My 1988 Ford Escort XR3i has the "infamous" you could say Bosch K-Jetronic system, ( better than Ford's EFi system from that era nonetheless )
However i have a small problem now, and that is that i can't get the idle speed below 1000rpm, even with the idle screw fully turned it ( in theory the engine should stall or idle very low if you do that )
I cleaned the throttle body when i did a clean up of the engine bay, it has a small hole on the top of the throttle body housing which is where the air flows into the engine with the engine at idle.
Upon starting the engine immediately i noticed the idle was really high, about 1200rpm ( cold ), as it warmed up it went down to about 1100rpm.
This is what usually happens when i clean the throttle body as it tends to get gunked up due to the crankcase ventilation system pushing oil vapours into the inlet ( thinking of installing a catch can instead )
However i always have been able to then simply turn the idle screw until it idles nice and smooth at around 900-950rpm, now even with the screw fully turned in i can't get it lower than 1000rpm ( 2 full turns from where it was before )
A few weeks back i advanced the timing a little bit, from about 8 degrees to 12, it was idling at 900rpm before than and about 950 after adjusting the timing.
I tried setting the timing back to where it was before, but that made little difference, the only way i can get it to idle at 900rpm or so is by retarding the timing to around 4-5 degrees, and the engine just doesn't like that.
Now i suspect i either have a vacuum leak somewhere, or the auxiliary air valve has stuck open, creating a vaccum leak.
In case you don't know the Bosch K-Jetronic system uses a valve that uses a bi-metallic element that bypasses air from before the throttle body into the inlet manifold, when the engine is started cold it's open, which raises the idle speed to achieve a smoother cold idle.
Once the engine begins warming up it is supposed to gradually close until it's fully closed once the engine reaches full operating temp, so i suspect that it works but is not closing fully.
I also think that it's running rich both cold and warm, the last time it was checked it gave a CO reading of 2.25, when according to Ford it should be around 1.0 - 1.5, could this have something to do with it?
Other than that the engine runs great, even though it idles at 1000rpm it idles very smooth, just too high.
However i have a small problem now, and that is that i can't get the idle speed below 1000rpm, even with the idle screw fully turned it ( in theory the engine should stall or idle very low if you do that )
I cleaned the throttle body when i did a clean up of the engine bay, it has a small hole on the top of the throttle body housing which is where the air flows into the engine with the engine at idle.
Upon starting the engine immediately i noticed the idle was really high, about 1200rpm ( cold ), as it warmed up it went down to about 1100rpm.
This is what usually happens when i clean the throttle body as it tends to get gunked up due to the crankcase ventilation system pushing oil vapours into the inlet ( thinking of installing a catch can instead )
However i always have been able to then simply turn the idle screw until it idles nice and smooth at around 900-950rpm, now even with the screw fully turned in i can't get it lower than 1000rpm ( 2 full turns from where it was before )
A few weeks back i advanced the timing a little bit, from about 8 degrees to 12, it was idling at 900rpm before than and about 950 after adjusting the timing.
I tried setting the timing back to where it was before, but that made little difference, the only way i can get it to idle at 900rpm or so is by retarding the timing to around 4-5 degrees, and the engine just doesn't like that.
Now i suspect i either have a vacuum leak somewhere, or the auxiliary air valve has stuck open, creating a vaccum leak.
In case you don't know the Bosch K-Jetronic system uses a valve that uses a bi-metallic element that bypasses air from before the throttle body into the inlet manifold, when the engine is started cold it's open, which raises the idle speed to achieve a smoother cold idle.
Once the engine begins warming up it is supposed to gradually close until it's fully closed once the engine reaches full operating temp, so i suspect that it works but is not closing fully.
I also think that it's running rich both cold and warm, the last time it was checked it gave a CO reading of 2.25, when according to Ford it should be around 1.0 - 1.5, could this have something to do with it?
Other than that the engine runs great, even though it idles at 1000rpm it idles very smooth, just too high.