Fiesta MK4 1.25 misfire

[jb516079]

Hi there, newby here.

I have a 1997 Fiesta 1.25 Zetec that misfires after about 3500 revs as I excellarate through the gears, I can only decribe it as "it's like the car has a rev limmiter".

The car revs fine when stationary and in nutral its just happens when I'm driving in all 4 gears.

The car starts up fine and all the plugs look ok with a light brown colour.

Please help

John

[swampduck]

Hi there, newby here.

I have a 1997 Fiesta 1.25 Zetec that misfires after about 3500 revs as I excellarate through the gears, I can only decribe it as "it's like the car has a rev limmiter".

The car revs fine when stationary and in nutral its just happens when I'm driving in all 4 gears.

The car starts up fine and all the plugs look ok with a light brown colour.

Please help

John

hey up , assuming you ve no warning lights lit up ,ie, engine management , then start looking at the simplest things first. the missfire is "under load" as in when your driving , not just reving at the roadside , try plug replacement , even if the colour looks good , then leads , coil , etc . if no joy go along the possibly weeping head gasket or sticky valve ,damaged rings route, but i m sure its not that serious . cheers aidan <_<

[jb516079]

hey up , assuming you ve no warning lights lit up ,ie, engine management , then start looking at the simplest things first. the missfire is "under load" as in when your driving , not just reving at the roadside , try plug replacement , even if the colour looks good , then leads , coil , etc . if no joy go along the possibly weeping head gasket or sticky valve ,damaged rings route, but i m sure its not that serious . cheers aidan <_<

Ok thanks for the reply and yes no warning lights on at anytime.

I was hoping for a cheap fix and not changing everything to find the fault £££££.

I have read that the "Coil Packs" go often so should I start there and I am I correct in saying that a misfire is either spark of fuel.

The car has done 107k miles and I dont know when the plugs where changed last, they are Motorcraft and the gap was over 2mm, I have now set t 1.3mm.

I must say they look fine so did not want to spent £16 at Halfords only to find I still have the fault.

Look forward to any replies.

[jb516079]

Come on chaps I need some help here, it's Sunday morning and I'm ready to fix this misfire problem but dont know where to start. Please look at my post yesterday as I have not got deep pockets to go buying every thing to diagnose the fault so some guidance needed please.

Also as a newby I was expecting to search the forum to find others who have had simular problems, I cant find anything - am I doing some thing wrong?

I log in, go to Fiesta and type in the search window "Fiesta misfire"

please help I want to fix this today.

regards

John

[jb516079]

Still no replies, there must be some teckies out there somewhere.

[gaz6076]

Cheapest option to start with is plugs. Then the leads and coil pack.

Without a code read its very hard to tell

[jb516079]

Well it's fixed and it's no thanks to this web site I'm sorry to say.

If I had followed the advice of the guys on this site I would have spent out nearly a £100 on Plugs, Leads and Coil Pack and still had the problem.

As I had no useful advice (plugs, leads, coil) I spent Sunday night surfing the web and found one guy who had had a simular problem who by disconnecting the MAF sensor found the fault went away.

So on Monday I disconnected my one and hey presto car runs fine, I then removed it to give it a clean as aparently this is common on Ford Scorpio's. The MAF sensor is just after the air filter box and is very easy to remove, I went to Halfords and purchased some brake cleaner although Carb cleaner will do just as well and used this with a cotton bud to clean the 2 elements.

I have pasted below the quote from the Scorpio guy which is a bit more techie.

Good Luck

John

I don't know if the Fiesta MAF sensor is a hot wire type, but I have a Scorpio for which problems with these sensors is a known issue. Although the sensor is after the air filter, we have found them to pick up residue which burns on and causes a false reading. An incorrect reading in this manner would not produce a fault code as such, but the fuel trims will be wrong, giving poor running.

Have you tried cleaning the sensor? (Again I'm assuming it's the same type). They are VERY delicate, but we've had a lot of success using carb cleaner. This is available from any motor factor in aerosol form, and sprayed into the sensor will clean the wire up a treat. Make sure it's a residue-free type. Disconnect the battery after cleaning, this will reset the EEC, and the trims will be recalculated immediately.

Worth a try before you buy a new one.

HTH,

MarkP

[chas]

Well it's fixed and it's no thanks to this web site I'm sorry to say.

If I had followed the advice of the guys on this site I would have spent out nearly a £100 on Plugs, Leads and Coil Pack and still had the problem.

As I had no useful advice (plugs, leads, coil) I spent Sunday night surfing the web and found one guy who had had a simular problem who by disconnecting the MAF sensor found the fault went away.

So on Monday I disconnected my one and hey presto car runs fine, I then removed it to give it a clean as aparently this is common on Ford Scorpio's. The MAF sensor is just after the air filter box and is very easy to remove, I went to Halfords and purchased some brake cleaner although Carb cleaner will do just as well and used this with a cotton bud to clean the 2 elements.

I have pasted below the quote from the Scorpio guy which is a bit more techie.

Good Luck

John

I don't know if the Fiesta MAF sensor is a hot wire type, but I have a Scorpio for which problems with these sensors is a known issue. Although the sensor is after the air filter, we have found them to pick up residue which burns on and causes a false reading. An incorrect reading in this manner would not produce a fault code as such, but the fuel trims will be wrong, giving poor running.

Have you tried cleaning the sensor? (Again I'm assuming it's the same type). They are VERY delicate, but we've had a lot of success using carb cleaner. This is available from any motor factor in aerosol form, and sprayed into the sensor will clean the wire up a treat. Make sure it's a residue-free type. Disconnect the battery after cleaning, this will reset the EEC, and the trims will be recalculated immediately.

Worth a try before you buy a new one.

HTH,

MarkP

[chas]

Hi there, sorry you were unable to find help here, there were some teckie guys around here recently, have to say I've not found much help with a recent queiry, then again I have an oldie fiesta (1997) that I use daily (when I can). Maybe the bulk of the people on here are fiesta fans and not fiesta maintainters

[gaz6076]

Sorry my advice wasn't helpful. Like I said it would be hard to tell without a code read. Never heard of the MAF (Mass Air Flow) sensor causing such a problem but you learn something new every day I guess. It will be one to remember in future.

Just goes to show you what a bit of googling can do...

[JonLa]

Hmm. What exactly is a misfire?

My 2000 Fiesta 1.25 is struggling a bit at the moment - might be the same thing - it judders a bit in the middle gears, and when braking or accelerating. The clutch bite point seems to be a bit higher too, but otherwise it feels like the car is straining a bit. Thought it was the exhaust, which was knackered anyway, but a new exhaust hasn't fixed it..

Edit: just looked up misfire, that's not what's happening, sorry to hijack thread...

[dontknow17]

Hi everyone,

Im looking at buying a mk3 1.3 fiesta, extremely cheap, the seller has no mechanical knowledge or experience atall and its an MOT failure. i can fix everything except the running problem....

could it be the same problem as described on the mk4 1.25? its rough on idle and is misfiring and running extremely rough under load. spark is strong, fueling seems ok and i dont think the jets are blocked....its carbed so fairly straight forward in that respect. the engine has 101k on it but has only been driven by old ladies and the seller (50 year old man driving the daily commute of 10 miles each way) so i wouldnt think it has been hammered.

please help???

Thanks

Elliott

[parkodrive]

Could this issue with the MAF cause poor fuel consumption? I'm sure my '98 1.25 16v is doing far less than is should but I dont know for certain as the gauge may or may not be busted. I do however expeience similar issues as the OP.