f.p. sensor $

Kevin Powers · 08-09-2002, 05:37 AM

an individual i have been in contact with has stated that his fuel pressure sensor (74' 2.0) is bad and needs to be replaced. his mechanic told him it would be $500 !. he then contacted a parts supplier and was informed the part was over $1000 !!!. does this sound right? are these parts made out of platinum or something? is it a rebuildable or fixable part ? input appreciated.

kevin

Will98D · 08-09-2002, 06:10 AM

From the PP catalog, it looks like the D-Jet fuel pressure sensor is $595, and the fuel pressure regulator is $41.10

Hope the guy is right in his diagnosis at that cost!

JWest · 08-09-2002, 06:25 AM

I might be leary of a mechanic who called it a "fuel" pressure sensor. If he does not know that it is an "air" pressure sensor, then how can he properly diagnose it as the cause of the problem?

Will98D · 08-09-2002, 07:48 AM

i want to echo the post above by J Adams... I knew it was a manifold pressure sensor but went ahead and typed fuel... anyhow, it's expensive so I hope the guy gets a second opinion.

norustscott · norustscott's Garage

I have found that price fluctuate wildly on this Item...Purchased a new unit for $275 about a year ago....It is not the one year only 1973 unit...but in works. I think Brad Andersons site has all of teh part numbers plus every thing else you want to know about the MPS

anthony · 08-09-2002, 08:17 AM

Brad's page is at:

http://members.rennlist.com/pbanders/DJetParts.htm

The best price I could find on that part now is $550. Performance Prods sells refurbished units for a couple hundred but Brad says they aren't calibrated quite right. Your friend's best bet might be to make an appeal here or on rennlist and see if anyone has a good used unit for sale. They seem to go for $150-200. The next option would be to hunt one down at dismantler that specializes in Porsche parts. Brad's advice to me was that if I was going to keep the car for a long time I should probably buy a new unit to have on hand. He thinks $550 will seem cheap in a few years.

pbanders · pbanders's Garage

Yes, the price for a new manifold pressure sensor is about $500 . Personally, I suggest buying from Pelican as they sponsor this list and their prices are competitive. The list price from Bosch is about $1000. Given that these units are all in short supply and haven't been manufactured in years, I don't expect prices to come down in the future.

The other recourse is to buy a rebuilt pressure sensor. The only current rebuilder that I'm aware of is Bret Instruments, which sells only through distributors (e.g. Performance). I have spoken with the owner about their operation, and Hamid S. recently visited Bret and had a look at the operation.

Bret's rebuild procedure is as follows:

1. Remove case rivets and disassemble MPS
2. Replace full-load diaphragm with a diaphragm of their own design (different thickness and bellows configuration than OEM)
3. Replace aneroid cells with cells built for them by a local jobber (very similar in appearance, but made of stainless steel instead of bronze/brass)
4. Tap case for screws for reassembly
5. Reassemble full-load diaphragm assembly, using thick grease for a gasket sealant
6. Add thin circumferential O-ring for case vacuum seal and reassemble case
7. Calibrate part-load setting, transition setting, and full-load setting using a bench instrument of their own design, to a calibration derived from a "gold unit" (new OEM unit).

Hamid found out that Bret calibrates ALL sensors to the exact same calibration standard. From what we could tell by analyzing a rebuilt unit he supplied me, the calibration they use is roughly equivalent to the 1.7L 914 sensor (0 280 100 049). Bret is able to get away with this because virtually all MPS's have exactly the same part-load calibration setting. Most of the difference is in the setting of the of the full-load calibration, which has an interactive relationship with setting the transition calibration.

As a result of these differences in materials and calibrations, Bret rebuilts often exhibit a part-load to full-load "flat spot", most likely due to the higher stiffness of the full-load diaphragm. They also exhibit an off-idle "bog" which I believe is due to the initial friction at the pivot point and the stainless steel aneroid cells. They also are usually too lean at full-load for 2.0L motors, resulting in somewhat diminished maximum power.

My suggestion to all 914 owners is to bite the bullet and buy a new OEM unit, and to purchase any unmolested (non-rebuilt and non-adjusted, with the epoxy seal on the end intact) and vacuum-tight MPS of correct part number that they can lay their hands on. Once these things are gone, D-Jet will be living on borrowed time.

red-beard · red-beard's Garage

Manifold Pressure Sensor
C6010-12870 Bosch $1063.77 $541.18

First number is list, second is price.....Lowest I've found.

Personally, I'd pay the few extra bucks and buy it from the bird.

Sheesh. $200 difference for a calibration change.

James

Ron Meier · 08-09-2002, 09:57 AM

If you find a used one, hook it to a mighty vac and pull vac on it - if it holds for 15 secs it's supposed to be good.

Part numbers are:

0 280 100 043 (Bosch Number)
039 900 051 (VW/Porsche Number)

anthony · 08-09-2002, 09:59 AM

AFAIK, it should hold vacuum for several minutes not 15 seconds.

red-beard · red-beard's Garage

Wasn't there a "tongue test"? Where you suck on it and let it hang on your tongue? OK, OK, I know i'm gonna get greif on this one.....

but I am serious....Of course, I may have read it in Dr 914's book or some such voo-doo reference book.

Sounds likte there is a market to "adjust" MAP sensors from 1.7 to 2.0.

