D-jet MPS plug & schematics& help, oh my!

[sean_V8_914]

I seek guidance from the wise ones. My 1.7 D-Jet car runs smooth, (used to be a 1.8L-Jet till the rings let go) starts right up, idles nice, does not seem to get too hot, but...woof woof , what a dog (compared to 1.8 L-Jet) My questions are: Is this right? which way does the MPS plug go in?(I think it runs the same both ways) Engine components config is 1973

[sean_V8_914]

I remember seeing a web site with all the schematics, plugs and pin numbers. Anyone remember who's fine site that was/ is? .I think I remember that they were hand schetches

[Howard H]

Sean:

While I don't know the website that you're refering to, I can't think of a more comprehensive source of info on the care and feeding of an MPS than the one Brad Anders set up on Rennlist.

Here's the URL. Hope it is of some help.

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

Best of luck,
Howard

[sean_V8_914]

very good site indeed, thanks. however, I did not find info on which way the plug goes in the hole on teh MPS.

[bowlsby]

Sean, the MPS connector goes in either way...It does not matter.

The two outer and two innner poles each serve a separate coil, so the plug can be reversed without affecting anything.

[Bleyseng]

Is it a Calif 73 1.7L @ 72 hp or a US 1.7L @ 80hp spec?.. That would explain why its a dog compared to the 76hp 1.8L.
Bump up the compression!


Geoff

[sean_V8_914]

thanks. I tried the plug both ways but i allways like to know why something works or...
US or CA spec....how can I tell. Is compression the main difference? I put it together with spare parts, using Brads site as a refference to select FI parts. The long block was allready together. I had to come up with an engine, ASAP!!! Ya see, there is a little story about dealing with Police and tow trucks that explains why a 1.7 now lives in my 1.8 car

[red-beard]

Can you post the engine serial number?

[Dave at Pelican Parts]

Why the plug can go in both ways:

There are two coils inside the MPS. The "reading" off of it has to do with the inductance between the one and the other.

One coil goes from the left-outer pin of the plug to the right-outer pin of the plug. The other coil goes from the left-inner pin of the plug to the right-inner pin. So either way you go, you are hooking up the two outer wires to the one coil, and the two inner wires to the other coil. There is nothing "directional" about current flow through either coil, so this works just fine.

--DD

[sean_V8_914]

thanks Dave
James: I'm writing the police story for a post. working title is "Police provided encouragement & motivation" when I finish, I'll go get the engine number. I am so happy I have my 914 driving again! I think I want to put a big bore kit on the 1.8 since the bottom end is still tight....or maybe, I have a 78 bus 2.0 with the 1.8 914 heads(bigger valves) I might try it with the L-Jet. I like L-Jet now

[red-beard]

How are the heads on the 1.8?

James

[red-beard]

OH! and now you have NO EXCUSE for not coming to Baja!

Don't worry about the 1.7 engine. Both of the sphinchter clenching, passenger puking, twisty curvy roads are down hill!

James

[sean_V8_914]

Baja II, I'm there! Sue loves rollercoasters and Mt Palomar rd in a 914. My 1.8 heads are nice, mild port job on em. the porting really perked up my 1.8. I've been told they should do OK on a 2.0

[red-beard]

If you put the 96mm kit on the 1.8, you'll have almost a 2.0. That, and using higher compression ratio pistons should get you up higher than a stock 2.0.

From my understanding, you can continue using the L-jet.

James

[sean_V8_914]

are you saying that a 1.8 with 96mm big bore will put out higher HP than the 2.0?

[Dave at Pelican Parts]

It can, depending on how you build it. An 8.5:1 1910cc (96x66) engine will probably be right about or just over what the stock US-spec 2.0 puts out. At a guess.

--DD

[sean_V8_914]

Dave, do you think that 1.8 big bore is a better combo than the 2.0 Bus mojo with the 1.8 heads? I could go big bore on teh bus motor. I just dont know what is better bang for the buck. I only paid $100 for the bus 2.0

[Bleyseng]

The only difference is the crankshaft strokes, 71mm vs 66mm. The bus stuff is fine as long as you arent using the hydro valves and the crappy heads and low compression pistons (7.3-1)
The 2.0L heads are the best due to their air flow capablities. If your 1.8L heads are ported they should work great on any combo.

Geoff

[Dave at Pelican Parts]

What Geoff said. To clarify one bit, he means that the 2.0 914 heads are the best. The 2.0 Bus heads are actually the worst ones to use in stock form. (When you get to "extensive modifications", then it doesn't matter much which heads you start with. Though there are those who claim that the late "square" exhaust ports can be made to flow better than the stock "oval" ports can.)

I'd take a high-compression 1910cc over a low-compression 1971cc any day. (Assuming it were legal for my racing class.)

--DD

[sean_V8_914]

thanks guys.