What the??? Barely getting 19 MPG!!!

[ShagFestiva]

From what I understand, if the vaf is not sitting level the car runs like crap. Hopefully getting those wires lengthened will solve at least some of the problems. Im stumped on the stalling out when you disengage the clutch. Could maybe have something to do with the sensor behind the pedal?

[resuwrecked]

But but after a test drive, when warmed up, I hear a clicking sound, like a relay, coming from near the fusebox under decelleration, and as soon as I put the clutch in, it will stall if I don't give it gas....
...work on the intake tube so that the VAF is level, and check for vacuum leaks. If it doesn't help, I don't know what else to do!

\

I'm pretty sure the clicking you're hearing is the fuel pump relay. When the VAF opens it turns the relay on. So you must have a combination of poor vaf orientation and unmetered air leaks causing the door to shut completely and cut power to the fuel pump. Fixing vac. leaks should also bring your idle down and you may have to readjust the idle stop screw. Check over the IAC components too.

[grey]

Is there am oil passage under the distributor cam ?
I know some earlier b6's had this....a tiny hole that let oil in.

Block the hole.

[Pocket_Rocket]

Is there am oil passage under the distributor cam ?
I know some earlier b6's had this....a tiny hole that let oil in.

Block the hole.

Distributor cam? Don't you mean the distributor gear? Well, I never paid attention to see if it had a hole on it.

So, here's a little update. As we speak, I just finished lenghtening my AFM wires and leveling it. All I need now is my new distributor (big thanks to Maxtiva) which I'm still waiting on because the delivery guys are too dumb to find my address (google maps anyone?) and we'll see if it solves the problem. In the next days I'll drive it to see if leveling up the AFM helped. But while I'm here, I just wanted to share a cool tip. Since the BP's intake tube is on the wrong side, my AFM was holding up only with zip ties. Well last week at school, we were learning about sheetmetal bending to form fascias, window trim covers and such (I'm in a carpenter's class), and we had access to a sheetmetal folder. Turns out you can make sweet sheetmetal brackets with this thing, and strong too, if you know how to do it. Plus, being aluminium, it won't rust. I took a 6" wide strip, folded it on itself 3 times in 2" wide sections and bended the ends so the part won't "open up". Turns out it's plenty strong to support the AFM and it's really light. I bolted one end to the two bolts holding the starter's bracket to the tranny, and the other end to a bolt on the AFM. Pretty cool, and the best part is, the bracket being under the AFM, it's not visible, so it makes for a clean look!

[Pocket_Rocket]

Changes the disty, still has the same problem. So I'm left with checking the coolant temp sensor and IAC. How to you test those? I just have a crappy Haynes manual that tells me how to replace but not how to test like the Chilton does.

[Pocket_Rocket]

Changed the coolant temp sensor for a known good one, but still got the problem, so I'm gonna check the IAC. I've heard it works with some kind of thermo wax to open and close the valve, so how do go about testing it? Can you still do it with a tester?

[1988redfordfestiva]

yeah oem volt meter to the wires and test it will lose or gain voltage when it is open close so best if u have that then u can see if its working first unplug and use in hand then test when in iac remove back cover of wires of iac to test if u get nothing or u get the voltage then its fine but the festy i'm not sure exactly

[resuwrecked]

I removed my iac on my old b3 motors and made a blockoff plate to get rid of it on my bp. I never had stalling issues. The iac is a stepper motor valve.

[mr2gq]

I dont think the AIN would effect the gas that much if any at all . Just mostly drivabliliy issues

[Pocket_Rocket]

I dont think the AIN would effect the gas that much if any at all . Just mostly drivabliliy issues

Well after correcting the timing and levelling out the AFM I am now getting almost 25 MPG for city driving, and I cleaned the inside of my muffler tips (which had a good coating of soot) and they've stayed clean up to now. So some of the problem got taken care of it seems. So I'm gonna check out the IAC, and by the way, anybody have the specs from the shop manual to test it, like voltage or resistance? Also, it caught my attention that there is some kind of gizmo under the intake manifold between the two center runners, with what seems like two coolant lines going to it. Anybody knows what it's for?

