Another new guy question, diagnosing a rough running engine Options

[A Havland]

Hello all. Finally saved up enough to get a 914. It's a 1974 2.0 in silver. I am working through a few issues. When I first got the car home it was hard to start so I did a valve adjustment and now it starts right up. The next hiccup is the engine runs very rough just above idle until it is completely warmed up. I checked the AAR valve and it seems to open when the car is cold. I took out the air sensor and it passed the olms and vacuum test. Replaced the plugs but the old ones looked good. Light grey in color. I could use some help if anyone knows where the two wires in the white connector goes. This is all new to me and the learning curve is steep (at least in the beginning). Any help would be appreciated. Thanks.

[Superhawk996]

(IMG:style_emoticons/default/welcome.png)

Not sure why no one has replied to this thread yet. Bumping back to the top.

Very had to tell from your picture.

All white wires with no tracer color are associated the fuel injection and the ECU. That is for 100% for sure.

I’ve got to be honest, I’m not sure what that connector is just based on the two wires and the connector shape. The fact that your engine is running is also throwing me as well as its location. I’m going to throw a wild ass guess out there - mis routed wire from the cold start injector (and missing the rubber boot)? Honestly I don’t know.

Need some of the other D-jet experts to chime in and help the new guy!

Note; that exposed vacuum port off the distributor vacuum advance line ought to have a line on it - even if it’s just the one that goes to atmosphere - need to keep water out of that canister.

@jeffbowlsby - can you post a link to your vacuum hose diagram and take a look at that connector?

[Cairo94507]

(IMG:style_emoticons/default/welcome.png) Welcome to the club. If you have not already done an introduction post with some pictures of your car, please do. It gives us all an opportunity to see what you are working with.

Posting pictures on this site can be challenging. I understand posting directly from your phone makes it easier, but I have yet to do that.

I do not have a Type 4 engine in my car so I can't be of any assistance with your running issue/wire connector - but hey, it is running and that puts you ahead of the pack. (IMG:style_emoticons/default/beerchug.gif) Michael

[JeffBowlsby]

Welcome to 914s! (IMG:style_emoticons/default/welcome.png)

Here are a few links to a couple pertinent diagrams related to your questions. Also check out the links in my signature when you have time, to add to your learning curve. You're welcome. (IMG:style_emoticons/default/smile.gif)

FI harness: https://bowlsby.net/914/WiringHarnesses/doc...GAcode_2.0L.pdf

Vacuum hose A: https://bowlsby.net/914/Classic/zTN_FI_Hose..._Late1974_A.jpg

Vacuum hose B: https://bowlsby.net/914/Classic/zTN_FI_Hose..._Late1974_B.jpg

Tech Notebook: https://bowlsby.net/914/Classic/TechNotebook.htm

[Superhawk996]

Oh, oh, . . .

Now I wanna’ change my answer; I’m going with TS1. I didn’t realize that connector shape was the same as the injectors. I think that is closer to the right location and like the cold start injector wouldn’t seriously affect the engine just running.

Clearly I have no idea and I’m just guessing (IMG:style_emoticons/default/lol-2.gif)

But for OP; this is sort of how it goes, some basic knowledge (ie white = fuel injection) and then some deduction / process of elimination. You’re going to have to do some looking up on the plenum at TS1, the cold start injector, etc and see what is missing a connection. Use your phone and/or an inspection mirror to see better under the tangle of hose, wire, and intake runnners that make head on inspection difficult.

[Superhawk996]

Here are a few links to a couple pertinent diagrams related to your questions.

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[emerygt350]

definitely ts1 just south of the TPS mounted into the top of the plenum towards the driver side of the throttle body. Not a critical sensor so it could be the reason you are getting odd off idle issues but otherwise have a decent running engine. I suspect there is more though.

[914sgofast2]

The vacuum advance hose is clearly missing from the nipple on the distributor. There needs to be a vacuum hose from the nipple on the vacuum advance diaphragm connecting to a nipple on the intake plenum. Without it, you car will run, but with "flat spots" where it seems to lose power briefly.
I think others have answered your question about the electrical connector that has come off its position.

[yellowporky]

From what i have experience with my D-jet car is the rough warm up cycle is associated with the head temp sensor. I purchased one of the head temp extension to make it warm up slower but have not had a chance to install it.
good luck.
Chris

[emerygt350]

The vacuum advance hose is clearly missing from the nipple on the distributor. There needs to be a vacuum hose from the nipple on the vacuum advance diaphragm connecting to a nipple on the intake plenum. Without it, you car will run, but with "flat spots" where it seems to lose power briefly.
I think others have answered your question about the electrical connector that has come off its position.

This is a 74 so it may just have the retard part of the circuit. That other hose on the vacuum can on the distributor should be headed to the back side of the throttle body, the advance would go to the TB port pointing towards the passenger seat, but late 74s did not have that (mostly, I think).

also, just fyi, advance has to go to ported vacuum, not the plenum, or bad things happen.

[Dave_Darling]

There needs to be a vacuum hose from the nipple on the vacuum advance diaphragm connecting to a nipple on the intake plenum.

No.

The advance hose gets hooked to a port on the throttle body that gets a "high vacuum" when the throttle valve is just barely open. This is "ported vacuum", and it drops when the throttle valve is open more than a crack.

The retard hose gets hooked to a port on the throttle body that sees something relatively close to, but not identical to, the vacuum in the manifold (AKA plenum).

Most of the 74+ cars had throttle bodies with only one fitting, that for the vacuum retard. The dashpots on the distributor were the same, with two ports, probably because it was cheaper than tracking two different versions of the part when building the car in the first place.

--DD