Cold run issue

htfx19

htfx19

Herzel Frenkel
My car, '87, FI/AC, stock, is starting upon a touch and runs like a charm, idling too. Only that on a short span of temp, about 5 min into running and up to 15 min or so it dies at idling. I have to keep the revs up by the pedal during that time. It dies real fast, just let the RPM drop and it's dead.
Any ideas?
Enjoy
 
have you been playing around with the Idle screw? if so that might be the problem, if not maybe try starting by playing with it a little once the car is up to temp. GL
 
!

But then it idles fine AFTER 15 minutes? (Please respond).

There is an auxiliary throttle body bolted to the front of the engine block. It is designed to open when cold to provide a fast idle when the engine is cold. As it warms, it closes and slows the idle as the engine gets warm and needs less gas to idle correctly.

Your symptoms don't really make sense, but it may have something to do with this system.

Usually if the idle is too LOW when cold, or too HIGH when warm, it's because the aux throttle body is stuck or bad. But because the idle speed may have been changed to compensate for the bad part, it's tough to say what may be happening.

IMPORTANT: Reply on my first question above.
 
Idle screw?

Do you mean the throttle screw? The one at the top of the inlet manifold?
No I haven't touched it in ages.
 
Idling

Eddie: "But then it idles fine AFTER 15 minutes? (Please respond)." Yes, that's right.
"There is an auxiliary throttle body bolted to the front of the engine block", I don't seem to locate it. Do you mean the idling screw at engine center on intake manifold top? That is the main throttle, isn't it?
 
Knowing you Herzel, the other thing ya haven't touched...

... is the accelerator too.

I remember you saying ya never took it over 4000 rpm... Maybe a good old "Italian Tune-Up" and some otherwise spirited driving might be in order.

Why not look up Moni(?) and have him give it a spin around the block!

HA!

Otherwise, I bet some Fuel Injector cleaner and possibly an idle adjustment might help... but as you say, its only a temporary condition as the engine kinda transitions off the COLD running sequence to the normal operating temperature. A slightly sputtering fuel injector(s) would seem like the likely cause, along with possibly some fouled plugs.

HTH...
 
How right you are, Tony

Damn it,
I did visit Momi. He suggested some additive too (which I'd put in a few hours ago).
He also suggested some wild driving, so I have been pushing it up to 4050 rpm....
and a bit more.
We'll see what helps, I thought may be it is a more common issue.
Enjoy
 
Hey now, don't overdo it... 4025 rpm is my limit!

HAHAHA!

Once it's warm... try a 2nd gear stretch to 6500... you'll never be the same (man) again! I betcha even grow taller by a few inches too!
 
Aux air reg

Had the means to take a good pic. The two open tubes is the thermostat housing with out the coolant hoses hooked up.

DSC02677.jpg
 
Temp sensor

The one in the thermostat housing. Probably not giving a proper value as it warms up. Also check the F.I. harness grounds and the plug to the temp sensor for clean tight connections.
 
Thanks Jim & Sean

I don't remember ever seeing this thing although I did pull out my engine some 3-4 years ago. I guess it is my memory...
I'll check into it tomorrow morning.
Thanks a lot
Enjoy
 
Thanks Greg

I was thinking about it too. Do you think this sensor acts linearly or on some kind of a curve or is it more of an on-off device?
I'll check both things.
Enjoy
 
variable resistor

It's a variable linear resistor, the only values I have are:

7K-12K at 14ºF (-10ºC)
2K-3K at 68ºF (20ºC)
250-400 at 176ºF (80ºC)

From Brad Artigue's Bosch L-Jetronic Fuel Injection Guide
FIAT Fuel Injected Engines, First Edition - July 2004:
The coolant sensor is tested on the ECU connector. Unplug the ECU and connect an ohmmeter between
terminals 13 and ground (vehicle body). The meter should read:
7,000 to 12,000 OHMS at 14 degrees F
2,000 to 3,000 OHMS at 68 degrees F
250 to 400 OHMS at 176 degrees F
If the reading is 0 or less replace the sensor. If the reading is infinity check the wires leading to the
sensor for a break. If the wires are good, replace the sensor.
 
I think Gregory has it.

Sounds like a similar problem I had with mi 81 years ago. Mine just needed cleaning of the connector on the thermostat housing. I did however, put on a new one and the sensor also. It's worked fine since. I was getting a bit of steam leak in that area from a slight hose leak ,which caused the corrosion. My problem was somewhat intermittant and sometimes daily.
 
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