if thats the case, then if i disconnect it, why does it still rev when i hit the accelerator?

My engine is running way to rich, what is the problem?

You may have your MAP sensor connected to a ported vacuum source and not full manifold vacuum. You may have a vacuum leak causing low engine vacuum to the MAP sensor. Your fuel pressure is not set properly or your fuel return line is restricted. On a TBI system your base gasket may be the wrong size or not sealed properly. On an MPFI system you may not have the vacuum line connected or a secure connection to the fuel pressure regulator; this is also a full manifold vacuum source.



My engine is running to lean, what is the problem?

You will see a recurring theme in these troubleshooting notes and that is vacuum leaks. This is the biggest cause of engines running too lean and should not be taken lightly. Fuel pressure is not coming up to proper pressure. See discussion on fuel pressure in previous paragraphs. Plugged fuel filter; make sure that your fuel tank is not contaminated.



I do not seem to have as much power as I should?

Verify that you have set your timing properly by disconnecting the set timing connector, setting the timing to the specified value, reconnecting the connector and shutting the engine off and starting it back up before proceeding. Ensure that your plug wires are properly connected with the correct firing order. Your fuel pressure may be insufficient; see fuel pressure discussion in previous paragraphs. Verify that there are no vacuum leaks and that the MAP sensor is properly connected.



My engine takes longer to start than I think it should.

Check that the MAP sensor is properly connected to a full manifold vacuum source. Ensure that the vacuum source to your MAP sensor is free from restrictions and has a secure connection. Check for vacuum leaks, this is the most common cause. Make sure that your timing is set correctly. Fuel pressure is not adequate for proper operation. See previous paragraph for discussion on fuel pressure and proper operation. Fuel pump relay is not coming on or is faulty. On a TBI system verify that the crank wire is connected to the crank side of the ignition switch or the crank side of the starter solenoid.



The RPM of my engine does not come down when I come to an idle.

More than likely you have a large vacuum leak, verify that your system is free from vacuum leaks. Your ignition wire is connected to a battery source and not an ignition 1 source. The engine has not come to full operating temperature as of yet. Your thermostat is inoperable or opens at too low of a temperature. You should be using at least a 180oF stat. Throttle cable or throttle on the throttle body is not coming to a complete close. Throttle plate is binding in the throttle bores.



I am not getting as good of fuel economy as I think I should.

If all is set up properly with the installation of your fuel injection system you are probably getting as good of fuel economy as you are going to get. Ensure that your timing is set properly, your thermostat is in good working order and your fuel pressure is at the specified pressure. You may have other factors such as tires, brake drag or other external issue from the fuel injection system that is not working properly. Re-evaluate your driving habits and insure that you are driving in a fashion that will provide you optimum fuel economy. If you are trying to race everyone from the light chances are you will not get the fuel economy that you expect.



The engine is reving up and down when I come down to an idle.

This is usually an indication of a vacuum leak; again make sure that you have no vacuum leaks. This could also be an indication of the wrong base ignition timing. Verify that you have set your ignition timing correctly. Your engine may also require more air going through the throttle plates at idle than it is currently set for.

i need some help, i have a feeling my map sensor is rooted, i am pulling 18-22l/100km, new leads, new plugs, new oil. it has nothing to do with my driving, because the easier i take it, the more it guzzles. (the car has never been close to the redline whilst ive owned it).

this is really pissing me off. 50 dollars of fuel gets me 220 km. WHAT THE HELL!

so anyone with any experience, or who can offer some help, please, please post!

the car is a 2000 au2 fairmont vct. the economy was bad before, but worse now.

OK. here is where it "should" be:




And here is how to test it:



Ignition On: 0.155-0.156KHz
Engine Idling: 0.101-0.103KHz
Engine Revved: 0.90KHz (Approx)
Idling in Drive: 0.105-0.106 KHz
Idling in Drive with A/C on or Steering Load: 0.109-0.111KHz

Of course you are going to need a Digital Multimeter to test this.

Yep, see my sig.


Poor fuel consumption
Running Rich

Its not there on the AU VCT.
It is a small black square that is directly under the throttle body on the manifold. That is the signal box but the actual sensor is what dies in most cases.

I've got crappy fuel economy at the moment too - lucky to get 320k out of a tank. My power "seems" ok but she is feeling sluggish off the line. The car feels best when it's absolutely stinking hot (like 40 degrees!) but the humidity isn't up - it rarely is very humid at 40+ temps - ie. at 38 degrees and massive heavy humidity there's some noticeable loss of performance (tho not much - gotta love the JMM cam). The next best performance is on a coolish - not cold, just cool - dry morning. Idle is generally fine except when starting up when humidity is high - idling for a little while and some "blipping" is required then to stabilise it.

I also have a wolf AF1 mixture meter spliced into the HEGO and it shows uniformly "ideal" mixture reading (which surely can't be right if I'm chewing this much fuel??). All this makes me think my problem is the HEGO sensor - I'm hoping to have it replaced within the week so will post how it goes.