Cant get idle down below 1000

[Andy_]

If anyone has an idea of where to go next it would be appreciated.

Cant get idle below 1000 rpm.
Smoke tested all vac system, no leaks.
Backing out the idle switch at idle makes revs jump to 2000.
Removing idle ecu inner plug makes revs jump to 2500.
Bridging black/ yellow and black grey on idle ecu makes no difference.

Tested with a new idle motor as old was sticking. Passes 2nd test as well (ignition on, opens, slowly closes).
Tightened all pins on bulkhead connectors.
Black on idle ecu and 2x pins on lambda grounded( plus ecu chassis ground).
Dwell test runs 15-25 on 8 cy.

Adjusting mixture screw anticlockwise, min revs achieved 900 before stall. Dwell is way off scale then.

Testing ground on green/ black (after bridging diode at idle ecu) is always grounded, unless vac solenoid is disconnected. Then lifting throttle cuts ground.

Removing and blocking vac solenoid>distributor / disconnecting vac solenoid makes no difference.

What is the item in wiring diagram up and left to the solenioid? It has 10uf on it?

Car drives fine, just high revs. Any ideas of what to check next greatly appreciated.
Car is auto, transmission vacuum connected/ good.

Ive been trying to fix this and have no idea what to test next. Its like there is a massive air intake leak somewhere thats not showing up. Thoughts please?

[Andy_]

Ps replaced cpr with deloreango one about 6 months ago, pressures were fine when installed.
Other things checked;
Curb idle screws are all tight.
Blocking hoses to canister : no difference
Blocking auto trans vac hose : no difference
Lifting throttle makes vac solenoid click when idle switch breaks contact

Doing all my tests seems to have made it even worse, now idling 1200

[Andy_]

Ps confirmed rpm with dwell/rpm meter. Binnacle tach reading correct rpm speed

[David T]

Ps confirmed rpm with dwell/rpm meter. Binnacle tach reading correct rpm speed

Inspect the decel valves and springs on the throttle plates. Make sure the adjustment for the throttle plates allow the throttle plates to close all the way without binding.

[Andy_]

Pps i knew dave would be suggesting deceleration springs so ive just cut them out and temp sealed them with bolts and washers. Will get them welded up (assume aluminium?). Someone on turbobricks suggested soldering them to another op in 2005, not sure how long that would last!
https://turbobricks.com/index.php?threads/b28f-to-b28e.32404/page-2

Anyway that got idle down to 1000. So if i can find what i messed up today maybe will drop again?
Gotta do 200 miles in a few weeks would like it running good, anywhere under 1k !

[Andy_]

Inspect the decel valves and springs on the throttle plates. Make sure the adjustment for the throttle plates allow the throttle plates to close all the way without binding.

Knew it, seems you were right. Any idea what i would have messed up that would have increased revs by about 200 today? (See previous post!).
Thanks for your help72212
72213

Seen bitsyncmaster suggest springs before, you beat him lol

[FABombjoy]

Someone on turbobricks suggested soldering them to another op in 2005, not sure how long that would last!!
I soldered mine in 2015 with 60/40, it's unchanged.

The melting point is 361F - how hot are you planning to run? :D

[Andy_]

I soldered mine in 2015 with 60/40, it's unchanged.

The melting point is 361F - how hot are you planning to run? :D

Yeah i dont know if i?d trust my soldering skills tbh.
72214

I know nylon nuts are only good to 110c -ish.
Searched part number 7400269424, thought i might be able to find sealed version. No.
What did you use to seal them? I assume a oxy torch?
Whats the material? Brass? Thought they were aluminium, was going to get them welded.
Did not realise solder would be alright. And whats 60/40? Is this a job for a plumber?
I?ve got map gas, maybe could have a go.
Have you got a pic of how much you built it up?
Thanks for your assistance

[Jonathan]

Knew it, seems you were right. Any idea what i would have messed up that would have increased revs by about 200 today? (See previous post!).
Thanks for your help72212
72213

Seen bitsyncmaster suggest springs before, you beat him lol

Hey, what are we looking at here specifically? I mean, about the decel springs and throttle plates... what is the picture showing that is defective about yours?

Does throttle body cleaner help us with these? I used it not that long ago on a 2019 Chevy Cruze with a check engine light related to my air flow calculation and it resolved the issue. Plate was visibly gummed up with residue and preventing it from moving freely. Would cleaning our throttle plates similarly help?

[Bitsyncmaster]

Hey, what are we looking at here specifically? I mean, about the decel springs and throttle plates... what is the picture showing that is defective about yours?

Does throttle body cleaner help us with these? I used it not that long ago on a 2019 Chevy Cruze with a check engine light related to my air flow calculation and it resolved the issue. Plate was visibly gummed up with residue and preventing it from moving freely. Would cleaning our throttle plates similarly help?

