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> Winter D jet tinkering, Are parts still available?
robkammer
post Jan 9 2026, 01:38 PM
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All: Started this morning to get the BB's few quirks figured out while it's still winter. Last year the car ran great, but it had trouble staying running for the first 5 miles or so. Cold start no problems, let it sit and idle for 5 minutes, ls no problem. Once underway, as soon as I let off the pedal, it would want to stall. I was able to get through it by using the hand brake, but that's a pain.
I know I have a bad vacuum valve that is supposed to shut the throttle body down on decel, but I've just plugged it and left it place. If it's not plugged, the open vacuum takes the idle way too high. It's been like that for two years, but not for long if I can find a new one.
The AAR is working but I'm not certain about the Thermotine sender. I'm sure Jeff B or someone smarter than me has the specs to bench test one.
If anyone has suggestions on what might be the problem here, I'm open to all suggestions.
Cheers!
Rob


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brant
post Jan 9 2026, 03:33 PM
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Test your CHT.

It could be failing when fully warm ?
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FlacaProductions
post Jan 9 2026, 03:34 PM
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Fuel hose kink that after it gets going, collapses and restricts flow?
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emerygt350
post Jan 9 2026, 06:19 PM
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This sounds like a bad aar
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rjames
post Jan 9 2026, 08:46 PM
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QUOTE(emerygt350 @ Jan 9 2026, 04:19 PM) *

This sounds like a bad aar


If it was a bad AAR it wouldn’t idle well when cold, or would idle high when warm.
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emerygt350
post Jan 10 2026, 05:58 AM
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If it's gone, but it can be a slow death with such an analog device. Just might not be opening all the way when cold but still closes eventually.
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emerygt350
post Jan 10 2026, 05:59 AM
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And I have no idea what a "thermotine sender" is.
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robkammer
post Jan 10 2026, 07:22 AM
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Thanks for the replies. The AAR is functioning well. The sending unit is mounted on the intake manifold and connects to the AAR, and to the wiring harness that goes to the FI control box. Thermotine may not be the right name, but it's feeding the AAR.
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emerygt350
post Jan 10 2026, 07:36 AM
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Perhaps you have something miswired? The AAR is fed only by a switched 12v wire. Perhaps the temperature sensor mounted near it (just towards the passenger side a few inches) has been confused with the AAR system? That temp sensor mounts to the surface of the block towards the front of the plenum and does feed into the ECU. Although it has nothing to do with the AAR.
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bdstone914
post Jan 10 2026, 07:46 AM
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@emerygt350

' date='Jan 10 2026, 05:59 AM' post='3240252']
And I have no idea what a "thermotine sender" is.
[/quote]

Thermo time sensor that sends a signal to the cold start injector.
Only affect cold start unless it it shorted and sends constant signal and extra fuel is continuously injected.
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bdstone914
post Jan 10 2026, 07:47 AM
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sechszylinder
post Jan 10 2026, 08:47 AM
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It is difficult to determine from a distance because it can have several causes, all of which have to be examined.
but maybe you should have a look at the troubleshooting table on this page if you‘re not already aware of this site :

https://members.rennlist.com/pbanders/DJetParts.htm

br

Benno (IMG:style_emoticons/default/smilie_flagge6.gif)
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robkammer
post Jan 10 2026, 10:38 AM
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Thanks fellas, all good info. My mistake, Thermo time switch, duh. I've been looking through Brads Djet manual. I am mistaken that the TT switch feed the AAR info. I'll check my diagrams when I get to the shop. Does the CHT sensor control the AAR?
One thing that seems certain, most of these parts are going to be hard to find if needed.
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sechszylinder
post Jan 10 2026, 11:01 AM
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QUOTE(robkammer @ Jan 10 2026, 08:38 AM) *

Does the CHT sensor control the AAR?



no definitely not.
The CHT is directly connected to the ECU. Sometimes there is a series resistor connected in between the CHT and the ECU, but the AAR get its power from the relay plate, which is on, when you turn on the ignition.

br

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robkammer
post Jan 10 2026, 02:37 PM
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Thanks Benno! That makes sense, hot all the time regardless of temperature, I think. I've spent some time reviewing the wiring diagrams in the Bentley and others, nothing gives a clear picture of the EFI routing or of the various sensors and devices. Right now I'm debating with myself about pulling the motor, just because I haven't yet and I know it needs some love, and that would make it a lot easier to clean up and organize the intake area. I had planned on a full suspension refresh on on of our other cars, maybe I can get that done before driving season and then put the BB on the rack.
In the meantime, I'll be reading through Brad Anders excellent collection of D-Jet info, It sure can't hurt.
Rob
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