rough running
stalls at idle
backfires
0-50 takes several minutes (notice I didn't say 60 - can't hit that)
strong smell of raw gas

all speaks to at least one cylinder not firing

No visible signs of leaking fuel.
2 new injectors don't seem to have helped
Trigger and Ignition points replaced
Ignition wires checked and rechecked
Timing was supposedly set, but will check myself when I get home.

Why is this thing so cranky?

Firing order?

All that time and money and it still isn't right??? Can you tell Autobahn to fix it once and for all and not pay anymore. This is ridiculous!

I called Autobahn this morning, after the white knuckle drive into work, and let Mike know how disappointed I was.

Thing is, initial cold start seems OK. As it warms, it gets progressively worse to the point of undrivable.

CHT could be bad. Could also be a bad ECU.

Wow,

This sounds like a simple fix.

Already mentioned to check the CHT, shoot, just buy a new one and install it. Why even mess with it, cheap.

There's only a couple of things on D-Jet that cause such rich running conditions, here are a few that I can recall off the top of my big head/little brain:

CHT bad
ECU bad - I had one once that made my 914 run really, really rich.
Trigger points bad - I think I noted you already replaced those
Bad injector(s) - not closing
Cold start injector staying open

There are others, but those are usually the common ones. Make a list, go through each one at a time. You'll get it.

Cold start valve not closing? I can't remember, does a 73' D-Jet have one? Unplug it when it's warm, easy test.

Also screams bad AAR.

Work done at reputable shop

CHT - replaced <20K ago. Do they go bad often? Can I test it's functionality? Just a resistance value, correct?

Trigger points replaced last summer and again this last visit to shop - seems like they are ruled out.

Yes, '73 has cold start injector and always suspected it was malfunctioning. However, engine is rough even cold and especially under any load.

2 brand new injectors this summer and other 2 tested out of engine for spray pattern at shop and were OK

What is AAR?

Could dizzy be failing to advance? Stuck weights? It seems to move freely cold , but I've never held it hot.

AAR= auxilary air regulator. Open when cold, closes when hot. If stuck, it will be a huge vacuum leak. Again, easily checked. With engine warmed up, remove the AAR vacuum line from the air box side, there should be no vacuum.

Are they reputable w/ 914 owners or the pinky rings? Sounds as if they aren't familiar w/ our 914's.

maybe your timing is off?

Yup, could be that, vac hose connected or disconnected when timing set?

Vac hose hooked up to correct side of can?

Those make a huge difference.

what about the timing chain?

Its a 4 cly Trent! It ain't got no stinking timing chain!

whoops forgot about the 4 cylinder part, just rebuilt a jeep liberty 6 cylinder and I had such a hard time with the timing chain.

ruptured MPS? Have you checked to see if it holds vacuum?

Jim

What service did the shop perform for the $1800?

Take the intake manifold off and look for a 3 way vauum hose. It cracks, it cannot be seen with the main plenum on , and it will casue all of these issues. I know because years ago I pulled an engine to rebuild it convinced it was in need, ended up finding that piece was hard as a wedding dick and split in 2.

O.k. slight brain fart. It is not a 3 way vacuum line it is a 3 way metal thingy ma hooch and it has a hose that makes a awkward angle to the plenum. thereis also a line on the underside, that can't be seen. This diagram only shows the 2 on the top 13mm one to the filter housing and one to the boot. I don't recall where the one on the underside goes.

I know I say this a lot, but make sure cyl 3 plug wire is tucked under injector pipes and not near the MPS. MPS goes crazy with a wire too close.

Also sounds like you could have that vacuum leak just mentioned, like the AAR hose that goes to the air cleaner is open. Put a CV ball bearing in it 1 inch from the AAR and see if your idle smooths out. Then if it works, go buy a good used AAR.

And check your firing order. Or, it may be that the plug wires are not fully inserted into the dizzy cap and coil.

Had that problem more than once.

John

BTW- my #3 plug wire was looped close to the MPS, and then I read your advice a couple of months back and moved it under the intake pipe- like night and day !!! She smooooooooothed right out, pulls stronger runs quieter. That was GREAT advice!! Thanks!!!

Jim

Isn't it a pisser that the MPS can get screwed up by a plug wire?

Glad it worked out!

I have counted 5 that have done it with instant results since June.

J

So I had the chance to drive her back up to Autobahn this morning and the mechanic comes out, listens to her, reaches into engine bay to tinker a little here and there, then applies some pressure to #4 injector. Suddenly, she smooths out and purrs like I haven't heard in awhile. He gently wiggles injector and you can see/hear difference. It's one of the remaining old ones that tested fine, but in use, it's not so great. We'll get that replaced and see if she's a long term driver. Whatever he did, made her drivable all the way down to Framingham - was even able to accelerate into ticketable speeds on the Pike and blow the raindrops off the windshield.

Cool!

Glad to hear this. I replaced all my injectors not too long ago. One just suddenly started leaking like there was no tomorrow as I was pulling out of the driveway. Lucky or what?