Fiesta starting problems

Your going to have to do alittle investigation and tell us whether you have a spark and fuel from the injector when the engine wont start- there are too many possibilities without knowing this. Its definately temperature related, and these CFi cars are fraught with problems!

Possible faults could be:

Simple poor connection / dry joint in fuse or relay. poor connection on fuelling or igntiion side. faulty air temp or coolant temp sensors (quite likely- but you dont report any other running problems) faulty crank sensor.

Tim..

Tim,

Thanks for the reply. The coolant temp sensor was changed a while back when I suspected that might be the cause of the problem, but to no avail. It's been one of these awkward things that when you take it to the garage it starts fine. It's only recently became apparent that between 90 mins and 5-6 hours of inactivity causes the problem. There is a running problem in that the car jerks and shudders a bit in high gear at low(ish) speeds. This is very similar to a problem I had with a Rover a few years ago and it was diagnosed as being a misfire caused by the valves sticking, most probably caused by doing short journeys. Since i'm still doing the short journeys I suppose that could still be the case. Another odd thing happened the other day. I stopped at the garage to buy a paper and when I came back and turned the key in the ignition it was absolutely dead, as if the battery had been disconnected. A few more turns proved fruitless so I popped the hood for a look, gave a few wires and terminals a wiggle to make sure they were secure, which they were, jumped back in and it started no problem! Very bizarre. The car's going in for a service and MOT next week so i'd like to pass on any advice to the mechanic that I can.

Colin

Well a dead electrical system altogether is fairly easy to trace- especially when its dead! Sounds to me like you need a systematical approach to checking / undoing / cleaning the main feeds and earths starting at the battery and working through- dont forget the engine to chassis earth strap(s) too- these are often the cause of all sorts of weird problems.

Pull out the igntion relay, fuel pump, and main relays from the fuse box and replace carefully, and engine related fuses, and i'd also pull off the steering column shroud and check the multiplug which feeds the ignition switch.

As for the running problem- these CFi engines never run that well at the best of times- the low speed hesitancy is most likely a gummed injector (very common) so have this ultra sonically cleaned (properly) first, and then move onto ensuring the engine is reaching full temperature, and checking the resistances of the coolant and air temp sensors from cold to running temperature.

If after that its still just as bad, then you need an accurate fuel pressure gauge and tweak up the line pressure afew psi- as they usually run weak.

Tim..

Single point injection on this one......Give a lot of problems....I have replaced numerous charge units... Also.... The loom of wires leaving the fuel charge unit are all together in a bunch.... 4 different units in there.... well..... if you follow this loom where they cross the Speedo cable you may find the loom chaffed through and one of the wires making ground via the inner of the cable.... approx 10 or

JK

I had similar problems with one of these, when it was in its no start condition I found that by removing the fuel pump fuse I could get the engine to momentarily start, then with the fuse replaced you could coax it into life. This showed that the vehicle was overfuelling. The cure was to add a small resistor across the coolant temp senso which makes the cfi system think the vehicle is warmer. This worked perfectly to cure a difficult problem, an AA bod in their workshops passed on the info.

So, if your vehicle can be coaxed into life by weakening the mixture as I describe it would be worth trying a resistor, I can't be sure of the value off hand (I will check tomorrow) but try about a 100 ohms first, as far as I know it cannot hurt even if the value is wrong.

MrCheerful

Thanks very much for all the advice - much appreciated.

About the running problem, would adding 'redex' or something similar into the fuel tank help the possible gummed injector? Or is ultrasonically cleaning the only option at this stage? How much would something like this cost? Given the age of the car i'm reluctant to spend too much cash on it.

Colin

A valid work around- though usually the root of the problem with a car experiencing this problem is the air temp sensor in the air filter case being up the spout. These cars quite commonly spit back through the intake and it only takes acouple to fry the sensor giving you the flooding when nearly cold symptoms.

Tim..

Some further info on the saga .........

The car has started cutting out, usually on the approach to roundabouts, traffic lights, etc. but it would start again fairly quickly until a couple of days ago when it just wouldn't start again. Decided to call out Direct Line rescue since i'm paying the annualy fees to see what they had to say. The guy checked I was getting a spark from the spark plugs which was fine, then he announces that the ignition coil was gone and not producing a spark. Is this possible? Anyway, I took him at his word and got towed home. Next morning I decided to turn the car over just to see, expecting it not to start if the ignition coil was gone. Car started first time as has been the pattern recently. Now, i'm not sure, but I would assume if the ignition coil was gone then the car wouldn't start. Is that the case? After reading some other posts the cutting out problem seems to be commonly linked to the throttle position sensor. Is it at all possible that this sensor could be causing the starting problems as described earlier? The car's going into the garage tomorrow for an MOT, but my mechanic has no diagnostic equipment to check all the electronics. I understand that he could check voltages and current, etc. on the sensors. Is this a sensible thing to do? Cost of a new throttle position sensor is £77.12 + vat.........ouch!

Thanks,

Colin

NO! A faulty TPS will not cause a no start situation. Either you will have stalling or idle stuck high.

