Ford Fiesta (1995 - 1999) - 98 1.4 Multiple misfire under load | Technical matters | Back Room Forum

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Thu 7 May 2009 20:51

98 1.4 Multiple misfire under load - Drwavey

I've already tried a few things but I'm struggling to figure out what is causing my S reg fiesta 1.4 v16 zetec to misfire and hesitate under acceleration and could do with some help. Thanks in advance!

The car seems a bit sluggish all the time but the misfire is especially evident under heavy acceleration such as on an uphill motorway approach slip road. The car will hesitate and not increase in rev's or speed and then is will suddenly kick in and accelerate ok. The hesitation continues to be very noticeable at high speed as the power seems to drop out a bit and then kick in again.

The EML light is not on but I have had it diagnosed - no errors showed. The mechanic said it was a multiple misfire at speed so I've changed the plugs (old ones looked good), HT leads (old ones seemed to show signs of arcing although the resistance was fine), and fitted a new coil pack. I changed one thing at a time and after each change there was an improvement but the problem wasn't solved and the improvement didn't last long.

Could it be a blocked/damaged Cat from the neat fuel as the misfire has been happening a while now, or an exhaust manifold leak or a faulty lambada or engine temp sensor? Or maybe a fuel problem? Or something else altogether?

Any help really appreciated - I'm not sure what to try next and can't afford to just change everything!

Dave.

Edited by Webmaster on 07/05/2009 at 21:06

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Thu 7 May 2009 21:00

98 1.4 MULTIPLE MISFIRE UNDER LOAD - bell boy

a quick co check at your friendly? mot garage would confirm a wrong mixture
you could also try dis connecting the maf on this car and see if acceleration improves its at the end of the air box trunking down on the right hand side next to the engine

this will store a code in your ecu but dont worry about it if if makes the car run better because once you change the component and then take the battery off for 20 minutes the code goes anyway

easiest way i find to see if the baffles have gone in an exhaust is go up a long steady incline hill build the speed up to 45/50 and then boot it and see if the speed builds up or does nothing at all

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Thu 7 May 2009 22:37

98 1.4 MULTIPLE MISFIRE UNDER LOAD - Drwavey

Thanks bell boy, I've just tried disconnecting the maf but found no improvement, it just makes the idle rough and it nearly stalls at the lights so I've reconnected it. Forgot to say I changed the air filter at the same time as spark plugs.

I'll try and get a CO check done asap and get back with the results.

The description you gave about testing baffles seems to be what mine does - it hits 50ish on a long steady uphill and then begins hesitating. If I try to accelerate hard it will hold its current speed and revs but not increase, it will kick and try and go and then it suddenly releases and accelerates away. If the baffles have gone would this cause the misfire by increasing the back pressure - wouldn't they have to be really blocked? Could this same effect also be caused by the manifold leaking?

Thanks again! Appreciate your help.

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Fri 22 May 2009 19:59

98 1.4 MULTIPLE MISFIRE UNDER LOAD - Drwavey

Ok well I've found out from my friendly mechanic that it's running lean - he reset the ECU and suspected it was a MAF problem. It's def not misfiring - only hesitating. I've just cleaned the MAF, but although there is an improvement in overall performance it's not solved the hesitation. Could it need a new MAF instead - not too happy about shelling out £60 just at a guess as it seems to me it could also be the Lambda, which is another £70 to just try and see if that solves it!

It seems to me that there is a blowing sound when I accelerate hard from a rolling start - typical roundabout scenario - there are no holes in the exhaust from the cat back, so is that likely to be the manifold?

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Wed 23 Jan 2013 18:22

98 1.4 MULTIPLE MISFIRE UNDER LOAD - precious

did you get this problem sorted I appearto be haing the exact same problem with my ford fiesta and have paid for the head gasket to be fixed, the camshaft but no luck!!!

An help will be very much apprectiated

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