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Discussion Starter · #1 ·
I have a 1994 ford e-350 yellow cube van (those sold by ryder), gasoline 8 cyl. 7.5L engine. About three months ago I was driving and suddenly notice lack of power. Pedal to the floor and only 30 mph.
To my surprise local Ford dealers declined service or any assistance stating that the truck is too old. Since I have visited 4 mechanics, no one have found a solution. So far they replaced the cath, the computer and the ignition, did a light timing test (ok) and fuel pump flow test (ok). They all stated that the transmission seems ok too.
Yesterday a friend run a spx scanner test, found errors 538 and 632. I found error 538 to be CID Circuit failure which I thought was going to be the solution but I was directed to this forum by Cuda_Jim who stated:

"Your friend didn't perform the test correctly.
538 = Dynamic throttle Response test not complete (slam throttle to the floor)
632 = move the gear shift from Park to drive and back to park again.
They can be ignored and have nothing to do with your problem."

So I'm back to square one.

Any hint's on this lack of power issue? By the way the MPH meter goes wild (jumping up and down)

Thanks

J
 

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The speedo jumping can confuse the trans, get it fixed first.
The speedometer gets it's signal from a sensor located on the top of the rear differential housing, remove it and clean off the debris. Instal and check.
If this doesn't work you may need a new sensor. It's called A RABS (Rear Antilock Brake Sensor). If you ask for a VSS (Vehicle Speed Sensor) you'll get the wrong part.

Not sure how sophisticated your friends scanner is, you might need to have a pro scan it. After all, He didn't know about the things that need to be done during the test so I'm guessing he's not very knowledgeable with Fords.

When was the last tune up?
Has a compression test been done?
 

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Discussion Starter · #3 ·
Thanks Jim.

Again, I am not a mechanic but I know one of them did a compression test of some sort, but from what I understood it was to check fuel flow. I will look for the RABS, a few months ago the truck was giving an ABS warning which disappeared, and this could be a culprit. My scanner friend, you may be right, he was trying to be helpful but I don't think Ford is his thing, the sad part again is that no Ford dealer want to look at this because of the truck age and I'm in Puerto Rico, not many Ford dealers to go!

Last tune up was about six months ago, the truck is used for TV broadcast, it does not run much, less than 1k miles in that timeframe.

Will look for the RABS and post the results.

J
 

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You can pull codes without a scanner.

http://www.fordforumsonline.com/for...ll-diagnostic-codes-obd-1-pre-1996-fords.html

I agree with Cuda, that with the speedo jumping all around that it may be due to a faulty VSS/RABS sensor that is mounted on the top of the rear diff.

Your trans is computer controlled. Another sensor that the PCM uses to set shift points is the Throttle position sensor. A properly performed diagnostic codes self test should let you know if the TPS is faulty.
 

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Discussion Starter · #5 ·
Still no solution

Hi again.

After some frustating weeks waiting for a a mechanic I decided to go FYS. I changed both the RABS and the TPS, still pedal to the floor and lack of power. Trasmition shifts well but you can't hardly reach 35 mph. I was asked to ask if you guys think this could be related to the Knock sensor?

Thankfull;

Javier
 

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don't mean to get off track, but jim, you said the speedo gear is in the diff. i always thought it was in the tail of the trans...
 

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I have to agree with Jonzo.The speed sensor is located in the transmission tail shaft housing.The RABS sensor has nothing to do with vehicle speed except for the RABS.
Secondly the transmission is controlled by a TCM,which gets some inputs from the PCM.Trans codes are stored in the TCM and without a NGS tester your not going to see them.

I would agree with Jims diag of a bad vehicle speed sensor,but not the part he described.
 

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Gentlemen:
In 1992 Ford stopped putting the VSS in the trans, and made the RABS in the rear diff do double duty. It serves as both the RABS sensor, AND the VSS.
 

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I missed this part in the original post
"yellow cube van"
If this is a dually then it has a D60 rear end, the VSS will be in the trans.
 

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Thank you for the confirmation Jim.
 

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My '99 motor home is a dually with the RABS and VSS one in the same and is located in the rear.
 

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I didn't see anyone mention checking the fuel filter . Was this checked? Will the engine go to top RPM in park? If it doesn't sounds like a plugged converter.
 

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Discussion Starter · #13 ·
Fuel filter was checked, fuel flow as well, catalytic replaced, Rabs replaced, Tsp replaced, computer overhauled, timing light check done and was ok. Still wanting to know if this could be related to the Knock sensor.

Thanks

J
 

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It might be the Knock Sensor (KS). You can duplicate engine knock by sharply striking the block/head with a hammer while monitoring the timing with a light. The timing will retard.
Hook it up to a scanner that is capable of monitoring sensor PIDs..... watch the timing while attempting to drive it to repeat the symptoms.
 

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Having worked for Ryder, in different capacities, many moons ago, I recall their vehicles had speed govenors on them . They were located under the dash. Find someone familiar with that part and you may solve your problem. Wish I could be more help! Hank
 
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