L-jet issues

[yousaidpoo]

Car is a 1974 1.8 L-jet

Problems:
a) the engine is very hard to start. it will have to crank for about 2 or more seconds to get the engine to fire, and then it sometimes doesn't continue to run. if i give it some gas as it fires initially, usually i can get it to start and idle.
b) engine is idling low (around 700rpm) even with the idle speed adjuster cranked all the way up. its idling a bit rough too, causes the car to wobble when idling.
c) i have driven the car some and it seems seriously down on power, and sounds like it may be missing/backfiring a little bit.
d) car smokes when it gets warm, but i think that is mainly from some oil residue on the exhaust pipes, which i need to get off. (which brings up another question, will engine degreaser get all the oil off?)

car may even be down a cylinder I've never driven or ridden in an old VW/Porsche and i have heard they run rough, but i don't know how rough. I have pulled the plugs and checked them, they all feel hot and are dry, but the block could be getting hot and transferring heat to the other plug

here's what i have done recently:
-replaced every inch of vacuum hose
-replaced every inch of fuel hose
-installed an in-line fuel pressure guage (on the hose that runs across the top of the engine)
-put a fuel pump switch in the car, but as far as i can tell, this hasnt affected the FI operation at all
-adjusted valves (multiple times)
-new cylinder head temp sensor
-new spark plug wires
-new spark plugs
-new air filter

I'm thinking it may have something to do with the FI brain? There is a shop downtown called transporter werks that specializes in VW transporters, which as you probably know have the L-jet, and I am going to hopefully get some help from them.

Anybody that lives within a reasonable distance of Raleigh, NC, if you would be willing to help i would very much appreciate it. This is the first car i have worked on besides my '95 Accord, so i'm still learning...
Phone #: (919)649-7263

[jamcleod]

how about a compression check? how about a dwell/timing check? the compression check will help tell about the condition of the inside of the engine (rings, cylinder compression which is necessary for proper combustion, condition of valve seats for proper valve sealing). dwell/timing has to do with basic firing of spark plugs at correct time. i have a 74 L-jet. when i got in this morning to drive it for the first time in about a month, i turned the key and it fired right up. the cold start valve enriches the mixture when cold so that could be checked too to help with hard start-up. i've heard the brains rarely go bad. brains are cheap enough to buy a spare to switch out.

the factory workshop manual even states that "L-jet is the more modern fuel injection system" and i can attest to the fact that it can be made to run right.

keep at it/keep the faith. thank your lucky stars you don't have to mess with a Manifold Pressure Sensor or buy a new one

[yousaidpoo]

i have checked timing/dwell and its right where it needs to be

on the subject of compression, i have tried to test it, but the tester i have does not have a very long fitting part that screws into the head, so its difficult to do with the engine tins on. Know where i can get a compression tester that will work easily with a teener?

Hadn't thought about checking the cold start, i'll do that, but my main concern is the running/idling rough.

BTW; engine was recently rebuilt (by me) with new seals and all that fun stuff. I got the car after it had been parked for ~15 years, and just before the car was parked there was a full rebuild done (new rings, cylinder hone, new valve seats, etc.) and basically all i had to do was gaskets and such.

[Dave at Pelican Parts]

I wouldn't be surprised if there were vacuum leaks. The rubber boot from the air flow meter to the throttle body likes to crack in the pleats, where it's tough to see. The oil filler cap has a gasket and an O-ring that need to be in good shape. The gasket below the oil filler also need to be in good shape. The large "vacuum hoses" from the plenum (manifold) to the intake runner pipes can leak. The seals between the intake runners and the heads can leak. The seals around the injectors can leak... Pretty much anything between the AFM and the heads can leak.

--DD

[yousaidpoo]

injector seals need to be air tight, correct?

[srb7f]

Yes, they should be airtight.

I don't mean to insult your intelligence, but I had a similar problem with my 74' 1.8, and after an afternoon of checking the vacuum hoses, everything else I could think of, it turned out to be that I had neglected to plug in the connector that goes to the air intake sensor.

Only other thing I can think of offhand would be adequate fuel pressure.

For compression, I found a generic one at Sears that came with a little extension that makes it perfect for a 914.

Don't worry about the smoking, these engines will do that anytime they've been sitting for a long time. It will go away once you drive the car some more.

[ratwell]

- make sure the battery is charged up
- test the pressure regulator to see if it can hold fuel rail pressure after the engine is off
- test the fuel pump output to see if it can produce enough fuel according to the spec

[yousaidpoo]

just got back from picking up new injector o-rings. hopefully that will fix the problem.

srb, not insulted. i've done the same kind of things multiple times (i.e. wondering why the car wouldnt start after i put in new points... left the distrubtor cap off...)

[Mark Henry]

Dave touched on the oil cap issue, there are 2 flat seals.