Question: Would the MAP sensor from another car work? I know that some Mercedes used D-jet. I don't have the Bosch book with me, but it had a list of FI model and what vehicles used them by year. I want to say Merkur used D-jet as well.

Brad - I agree about borrowed time, except that if we know the input/output response of the MAP sensor, we could build an analog or digital converter to make those signals from some modern, off the shelf model.

And there is always Megasquirt with it's built in MAP sensor.

James

Ron Meier · 08-09-2002, 12:00 PM

James:

You watched "Professor 914 - The baddest attitude in town" preform the "tongue test" in the murder capital of the world.

I thought since B & Brad write professionally, I would attempt to clean up my act and use tools instead of my normal barbaric methods. They didn't call me "Get a bigger hammer Meier" at the track for nothing.

pbanders · pbanders's Garage

Personally, I find the "tongue test" to be often misleading. A good MPS should hold 15 in. Hg of vacuum for at least 1 minute without dropping more than 1 in. Hg. Why any drop at all? Some of them weren't sealed so great in the first place. I've seen NOS OEM units out of the box that leaked at this level. The leakage is typically from the paper seal between the part-load stop plate and the body of the MPS.

Any more leakage than this spells problems. Most likely, a fatigue crack forming in the full-load diaphragm, signaling impending doom.

As for readjusting MPS's from 1.7L to 2.0L specs, it can be done, but to do it right requires a specialized setup and a calibration standard. Now, for the question I've been asked - can you do this? The answer is "yes", but I'm not currently geared up to do it as a business!! As they say in show business, "don't call us, we'll call you" - I'll let people know. BTW, Bret does not support doing calibrations, and they only calibrate to one standard, anyway.

Brad Roberts · 08-09-2002, 01:26 PM

I love these posts. Keep them coming.

We WILL have a laptop programmable system for 914's complete for under 800$ before the end of the year.

All GM sensors (from your local parts store)

New harness (Hey Jeff)

O2 sensor plus O2 bung.

The first test's have gone really well on a stock 2.0.

You wont have to change anything but external parts on your current car. Fuel pump/lines/ everything stays in place.

This system will run any 4cyl displacement you put under it.

B

pbanders · pbanders's Garage

Brad, sounds good. Does it use the D-Jet injectors?

pbanders · pbanders's Garage

James asked - can we use MPS's from other D-Jet applications?

Answer is, yes and no. The MPS's used on the 914 are what I call "short nose, w/full-load diaphragm". There were other types - e.g. the Type 3's used a "long nose" version (has a different coil spring, which changes the vacuum level where full-load behavior begins), the MB's didn't have the full-load diaphragm, etc.

There were also some minor differences in the length and size of the adjuster screws on the full-load diaphragm. If you have a unit that is physically similar, and you have the calibration equipment and the curve, the answer is a "yes, in most cases".

red-beard · red-beard's Garage

For calibration equipment, what do you suggest?I but I can come up with a decent vaccuum pump and pressure regulator. I have access to some calibrated pressure transmitters (0-30 PSI differential) and meters to read them. What I don't have is the curve showing what the MAP sensor should be doing and the signal it should be producing at what pressure.

James

Brad Roberts · 08-09-2002, 04:06 PM

Brad (Doctor, shake hands, Doctor)

The plan is too utilize whatever factory inejector the car had, whether that be L or D. We have tested with D jet injectors currently.

We are finding (others may have already found) that the factory used a decent injector in all the cars. They will support some more HP without causing the pentle (SP?) to hang open.

B

pbanders · pbanders's Garage

James - the calibration equipment needed is a tester that simulates the trigger contact points closing at various engine speeds. An ECU is fed this signal, along with standard resistance values for the air and head temp sensors at operating temperature, and various voltage and ground levels, and simulation of the throttle position sensor inputs. A constant engine speed is selected (I use 2500 rpm) and the pressure sensor is connected to a hand vacuum pump and a calibrated meter. The pressure is varied from 15 in. Hg down to 0 in. Hg, and at each 1 in. Hg increment, the injector pulse width is measured. The three adjustment screws on the MPS are adjusted to match the profile to that of a NOS OEM standard that has been previously profiled.

Brad - sounds good. It's "pintle", doc, whatever that means. D-Jet injectors are considerably "oversized", the 2.0 injectors are 25 lb/hr injectors. For some reason, they used a very low duty cycle - be careful, they may have reliability problems when used at modern duty cycle levels.

Also be aware that under cold-cold start conditions (less than 32 deg F. ) air cooled motors need LOTS of fuel - as much as a 4:1 mixture or richer. As a result, the injectors are open for a LONG time - almost the full cycle. In fact, I suspect that when the temp is low enough for them to be open 100% of the time during cranking, that's when the thermoswitch kicks on and starts the CSV. When you're setting up your replacement system, make sure you give enough fuel when cold or you'll have some "cranky" customers...

bowlsby · 08-09-2002, 06:14 PM

James, Check out Brad Anders website for details of the MPS ...thats MPS...not MAP....calibration. The special tool is an inductance meter. I have the meter and have done the recalibrations and it works well, but I want to focus on harnesses....which reminds me...

Brad - I need to see this new FI setup...Is Megasquirt any competition for it or does yours do better magic tricks...? The custom harness should not be a big deal if its similar to the stock ones...