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Posted by: pmead Jun 25 2017, 03:45 PM

Ok, I know its been discussed many times, and have searched the archives but I still have a small idle issue. Car is a 73 1.7 with stock injection. Car runs great, great mileage, runs cool, quiet, etc..... but after a hot start will idle slow (around 200-250) for about 2 miles of driving then returns to 950 and is great until I shut down for a few minutes and start it again. Then the idle will drop for a couple of miles again. I have tested every component and all components are in spec. (car does not have deaccel valve) Yesterday I replaced all vacuum lines, intake gaskets and sleeves injector seals etc.. I was hoping I had a phantom vacuum leak but car still does the same thing. The cold starts are fine. I have read that some people have spaced the cylinder head temp sender away from the head. Is this the cure????? By the way, timing, dwell, valve lash, compression are all correct. Am I expecting to much of the D-jet?? The car does not stall, but it does not seem correct and I like things to be correct. Any Ideas would be appreciated.

Posted by: bdstone914 Jun 25 2017, 04:20 PM

According to the late Cap't Krusty who wrenched on them to over 40 years, no.

Posted by: Rand Jun 25 2017, 04:38 PM

You asked multiple questions.

* Yes a perfect idle is realistic. My 1.7 and 2.0 djet cars have all idled flawlessly in all conditions once dialed in. From cold start to any temp.

* No, spacing the sensor away from the head is not a cure, it's a hack.

* No, you are not expecting too much from djet. If everything is in spec, they run perfectly. Start, cold, hot, altitude, nothing should affect it. If it's not acting perfectly, something is wrong.

Might be a good time to clean up the dizzy, and make sure the advance plates can move freely through their full range. Quite possibly contributing here, and no matter what, need to know that anyway.

Posted by: pmead Jun 26 2017, 05:15 AM

Thanks for the replies. When I got the car the PO had replaced the points and the rubber green wire plug was keeping the plate from rotating. I have corrected that issue and put in a pertronix. I will keep looking for the hot idle issue. When I posted I was thinking some else may have had the same issue and might know the cause.

Posted by: saigon71 Jun 26 2017, 05:28 AM

I've always had this problem. My D-jet is well sorted.

Here is an interesting thread on what's going on:

http://www.914world.com/bbs2/index.php?showtopic=298261&hl=

Posted by: pmead Jun 26 2017, 08:31 AM

Good information Bob! I will research the resister approach to the CHT sensor. I don't personally like the idea of adjusting the mixture all of the time with a box. I have a FFR cobra with a crude Digital Systems ECU that controls a set of 8 throttle bodies. The on-the-fly adjustment is cool but can also be a pain cause I play with it to often. Maybe some one with better electrical knowledge than me will chime in.

Posted by: saigon71 Jun 26 2017, 01:28 PM

I run my idle slightly higher than recommended in the Haynes manual (about 1000-1050 RPM). This keeps my engine from stalling during the hot start condition you mentioned.

Unless I get stuck in stop & go traffic, the condition clears in a few minutes. So at this point, I'm just living with it.

Posted by: 76-914 Jun 26 2017, 02:28 PM

Paul Landers touched on this. The CHT becomes heat soaked after the engine shuts down which effects mixture and in turn idle. Once driven the air cooled head cools a bit and the CHT signal is corrected. The spacer helps with cold start warm ups, IIRC. Been awhile as I went water cooled a few years back.

Posted by: 914_teener Jun 26 2017, 02:39 PM

He goes by Brad Anders me thinks Kent.


Landers is the place where your fuel pump goes out on the way to RRC, and the epicenter of the last big one.

Posted by: pmead Jun 28 2017, 06:15 AM

I made a CHT sender spacer yesterday and it helped the low idle after a hot restart. Not perfect but now it will idle at 500 for a couple of minutes before going back to 950-1000. Before it would bounce at 100-300 rpm. I will drive it a while and see if I can with live it.

Posted by: 76-914 Jun 28 2017, 07:03 AM

QUOTE(914_teener @ Jun 26 2017, 01:39 PM)

He goes by Brad Anders me thinks Kent.


Landers is the place where your fuel pump goes out on the way to RRC, and the epicenter of the last big one.