"Trailer-hitching" bucking problem, Rapid detrioration from running perfectly Options

[boxster914]

Hi everyone

My perfectly running 71 914 1.7 D-jet has deteriorated rapidly this past week.

Early in the week I noticed what felt like a power drop out during a drive. It was very slight and only happened once and I wasn't sure I didn't cause it by unconciously lifting off the gas.

The next drive it happened a few times and was more pronounced. It was then that I knew this wasn't an imagined problem.

On the third drive it was like a bucking bronco, surging and stopping and the engine cut out a few times. It was undriveable.

Today it will start but won't run. The engine cuts out when I try to rev it and the red light comes on.

I've done some searching here but haven't been able to draw any conclusions or come up with an actionable strategy to diagnose the problem. I'm seeing people trace it to spark plug wires, air fuel ratios and bad distributors.

Is there a step-by-step process that you can recommend for me to get to the cause of this? (I'm a newb so I probably will need help with abbreviations like AFR, TPS, etc.)

Here is a video of it's rough idle yesterday when it was still running.

https://youtu.be/n61CP6O8UgM

[rjames]

The vacuum hose goes to the retard port of the throttle body and is used to retard the timing at idle. Shouldn’t have anything to do with the bucking problem. Disconnecting it would cause a high idle, or if the vacuum canister was bad it would cause idle surging.

[emerygt350]

The vacuum hose goes to the retard port of the throttle body and is used to retard the timing at idle. Shouldn’t have anything to do with the bucking problem. Disconnecting it would cause a high idle, or if the vacuum canister was bad it would cause idle surging.

Now I see it, couldnt recognize the dizzy in that photo. What a tangle.

[wonkipop]

The vacuum hose goes to the retard port of the throttle body and is used to retard the timing at idle. Shouldn’t have anything to do with the bucking problem. Disconnecting it would cause a high idle, or if the vacuum canister was bad it would cause idle surging.

Now I see it, couldnt recognize the dizzy in that photo. What a tangle.

different plenum and throttle body set up to your 2.0 as well emery.
kind of closer in resemblance to 1.8 would have looked strange to you.

interesting comments about dizzy malfunction in comments.
-----that it would raise idle in a D jet.
in a L jet it would probably not idle at all - would be pulling in extra air afm can't measure. interesting differences in D jet!
idle could probably come up in an Ljet if the retard didn't work on the distributor,
but would have to happen without letting air into the throttle body.