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How to test for a faulty MAP sensor 

 

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Posted: Sat Mar 19, 2005 7:55 am 
Getting Side Ways
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Ride: 2000 AU II Fairmont Ghia

Location: Brisbane Most of the time/Sydney Some of the time
QLD, Australia

voxace wrote:
Yep, see my sig.


Poor fuel consumption
Running Rich

Quote:
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 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.



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.




those are the only ones that apply to me. i dont have idle/power issues, just the fuel is being burnt up hardcore

 

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Posted: Sat Mar 19, 2005 5:45 pm 
Getting Side Ways
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Ride: ford au wagon 4.0 na

Power: 170 rwkw

Location: Merrylands
NSW, Australia

Casper wrote:
voxace wrote:
OK. here is where it "should" be:

Image


And here is how to test it:

Image

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.

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.


As Casper said the map sensor is under the throttle bodymount on the underside. Also be aware that the AU 1 AND AU 2 had different map sensors. It actually fits inside the manifold by 2 torx screws.

 

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Posted: Sun Mar 20, 2005 6:13 am 
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Ride: AU Fairmont S

Location: Werribee
VIC, Australia

These are all my symptoms:

Engine is running to lean
I do not seem to have as much power as I should
My engine takes longer to start than I think it should
I am not getting as good of fuel economy as I think I should
The engine is reving up and down when I come down to an idle

PLUS:

Idle badly hunting
Choking at take off or when driving slowly (eg; when in bumper to bumper traffic and car is rolling and you press the acc and it chokes and goes to stall)

Then ofcourse there's the actual stalling. Yeah that was fun on Heatherton Rd on Friday - to have it choke and stall twice in heavy arvo traffic. That's 3 times it's stalled on me last week in traffic and once while reversing into my driveway.

It's either a vacc issue or just a P.O.S!!
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Posted: Tue Mar 22, 2005 5:04 am 
Getting Side Ways
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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.

 

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Posted: Tue Mar 22, 2005 2:57 pm 
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Greenmachine wrote:
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.


My EA sucks up around 17 lts / 100kms with AVERAGE driving... high 18s when pushin it, and around 15-16 lts when lettin her roll around. So yeah, I get an average of around 320 kms out of a tank of fuel street drivin.

I got some improvement with consumption after replacing the O2 sensor, about 2-4 lts / 100kms, K.O.E.O test faulted it, I have also swapped a pair of MAP sensors from other EAs and it made no difference when testing.

I was thinkin maybe my piston rings are worn, just not gettin all the bang outta the fuel, it smells like it could be running a little rich although the ECU is not reporting it (could be my 15 year old cat. on its last legs).

 

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Posted: Tue Mar 22, 2005 2:57 pm 
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Location: Katherine
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Greenmachine wrote:
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.


My EA sucks up around 17 lts / 100kms with AVERAGE driving... high 18s when pushin it, and around 15-16 lts when lettin her roll around. So yeah, I get an average of around 320 kms out of a tank of fuel street drivin.

I got some improvement with consumption after replacing the O2 sensor, about 2-4 lts / 100kms, K.O.E.O test faulted it, I have also swapped a pair of MAP sensors from other EAs and it made no difference when testing.

I was thinkin maybe my piston rings are worn, just not gettin all the bang outta the fuel, it smells like it could be running a little rich although the ECU is not reporting it (could be my 15 year old cat. on its last legs).

 

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Posted: Tue Mar 22, 2005 4:50 pm 
Getting Side Ways
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Argh! You've got me worried now - oh well all I can do is still change my O2 sensor and see what happens. I'm not getting outright fuelly exhaust smell and I'm pretty sure the old beast isn't taking excessive pedal for the response - except for some sogginess off the line she's actually making real healthy performance. Oil consumption is virtually zero (ie. I haven't put any oil in for about 4 months) and the plugs colour is good. This crappy consumption started suddenly - we were living about 23 km out of town and noticed no problem with economy (easily getting over 500km/tank) then we moved into town and again I didn't notice any change as such until it occurred to me that we were filling up only a little less often than when we were clocking up heaps of km living out of town. When I ran the figures I nearly died! - and now I just about cry as I watch the guage.

