OK, this is a restart of a thread I started 2 years ago and is now archived. Why? Well, to make a long story short I used to host my own photos and due to being a total retard I forgot to renew my domain name and lost it...and all the pictures too. Hence, there is no record in the archives of my EHPS thread with photos. To preserve it for postarity and to update the thread with newly discovered info I am letting fiero.com host the pics for this thread. My apology to Cliff for the bandwidth feeding frenzy

Some of you may or may not know that I came into possession of an original EHPS set-up for a 1988 Pontiac Fiero. These things are as rare as hens teeth and I felt it appropriate to start a thread about the technical aspects of this unit for the education and entertainment of all PFFers. To begin with, I first removed what is called the "Hanger"



If you own a 1988 Fiero you will note a variety of features on your car that were designed for the potential installation of Power Steering. The most obvious of these, to anyone who has opened the front hood, is the two holes in the upper splash shield just behind your lug wrench. The holes are plugged with two blanking caps. It is through here that the "Hanger" is mounted using two 6Mx1 bolts with a 10mm wrench.

The hanger itself is mounted to the PS reservoir with (2) 6Mx1 bolts using dished retaining washers on the back side and (2) standard 6M washers with Flanged nuts on the front. The hanger has two built-in rubber washers on the front side against which the reservoir mounts. This is undoubtedly designed to reduce the possibility of cracking the reservoir from body flex and vibration. I expect it also reduces the transfer of vibrations to the chassis. The only markings on this hanger are a date code "03 27 87". I also note the use of blue Locktite for the two mounting screws.

The Reservoir itself is a composite material. It appears to be similar to standard polypropylene but with a fine fiber as part of the blend. There is no stamp indicating composition or even a part number. The thing is clean! The rumor mill says the part number is 26000889 but I can not confirm that. The cap is a real signature piece with the words" USE ELECTRO HYDRAULIC STEERING FlUID ONLY" emblazened across the top. The manual recommends the use of Fluid with part number 9985567 but a hand written note in the margins states that GM 12345348 or Texaco 15 Aircraft hydraulic fluid will work too.







The Reservoir is mounted THROUGH the mounting bracket to the hanger. The mounting bracket is a single peice of stamped steel with the letters "GH" stamped on the back side and a single sticker on the top with the numbers "7849457" and "3287GM / A1". This is a solid bracket weighing in at 2 pounds.





The complete unit looks like this:



I'll be going over the EHPS unit first and then I will do a break down of the rack and actually install it on a 1988 Front-end I have on a dolly.

This is how the unit goes together.



The reservoir is connected to the electric pump with a 5/8th inch hose. The writing on the hose reads "KV 61 446 5/8 PS RESERVOIR B 01 15 87"

It is held in place with crimp clamps (similar to the ones you see on axles). Since I do not want to destroy this unit I elected to leave these as is and not try to remove the hose from either end.

The Motor assembly is very interesting. Together with the reservior and hose the whole unit weighs 6 lbs and 6 oz. There is a sticker on the side with the number "50459503167" and a date code of "11 2 87". This is especially telling since the rest of the EHPS parts were made as early as January 1987 but the motor is dated 2 and a half months into the 1988 production year. GM MAY have been having trouble with the Controller or Motor and needed to modify it before the planned mid-year introduction. There is also a number etched into the bottom of the housing with a Dremel tool reading "251173". I can't even speculate the significance of this number but someone went to some trouble to put it there. The pump is mounted to the Bracket with (4) m5x.08 screws with a 8mm hex head socket.



I'll do the Controller next.

WOW! This is amazing. It's like opening the lost Arc.



It opened very easily. The screws appear to be T-27 Torx screws with coarse threads. the back half of the controller is plastic and the front is a giant aluminum heat sink. The inerds have a very......80's look about them. Look at those Capaciters! The whole thing is encased in a soft gelatinous rubber-like goo. I resist removing since I do not want to destroy this but I can just barely make out several part numbers under the goo and if I had a schematic I could easily replicate this thing. There really is not much to it. Although, there does appear to be at least one proprietary microchip. I'm sure it can easily be replaced today with something else but the firmware is a mystery.



The controler has a 2-pin plug for the power input and ground and a 4-pin plug for the VSS input and current regulator.



The whole thing is connected to the pump with 3 "knife-blade" like tabs in a large plug. Very heavy duty!

I'll start a parts list next:

Here is a Schematic I have (thanks to Carbon for the parts identifications).



