I bought a fuel injected 2.0L with all the goodies. The ecu was found to not be sending power to the fuel pump so we put an ecu from a 1.7 in it and - bam - power to fuel pump. We then noticed a engine surging problem at idle and put in an mps from a 1.7 and surging problem went away. What problems can this set up cause??
Jim

It will be certainly running too lean all the way, maybe more in the top RPMs, even if you bump the fuel pressure I don't think it will compensate. Running lean is playing with fire I heard.

Edit: I think your best solution, timewise and money wise is to find a good used ECU which shouldn't be too bad since they usually don't break.

And have the good MPS calibrated by Jeff or Bleyseng to the proper specs.

worst case would be it would run too lean and burn a piston.....

do you have access to an air/fuel ratio monitor??

just monitor the plugs and possibly increase the fuel pressure if you have problems....

congrats on having a running car

Lean? A 1.7 MPS would be used to seeing less suction than a 2.0 puts out, right? And in the highter RPMS when the TB is open the MP will increase towards atmiospheric which would be the same for both cars, I would suspect. Doesn't the MPS go to full rich when the hose is disconnected/ reading atmospheric? The FI brains for the cars are not an issue if you are using the 2.0 injectors on the 2.0 engine. I would actually suspect a slightly rich running condition, but YMMV. Am I thinking wrong?

Absoleutely monitor your plugs, though. Its easy and tells you a lot.

Check Brad Ander's site for more info.
http://members.rennlist.com/pbanders/

QUOTE (Dr Evil @ Aug 5 2005, 08:59 AM)

The FI brains for the cars are not an issue if you are using the 2.0 injectors on the 2.0 engine. I would actually suspect a slightly rich running condition, but YMMV. Am I thinking wrong? Absoleutely monitor your plugs, though. Its easy and tells you a lot. Check Brad Ander's site for more info. http://members.rennlist.com/pbanders/

Well if there would of been no issue I think Porsche would of skipped the resistor on the 73 2.0 which used the same ECU as the 1.7

though have a good read of Brad Ander's site and monitor that sucker.

You are fine at idle because the MPS settings are the same as the 2.0l.
Partload (crusing) will be lean and WOT is much leaner so running hot or worse case you could hole a piston.

Find the right ECU (74-76) and the right MPS(043) to match up to your set up.

74 thru 76 ecu will work - or just 75 or 76 ecu?

Can you recal my 1.7 mps - it say 030 on the side I thought?

Jim

1974-76 ECU's all take the 043 MPS and interchange.
I can recalibrate your 1.7L MPS to a 2.0l with a little trouble. (ie I take it all apart to recalibrate it to a 043) It does cost money to do this thou.

Is this correct??

Why $100 if good parts are supplied but $50 otherwise - a typo I suppose.

Email me at jim.j.kelly@airbus.com if you have a chance as I am at work.

Ok, here is my two-bit 914 home operation....

Repair and recalibration of MPS's. I repair MPS's and recalibrate them to 037 and 043 spec when I have stock or I can rebuild your 2.0L MPS with a good donor diaphram from YOUR 1.7 MPS.
Cost is $50 to calibrate your good MPS, $100 if you supply the good parts
Cost is $200 for a rebuilt 037 or 043 MPS (out of stock right now)
shipping is extra
Located in Seattle, WA

Email me for details