CIS Questions

[TimD]

So I'm a CIS n00b for sure. Unfortunately I can't find instances of people having similar symptoms to mine.

1. My car has a BAE turbo. (perhaps irrelevant)
2. It always starts perfectly (crank or two, hot or cold) and the idle is good (other than some hunting when cold, which goes away if I lean it a tad)
3. For the first minute or so that it's running in a day, the power is awesome, it'll smoke the tires if you want it to.
4. After a very short amount of time (1-2 minutes), the power is gone and it's bogged down (still accelerates, but hesitates around 2000-2500 rpm)

I've noticed that when it's in this fit of having no power, the metering plate will open about 3/8" and then promptly slow and creep open. If I open the throttle and push on the plate myself at the same time, the car revs right up.
It seems that the plate requires a lot of force to open (although it is very smooth to do so).

It would appear something is dampening the plunger (its very clean). When I move it in and out with the distributor out of the car, I hear a 'pssst' with every movement.

a) Should the plunger move undampened with no fuel lines hooked up? (no pressure)
b) Is it possible some passages in the distributor are restricted?
c) What kind of behavior should I expect from the plunger? When cold? When hot?
d) Is this the problem?
e) How can I rectify the problem?

Thanks,
Tim

[David T]

So I'm a CIS n00b for sure. Unfortunately I can't find instances of people having similar symptoms to mine.

1. My car has a BAE turbo. (perhaps irrelevant)
2. It always starts perfectly (crank or two, hot or cold) and the idle is good (other than some hunting when cold, which goes away if I lean it a tad)
3. For the first minute or so that it's running in a day, the power is awesome, it'll smoke the tires if you want it to.
4. After a very short amount of time (1-2 minutes), the power is gone and it's bogged down (still accelerates, but hesitates around 2000-2500 rpm)

I've noticed that when it's in this fit of having no power, the metering plate will open about 3/8" and then promptly slow and creep open. If I open the throttle and push on the plate myself at the same time, the car revs right up.
It seems that the plate requires a lot of force to open (although it is very smooth to do so).

It would appear something is dampening the plunger (its very clean). When I move it in and out with the distributor out of the car, I hear a 'pssst' with every movement.

a) Should the plunger move undampened with no fuel lines hooked up? (no pressure)
b) Is it possible some passages in the distributor are restricted?
c) What kind of behavior should I expect from the plunger? When cold? When hot?
d) Is this the problem?
e) How can I rectify the problem?

Thanks,
Tim

I would check the control pressure regulator, that requires a fuel pressure gauge. I would also check the vacuum advance system and the duty cycle on the Lambda system. Since you have a turbo it means you have a lot of extra plumbing. That means more possible vacuum leaks. It should all be checked for vacuum leaks. You also have pressure switches added for the turbo system. They all need to be checked for operation. They may not be hooked up correctly or not working right.

[Ron]

+1 David.


a) If there is NO pressure in the system (push the plunger all the way down one time to be sure) the plate will virtually float. Basically, it is balanced to slightly favor the closed position. (With the assembly removed, you can tilt the body and the plate will remain in the same position once it opens.)


b) Possible. But since you can make it rev OK manually, it isn't likely, unless it is in the control pressure section.

c) With no pressure, after you push it the first time, it should bounce right back to closed if you just tap it or press it fully. It should be very free floating. With the pressure up, it should move with the effort similar to, say, what it would take to burst a firm grape? If not, you might verify that the roller the plunger rides on is free. (I found one that was stuck and had a flat spot worn on it.)

d)?

e)Check all of your basic settings, primary and control pressures, plugs/gap, static timing, advance operation, etc, that you have no vacuum leaks, and THEN your CO last.

[Bitsyncmaster]

What the engine does cold until the lambda system goes closed loop (about 1 to 2 min) is run the AFR in the 11 to 12 range. I have measured that AFR with a tail pipe wideband unit. So assuming your engine works the same, you will have much better acceleration and more power with those rich mixtures.

If that's what your want all the time, you can disable the lambda and run open loop or instal a wideband controller and set your AFR closed loop.

[TimD]

Thanks for the replies guys.


Since you have a turbo it means you have a lot of extra plumbing.

I think this may be a turbo misconception. The BAE system has one vacuum line to control the wastegate and oil feed and return lines for the turbo. It's otherwise just exhaust and intake piping.

I should have also mentioned the O2 sensor is currently disconnected.

I reassembled everything and leaned it out to avoid the surging. - It ran considerably worse. I ended up richening it right to the edge of where it would surge (or hunt) indefinitely and I'm able to drive it, but it still seems to have about 90 horsepower.

I did find a thread where someone experienced similar issues and it ended up being bad injectors. I will test the injectors next weekend and let you know.

Thanks again,
Tim

[DMCMW Dave]

I should have also mentioned the O2 sensor is currently disconnected.

I reassembled everything and leaned it out to avoid the surging. - It ran considerably worse. I ended up richening it right to the edge of where it would surge (or hunt) indefinitely and I'm able to drive it, but it still seems to have about 90 horsepower.

