light bulb [with optional switch]. Test with light off, test with light on. Wiggle wire - light off, you should get 12v and light on < .5 drop. If >.5 you have a short or open = BAD wire!

You’re going to have an intimate relationship with your multi meter.
Joe62Tampa
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Re: Dr. Jekyll... rough running 2.9

Post by Joe62Tampa »

Bob, thanks for the heads up from the Facebook (FB) group. None of my cars would be running if it weren't for this community (here or on FB)! Foraging into electrical issues of this degree/magnitude is new territory for me. Imagine that considering I've had my XR4 for a good 15 years.

WIRING & FUSIBLE LINKS
I'll likely come back to your list to address any further issues after the fusible links are replaced. I highly suspect these are a huge contributor to the car running poorly. I'm surprised it ran at all, or that sometimes it ran ok; but other times not, then sometimes when cold, sometimes when warm.

CODES
The OBD codes have me a bit perplexed too especially since the code reader is the correct one for Ford OBD 1 (made by Innovative Electronics).
I replaced the Scorpio's distributor a couple years ago. I'd suspect it's fine.

CRITTERS FEASTING ON WIRING
OMG - I've had this happen to my Audi twice. Once, there was no boost protection and the next time was the opposite problem. Yep - it happens here in the desert.

Following is the update I posted on the FB group. I'll see if I can upload all the photos together.
========
An update on work I was able to do. I went with the easy start and I checked the power lines that are typically mounted at the battery. This car has a separate terminal post that somebody in the past had done along with an added trickle charger. I took off all the lines from the terminal post and they were cleaned. One of the fusible links looks like it's more than half shot, gone. The sheath looks fine down the path but not right up against the eyelet. I pulled apart everything covering the two poImagewer lines to the point where they meet the primary wire, likely 12 ga. It looks like the wires are spliced together with a large crimp for the 12 ga side and two smaller crimps for the 16 ga wires.
2 new fusible links purchased. I need to find a method to securely splice the three wires together. (The butt connectors I bought obviously are not going to work.)
I included some photos of some of the easy to find grounds. They look good as-is (without having loosened them for now).
I wonder how much this will improve the car's running behavior before I do anything else?

https://www.dropbox.com/scl/fi/x5sc619d ... kss4a&dl=0
https://www.dropbox.com/scl/fi/4n213g72 ... xc8ft&dl=0
https://www.dropbox.com/scl/fi/s7moky5r ... cco2h&dl=0
https://www.dropbox.com/scl/fi/0d6l5zpd ... cg2gp&dl=0
https://www.dropbox.com/scl/fi/ax3nhjob ... jymk0&dl=0
https://www.dropbox.com/scl/fi/6aum2bks ... irl62&dl=0
https://www.dropbox.com/scl/fi/uom48a7v ... lfn5o&dl=0
https://www.dropbox.com/scl/fi/9tp5xs61 ... h6wt3&dl=0
1987 XR4Ti with about 62,000 miles, Azure Blue.
T-5, Mustang front brakes, T-bird rear disks
mc2racing: full/new suspension and all bushings.
stock turbo, T-bird VAM and LA2, ~ 15-17 lbs boost, Rapido intercooler
40-Bob log header, full 3" exhaust
Ed Lijewski
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Re: Dr. Jekyll... rough running 2.9

Post by Ed Lijewski »

new fusible links purchased. I need to find a method to securely splice the three wires together... I wonder how much this will improve the car's running behavior before I do anything else?
I'm betting YUGE % improvement.

I'll post a vignette on why/how that was the source of your issues later below.

YMMV
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Bob Weir
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Re: Dr. Jekyll... rough running 2.9

Post by Bob Weir »

Joe
The condition of the fusible link wires is a definite signal to pull apart the fuel injection [FI] harness. I soldered mine together covered with shrink wrap & electrical tape.

I seriously suspect some bad wiring in FI harness. It has another 2 to 1 splice in it. One of the wires goes under the throttle body to the water temp sender. Poor performance is often blamed on H2O sender. I suspect bad wiring.

If your FI harness is bad, one of our "breakers" will have a slightly used one. But there are two different connectors to the harness portion that goes to the fire wall. Be sure to specify which one you need! Obviously the oval female won't connect to the circular male. Many German cars in the 80s & 90s had deteriorating [environmentally friendly] insulation that could not tolerate heat over the years.

The FI harness is easy to R&R. You do not have to remove intake manifold or anything else.

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