If the coil pack was faulty you wouldnt have a spark at plugs at all. Period.

Go back to what I said in the OP and investigate the crank angle sensor and or connector.

Tim..

Tim,

Changed the crankshaft position sensor and the car now starts no problem and is running fine.....but......failed MOT. CO emissions were high, 4.83% when they should be less than 0.3%. One or two other mechanical problems - rear shocker, brake discs and brake pipe are all needing attention, as well as some welding under the sills. Total cost for these works is in the region of £220. My mechanic has then suggested a ford diagnostic to source the cause of the CO emission problem, rough cost of this will be around the £50 mark. Adding it all up I reckon I'm looking at a repair bill of around £400 and the car isn't even worth that. I'm thinking the cat might even be damaged due to some backfiring when it was having the starting problem.

Sod's law - the car is now driving great, but I'm going to have to scrap it for a new one. Bummer!!

Thanks once again for the input and advice.

Colin

Well, even with a failed cat, but otherwise working o2 sensor and engine management, the co emissions shouldnt be anywhere nr 4.5+%, so you have a running problem to find and fix first. Are you sure the engine was as hot as it will go when it had the emissons test?

Tim..

The emission test results were as follows:-

min. max. Fast Idle Test Fail Engine Speed Pass CO Level 4.84% Fail - 0.30 HC Level 322ppm Fail - 200 Lambda 0.89 Fail 0.95 1.09

The engine wasn't running as hot as it would go, I'm quite sure of that, but looking at those results it's hard to see if it would have made a great deal of difference.

Tim, if you don't mind me asking, what's your profession? Your intimate knowledge on these matters is most impressive.

Cheers,

Colin

Well, I guess I could be termed jack of all trades and master of none. I worked for Ford in their electronics R&D dept for acouple of years, then did some work on turbo charging the 2 litre Zetec for rallying in the Focus before cosworth took it on, then moved to be a mysteryshopper for Volvo concessions, Now run a small "tuning" outfit. on the side. This covers electronic diagnostics, diesel tuning and the like. I have a passion for cars and electronics, so this marries the two together. We see various vehicles in with fairly unexcitting problems, and after a while the troublesome ones soon make themselves apparent! Ford CFi's spring to mind!

Going back to your car, at the time of test it was running quite rich- as it might 3 or 4 mins after cold start- so how warm was it, and is the thermostat allowing it to get to operating temp- i.e. 85-95 degrees C.

If it is warming up properly, then we need to address the coolant temp sensor and the fuel pressure for being in spec.

Tim..

Tim,

Well now........don't suppose you offer a mobile tuning service to Glasgow.;-) I am in a bit of a quandary I have to say. With the level of expense expected to get the car through the MOT I had more or less resigned myself to getting a new car this weekend. But with the starting problem/ cutting out all but eliminated, I'm totally bemused as to the best course of action. Spoke to my mechanic this morning and asked him if he thought giving it a good thrash on the motorway for half an hour before testing the emissions would make a difference and he reckoned it wouldn't do much. However, he did suggest if I wanted to he could hook it up on Monday morning and see what the reading was. Being without a car though is something I can ill afford, hence the decision to get a new one this weekend. I tell you, if that crank sensor hadn't worked it would have made the decision a LOT easier, but it's now running better than it ever did. I'm sure the car is warming up properly, it just never gets a really good long run. I'm only 5 miles to work and most of the journeys are just short hops to work, school, shops, etc. I replaced the ECT sensor last year in a vain attempt to cure the starting problems. Among other things you actually advised replacing the crank position sensor over a year ago to me, but since the car was always eventually starting I didn't bother chasing around and replacing all the sensors. If only I had!! Your advice is definitely valued, if you were in my shoes what would you do?

All the best,

Colin

I tell you, if that crank

If I was in your shoes, i;'d have had the car on the computer and exhaust analyser and determined the problem within afew minutes!! It will probably cost you £60 tops to repair, assuming as I think, its a simple sensor problem.

A good thrash on the motorway can do a world of good- asssuming the engine is in good mechanical order, valve clearances, fresh clean oil etc, so its worth a try- you have nothing to loose.

An indication to running temperature- the gauge should be reading around 1/3 to 1/2 way into the N-O-R-M-A-L section. Anything below and we're going to be getting a thermometer out and check the old fashioned way- dip it in the header tank at a point when the gauge stops rising any more. If its not warmed up to ~90 degrees your wasting your time going any further. Another indication of an engine which isnt warming up is a stuck high idle speed. What was the natural idle speed on your emissions certificate?

We never actually got passed the first fast idle test - the car cut out at the start of the 2nd fast idle test. After this he changed the crank sensor, hooked it back up again and was getting similar readings to the first test. After that he called me to give me the good news. You say probably around £60 to repair but this is of course after a diagnostic which will set me back around £50. Added to all the other problems i'm pushing 400 quid and I just don't think it's worth it, especially considering the strain i've been putting on the starter motor and battery recently. The MOT has actually expired as well and a neurotic wife is aghast at the idea of me driving around with the car in that condition. The temperature gauge seems normal as you describe as well.

Colin