I did find a thread where someone experienced similar issues and it ended up being bad injectors. I will test the injectors next weekend and let you know.

Thanks again,
Tim

If you have the O2 sensor disconnected, nothing changes at warmup. So - what does?

When cold, the warmup regulator goes low-pressure which richens the mixture. As the engine warms up this leans out.

When cold, there is vacuum enrichment via the vacuum hoses and delay valve on the warmup regulator. Once the coolant gets warmed, the vacuum is removed and this enrichment is not present.

When cold, there is no vacuum advance on the ignition distributor. At the same time vacuum is removed from the warmup regulator it is presented to the ignition distributor. Vacuum advance goes away when you floor it (and the turbo pressurizes the vacuum system) so this probably isn't part of the problem.

I think you are probably on track with bad injectors or fuel distributor. Pull the injectors and do a flow test - that will tell you a lot.

[David T]

If you have the O2 sensor disconnected, nothing changes at warmup. So - what does?

When cold, the warmup regulator goes low-pressure which richens the mixture. As the engine warms up this leans out.

When cold, there is vacuum enrichment via the vacuum hoses and delay valve on the warmup regulator. Once the coolant gets warmed, the vacuum is removed and this enrichment is not present.

When cold, there is no vacuum advance on the ignition distributor. At the same time vacuum is removed from the warmup regulator it is presented to the ignition distributor. Vacuum advance goes away when you floor it (and the turbo pressurizes the vacuum system) so this probably isn't part of the problem.

I think you are probably on track with bad injectors or fuel distributor. Pull the injectors and do a flow test - that will tell you a lot.

If it starts up and runs OK when cold I doubt the injectors are the source of the problem. The "extra" plumbing is all of the intake and pressure ducting into and out of the turbo, not just some skinny vacuum hoses. You need that O2 sensor hooked up and the Lambda running. If the O2 sensor is not hooked up I have to wonder if any of the pressure switches for the turbo are hooked up and working. One of those switches is supposed to bypass the O2 sensor under boost. Like Dave S says, you need to go over all of the systems that operate during warm-up and see what is going on causing the car to run badly once it warms up. Since you say these symptoms came on suddenly the CPR is a prime suspect. Messing with the mixture screw is only going to add to the "To Do" list to get the car running right. That can't change by itself and now you have to get it back to where it is supposed to be.

[WelmoedJ]

My contribution may be useful or not.
I have been assisting the guy who built a D Turbo from a standard engine block and photographs.

Though that car is no longer using K-Jetronic, some of the problems met during testing may apply.
Firstly I have to mention that this turbo has a semi-free flow exhaust system: standard look-alike exhaust manifolds, special muffler, no cross-over pipe.
It has two turbo units with intercooler.

At first the car ran either smoothly while idling and at low speed, but had no exceptional power when pushing the pedal down.
Because of the exhaust setup two lambda sensors were installed.
That did improve running and using the turbos but not satisfactory.
The electronics to control injection, timing and fuel quantities required the lambda sensors to be on their own control circuit.
Only then the car was able to run idle and low asl wel as high speeds with the right fuel quantities.

While testing we also noticed that the turbo's require a better grade fuel (RON 98 - European) and a slightly richer mixture.
Now that all settings are in their optimum, the car produces 240 BHP (wheels) and a way higher torque than a standard D.

So I agree with Bitsyncmaster that you must not lean out the mixture, but keep it richer than a standard D.
Dave S will most likely agree, but may have a better insight and experience than I.

[Ron]

David,
You mentioned pressure switches (plural) more than once, but while working on a couple of turbo cares recently, I've only see a vacuum line to the waste gate and mention of a Hobbs valve during conversations.And like tim says, there is little else mentioned in the BAE documentation. Can you elaborate on exactly what they are or any other info not in the doc?
Thanks.


==========


+1 on not leaning it out.
Everything I've ever read calls for defeating the upper ignition advance and enriching the mixture to prevent catastrophic damage in the upper RPMs...

[David T]

David,
You mentioned pressure switches (plural) more than once, but while working on a couple of turbo cares recently, I've only see a vacuum line to the waste gate and mention of a Hobbs valve during conversations.And like tim says, there is little else mentioned in the BAE documentation. Can you elaborate on exactly what they are or any other info not in the doc?
Thanks.


==========


+1 on not leaning it out.
Everything I've ever read calls for defeating the upper ignition advance and enriching the mixture to prevent catastrophic damage in the upper RPMs...

I am not as familiar with the BAE setup as I am with the Island setup but they are similar enough (the major difference is the # of turbos and the physical difference in the plumbing). When under boost you must use a pressure switch (commonly called a Hobb's switch) to force the Lambda system into full enrichment and ground the O2 sensor. You have to limit the mechanical advance and use the highest octane gas you can get. There are other "tricks" too. There is a mod to get a "fuel spike" off the CPR under boost, water injection, boost gauge, AFR gauge. I have collected a whole file on the Island and the BAE turbo systems. Let me know what you need.