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Woohoo, another issue...
#21

It will go past 3k, but not consistently like it did a week and a half ago. Dunno what coulda changed. If I dont have code 42 after work tomorrow I go try smog.
Johnny

86 XR
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#22

Sounds like you've tossed the kitchen sink at her and at least can be confident in all that has been checked. I still would swap in known good TPS, check voltage as well. I found the TPS on the '90 NA is fixed, the 85XR is adjustable.

Not familiar with the 8AU or the XR harness pinning at the ECU. NA 2.3 from a 1990 Mustang uses pin 24 to bump idle/engine speed under load of the A/C compressor.

You might examine it (?) because as you let off the throttle, it will step the Idle up for A/C. Could be an A/C switch malfunction sending a signal to the TPS to compensate for compressor load.

Either way, best luck man. Helps us all if you get it figured out so please keep us posted !
Mike L

89 LX 5.0, 5spd ragtop, leather, 55k survivor. My bride of 27 years.

1990 LX hatch 2.3 auto. Swapped to T5. Dormant 5 years. Running turbo swap now.

Owned multiple 4, 6 & 8 Fox Mustang/Capris. Logged over a million miles in my SOHC 2.3/2.5 Ranger trucks.

Lima Lifer !!!
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#23

(10-14-2021, 10:02 PM)LuvRfoxes Wrote:  Sounds like you've tossed the kitchen sink at her and at least can be confident in all that has been checked. I still would swap in known good TPS, check voltage as well. I found the TPS on the '90 NA is fixed, the 85XR is adjustable.

Not familiar with the 8AU or the XR harness pinning at the ECU. NA 2.3 from a 1990 Mustang uses pin 24 to bump idle/engine speed under load of the A/C compressor.

You might examine it (?) because as you let off the throttle, it will step the Idle up for A/C. Could be an A/C switch malfunction sending a signal to the TPS to compensate for compressor load.

Either way, best luck man. Helps us all if you get it figured out so please keep us posted !


Plan is to check TPS using the BoB(Break out Box), that way I can see if the wiring between EEC and tps is any good.

I'll also swap and check again, I have a known good used tps here.

I'll check the A/C switching, though, IIRC it is the IAC that bumps engine speed under various conditions including high engine temps to get the coolant flowing faster. I know seems odd, as higher rpms can increase heat, but that's what I recall reading in the service manual once about IAC operation. I do have another one of those to swap too.

I think I am also going to remote mount my tfi, as it's been on my list, and it certainly can't hurt.

Incidentally, I did get a 1988 Volume H so I now have pinpoint tests for some of the codes I was getting. As look at those, it takes me to the same point that lead me to replace the EEC in the first place.
Johnny

86 XR
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#24

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I hate to beat a dead horse, Johnny ~ BUT.......have you checked the f/pres during this anomaly? It needs to be 40-ish psi greater than whatever boost you're at when the prob is occurring. If you don't have a dash-mounted gauge, you can tape a hose-mounted "test" gauge on yer w/shield so it's visible from inside.

Think about the prob you're having ~ it can only be a lack of sufficient fuel OR spark (nothing else that I can think of). You can simplify  your diagnostics with regard to spark, by removing the SpOut connector and setting your timing at, say, 23°. Doing so eliminates the EEC from interfering with advancing/retarding the timing and holds it locked.

As for fuel ~ if the rail pressure increases properly with boost (40-ish psi "delta")......the only other fuel-related issue would be a lack of proper pulse-width modulation to maintain the proper AFR (IOW, back to the EEC). My 2¢......  <shrug>
Placerville, California
(former)  '78 2.3T Courier w/blow-thru Autolite 2bbl carb ~ (current)  '87 2.3T Ranger w/PiMP’d EFI
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#25

Thanks Ray,

Like I said I've used a hand pump to simulate boost, and I can see fuel pressure come up like it should. Ive lost my fuel pressure gauge that I could tape to the windshield, and I think I'm close enough to some rural roads to use a new one, if I fab it, without getting the cops called on me.

A dash mounted gauge is in the future for just this issue, but I need to pass smog before I can justify too much more money on this project to "she who must be obeyed".
Johnny

86 XR
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#26

(10-15-2021, 01:02 AM)Milehighxr Wrote:  ......I've used a hand pump to simulate boost, and I can see fuel pressure come up like it should. 
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What kinda gauge did you use......one that attaches directly to the rail-mounted Schrader valve?  <shrug> For shíts & giggles, try locking the timing at 23°, thus eliminating the EEC's intervention.
Placerville, California
(former)  '78 2.3T Courier w/blow-thru Autolite 2bbl carb ~ (current)  '87 2.3T Ranger w/PiMP’d EFI
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#27

Ray... I have several minor issues on my '90 Mustang tune, still learning so I read a lot here. I'm one that is better at seeing hands on, but I try lol. Really don't like asking dumb questions, soooo....

