Still running rough

ChrisB

ChrisB

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My 72 CSL (injected) is still running rough and I’m hoping for a few ideas.
Thought is was the vacuum hose as it had snapped off the vac unit and was sucking air. This is fixed but the issue continues
Starts fine, idle is sometimes fine at about 800, but sometimes up to 1400 and sluggish to return when blipped. Runs great under load and higher rpm, but lumpy at low revs and neutral throttle.
It’s a new car to me and unfamiliar with the injection cars, so any pointers appreciated. Thanks. Chris.
 
I would grab a can of brake clean with the “straw” and carefully squirt every inch of the intake with special attention to the injectors.

then check the throttle linkage is not hung up on something silly like the carpet by the gas pedal.

disconnect the TPS and let it idle… any change?

always begin an idle problem with a valve adjustment and check/set your points.

Total cost- 3£
 
sfdon said:
I would grab a can of brake clean with the “straw” and carefully squirt every inch of the intake with special attention to the injectors.

then check the throttle linkage is not hung up on something silly like the carpet by the gas pedal.

disconnect the TPS and let it idle… any change?

always begin an idle problem with a valve adjustment and check/set your points.

Total cost- 3£
Click to expand...
Ok, thanks. Linkage is good, been through it. Returns nicely to stop. It’s only covered 2k since it was rebuilt 12 years ago and pretty much zero in the last four.
Could you explain what you mean with squirting the inlet and injectors. Don’t quite follow. Appreciated. Chris.
 
With engine running squirt brake cleaner everywhere at intake including rubber seals on injectors.

Listen carefully for idle change.
 
To elaborate on what Don has above....
Vacuum leaks (unmetered air entering the intake system) can be a real problem.
By spraying around areas that may be leaking - you are interrupting the possible inflow of air by sucking in a bit of 'fuel' instead.
The engine then (momentarily) runs different (usually better) and you get feedback on where the problem area is.
This method also works on carb engines also (including seeing if the throttle shafts leak or carb base is warped/gapped - each allowing in air).
 
dang said:
Or if you smoke cigars you can do a smoke test. ;)
Click to expand...
I used something like this:
IMG_4413.jpeg

but as Don stated his way to trouble shoot will give you quicker results. Vacuum first, also the ignition part, fuel 2nd.

You stated ‘still running rough’? Is it always been like that in those 12 years or did it change from one day to another?
Did you never run the engine in those last four years? Maybe one of the injectors could have issues with now a days fuel. Or maybe a failing cold start injection valve..

Try this link to get to know more about the D-Jet system, might be of help:
 
sfdon said:
With engine running squirt brake cleaner everywhere at intake including rubber seals on injectors.

Listen carefully for idle change.
Click to expand...
Don, have you ever used propane to find vacuum leaks? My friend uses a propane tank and holds it near components and can also connect a hose to it to get into smaller areas. Works pretty good the times I've seen it in action.
 
Wes said:
I don't advise the propane test while having a cigar...
Click to expand...
I bought a welding cart a while back and it didn't come with assembly instructions. I found a video on YouTube but it was so bad I decided to make my own video showing how it goes together, but I decided not to post it because if you can't figure out how to put a cart together you probably shouldn't be welding.
 
BMW3.0CSi said:
I used something like this:
View attachment 187699
but as Don stated his way to trouble shoot will give you quicker results. Vacuum first, also the ignition part, fuel 2nd.

You stated ‘still running rough’? Is it always been like that in those 12 years or did it change from one day to another?
Did you never run the engine in those last four years? Maybe one of the injectors could have issues with now a days fuel. Or maybe a failing cold start injection valve..

Try this link to get to know more about the D-Jet system, might be of help:
Click to expand...
A great article thanks.
The car is new to me, it only done 2k in 12 years and about 100 in the last 4-5.
It’s now idling increasing high with no vacuum leaks that I can find. The plugs are all an even colour but whiter than I would expect.
 
Is the CSi-L still have the original D-Jet?
4 years is a long time to sit for any car & there are always, always something amiss when brought out of storage.
I store my cars for 4-5 months, full tanks, battery tenders, covered in a heated garage. Invariably in the Spring one or another has something amiss.

Seems the vacuum leak issue has been addressed adequately.

