My First 914!

[mmmmgood79]

I recently bought a 1975 914 2.0. I followed the guidelines set out on this website for buying it, but apparently I missed one or two steps. The car runs excellent and the engine has good compression, however I cannot get it to pass Oregon DEQ. I know there are forums on this site that delve into that and I have tried many of the tips and tricks to pass with no success. It is at the mechanic right now for one last shot. I finally passed the HC test by removing the vacuum advance, which I thought the 1975 did not have. I now believe that the car has the older FI (D-jet). I almost passed the CO by turning the screw on the brain all the way CCW, but I was at 5.4% and am supposed to be at 2.5 (My first test had me at 9.5% co). Alas, I decided that I would just shell pout the money for a catalytic converter, yet in my research I realized that my car has pre 1975 heat exchangers, and no after market muffler /catalytic converter combination has the trapezoidal connections that those exchangers come with. No matter where I look, I cannot find 1975-1976 heat exchangers with the triangular pattern, is there a reason for this? Any help on any of this would be very grateful. Thanks.

[Tobra]

I don't think any of the pre'75 cars had cats, so you probably won't find any to fit. It sounds like you maybe have a pre 1975 motor. If you are going to use one, it will probably have to be some custom deal. If you could post pics it would be helpful.

[Dave at Pelican Parts]

All of the 2.0 liter cars should have D-jetronic FI. The idle spec for CO measurement was 3.0% for the D-jet cars up through 74. 2.5% is a little lean but should be doable; I think the spec for non-catalyst 75+ 914s was 1.5% (though I could be mixing that up with a different figure). Higher numbers generally indicate a richer mixture, while lower numbers generally indicate a leaner one.

How's the basic engine? Valves all adjusted to spec, good compression, and so on?

Check your fuel pressure. It should be 29 PSI any time the engine is running. Higher pressures will give you richer mixtures, and lower pressures should give you leaner mixtures.

Check and re-check your ignition system. A poorly-performing ignition can lead to incomplete combustion which will register as excess HC and CO. Incorrect timing can lead to high CO or high NOx, depending on which way you go. (And I don't remember which way is which.)

A very lean mixture could also lead to incomplete combustion and misfiring.

Check to see if your manifold pressure sensor is holding a vacuum. Pull a ~5" vacuum on it with a vacuum pump (e.g., MityVac) and see if it holds pressure for 5 minutes or more.

Check the resistance of the head temp sensor circuit. If it's more than a few hundred ohms when the engine is warmed up, the mixture will be too rich.

Air leaks, particularly near the heads, can cause weird running problems and quite possibly emissions problems.

Most 75-76 914s did not have catalysts, even though all of the ones for the US had the nasty roundy-round system that allowed for the cat. You should, if everything is in good working order, be able to pass that emissions test.

--DD

[bowlsby]

There are more details about the emission standards, the factory equipment on your car and testing procedures for the 75 2.0L that you may already know about, or find interesting here:

http://bowlsby.net/914/Classic/Emissions.htm

Do you also have a functioning air pump/injection system installed? You should.

Post photos of your system to help us better understand which engine/exhaust you heve.

Assuming it truly is the original 2.0L (so many engines have been swapped) it sounds like the exhaust system may have been backdated to the earlier version. The factory exhaust for 1975 was part of the emissions system. It has heavy metal manifolds that help reduce emissions ('thermal reactors's), so if you are missing these that could be part of the problem. Here in CA, the seller is requried by law to provide a smog cert upon a sale, don't know Oregons' rules on that, you may have some recourse.

I have a complete factory exhaust correct for a 1975 1.8L/2.0L available if interested, everything from the heavy manifolds, the HEs, muffler hanger, 2 cats, a cat bypass tube and the factory 2-piece muffler, all in great condition. LMK if interested at jabowlsby-at-gmail.com

[Dave at Pelican Parts]

Jeff, are you sure about the thermal reactors? I do not believe that is correct; I think that the regular 75-76 exhaust pipes are just pipes with heat exchanger wrapping around them. The CA-spec cars had the catalyst (and MA as well, I think?) but others had a bypass pipe.

Let me see if I can find the "changes to 75 models" document...

--DD

[bowlsby]

Hi Dave! The way I understand it is that the reaction tubes are heavier gage metal than their predecessors and accumulate the heat from the heads/exhaust to help burn off unburnt fuel vapors, but I don't know the chemistry involved. We know the 75-76 engines run hotter because of this exhaust system and it was the intended design for emissions purposes. Here is one page from teh 1975 S&T manual, it identifies the exhaust system parts, but doent explain their function. What say you?

[Dave at Pelican Parts]

I say that is a reasonable interpretation of the name "reaction tube", but I am not sure how that would work. It certainly looks like it's just a way to get the exhaust gases to the exchanger part...

I guess I don't know!

--DD

[mmmmgood79]

Thanks for the input. I am sorry I have not put pictures up. I decided to give it one more shot between me and my mechanic and my car has been at the shop all week. I passed emissions and will be registering it soon. It seems that getting all of the original parts for a '75 exhaust with catalytic converter is very difficult and pricey. That and I feel that if the car was running so rich in the first place, the exhaust is not the problem. Anyway, I appreciate your tips, now I have to start tackling electrical problems...