As I understand checking for consistent spark, I move timing around 23* BTDC on the distributor with the spout connector removed to avoid advance/retard by the LA3, then check spark going each cylinder ?
Mike L

89 LX 5.0, 5spd ragtop, leather, 55k survivor. My bride of 27 years.

1990 LX hatch 2.3 auto. Swapped to T5. Dormant 5 years. Running turbo swap now.

Owned multiple 4, 6 & 8 Fox Mustang/Capris. Logged over a million miles in my SOHC 2.3/2.5 Ranger trucks.

Lima Lifer !!!
Reply
#28

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YES. Mike.....Set the timing as you normally would (with the SpOut connector removed) ~ BUT......set it at 23° BTDC (instead of the usual 10°), then leave the SpOut connector unplugged. This will allow the TFI distributor to be a standalone ignition source, without any intervention by the EEC. 

Of course, it also means that you'll be starting it at 23°, idling at 23°, WOT @ 23°, etc., etc.. It's only temporary, just to make sure that the computer isn't doing anything strange to the ignition, thus causing a prob. If one still persists, however, it doesn't mean that the EEC is "off the hook".......since it could still be causing probs with fueling. It also doesn't let the dizzy off the hook......since probs can be due to a TFI or PIP issue.  <shrug>
Placerville, California
(former)  '78 2.3T Courier w/blow-thru Autolite 2bbl carb ~ (current)  '87 2.3T Ranger w/PiMP’d EFI
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#29

(10-15-2021, 01:18 AM)TurboRay Wrote:  
(10-15-2021, 01:02 AM)Milehighxr Wrote:  ......I've used a hand pump to simulate boost, and I can see fuel pressure come up like it should. 
.
What kinda gauge did you use......one that attaches directly to the rail-mounted Schrader valve?  <shrug> For shíts & giggles, try locking the timing at 23°, thus eliminating the EEC's intervention.

Fuel pressure gauge mounts directly to schrader valve. I had one that I modified to have a much longer hose that I could duct tape to the windshield while driving. That one has grown legs and disappeared on me.

I really need to get rid of this intermittent high idle when the clutch is depressed. I've swapped the TPS for another known good one, and took for test drive today after clearing continuous codes. No change. However, I did have no continuous code 42, but I had code 14, more than one pip pulse. Went thru diagnostics, and got to the point that the TFI needs replaced. I'm gonna relocate it, and try one of my other TFIs, that may or may not be good. I have them on hand so might as well. New ones, if any good are like $130.00 last I looked, and seems the only way to test them is to install it, and then no refund if it's bad.

Something else I noticed too, I plugged my breakout box(bob) into the harness, and connected the EEC. I sat in drivers seat and worked gas pedal and watched the TPS voltage thru the BOB. I don't get more than 2.76v with my foot thru the radiator. WTF over. Made one of the kids push gas pedal to floor, and then checked to make sure throttle body was maxed, and sure enough, I still had more travel on TB. I could get 4.5v at WOT thru the BOB, but not if I use the gas pedal. So, my XR may be a candidate for a TSB regarding the throttle cable(I have to pull it up again), basic jist, is that some XRs shipped with a longer than necessary throttle cable. It's not the reason I'm not passing smog, it's been like this even when I passed smog in the past, but it keeps me from hitting WOT. And yes during KOER test the car passes the "mash throttle to floor" test.

Next weekends project is to replace TFI, while relocating it.

Dumb question time, is not having the VSS connected giving me issues, or does it matter with an 8UA?
Johnny

86 XR
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#30

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With your symptom of intermittent high idle when the clutch is depressed, I suggest checking all ground connections to make sure they're clean and tight....including engine-to-chassis, the three(?) at the EEC harness near the computer, and the orange ground return wire attached to the compressor housing. 

BTW ~ It won't affect the high-idle issue w/pedal depressed, BUT......you don't have a manifold reference hose connected to your BPS sensor (looks exactly like a MAP sensor) do you? That nipple should be open to the ambient atmosphere on OEM turbo Fords (from the factory, the BAP "hose nipple" had a cover over it that LOOKED like a plug, but it wasn't).  <shrug>
Placerville, California
(former)  '78 2.3T Courier w/blow-thru Autolite 2bbl carb ~ (current)  '87 2.3T Ranger w/PiMP’d EFI
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