 

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Posted: Tue Mar 22, 2005 9:51 pm 
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Your next bet would be to do the diagnostic, and see what it reads out. And maybe the oxy sensor...

A friend of mine has the same problem. We've done all, leads, cap, plugs, oil, map, oxy sensor, and it still has no torque and really s**t fuel consumption. Haven't checked the Instant fuel consumption, will do later.

On the diag it told us that his MAP is out of range, and his TP is outof range. And that he didn't open it to WOT during the test, which he did, so I assumed that it was the TP thats f**k up....and it didn't know that he did open it to WOT.

The only thing left is the TP, and I hear that there's a way to callibrate these? anyone?


We also checked compression and timing, all of which seem fine.


Cheers

 

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Posted: Tue Mar 22, 2005 11:26 pm 
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justfordima wrote:
On the diag it told us that his MAP is out of range, and his TP is outof range. And that he didn't open it to WOT during the test, which he did, so I assumed that it was the TP thats f**k up....and it didn't know that he did open it to WOT.

The only thing left is the TP, and I hear that there's a way to callibrate these? anyone?


Cheers


EF/EL you put the reds on, turn all accessories off and start the motor. Let it idle for 1 minute then switch off. Bring back on to reds and hold throttle flat to the floor ( without the motor running of course ) for one minute. Completely turn off and leave it for a couple of minutes.

 

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Posted: Wed Mar 23, 2005 12:30 am 
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lol, and to think I was searching everywhere for it... lol.
Thanks jaysen :lol:


Cheers

 

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Posted: Wed Mar 23, 2005 4:52 pm 
Getting Side Ways
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Ride: 2000 AU II Fairmont Ghia

Location: Brisbane Most of the time/Sydney Some of the time
QLD, Australia

how do you do the diagnostics?

im talking au2 vct here, not ef/el


i havent had a chance to pull off and check the map sensor, or get to it for that matter, and how d i test the oxy sensor?

i have, however, noticed a strangeish smell from the exhaust.. a harsh, ammonia-like smell. i have been filling up on premium, mainly from mobil, but shell occasionally too, so fuel quality shouldnt be an issue.

this weeks tank lasted me 4 days, 250 km highway drive, 180 city. pissweak effort.

avg consumption is 20.3

 

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3.45 LSD

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Posted: Wed Mar 23, 2005 5:03 pm 
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Man! In a way that's worse than my consumption even though they are around the same figure, my driving is city only.

Stick a Pin in the black wire coming from the oxygen sensor, hook this to the red probe of the multimeter, hook the black probe up to the negative battery terminal.

Start the motor, should be around 0.85V for a minute, after which it should settle down to around 0.45V.

 

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Posted: Wed Mar 23, 2005 5:24 pm 
Getting Side Ways
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ok, just finished.

teh initial voltage was 0.24, then held for maybe 10 seconds, hen fluctuates from 0.3-1.0V

it fluctuates constantly, doesnt average out or sit close to anything...
:(

still have to test the map sensor

 

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Organza 2000 AU 2 Fairmont Ghia
4.0 VCT
JMM Race Series Exhaust
AWC TS50 Front bar
3.45 LSD

Coming soon:
G&D Airbox
CAPA Edit

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Posted: Wed Mar 23, 2005 5:25 pm 
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Those test figures are for a good sensor reading correct mixture - but what if the problem is the sensor making correct readings for rich mixture?? (ie. whole reason why the fuel chewing in the first place).

edit - I should explain: there will be two ways that a faulty O2 sensor can be causing consumption problems - first is if it's buggered so the ECU goes to a default rich schedule - this will show with the multimeter test - second way is if the sensor tells the ECU that good mixture is lean / rich mixture is good - in which case the multimeter test will show spot on figures even tho the engine's rich.

 

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Posted: Wed Mar 23, 2005 5:42 pm 
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janek wrote:
ok, just finished.

teh initial voltage was 0.24, then held for maybe 10 seconds, hen fluctuates from 0.3-1.0V

it fluctuates constantly, doesnt average out or sit close to anything...
:(

still have to test the map sensor


Sorry I should have mentioned that it would fluctuate. But 0.45v should be about the 'average' reading if the car is runnign properly.

You can test it out of car to elimate the issues Greenmachine is talking about, but who could be f**k lol... 8-)

 

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