Running Rich

[Guest peter2b2002]

got a problem on my 2b it's a 2lrt efi pinto, all was well last year but when i started her a couple of months ago the tick over was rough once the engine had warmed up,when reved up dark smoke comes out the exhaust and flames, it used to pop but never flames it also smells if its running rich, i have cleaned the air filter, washed out the air valve and butterfly , the probnlem seems to be worst once the engine warms up , the temp guage reads normal , is there another temp sensor that feeds the ecu that may be fooling it?

pete2b

[Guest Dan_Beeston]

Yep, the ECU read coolant temp from the sensor in the middle of the inlet manifold, the gauge reads it from the one in the head.

 

Other things that could cause rich running:-

 

MAF flap stuck open (or sticking)

Fuel pressure regulator sticking

Crap in an injector (causing it to stick open a bit)

 

It could be the warmup inrichment is not shutting off due to a dicky temp sensor, try unplugging the sensor underneath the inlet manifold and seeing if it makes a difference, the ECU should then revert to a default coolant temp vaule (hot, I would presume?)

 

Hope this helps!

 

Dan

[Guest Takumi]

What kind of air metering system does the efi have.? sprung flap, or MAF..?

 

I know the MAF systems has a tiny wire element temperature sensor, which lies in a sperate air path to the main housing. they can collect dirt and become damaged, I have read that you can clean them with pure solvent, like alcohol or toluene and a long fine brush.. very easy to damage, easier to get a salvaged MAF sensor from a scrappy..

 

The moveing flap type of system, not sure if there is a similar wire element somewhere that acts as the temperature sensor.. Might the flap itself is worn, > it must be acting on some potentiometer somewhere to measure its movement >that might be on its way out..

 

Or the obvious, air blockage in the inlet, or for some reason the fuel pressure has gone high? possible regulator problem..

 

I would take the whole Flap/MAF metering device and dunk it in a pot of petrol for 5mins.. or atleast only the mechanical side, hold it by the plug side..

 

cant think of much else..

 

 

all the best,

 

tak

[Guest Dan_Beeston]

Pinto EFI has a moving flap jobbie (allthough technically is still a MAF sensor) There is an air temp sensor built into them too, but I thnk it's a PTC type so pretty robust.

There is a Potentiometer under the big black plastic cover on the bottom, as Tak points out it may be on the way out, you can measure the output voltage as you slowly move the flap from one extreme to another, it should smoothly increase (or decrease) with the movement of the flap. Any sudden losses of reading suggest the track is breaking down.

 

Slightly OT but in case anyone is interested:- The MAFS with the sensitive wire are not actually air temp sensors as such, they heat the wire and monitor how much the passing air cools it down, thus giving them a MAF reading that also takes air temp into account, clever huh?

[Guest Takumi]

I did know how they work..

 

 

Edited March 14, 2008 by Takumi

[Guest old_timbo]

How old is the fuel? Unleaded only lasts about 6 weeks before it significantly degrades. When I had old fuel in my carb Pinto 2B I had misfiring and black smoke, but all was OK with a fresh tankfull.

 

Tim

[Guest Dan_Beeston]

Sorry Tak, didn't mean to teach you to suck eggs