Another idle question, L jet 1911 Options

[malcolm2]

I just cruised 300 miles on I40 going to NC. I got to the top of the exit ramp and she idled to zero. I drove about 3 miles thru town using the big toe to brake and the little toe to keep the revs at about 1500. By the time i parked she was idling as normal.

I have to do the same thing every morning til she warms up. Is that a vacuum leak?

Heading another 2 hours in the AM. Is there a quick fix i can do to get thru the weekend?

[timothy_nd28]

Check the CHT sensor.

[malcolm2]

Check the CHT sensor.

Thanks Tim,

To save me from having to search on this tiny phone screen, can you reply with test method? Visual connection I can handle and I did bring a Meter.

[timothy_nd28]

Sure, unplug the connector at the CHT sensor and measure the resistance from the connector end that leads to the CHT to engine ground.

Take a measurement in the morning before starting the car and report back the resistance of that sensor along with the outdoor ambient air temperature.

Repeat the test after you have driven the car, and the engine is up to temperature.

[pete000]

I am fighting a L-Jet low idle when cold. Car just wont Idle for many minutes upon cold start up. I have tested just about everything and replaced every hose. Next up is to do a smoke leak test and check to verify correct fuel pressure. Mine does seem to be running lean when I check the AFR. I will adjust that last. Last but not least will be the installation of a 914-6 hand throttle if all else fails.

Vacuum leaks are the biggest issue usually.

[malcolm2]

Sure, unplug the connector at the CHT sensor and measure the resistance from the connector end that leads to the CHT to engine ground.

Take a measurement in the morning before starting the car and report back the resistance of that sensor along with the outdoor ambient air temperature.

Repeat the test after you have driven the car, and the engine is up to temperature.

Saturday was no prob. We drove 2 hours on the interstste and when we exited it idled as usual. I still had the cold start idle trouble but once the cht gauge is over 300, it idles. I'll try the test Sunday and report back.

Thanks Tim

[timothy_nd28]

While you are at it, check the resistance from pin 6 to pin 27 at the air flow meters connector with the engine cold. In fact, mirror this test after you check the CHT before driving.

It would be nice knowing if temp sensor 1 and 2 are both within spec.

[malcolm2]

As luck would have it, the damn cheap voltmeter I brought has a dead battery. Seems to be running as usual so I'll check when I get home and report my values.

[malcolm2]

OK Tim, I checked the resistance with the engine cold. It was 1.67. I have now started the car and it is idling with my help. The next reply will be with cylinder head temperature at 350*F


With the car just idling in the garage and no real load on the engine, I could only get the CHT to 300. At 300 the resistance was 0.078.

1.67 at the 2k meter setting and 80 degree air temp
0.078 at the 2k setting. IIRC. 300 CHT
0.124 at 2k and 200 CHT

Weather permitting, i will drive to work in the am and get a better hot reading.

At work after 20 minutes on I40

0.045 on 2k scale

[timothy_nd28]

I graphed your numbers against what's in the manual. With some curve fitting, both graphs line up somewhat. So, I'm pretty sure your CHT isn't the issue here.

Did you test the temp sensor in the airflow meter yet?

[malcolm2]

Oops. Forgot that suggestion. I'll get that today.

Thanks

[malcolm2]

I got you some cold readings. The meter kept gping up. I first opened the lid and got
1.363
Got the meat thermometer and waited 10 min.
1.439 at 87*F
1.489 at 86
1.613 at 83 after 20 min with the lid up and a fan blowing in.

You know, facebook can figure out up and down why can't this forum? Oh well.

[timothy_nd28]

It calls for 2000 ohms at room temperature which we are in the neighborhood.

The adjustment screw on the AFM, is it screwed all the way in? Inspect the AFM's flap, make sure it still swings freely.

If I understand correctly, you can't idle when the engine is hot? What did you set the valve lash for?

[malcolm2]

I have not moved the adjustment screw since we tinkered with the AFM. Can't say i remember where we stopped with it.

The loss of hot idle only happened that one time, after 3 hours at 70 mph. Sunday we did 6 hours give or take and it idled fine when i exited. I do have cold idle issues.

Lash is zero. Checked a few months back when dr evil had the tranz.

[malcolm2]

It calls for 2000 ohms at room temperature which we are in the neighborhood.

The adjustment screw on the AFM, is it screwed all the way in? Inspect the AFM's flap, make sure it still swings freely.

If I understand correctly, you can't idle when the engine is hot? What did you set the valve lash for?

update on the AFM temp1 ohms.

air temp 80 this AM got 1.870 ohms,
drove to work, air temp in the engine compartment was 90 and got 1.254 ohms

So I think you are correct, maybe temp1 sensor is OK. Is 1254 good for a HOT reading? At least it is going the right way, correct?

more resistance when the air is cooler.

I am going to read thru the AFM adjustment again to see if I can remember how I left the screw.

http://www.itinerant-air-cooled.com/viewtopic.php?t=7761

I'll check the AFM flap today. Plus, the L-Jet TS guide mentions the CSV as a possible cold idle problem.