Loud Bang And Then Limp Mode?

[mason]

G'day all,

I was hoping to draw on the depth of experience and knowledge on the forum to answer a question.

I was sitting at the lights on Sat night in my XR6T when I heard a loud bang, almost like someone had run up the back of my car. I turned around and checked and it wasn't the case. I pulled over and nothing, not even a scratch. The sound definately came from the car.

The car immediately felt like it had lost power. Driving it the day after felt the same.

I had it checked by a Ford dealer today and they could find no fault, they say its running correct boost and has no warning codes. On the way to and from the dealer it felt better but I'm not convinced that its running 100%.

Temps, fuel economy are fine, no smoke from exhaust or rough running.

Does anyone have ideas what the cause of the noise might be?

[FPV TRANNY]

I had the bang happen when I was driving to the sunny coast.Felt like the diff fell out.Dunno what it was.It never happend again

[cooltint]

Hi Guys,

I've had a similar experience recently whilst driving in a spirited fashion in the 'phoon.

I was in 3rd gear (I think?) driving through the twisties when I came upon a slower moving vehicle, I slowed down, using the gears but then when accelerating again it wouldn't rev past 4,000rpm and sounded like it was flooded or something (weird noise hard to explain), so I changed up a gear and it just went bang, sounded like the diff or transmission wanted to join me inside the cabin.

Anyway it's in at the dealer as I write this trying to fix this and a couple of other minor issues at the first service.

If I get any conclusive answers I'll post them up.

Big AL

[Paradoxx]

That is really bizarre...

Were you moving when it went bang or were you stationary at the lights? You say it sounded like the noise was from the back... something burning through the exhaust? Someone chuck a bunger in your tailpipe?? hehe

[cs123]

I wonder if it could be a backfire caused by a cam timing issue

[4ST-XR6]

Cam timing issue, possible but highly unlikely, and If it was a cam timing issue then it would be a VCT issue, and that normally logs a fault code and can be checked easily via the datalogger using the PDS (ford diagnostic tool). The most common cause of limp home mode is a faulty TPS (throttle position sensor) which almost every time logs a code P1270, and P2110. Ford has recognised this and has a new revised TPS. I cant remember the date after they changed to the new TPS but I will find out, the old and new can be distinguished with the old style having a dimple the sensor about as big as the tip of your finger and the new style not having the previously mentioned feature. As for the bang, could be a fuel issue, has your vehicle been modified? from memory there is the ability to change paramerters for fuel which is a swithed calibration type set-up, one setting tells the PCM to use calibration x and the other set-up tells it to use cal y, with more accurate adjusments being made for each, but I think that was on models from BA late 02 to 04. I will find out for sure on monday. If a backfire was the issue, depending on how severe, the MAP sensor is sometimes damaged, which again logs a fault code, and can be monitored with the datalogger.

hope this helps. I apologise for being unsure in some respects, I will find out.

[RAP1D]

Hey mine did this last week... drove off from the lights in the wet, tyres slipped a bit then BANG from the back and off we went... a serioulsy loud bang too, like the dif blew... all fine now though

[rapidchris]

mine when bang, but mine didnt continue to run.