1972 CSi idling issue

[Sgovindraj]

Need some help - just got this car and have a couple of issues. Occasionally, but often enough to cause concern, the revs will drop to zero and the engines stalls when in neutral. Also when cruising along there is occasionally some hesitation. What is the first thing to check before going down a rabbit hole?

Thanks! Newbie to the forum.

 

[Stevehose]

Vacuum leaks. Welcome to the forum!

 

[Sgovindraj]

Thanks - Never thought of that - thought it was an injector issue. Will poke around. If you have any ideas on how to find and fix the leak let me know.

 

[Stevehose]

Thanks - Never thought of that - thought it was an injector issue. Will poke around. If you have any ideas on how to find and fix the leak let me know.

Vacuum leaks are common and easy to check for. Inspect all vacuum hoses for condition, cracks, tightness, etc. You can test by spraying a little carb cleaner where they meet the ports to see if idle fluctuates and in hard to reach places. If the vacuum hoses check out then ignition electronics and fuel delivery would be next to check. I don't know injector trouble shooting but others here that do will chime in.

 

[Sgovindraj]

Thanks! Will check!

 

[Ohmess]

I had a vacuum leak on my M90 engine (not in my coupe, alas) that I found at the shaft that runs through the throttle housing. When checking hoses and spraying carb cleaner, assuming the hoses check out, spray carb cleaner at both ends of the throttle shaft to check for leaks.

 

[adawil2002]

May need to simply adjust the large screw under the throttle body facing the firewall, counter-clockwise 1/4 to 1/2 turn in 1/8s test drive & repeat as necessary until the stall condition stops.

 

[Sgovindraj]

Thank you! I’ll do that. I, however, did a smoke test and found smoke pouring out of this piece in the first picture. Smoke was coming out of the bottom of it (4th picture) and well as where it connects to the pipe.. I have no idea what it is. It was attached where the red arrow is in 2nd pic. The zoomed out picture shows you where it’s located on the engine.

 

[rsporsche]

when you say 'smoke' test ... did you input smoke into the intake system? i can't imagine anything good if smoke was coming out of the intake system that wasn't put there as a test for an intake leak.

 

[Sgovindraj]

I did - used a smoke machine and it came pumping out of that part that I removed in the pictures I posted above. I have no idea what that part is. Some pics below how I hooked up the smoke machine.

 

[Aussiecsi]

I believe that's the air filter for the air slider/AAV ( this draws in air on startup and remains open unti running temperature is reached ). I doubt that's the issue and would be inclined to adjust the "large screw" per Andrew's auggestion above .

 

[adawil2002]

Thank you! I’ll do that. I, however, did a smoke test and found smoke pouring out of this piece in the first picture. Smoke was coming out of the bottom of it (4th picture) and well as where it connects to the pipe.. I have no idea what it is. It was attached where the red arrow is in 2nd pic. The zoomed out picture shows you where it’s located on the engine.

That little canister, IMG_5229 is the called the Auxiliary Air Slide Filter. IMG_52230 & 52231 is where the neck of the can attaches to The air filter IMG_5232 that black thing in the middle is the Air Filter. It is part of the D-Jet Warm Up Regulation System for the 5th injector in the middle of intake runner side & sprays fuel into the throttle body on cold start at this point the Auxiliary Air Slide is fully open. As the car warms up, the 5th injector sprays less & less yet will still drip the Aux Air Slide closes in a similar fashion yet still let a little air through. This is a similar system on the 2002Tii with the bees wax filled Warm Up Regulators

On the newer Aux Air Slide Filters, the air filter is merely 2-sided taped in place & falls out easily. I found a small generic cone filter from a parts store has the same size filter. So I put the cone side in & peened the edge of the canister in & burnished the bottom end to hold the little cone in place in 2012. May be time to revisit that project & replace the filter.

 

[Sgovindraj]

Wow - thank you for that. Is that part not available anymore? Also - it seems like the consensus is that this filter is not the cause of issue I’m having. I’ll try adjusting the idle with that screw. But I’m guessing that this filter needs to replaced anyway. Would this work in its place? It's a K&N Crankcase breather filter

 

[Keshav]

This is what the whole Aux Air Slide / Filter looks like. A German forum member was selling these till recently.
Original part# 11 61 125 6467 and 11 61 125 6507

 

[coupedegrace]

I think you'd be well served by taking a look at the resources below. They explain how D-Jet works, what the different parts are, and how to trouble shoot it. And then just do what @adawil2002, @sfdon and other forum members suggest.

VClassics - All About D-Jet - good overview

D-Jet Articles by Dr. D-Jet -much more detail and quite helpful

Bosch D-Jet Manual - easy to get in the weeds with this one

One thing to keep in mind about D-Jet is that it was specific to the engine. The VClassics site is about old Volvos, so they write about D-Jet from the perspective of Volvos. The information is still helpful, but some things are Volvo specific. Dr. D-Jet is broader, but still comes at it mainly from the Mercedes V-8 world.

 

[sfdon]

To be clear- the cold start injector operates only below 95F and then only for 12 seconds.
Once triggered by cranking the engine the temperature-time switch and therefore the cold start injector and it’s controlling relay operates only once and only for 12 seconds. The ecu gets an additional cranking signal from that circuit that causes the injectors to provide more fuel when starting. And note that merely operating the starter without turning the key to On will not activate the cold start relay as it is powered by the ecu.

“

Temperature-time switch

35CEL 12S

 

[bill]

Need some help - just got this car and have a couple of issues. Occasionally, but often enough to cause concern, the revs will drop to zero and the engines stalls when in neutral. Also when cruising along there is occasionally some hesitation. What is the first thing to check before going down a rabbit hole?

Thanks! Newbie to the forum.

As for the hesitation, check/clean the throttle position switch. The copper contact traces on the PCB board wear away over time and may cause hesitation when cruising. For a replacement, check with SF Don…and get very friendly with him in the meantime as you will find for D-jet problems he is the Guru.
Does the hesitation also occur when upshifting?

 

[ScottAndrews]

I recall years ago that TJ Noto had a terrible random misfire issue on his CSL. It would not happen all the time, but occasionally the car would barely run. Turned out it was a faulty voltage regulator module (replaceable part of the alternator). When the alternator kicked in it would put tons of noise on the battery lines making the car underivable. Replaced the regulator and all was well.