[1988redfordfestiva]

i know theres one on the intake and one from the front there for the heater core for the heating system if your talking about that

[Pocket_Rocket]

Well, after replacing the disty and coolant temp sensor, my fuel economy seems to keep on getting better, and maybe it has something to do with the warmer temperature, but at least I'm now getting around 27 mpg from mostly city driving from my BP. However the idle is still acting funny when the engine is warmed up, and still occasionally stalls, although I don't really hear the clicking, relay-like sound anymore while it happens. But I was thinking; if my idle is steady at 800 rpm and jumps up to 1000-1100 when it's acting up, wouldn't that mean that unmetered extra air is getting in the engine somewhere? Something making the engine run suddenly richer would make the rpms drop (from having too much fuel and not enough air) while more air would make it run higher, kind of like the IAC valve does, am I right?

[JohnGunn]

if my idle is steady at 800 rpm and jumps up to 1000-1100 when it's acting up, wouldn't that mean that unmetered extra air is getting in the engine somewhere? Something making the engine run suddenly richer would make the rpms drop (from having too much fuel and not enough air) while more air would make it run higher, kind of like the IAC valve does, am I right?

Note: My comments are based on my B3 engine. To the extent your engine is similar it may or may not apply to your problem.

First, I think you are incorrect if you think that the increased air allowed to bypass the throttle through the Idle Speed Controller is unmetered. The computer expects all air that passes through the engine to be registered by the Vane Air Flow Meter. Air from any other source will confuse it and degrade performance in proportion to the size of the leak.

There are three ways for metered air to get into the engine.
1. The throttle valve in the throttle body.
2. The Idle Speed Controller.
3. The PCV valve.

Throttle Valve:
When your idle speed goes up I assume the throttle valve is not moving.

ISC:
The computer has the ability to increase the flow of air through the ISC when the idle speed drops as a result of an increased load on the engine, e.g. headlights, air conditioner compressor. You can check this if you have a tach on your car. Watch it as your car idles at the set warmed up speed. Turn on your headlights. You will see the speed drop for a short while before the computer brings it back up to speed by increasing the air allowed to pass through the ISC. If there is no increased load on the engine I don't see why the computer would try to make this adjustment. (Note: The computer gets its knowledge of the idle speed from the Crankcase Position Sensor. Seems unlikely that it would fail in this way, but something to keep in the back of your mind.)

You can eliminate the ISC as a suspect for your unexplained increase in idle speed in two ways.
1. Ground the STI connection as is done in setting the idle speed. This tells the computer not to use the ISC to correct idle speed. Then Try and reproduce the problem. If you see the problem then it is not being caused by the computer through the ISC.
2. You could also disable that part of the ISC by disconnecting the electrical connection on the ISC. That would make it impossible for the computer to increase the idle speed.

If you see this idle speed increase with either of these steps taken, then it is not being done by the ISC.

PCV Valve:
It would seem to me possible that a defective PCV valve, maybe intermittently sticking open, would allow enough air into the plenum to increase the idle speed by the amount you are seeing. I would probably buy a new one and clean the hoses between the plastic air intake duct and the valve cover, and between the PVC valve and the plenum. Then do whatever it takes to cause the failure, to test for effect.

In general, it is difficult to see how any of this would affect your mileage much. One possibility, however, does comes to mind. Something like a failing PCV valve that was sticking intermittently, might be enough to cause the computer to have to keep changing the fuel/air ratio and keep it from reaching the closed loop mode where it is only reading the O2 sensor and using that information to adjust the fuel/air ration for optimum levels.

On the other hand, any repeatable problem with engine idle is gift to anyone wanting to improve the performance of his car. It is relatively easy to reproduce and you have full access to the engine while testing it.

John Gunn
Coronado, CA

[Pocket_Rocket]

Thanks a lot John, I'll try your tips!

[Pocket_Rocket]

Thanks John. your tips worked, it was the ISC. Came back from school with my car starting to act up, shut it off, unplugged the ISC, and when I started back the car, it idled steadily at a rock-solid 1000 RPM (that's because a mechanic once turned the idle screw trying to solve the problem) so I guess my ISC is pretty much kaput, since I already tried cleaning it, with no success. So I guess I'll have to get a new one; anybody knows if an automatic Escort GT comes with the same ISC as the manual?