help with stalling...

[dezel12345]

Hello all, my friend found a 914 but there is a known problem he (rookie like me) is trying to troubleshoot.....
Car starts fine and drives/runs well but about 10 minutes into some good drving once in a while when you come to a stop the car will act as if its gonna stall (light on dash comes on) or it will outright stall.....it will start right back up and go again but we're wondering what could be the cause of the rpmsjust dropping like that when you slow down .....it either stalls or catches itself beforeit stalls...other than that car idles beautifully and starts up fine....and the stalling or acting like is not all the time....but sometime and usually after 10 minutes intoi driving when things are warm ...this is a 1.8 fuel injected vehicle......THANKS for any TIPS

[sammyg2]

My WAG would be the decel valve.

[dezel12345]

Sounds stupid but ???? where is the location and hot to test if you dont mind...... Thanks kindly dude ! I know I know...we have some books on order....lol

[dezel12345]

Is this the guy youre speaking of : does'nt look like that even bad could make it stall or does it ?

Deceleration Mixture Control Valve

Located at the pressure sensor bracket, this valve leans out the mixture when the throttle is closed. This is purely an emissions control device. If it is removed and its associated air lines plugged, no performance change will result. However, this may cause you to fail smog certification in some states. A leaking decel valve will cause a high idle condition (test by pinching off the air lines).

[sammyg2]

I wish I could be more specific but I've only owned three 914s, the first was completely stock and never broke so I never ever messed with hte fuel injection. the second had a weber side draft carb, the third had an 800 cfm quadrajet carb
There are people here who are experts on the fuel injection system, I'm sure if I jump in and start spouting facts they will blow me out of the water and correct all my mistakes
But having said that, I was under the impression that there was a device that controls the air/fuel when the throttle is closed that prevents the idle from dropping too rapidly when the manifold vacuum peaks, that's probably the device you described.
another question for the experts, could the throttle posistion sensor cause this problem?

[jamcleod]

just got the car? check all the basics: valve adjust, dwell, timing, idle speed adjustment, CO (fuel pressure not adjustable on 1.8). then go to vacuum leaks .... head temp sensor resistance, compression test. o-ring seal in the oil filler cap, gasket under the oil filler breather (?)... don't think throttle position sensor is adjustable on a 1.8.

[Tidybuoy]

I don't think this would be the throttle position sensor. The TPS tells the computer when the throttle is wide open & richens the mixture.

Several things affected the idle in my 1.8.

The first thing that I did was replace all of the vaccum lines. Leaks on the 1.8 cause big problems since the engine will be getting unmeasured air & tend to run too lean.

Don't forget, when fixing vaccum leaks, there are gaskets in the oil filler cap, a gasket around the throttle body, and a gasket under the oil breather (just below the cap).

The next thing is the points. I was never able to get my dwell set just right. I eventually replaced the points with a Petronics pointless system & my idle instantly smoothed out.

You mention the decel valve but I can't imagine it being affected by engine temp. Vaccum leaks do have an affect. For example: it's possible the the fuel mixture has been adjusted to compensate for vaccum leaks on a cold engine. As the engine warms up, it's needs change. Fix the leaks & you will be amazed how much better it will run.

[M. Hendrix]

Stop stalling!

There.





M

[Ron Meier]

On the early cars, there was a fuel cutoff on deaccelertion (via the tps and the brain).

Later they added the valve, which under high vac, open and allows additional air to avoid overrich mixture on closed throttle - deaccelertion.

You would have to read the book to get exactly when the used the fuel cutoff and went to the additional air control as I am old and forget things easily.

This is D-Jetronic stuff.

The L-Jetronic (what you should have) is airflowed controlled via a Vane Airflow Meter - the funky thing bolted to you air cleaner. ANY additional air (from leaks) will cause a malfuntion of your system, as if it don't go thru the vane, it don't get measured and the brain don't know what to do. If this vane sticks or is sticky, it will cause problems. I'm not sure if the 1.8 has the additional air valve. Guess I'll have to buy one to find out.

[dezel12345]

is the idle speed adjustment on there guys factory set and not suppose to be touched like the Fieros..or can you turn away.....? Also Iam not certain of the D Jet, LJet, what came stock on a 75 1.8 FI vehicle..nothings been altered...Thanks

[M. Hendrix]

L-jet on a 1.8. I don't know about L-jet, but on D-jet, you can adjust it without a problem.



M

[dezel12345]

This one has the pointless update...other than that its stock ...willcheck those 3 gaskets you spoke about < thanks>.....timing seems ok ....QUESTION...if the timing was off would it start right up with NO problems ?

>>>>>>>>

I

don't think this would be the throttle position sensor. The TPS tells the computer when the throttle is wide open & richens the mixture.

Several things affected the idle in my 1.8.

The first thing that I did was replace all of the vaccum lines. Leaks on the 1.8 cause big problems since the engine will be getting unmeasured air & tend to run too lean.

Don't forget, when fixing vaccum leaks, there are gaskets in the oil filler cap, a gasket around the throttle body, and a gasket under the oil breather (just below the cap).

The next thing is the points. I was never able to get my dwell set just right. I eventually replaced the points with a Petronics pointless system & my idle instantly smoothed out.

You mention the decel valve but I can't imagine it being affected by engine temp. Vaccum leaks do have an affect. For example: it's possible the the fuel mixture has been adjusted to compensate for vaccum leaks on a cold engine. As the engine warms up, it's needs change. Fix the leaks & you will be amazed how much better it will run.


__________________

[Dave at Pelican Parts]

Pretty much anything in the intake can leak vacuum. You want to make sure there are no leaks at all from the air flow meter all the way to the intake valves. Lots of hoses to check, check the injector seals, the head-to-intake-runner seals, the "manifold boots" (large diameter vacuum hoses going from the manifold to the intake runner pipes), the oil filler gasket and the oil cap seals, and on and on.

Check the timing and dwell. Make sure the ignition is in top working condition.

Check the valve adjustment, check the compression pressures.

Could be a mixture problem; often an overly-rich mixture will cause the engine to bog down before it comes back to a decent idle. Could be a lot of other problems as well.

--DD

[Ron Meier]

As I remember, on the vane airflow unit, there is an idle speed adjustment screw built into it.

[jamcleod]

idle speed adjustment is on throttle body. CO adjustment screw is on air flow meter