Other interesting items from the manual include an EHPS tester! Part number J-37094. This plugs into the 2 and 4 wire plugs to check all 6 lines. it has a ammeter and 6 diodes for diags, ignition, signal ground, vss, power b+, and power ground. I wonder if any of these suckers still exist. They also have a vss signal generator part number J-33431-B and an adapter cable J-37094-1 for the EHPS.

Based on diagrams I have been able to determine the wiring as follows:

The controller has one 2-wire plug and one 4-wire plug:

2-Wire Plug (S250):
A) Power Ground
B) Link X (fusable link directly to the power distribution block in the engine compartment)

4-wire Plug (S251):
A) Diagnostic
B) Fan E (that's the radiator Fan wire E)
C) Signal Ground
D) VSS input (this comes from the dashboard through pin G7 of plug C-100)


Also, the current to the motor is pulsed at 20 kilohertz, where the mixture control solenoid rate is 10 hertz. So the VSS controls the duty cycle in the same way an Oxygen sensor controls the CCC system of the mixture control solenoid.

Here is more:



Pump pics. It is pretty simple actually. A standard armature and shaft attached to a set of vanes. The whole thing is spring loaded and held in place by a large snap ring at the bottom of the pump.





OK, that's it for now. I will add more data later.

[This message has been edited by Toddster (edited 05-27-2007).]

Thanks for bringing this thread back to life...this should definitely be added to the "Builds" main section, once it is created.

quote Originally posted by jscott1: Thanks for bringing this thread back to life...this should definitely be added to the "Builds" main section, once it is created.

Yep, this thred is Fiero Tech history and needs to be archived with docs and pics intact. I'd have done it sooner but work has been dogging me lately.

Anyway, here is the memo that talks about the production test run:

how did you acquire this?

quote Originally posted by Hurricane: how did you acquire this?

I got on ebay beleive it or not. Dumb luck. I got up on a Sunday Morning, made some coffee, wandered into the office and decided, hey, I wonder what's on ebay (something I hardly EVER do). 30 minutes earlier this guy from Michigan who aquired this from an engineer at Pontiac had just listed it with a 'buy it now' option for $1250. I couldn't believe my eyes. I was looking at it like, "wait a minute, that can't be what I think it is". I read the auction 3 or 4 times and said "DAMN, this is going to be gone if I don't get it now."

Even after I bought it I wasn't sure it was real. I thought I might be getting scammed but I was willing to take the chance. When it showed-up I was delightfully relieved to discover that it was the real mccoy.

I've been doing research on EHPS ever since. I am trying to identify the 14 cars in the previous memo.

As for identifying the first Fieros to be equipped with EHPS I am trying to find the VIN code range that would include the N41 RPO code. The first of these cars would have been built during the week of Monday November 30, 1987 thru decision time per the letter above of of Friday December 11, 1987 of the following week. So far, the last car made with an 11/87 build date that I have been able to identify for certain is a Black Formula VIN 210379 and the earliest 12/87 build code vehicle is a Yellow Formula VIN 210612.

Hence, Since the scheduled run was set for Tuesday December 1, 1987 and I suspect they built all 14 that day, the vehicles that might have the N41 RPO code will be between the range of about 10400 and 10700 (Assuming 100 cars per day production).

I have heard of a white 1988 coupe that had the N41 RPO code but have not been able to locate info on it. Still looking.

I have also heard of a yellow GT with the N41 option. The color range was 09926-10225 were white and 10526-10825 were yellow (black was in between)

It's possible that the tail end of the white was the test run or the beginning of the yellow. I find it odd for the two to be true and separated with black cars. The white coupe story seems to have more credibility however.

[This message has been edited by Toddster (edited 05-28-2007).]

As far as I know all 88s ended up with the same rack, was it the 19:1 or the more responsive 16:1?

quote Originally posted by jscott1: As far as I know all 88s ended up with the same rack, was it the 19:1 or the more responsive 16:1?

That's a point of discussion Jonathan. I am pretty sure the GT and Formula got a 16:1 manual rack but I can't be sure there are any 16:1 power racks out there. I will test my racks versus a manual rack in time, but for now I assume they are the 19:1 racks.

.

[This message has been edited by jscott1 (edited 05-31-2007).]

quote Originally posted by jscott1: Are you saying there are 88s out there with two different ratios? This has been debated many times, but I know my 88 coupe and 88 GT both have the same rack with 3.25 turns lock to lock. EDIT - well let me qualify, the rack on my 88 coupe was 3.25 turns lock to lock before it broke. I replaced it with an 88 GT rack and it's still 3.25 turns lock to lock.

Turn to lock is not a good measure because of different wheel and tire combos, alignment settings, how deep the tie rods are set, and where the bump stops are located.