When you see the unevenly spaced springs, those are the ones that will cause high idle, leaking.

[FABombjoy]

What did you use to seal them? I assume a oxy torch?
Whats the material? Brass? Thought they were aluminium, was going to get them welded.
Did not realise solder would be alright. And whats 60/40? Is this a job for a plumber?
I?ve got map gas, maybe could have a go.
Its not much different than soldering pipes. Observe same precautions. MAPP gas will get it plenty hot enough in no time.
Clean, heat it up, dab solder on until the hole is closed. File smooth when cool.

[Bitsyncmaster]

60/40 is 60% lead and 40% tin. But any solder will work. Best if solder has flux inside it.

You will probably find your idle RPM will undershoot when you take your foot off the gas quickly with the deceleration valves not working. Soldering is good to test but you may want to find a replacement throttle body.

[David T]

You don't have to solder them up. Take some pens apart and use the springs. The springs get burnt up because you had backfires. You *could* use JB Weld to glue them shut too. It should never get so hot that the JB Weld would melt. Check your valve lash and timing. If you have a 5-speed you should try to keep the decel valves functioning but they are unnecessary for those with automatics.

[Andy_]

Mines an auto. I already knew bitsynchmaster would tell me my springs were bad lol. Think he did a while back.

So cut them out, sealed with locking washers and the idle dropped massively. Huge spaces between springs coils in some sections. Shaking the body made them move sideways. I have removed the valves now test proved.

Any chance anyone knows the volvo part number that doesnt have the decels, or which engine it came from? Someone tomorrow is going to try and solder them up for me but if i can get factory ones i would be happier.

I also cant see how i would have changed the springs. In the end i had to use tin snips to cut the pin holding the springs in.
This is what i have now72215

[Bitsyncmaster]

I also cant see how i would have changed the springs. In the end i had to use tin snips to cut the pin holding the springs in.
This is what i have now72215

The spring end caps screw onto the shaft. After they calibrated the valves, they bent the threads apart to keep it from changing. They are probably calibrated to open around 20 inches/vacuum

[Jonathan]

Is there much evidence among owners of the seal between the butterfly assembly and the lower housing failing? And that being a source of air leaks?

https://store.classicdmc.com/102772-butterfly-assy-to-lower-housing-gasket.html

I see DeLoGO sells an updated one that boasts less of a restriction to air flow. Anyone using this one in their car? Is this a good product?

https://www.deloreango.com/ca/dstrict-throttle-body-plate-kit.html

[Bitsyncmaster]

Is there much evidence among owners of the seal between the butterfly assembly and the lower housing failing? And that being a source of air leaks?

https://store.classicdmc.com/102772-butterfly-assy-to-lower-housing-gasket.html

I see DeLoGO sells an updated one that boasts less of a restriction to air flow. Anyone using this one in their car? Is this a good product?

https://www.deloreango.com/ca/dstrict-throttle-body-plate-kit.html

I am using the same part but it was sold by the original designer. I don't think the OEM seals caused vacuum leaks.

[Rich]

I found the parts diagram from Volvo for an '82 260 with the 2.8L fuel injected V6. Same motor was also fitted to the 264 and 265 models.

Link is here (https://www.volvopartswebstore.com/showAssembly.aspx?ukey_assembly=241640&ukey_make=865&ukey_model=20827&modelYear=1982&ukey_category=7072&ukey_driveLine=417) for that one, including the available parts list from Volvo. It doesn't list those butterflies, Item 41 in diagram. It does show its throttle butterflies as not having a decel valve port, only the 2 shaft mounting holes. But no part number.

The engines for the '80-'82 Volvo 260/264/265 (all of them PRV V6's) sold stateside were B28E and/or B28F I think. Both may be OK since the Bosch K-Jet hardware would probably be same for both of those engines.

Good luck hunting something down. Maybe somebody out there doing an EFI conversion on their D will have a whole K-Jet setup just waiting for you. For a price.


....Any chance anyone knows the volvo part number that doesnt have the decels, or which engine it came from?

Someone tomorrow is going to try and solder them up for me but if i can get factory ones i would be happier.

[DMC VIN 6639]

Yeah i dont know if i?d trust my soldering skills tbh.
72214

I know nylon nuts are only good to 110c -ish.
Searched part number 7400269424, thought i might be able to find sealed version. No.
What did you use to seal them? I assume a oxy torch?
Whats the material? Brass? Thought they were aluminium, was going to get them welded.
Did not realise solder would be alright. And whats 60/40? Is this a job for a plumber?
I?ve got map gas, maybe could have a go.
Have you got a pic of how much you built it up?
Thanks for your assistance

I have a spare butterfly that has good springs and plates. Good price