Re: Cool - first problem with Kermit



As an update.
The TMAP sensor appears to be producing duff information. When driving along the manifold pressure goes from normal up to full on (107, heh I don't know what the scale is) and then back down again. This causes one hell of a surge from the engine... repeat. Lots. The car is almost undriveable around town but it's better at a cruise. Not superb, mind...
Is there anything else that can cause this reaction other than a duff TMAP sensor or the wiring loom? I've cleaned the ICV, no effect (barely any crud in there either, heh).
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Its broken - tear it out - but the 1.7 Zetec in there....
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LOL!
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In decided to enlighten our sheltered souls with a rant as follows

Bitchy!!
Then again, I like Kas.
I'd get a scrap Zafira GSi and put the lump in the Ka instead.
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Apparently on date Thu, 02 Jun 2005 11:36:26 GMT, "DervMan"

Like you've realised, this is because the EMS is not getting a sensible reading from the MAP. Either the sensor or the wiring is wrong.

Well sensors are generally either faulty or dirty, and wiring can be intermittent. Beyond that it's unlikely that the EMS is faulty and you don't want that to be the case anyway.
One last thing you can try, force a retrain by disconnecting the battery. The EMS will be reset and will have to relearn all the compensatory thingamies. It'll run rough for a bit until it does. If it is software related, this will generally clear the problem, but I wouldn't expect it to help. Remember to clear the DTC after you've fixed things to see it if comes back, it'll keep being there until you do and people have been known to replace sensors a second time when the DTC continues to be reported because they've not actually cleared it.
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Hmm. I could reset the ECU...
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Really I have had a few fuel injected cars do this. The last - a granada became all but undrivable. It started OK but after 2 mins it began... It was a multiplug down the drivers side of the engine in this case, it looked dry, and wd40 didnt do any good either. Left apart overnight, with a fan heater on low, blowing on it sorted it though. Rain can be enough.
Sensors or EMS systems seldom go intermittent. HT leads can but they do it worst under load.
Does the fuel pump give constant pressure? it could be failing intermitently too.
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a
it
intermitently
Good call, I'd check out the fuel pump, too - maybe the fuel pump relay.
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DervMan wrote:

MAP sensor is "Manifold Absolute Pressure" sensor, and it merely senses the air-pressure in the manifold. In simple terms : It replaces the old-fashioned airflow-meter - the lower the manifold's airpressure, the more air is passing through it, so the more fuel it needs to inject.
It's Kangarooing cos it thinks there's either maximum airflow or no airflow, so it's injecting Lots/FuckAll fuel.
First, check the pipework. My old 405 had the map sensor mounted next to the radiator, and it was connected to the manifold with a bit of thin tubing. The tube split, so I duct-taped it together, and all was well again.
Assuming the pipework is fine, then it's either a duff connection, or a knackered sensor. If it were me, I'd just replace the sensor and clean the connection whilst I was doing it - a new one will only be a few quid from Ford.
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in

I'm pretty sure that the _higher_ the pressure, the more air is flowing through :-)
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Pressure falls with higher velocity and vice versa.
http://www.aoxj32.dsl.pipex.com/NewFiles/HTWPhysics.html
The above link is from my site and although the example uses divergent ducts to vary the velocity, the principle is the same.
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Paul Giverin

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in slurred :

Heh, yeah, I know about the Bernoulli effect, but in the inlet manifold the vacuum is generated by the engine, not by air-flow. When the throttle plate is closed you have maximum vacuum. When the throttle plate is open you have a pressure slightly* below atmospheric.
So pressure _is_ higher when more air is flowing... :-)
*the slight drop below ambient is due to the Bernoulli effect, but is negligible.
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Correct! With a turbo it can be 1 or 2 bar above ambient at full power!
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Albert T Cone wrote:

Me too :)
Cos at full throttle, you have almost no vacuum (so highest pressure). And at idle, you have lots of vacuum (so lowest pressure).
Well done that man :)
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