I'll be able to answer that one better when I get the racks out and compare them. I have a Bone Stock Formula and a Bone Stock Coupe that I intend to do a thrust test on. In other words, I will measure the distance the tie rod extends with each 360 degree revolution of the steering wheel. That will tell me for sure if the gearing is different or not.

According to the documented evidence, there WERE two different racks issued. The government spec sheet specifically called out for a 16:1 and a 19:1 variant. Whether or not this actually happened in 1988 on the assembly line or not is what I hope to determine.

Well i know, maybe tread is host only to the Fiero PS .

But a elektro hydraulic pump system is used in the Mercedes A Class this pump is very tiny like a bottle of a 2 liter coke .
And need plus ,minus ,and generator signal .
I am in Germany and conversions on the mechnical system like PS are not realy allowed or you have to approve them by the TUV .
But this unit i think could be great thing to convert it for the fiero .

quote Originally posted by Torch-Red87: Well i know, maybe tread is host only to the Fiero PS . But a elektro hydraulic pump system is used in the Mercedes A Class this pump is very tiny like a bottle of a 2 liter coke . And need plus ,minus ,and generator signal . I am in Germany and conversions on the mechnical system like PS are not realy allowed or you have to approve them by the TUV . But this unit i think could be great thing to convert it for the fiero .

Interesting Idea. It sounds like the Mercedes part is about the same size as the Pontiac pump without the controller. So it should fit in the same general location. the question is whether or not the electronic VSS input can be used (unlikely) or what other signal device is required. then of course there is the rack issue.

That also looks like a possible option for people wanting to add power steering without an engine mounted pump.
I'm very interested in the electronics of the EHPS system. I plan to add a C4 Corvette steering rack to my Fiero, but haven't decided how I'll do the pump yet. I'm watching this for any ideas...

quote Originally posted by Toddster: Interesting Idea. It sounds like the Mercedes part is about the same size as the Pontiac pump without the controller. So it should fit in the same general location. the question is whether or not the electronic VSS input can be used (unlikely) or what other signal device is required. then of course there is the rack issue.

THE CLOU IS YOU DONT NEED A VSS SIGNAL .ONLY KABELS +, - , and charging signal from the generator .............easy
10 years of working with mercedes cars ......

The Mini Cooper and Cooper S, at least up to the 2006 MY, uses electro hydraulic power steering. Being a similar weight and size, might be useful. I haven't had a chance to look at the newest Mini though.

quote Originally posted by S8N: The Mini Cooper and Cooper S, at least up to the 2006 MY, uses electro hydraulic power steering. Being a similar weight and size, might be useful. I haven't had a chance to look at the newest Mini though.

Look into it. There anen't that many good options for power steering in a Fiero. I've got the only two complete systems I know of and I am not selling them any time soon.

Anyway, Here is a cut-away image of how the system installs in the Fiero. I got this from Gary Witzenburg's book:




I got issues with the "never produced" comment

[This message has been edited by Toddster (edited 05-31-2007).]

quote Originally posted by Toddster: I got issues with the "never produced" comment

Well if produced means a saleable product...they never quite got there.

quote Originally posted by jscott1: Well if produced means a saleable product...they never quite got there.

true, I'm actually surprised at the price. I would think it would cost more. But then again that was 1988.

bump to keep it alive while I gather more info

Any luck tracking down the remaining VIN #s? I'm going to go look at my 88 just for fun to see those two mounting holes.

------------------
If you can't be good, be good at it.

i think i know where there is a yellow 88 gt with ephs. it is an old gm pilot vehicle i think. there is not much left but this past summer i looked at it and i beleive it still had the rack and ephs set up, let me know if you are interested i might be able to hook you up as i know the owner of the yard.

How much for the rack???

I doubt that I'd buy it, but I'd like to see it....Especially if it's local.

Bob

Tounge in cheek : We should send this off to china and have them make an exact copy of the whole kit for us. If their latest products (Iphone clone) are an indication of quality to come, it might even be better than Pontiac's original unit. (again, I'm not completely serious :dreaming

quote Originally posted by Austrian Import: Once you install the unit, could you mockup where the spare tire tub would go? I have a hard time visualizing where the unit would go (so it doesn't interfere with anything since there is so little room up front.)

The entire unit is on one bracket and it hangs on the front of the tire tub. On 88's the factory punched out holes to mount the unit. The filled the holes with plastic pop in plugs. They are on the driver side. The Fluid reservoir sits next to the driver side head light assembly. It does not go in the tire tub. It goes in front of the tub close to the radiator.

quote Originally posted by jweisman: How much for the rack???

