Scorpio engine help needed, please...

Scorpio / Scorpio Cosworth Discussions - Questions, problem resolution, general talk, technical tips and modifications.
Joe62Tampa
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Re: Scorpio engine help needed, please...

Post by Joe62Tampa » Sat Aug 24, 2013 8:27 pm

I had running problems on my XR4Ti under a high load. I did a number of things, some were mis-diagnosed such as

I had running problems on my XR4Ti under a high load. There were several things that (probably) additively contributed to that problem; however, your Scorpio's fuel pressure at the rail behaves the same as how it did on my car. Once I changed the fuel pressure regulator, the pressure at the rail held as specified by the shop manual. (The typically written "smells like gas" when pulling the vacuum line isn't sufficient. Although that indicates a failed FPR, it seems it can fail in other ways.)

I don't know all of the Scorpio's working mechanisms... just a shot, better than the effort to drop the fuel tank.

Up to that point, as a side note, I had:
- I dropped the fuel tank to replace the fuel pump. Coincidentally it was dead -- pure luck. (The steps to check for it being dead are almost as much work as just completing the job itself.)
- The ignition coil was changed. It was the primary or secondary resistance that was well out of specification.
- While I was at it, I cleaned the injectors - who knows after 25 years. (In my case, I replaced them as cleaning was not much less than finding new ones.)


My two-cents :-)

Good luck!
... more so, best wishes to your wife that she's on the mend or back on her feet.
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

caleyfan
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Re: Scorpio engine help needed, please...

Post by caleyfan » Sat Aug 31, 2013 8:16 pm

Thanks for the tip Joe62.
Based on your info I removed the inlet line from the rail and checked the fuel delivery pressure at that point. It still showed around 7psi. I also checked the flow rate and got about 16 fl oz in 1 minute which is way too low.
So, I dropped the tank and removed the pump and sender unit. It all looked good, no damage or blockages. I dismantled the unit and checked the pump performance on its own and got a reading of about 63psi. The pressure did hold when I shut the pump down. I checked the flow rate and got about 1 litre in about 40 seconds which is well within spec.

Now I'm really confused. I checked the fuel line from the pump to the rail and it all looks good. No damage and no blockages. I was able to blow the line out with just 5psi.

Unless I cleared / inadvertently fixed something when I disassembled it this does not make any sense.

I will reassemble the pump / sender unit and reinstall into the tank on Monday and see what happens.

I'll keep everyone posted and would be grateful for any more advice.

Ed Lijewski
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Re: Scorpio engine help needed, please...

Post by Ed Lijewski » Sun Sep 01, 2013 8:48 am

Puzzling. I wonder if the pump is getting less than 12 volts...XRs are infamous for issues with the fuel pump fuse/relay connections but not so much for Scorpios. Still worth checking.

YMMV ;-)
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caleyfan
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Re: Scorpio engine help needed, please...

Post by caleyfan » Sun Sep 01, 2013 10:21 am

Thanks Ed.
My next step was going to be to check the power supply to the pump. I noted the spec on the pump states a supply between 7 and 12 volts is required so I will check that as well as the current being supplied to the pump. If I find an issue with either voltage or current I will take a look at the relay first. Thanks.

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Re: Scorpio engine help needed, please...

Post by caleyfan » Sun Sep 08, 2013 7:31 pm

I think I have fixed the problem. I found two issues that would contribute to the engine issues.

When I checked the output from the fuel pump I dismantled the sender assembly and removed the outlet fitting from the top of the pump.
When I checked the output directly from the pump everything was good as I reported previously. However, when I reassembled the outlet fitting onto the pump today I noticed the seal was not as good as it should be. There is a small O ring seal between the pump and the outlet fitting and it was fairly brittle. When I blew back into the outlet fitting there was a small air leak before the non return valve in the pump. Problem #1. I replaced the O ring and the seal was nice and tight with no air leak. I thought this was the cure until I found another problem.

Before reassembling the pump / sender unit I pressure checked the rubber tubing that connects the pump outlet fitting to the sender outlet pipe. When I did this I exposed a crack in the hose that allowed a significant amount of fluid to leak out. Problem #2. I replaced the hose, reassembled the sender unit and then checked the operation of the unit and it delivered over 50psi.

The leak on the pump outlet fitting and the crack in the hose would have both contributed to the poor flow rate, poor delivery pressure and since they were both just before the non return valve they both allowed the line pressure to drop immediately the pump was shut off.

I reassembled the sender unit to the tank, connected the lines and success! The engine now runs like a champ.

Thanks to everyone who chipped in with advice. It is great to know you have so much support when trying to fix these issues and I hope my experience will benefit someone else in the future.

I'm sure I'll be back with other troubles in the coming weeks!

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In XS 7
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Re: Scorpio engine help needed, please...

Post by In XS 7 » Sun Sep 08, 2013 8:20 pm

:thumb Good to hear that everything is fixed, :cheers
Miguel.
89 XR4Ti Monique; Waking up a real "Night/Mare-Coor".
T5, NPR IC, PIMP ECU, Walbro 255, Dual piston BOV, Manual BC, 3" exhaust, One piece Aluminum drive-shaft, mc2 LSD, Boport 1.5 cam, Ported and polish head, big valves, 80# injectors, Bob's log, (soon HY35).

