Mk3 Mondeo 1.8 Petrol Poor Throttle Response
Discussion
Hi all, My 2004 Mondeo (1.8 Duratec engine) has a really noticeable flat spot when trying to accelerate from lowish revs (1500-2500 roughly)
After this, it seems to improve, but is never what I would call great. It starts and idles perfectly and there isn't any loss of speed on the Motorway.
It recently had new plugs, leads and coil for an un-related fault but this hasn't changed anything. The throttle body was spotless on checking and the car has only done 50,000 miles.
Most of my car knowlege goes back to the 70's so there are a lot of extra parts on a modern (relatively!) car that I'm not familiar with!
I was told that it could be the map sensor, but I wondered whether it would start and idle so well if it was that.
Thanks
Tim
After this, it seems to improve, but is never what I would call great. It starts and idles perfectly and there isn't any loss of speed on the Motorway.
It recently had new plugs, leads and coil for an un-related fault but this hasn't changed anything. The throttle body was spotless on checking and the car has only done 50,000 miles.
Most of my car knowlege goes back to the 70's so there are a lot of extra parts on a modern (relatively!) car that I'm not familiar with!
I was told that it could be the map sensor, but I wondered whether it would start and idle so well if it was that.
Thanks
Tim
Map sensor on its way out wouldn't be the worst guess. Spark timing, coolant temp sensor, VAC leak or egr stuck open could also be reasonable guesses.
You can use the free forscan http://forscan.org/ with a £3 obd dongle off eBay to check the map values the ecu is operating with.
Can do the same test with just a multimeter. Of the 3 wires into the map plug, find the ground by measuring voltage between battery negative and each wire in turn. One wire will give 5v, one something between 0.5 and 4.5 (signal) and one will show zero or almost zero. Use that as the ground instead of the battery negative and measure the voltage at the signal wire. Check it as you rev through the flat spot and up, it should vary linearly.
Definitely easier with forscan, especially when you need to test it under load.
You can use the free forscan http://forscan.org/ with a £3 obd dongle off eBay to check the map values the ecu is operating with.
Can do the same test with just a multimeter. Of the 3 wires into the map plug, find the ground by measuring voltage between battery negative and each wire in turn. One wire will give 5v, one something between 0.5 and 4.5 (signal) and one will show zero or almost zero. Use that as the ground instead of the battery negative and measure the voltage at the signal wire. Check it as you rev through the flat spot and up, it should vary linearly.
Definitely easier with forscan, especially when you need to test it under load.
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