Ford Fiesta 1997 - Ford Fiesta 1997 (Mazda 121) Revs Dropping

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Wed 7 Apr 2010 19:09
Ford Fiesta 1997 - Ford Fiesta 1997 (Mazda 121) Revs Dropping - leigh88

Good day!

I have a problem with my Mazda 121 (basically a ford fiesta). It has the endura -e engine.

When I am driving, and I step on my clutch to change gears or to free, my rev counter needle sometimes drops really really fast (like its weighing 5 pounds) down to 500rpm and then comes back up to about 950rpm. It never stalls though.

My speedometer needle is also very shaky (needle jumps up and down, by about half a millimeter).

When I step on the clutch to free for example, the revs gets stuck for a while at 2700rpm and then drops down (either fast or normal).

I recently serviced the car, changed the HT leads, changed the oil as well as the Idle Air Control Valve because it was giving other problems (rev counter went to about 4000rpm when I stepped on the clutch and I had no power even though the revs climbed normally. All this is sorted now. Eventually).

I would really appreciate any help. I love my car and I dont want to get rid of it!

Thank you.

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Sun 18 Apr 2010 21:00
Ford Fiesta 1997 - Ford Fiesta 1997 (Mazda 121) Revs Dropping - cj1000
hi your fault is probaly cause by the idle control valve, if it were me i d try cleaning it out and go from there its on the side of the throttle body clean it with brake cleaner/ carb cleaner and see how you go
hope this helps
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Tue 27 Apr 2010 09:46
Ford Fiesta 1997 - Ford Fiesta 1997 (Mazda 121) Revs Dropping - leigh88

Hi

Thanks for the reply. I have already replaced my idle air control valve because cleaning it didn't solve any problems.

I sill have the problem about the revs dropping, and I am really concerned that if I don't get it fixed I am going to brake something else.

I refuse to take it back to the local ford dealer. They told me stuff about my driveshaft that goes to my rear wheels is causing the problems. And that my rear wheel CV joints needs to be replaced. To me that doesnt sound right.

Regards,

Leigh

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Tue 27 Apr 2010 12:06
Ford Fiesta 1997 - Ford Fiesta 1997 (Mazda 121) Revs Dropping - mickyh7

Did you use a new Gasket when you changed your IAC ?

I would look for air leaks IN to the IAC.

While the engine is running,spray WD40/carb cleaner around the gasket area.

Any rise or fall in revs will indicate a leak

Good Luck !

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Wed 28 Apr 2010 11:46
Ford Fiesta 1997 - Ford Fiesta 1997 (Mazda 121) Revs Dropping - jc2

A Mazda 121 is front wheel drive so if your dealer is talking propshaft/rearaxle UJ's,he's useless.

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Wed 28 Apr 2010 17:33
Ford Fiesta 1997 - Ford Fiesta 1997 (Mazda 121) Revs Dropping - jc2

Or is it just the service receptionist???

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Sat 15 May 2010 14:14
Ford Fiesta 1997 - Ford Fiesta 1997 (Mazda 121) Revs Dropping - leigh88

Hi guys

Thank you so much for all your assistance. Sorry I am only coming back now but things have been quite hectic.

The IAC valve does have a gasket (like the cork ones), it is a rubber o-ring. I am not completely sure if it was replaced but I will get one from my local Ford dealer just to make sure. Shouldn't be too expensive.

I have one more question. How is the revs in my car determined? Is it determined mechanically by a cable that connects to the conrod as with older cars? Or is it determined by a vacuum in the engine? etc etc. The reason I am asking is that I think it will give me a good indication for where to look for the problem as well as that I will know if any mechanics are not as clever as they think.

I do agree with the possible air leakage. I will definitely try it out when I get back after the weekend.

Thanks for all your help so far.

Leigh

Edited by leigh88 on 15/05/2010 at 14:18

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Sat 15 May 2010 15:56
Ford Fiesta 1997 - Ford Fiesta 1997 (Mazda 121) Revs Dropping - jc2

The idle speed is controlled by the module which opens/closes the ABV/ISCV /IAC or whatever it's being called this week.The switch on the end of the throttle rod tells the module that the throttle is closed and the engine speed is then controlled by the valve-as soon as the throttle is opened,the engine speed is then a function of the throttle opening.

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