How much ya got?
http://cgi.ebay.com/ebaymot...QQrdZ1QQcmdZViewItem

Is anybody actually using an EHPS on their daily driver or even a weekender?

quote Originally posted by Fieroeddie: Is anybody actually using an EHPS on their daily driver or even a weekender?

Not to my knowledge. I did hear a rumor that one guy from the Space Coast Fiero Club bought one once but no pictures or details have ever been released so I think it's BS.

quote Originally posted by Toddster: How much ya got? http://cgi.ebay.com/ebaymot...QQrdZ1QQcmdZViewItem

I don't have that much the rack would be the only thing I would want

would it even be economically possible to attempt to reverse engineer the brunt of it? maybe combine it with some over the counter parts?

quote Originally posted by KaijuSenso: would it even be economically possible to attempt to reverse engineer the brunt of it? maybe combine it with some over the counter parts?

It would not be that hard. The Rack only needs a new custom hat and most of the other parts are easily replicated or used from a stock 88 rack. The controller is easy too. Just a plain circuit board with readily available parts, the pump would be the hard part but if there is a suitable replacement pump on the market that meets the same performance specs it could be substituted.

The 88 Fiero already has the rest of what you need including the VSS input to the intrument cluster, the mounting holes on the chassis, and the forward wiring harness pin outs.

quote Originally posted by Toddster: It would not be that hard.

Well it must be harder than it seems, because no one has made one for sale. Build it and they will come.

OK, I sold one of my EHPS units to Rick Truesdale. If the name sounds familiar you will find him in the latest issue of Pontiac Enthusiast Magazine. He has the yellow Fiero they featured. He is going to do some more research and writing about it. Expect him to pay a visit here. I expect he will add to the sphere of knowledge we all have on these units with his many contacts.

Hi everyone and Happy New Year to everyone, Rich TRUESDELL here.

As Todd explained, I bought one of his power steering units and I will be doing a story on it in an upcoming issue of Pontiac Enthusiast. Because Pontiac Enthusiast is bi-monthly I can't imagine that it will appear before the summer. In the meantime I want to research the project taking advantage of some contacts I have at GM.

If anyone has any information to share, especially if you worked on the Fiero program and can shed light on the power steering program, I invite you to contact me at autotronic@aol.com.

I have a very nice 4-cylinder, white base model 1988 Fiero that I am considering installing the unit I now have. I would prefer to install it in one of the 14 cars which Todd believes the system was originally installed. To do this, I need your help. I closely monitor every 1988 Fiero sold on eBay and on some Craigslist forums. If any of you see any 1988 Fieros for sale locally, can you contact the seller to see if the label on the top of the driver's side inner fender has the required N41 code? If you do find such a car, please contact me immediately, there's a $100 finder's fee involved. While I don't have a problem installing the unit in my 1988 Fiero, but if I go through the effort to do so, I'd prefer to do it in one of the original N41 cars. Todd's VIN research and the fact that the cars were probably white coupes or yellow GTs will narrow things down a bit.

If any of you can share any additional information on my 1984 International Research Motorsports Fiero, I would welcome the opportunity to talk with you. Kerry Atwell, who oens one of the cars has contacted me and I wouldn't mind starting a registry of the surviving cars. I am also looking for the large trunk insert so if someone has one that they're not using, please contact me at autotronic@aol.com.

I'd like to make a shameless plug here for my own magazine, Automotive Traveler. The first issue, which can be viewed at:

http://www.automotivetravel...0&mode=3&vol=1&iss=1

There is a story on my IRM Fiero on page 97.

I hope that you like what you see in issue one and will register for a free subscription which gives you full web site access and all four archived issues. The link can be found at:

http://www.automotivetravel...filer&task=registers

I am planning a Fiero driving adventure for this summer involving multiple Fieros, one from each year so keep your eyes open here for more details.

Time to get bak to work, have to get prepared for the Consumer Electronics Show this week and the Detroit Auto Show next week when I hope to talk to my contacts at GM and dig a little deeper into the EHPS.

Best wishes,

Richard Truesdell
Editorial Director, Automotive Traveler
Contributing Editor, Pontiac Enthusiast

Welcome to Pennocks Rick!

BTW, loved the Fiero article in the last PE. Keep up the good work.

Last of the EHPS units is now for sale on eBay

http://cgi.ebay.com/ebaymot...1QQitemZ170267996921

wow... free shipping!

I'm all heart.

Reading through this thread, I went out to check my 88 Yellow GT to see about the RPO codes. However, they are too badly faded to read. Is there a way to find out what the RPO codes for a VIN are? 1G2PG1192JP214000 12/87 production date.