When cold the 7th injector in the throttle body will increase RPM & as the the engine warms up, that injector slowly stops to a dribble. It's controlled by a warm up regulator called an 'Air Slide" or AAV. Sounds like yours may be working if cold start is 1400 settling to 800-900 at running temperature. Right @sfdon?

Does the CSL have modified cam?
That will cause a lumpy idle in their nature, they all do that.

What distributor are you running?
Could be the points, or the trigger points in the bottom are sticking or both. "90% of your fuel problems are in the ignition." -Bill Williams, sage advice.

The Atmospheric Pressure Sensor, APS, the silver gizmo behind the brake servo, could be a culprit.

May only need adjust the large Throttle Air Adjustment Screw under the back of the Throttle Body, a 1/16 to 3/16ths of a turn out.



IMG_3716.JPG
 
adawil2002 said:
Is the CSi-L still have the original D-Jet?
4 years is a long time to sit for any car & there are always, always something amiss when brought out of storage.
I store my cars for 4-5 months, full tanks, battery tenders, covered in a heated garage. Invariably in the Spring one or another has something amiss.

Seems the vacuum leak issue has been addressed adequately.

When cold the 7th injector in the throttle body will increase RPM & as the the engine warms up, that injector slowly stops to a dribble. It's controlled by a warm up regulator called an 'Air Slide" or AAV. Sounds like yours may be working if cold start is 1400 settling to 800-900 at running temperature. Right @sfdon?

Does the CSL have modified cam?
That will cause a lumpy idle in their nature, they all do that.

What distributor are you running?
Could be the points, or the trigger points in the bottom are sticking or both. "90% of your fuel problems are in the ignition." -Bill Williams, sage advice.

The Atmospheric Pressure Sensor, APS, the silver gizmo behind the brake servo, could be a culprit.

May only need adjust the large Throttle Air Adjustment Screw under the back of the Throttle Body, a 1/16 to 3/16ths of a turn out.



View attachment 187939
Click to expand...
Thanks, to the best of my knowledge it’s a standard D jet and standard cam. The car ran perfectly when I collected it a few weeks ago, and it’s steadily got worse, to the point I’m not happy driving it. It bucks at low/neutral throttle and the idle is now 17/1800 cold and varies between 900-1500 warm. Like I said I’m new to the system so it’s a steep learning curve. But I don’t think it’s an injector or trigger problem as the plugs are even colour (quite lean looking) and fairly sure no inlet leaks as I’ve tested. So bit stumped at the mo
 
ChrisB said:
Thanks, to the best of my knowledge it’s a standard D jet and standard cam. The car ran perfectly when I collected it a few weeks ago, and it’s steadily got worse, to the point I’m not happy driving it. It bucks at low/neutral throttle and the idle is now 17/1800 cold and varies between 900-1500 warm. Like I said I’m new to the system so it’s a steep learning curve. But I don’t think it’s an injector or trigger problem as the plugs are even colour (quite lean looking) and fairly sure no inlet leaks as I’ve tested. So bit stumped at the mo
Click to expand...
Like Don and Ada mentioned, check these parts. The AAV and cold start valve. I should check the AAV first (no 14 in schematics) based on the fact that it is running lean and that this type of valve has the possibility to get stuck after suchs a long time not running based on own experience.

Take it off and test it in hot water to see if it is still closing.
 

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While you are checking all this, I'd grab a book of automotive spells and stock up on eye of newt and mocking bird feathers. D-Jet is a bitch to trouble shoot and black magic works about as well as science...
 
Please correct me if I fail to understand.

Previous owner restored the car 12 years ago then barely driven & mostly stored for 4 years. You now have purchased this CSi-L.

Progressively & continual poor running with worsening power over time. Tends to be contaminants in the fuel system. There is a fine mesh screen at the bottom of the fuel pick-up/return, the 8 bolt flange in the fuel tank. There should be a fine brass cone filter on the intake side of the fuel pump, located under the car in the rear left in front of the spare tire well above the subframe. Depending on the fuel blend & age of the rubber cloth covered rubber fuel hose, it has clogged screens filters & caused chaos before.

My last consideration is the health of the battery. An old or dying battery does cause sensitive electrical woes, same with older bayonet style fuses.

Are you in Cambridge England, Massachusetts one of the others?
 
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