Forums Forums Enthusiast Forums A - Z Autowirral Running problems on RST again.

Its doing my head in now.

I mentioned it in the past but it went and now its doing it again. As i drive along it stutters and throws a load of fuel down the exhaust (i think) so you get a bang and sometimes flame. It seems to do it only under about half throttle and up and when the car comes on boost, but not always. You can hold 10psi or more and its ok then suddenly itll do it at 2psi. Its completely intermittent and i see no connection of circumstances between when its happened. Sometimes itll drive off, sometimes it wont.

Ive removed the filter, no change. Ive added injector cleaner, and it didnt do it again for a while but i dont reckon that helped. Leads and dizzy are ok. Some people suggested the cam but i dont want to fork out on it if it turns out not to be. After that it starts getting into electronics.

Any ideas anyone?

And can anyone suggest somewhere to go to get it looked at who know their stuff? Im getting fed up now.

Deffo an electrical problem.

Possibly the MAP sensor....

isnt it called MAF

MAF is a Mass Air Flow sensor and works with a hot wire to measure air flow in to the engine.

The Turbo'd fords use a MAP (Manifold Absolute Pressure) sensor to measure inlet manifold pressure as a way of measuring air going in to the engine

The both do the same job of measuring air going in to the engine, though technically the MAP sensor method is more accurate on a F/A car.

OK cheers. Would that still cause it to be intermittent though?

I went out today and it was fine but once it got some welly it started again.

Ill see about getting it changed either way, at least its one less thing it could be.

Its a pressure sensor - first time you give it some it may stick open and take a while to close again....

OK, ill give it a try then.

Does the type of sensor reprisent the pressure it can read. For example, a 1.5 bar MAP will read up to 1.5 bar, and a 2, 2.5 and 3 bar all the same or is there a difference?

What happened to the good old days of twisting screws on carbs eh?

I cant any map or maf sensors, and i had a look at the car and the things i can find are a pipe to the ecu from the manifold and a sensor on the charge carrier. Ive found these on burton power and its described as 'AIR CHARGE SENSOR ESCORT RS TURBO -5/90'. Do you think that is the sensor im after?

Ive only heard them called MAP sensor matey...

1 bar with MAP sensor is atmospheric, so a 2 bar sensor is accurate up to 15psi / 1 bar, and a 3 bar MAP sensor is good for 2 bar (30psi) boost pressure.

Its generally a small unit with a pressure / vacume feed and a loom connector.

There are quite a few 3 bar items, though Im not sure if these will run on your ECU

Well im running 17psi atm so id expect a 2.5 or 3bar jobbie then. I hope anyway. Ill have a proper look again in the light tommorow. Just had a look again and theres a black thing opposite where the cable pulls the throttle body. I always thought it was the throttle position sensor but it looks similar to the MAP sensors in pictures. As i said, ill have a proper look in the afternoon, im tired now.

Cheers for the help btw, much appreciated.

Chances are that is the TPS - the MAP sensors are generally mounted on the bulkhead, away from the heat and vibrations of the engine.

f you find you have a 2 bar map sensor (I belive this is std) and your running 17psi, that could well be the problem...

I had a better look today. That is the Throttle pot. Theres a funny pipe that runs round the back of the manifold but it then goes into a round filter type thing and back into the manifold at the back. Theres also a pipe from the top of the manifold that runs straight to the ecu. If i opened the ecu up do you think i might find the MAP sensor in there?

Sounds like something simple like your plugs - are they gapped properly? You could also have fuel leaking into the inlet through dodgy, leaking injectors or your Fuel Pressure Regulator.
Does it come on after a certain period of time (like motorway driving)?

Good point Station, though the S1 and S2 use a mechanical, Bosch, Fuel injector system - it could have something to do with that....

Its a bit of trial and error Dave, I think you really do need to change some parts for known working items to rule things out though...

I know the leads are good.
Ill try the plugs next. Ill whip em out n clean them if i get a chance on the weekend. Check the gaps too. I know they need to be pretty small on a high boost car.
It has a brand new higher pressure electronic pump so i know thats good but im not too sure about the rest of the fuel system. I guess ill have to get the injectors spray tested and leak tested.
I dont really want to get too involved about the fuel injection system, i dont really know much about it to be honest. I know how it all works, just no experience with it.