Ed Lijewski
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Re: Scorpio engine help needed, please...

Post by Ed Lijewski » Mon Sep 09, 2013 7:28 am

A salute and tribute to reasoned, rational, open-minded and persistent problem solving. :headbang :notworthy :cheers

I don't recall anyone ever reporting on finding and resolving those specific issues before; definitely trail blazing sleuthing there.

YMMV ;-)
Descartes: "Cogito Ergo Sum"
Lijewski: "Sum Ergo Drive-O. Mucho!

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MerkurRS
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Re: Scorpio engine help needed, please...

Post by MerkurRS » Sat May 14, 2016 1:41 am

Ed, I am going to follow some of your troubleshooting tips here....

The 88 Scorpio I just picked up starts if I give the throttle a tap (not normal) and will idle - albeit high at about 1000 rpms. If I press on the throttle more, it wants to die unless I get it above 2000 rpms , it will run.

I did drain the fuel out- fresh stuff in there now- runs about the same honestly.
Next I will check timing, pull the plugs, replace wires (newer, longer, blue'r wires look like crap). I didn't find a vacuum leak, but I won't rule that out yet.
2012 Audi S4 Prestige, Black-Optics, APR tuned - runs low-11's
1989 Scorpio-White, a/t- a true survivor car!
1988 Scorpio - Burgundy, a/t- a low mileage survivor!
2004 VW Passat Sedan -W8 6-Speed
2003 VW Passat Variant W8 Auto
1970 Ford XL 390 ci. Convertible
1970 Ford XL 429-4v Convertible
2000 Excursion V10

Ed Lijewski
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Re: Scorpio engine help needed, please...

Post by Ed Lijewski » Sat May 14, 2016 6:20 am

You might consider working your hand vacuum pump On/Off on the EGR valve in case it's stuck open (with a few light hammer raps on it as well).

YMMV ;)
Descartes: "Cogito Ergo Sum"
Lijewski: "Sum Ergo Drive-O. Mucho!

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MerkurRS
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Re: Scorpio engine help needed, please...

Post by MerkurRS » Sun May 15, 2016 9:04 am

After many hours of troubleshooting- it appears as if it is something related to either the Idle Air Control Valve or Throttle Position Sensor?

Running and warm, the idle is almost 2,000 rpms and it wants to stall upon acceleration.
When I disconnect it, the idle drops fine and it accelerates ok.
When I use my old-fashioned EEV IV tester and it goes through the tests, the idle drops to an acceptable level and everything is fine.
I checked grounds, resistance between pin 21 and the IAC plug and everything seems ok.
EGR works.
I cleaned the throttle body.

I can clear the codes in the EEC with the STAR tester and then the car starts and idles fine...until I press the gas petal. Then the idle jumps up again to 2,000 rpm's all over again. I did replace the TPS for good measure. I know the IAC is OK because I swapped it with my other car that runs fine.

Maybe it is the EEC?
It's strange that it works under test mode, once codes are cleared, but not running.

Suggestions anyone??
Last edited by MerkurRS on Sun May 15, 2016 12:00 pm, edited 1 time in total.
2012 Audi S4 Prestige, Black-Optics, APR tuned - runs low-11's
1989 Scorpio-White, a/t- a true survivor car!
1988 Scorpio - Burgundy, a/t- a low mileage survivor!
2004 VW Passat Sedan -W8 6-Speed
2003 VW Passat Variant W8 Auto
1970 Ford XL 390 ci. Convertible
1970 Ford XL 429-4v Convertible
2000 Excursion V10

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Bob Weir
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Re: Scorpio engine help needed, please...

Post by Bob Weir » Sun May 15, 2016 9:41 am

Hi Saul,

Two thoughts for you:
Wiring harness go here >
viewtopic.php?f=29&t=27563&p=255255&hil ... or#p255255

EEC
Easy to swap for test and then take apart and see if it has a burned connection on the circuit board.

My Scorpio had both these situations.

Ed Lijewski
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Re: Scorpio engine help needed, please...

Post by Ed Lijewski » Sun May 15, 2016 11:19 am

Identify the pin for the IAC from the wiring diagram; disconnect ECU frim harness and inspect pin and connection. No guarantee that will cure it...

YMMV ;)
Descartes: "Cogito Ergo Sum"
Lijewski: "Sum Ergo Drive-O. Mucho!

Ed Lijewski
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Re: Scorpio engine help needed, please...

Post by Ed Lijewski » Mon May 16, 2016 7:45 am

This issue somewhat parallels the infamous random Scorpio high idle gremlin. I fought it.

It seemed possibky related to three things (none involving the IASC or TB: distributor shaft wear, ECU internal issue, battery negative post ground to battery tray. I switched ECUs (instslled a GH6 or some number like that, can't recall ATM) and distributors, but what may have been the problem was a defective negative post-to-battery tray/body ground (long story for Carlisle).. I installed a 6 gauge cable connected from the negative post to the super-cleaned existing ground point of the battery tray.

Even if you want to keep everything OEM for the future, you might try that as an experiment.

YMMV ;)
Descartes: "Cogito Ergo Sum"
Lijewski: "Sum Ergo Drive-O. Mucho!

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