PSpirine
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| posted on 26/11/12 at 10:13 PM |
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Help with Fiesta Diagnosis?
Colleague at work asked me to look at her car because of the following symptoms.
"Choking/stuttering under load"
"This morning when I started the car, and turned the heater and headlights on, engine stalled. Only ever did this once and didn't
repeat"
Car is a 2004ish 1.4 Zetec Fiesta (5 Door).
I had a look at it this evening. Ran the self-test on the cluster for some diagnostics:
Got two DTC codes, E510 and D262, both of which seem to just indicate comms faults (HEX translation to U1262 and U2510), and are fairly common.
Definitely nothing engine related. No other dtc's logged.
At first I thought it might be a duff battery. With ignition on, it's at around 11.9V. Switch EVERYTHING on electrical and it drops to about
11.3V. 14.0V when engine running at idle. So looks like the battery is weak, but don't think it's causing the problems, even though it may
be making it worse. Even after draining it for a while, car springs to life with no problem.
When driving, it has a low-rev misfire/flat spot when under load (i.e. up a hill, 1800rpm in fifth or fourth, it jerks quite badly). Less pronounced
at higher revs but slightly noticeable around 3500rpm as well.
Once I managed to recreate this on demand, after about 5 seconds of continuous stuttering, the Check Engine light comes on (flashing), but disappears
about 10 seconds after the failure mode is stopped (i.e in normal driving). No additional dtc's logged onto the self-test.
So.. with that in mind I'm thinking it could be:
- MAF
- Ignition leads
- Coil Pack
- Fuel/Air filter
- O2 sensor
A quick look under the bonnet reveals there is no MAF on this car (unless it's very well disguised, so it rules out number 1!)
What are your thoughts? All of the above are easy to swap so I'd do the work for her, but coil packs are pricey I understand, and an O2 sensor
is 2nd costliest. Do I start with the cheapest and work up (filters will be a tenner, ignition leads about £25), or does this definitely sound like a
coilpack/o2 sensor?
Also, am I right in guessing that running a proper scanner on it may reveal engine DTC's which aren't shown on the self-diagnostics?
Thanks,
Pavel
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needforspeed
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| posted on 26/11/12 at 10:21 PM |
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coilpack plugs and leads. can check if the lambdas switching properly with your diag equipment or a multimeter. bit strange it cutting out on first
start up tho unless it was missing on startup?
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Davegtst
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| posted on 26/11/12 at 10:36 PM |
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Pull the ht leads off and check the wells aren't full of water from the washer jets or oil from the rocker cover leaking. Used to be very
common on these. If there is any water change the leads and plugs.
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PSpirine
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| posted on 26/11/12 at 10:47 PM |
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Thanks chaps, I'll have a look under the cover (can't get to the leads without taking half the intake off!) when I've got some
tools.
On the plus side, it appears a set of Bosch leads and a coil pack only come out to about £60 which is less than half what I was expecting.
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britishtrident
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| posted on 26/11/12 at 10:50 PM |
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The MIL is illuminating because a misfire is being detected.
It really needs a proper diagnostic scan that reads live data and pending codes but it looks like Coil packs + Plugs & leads and I am
pretty sure the battery has dead cell that will really cause serious starting problems as the temperature drops. A dead cell can be tested for
with a cranking voltage test or using a high load volts drop tester.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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PSpirine
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| posted on 26/11/12 at 11:01 PM |
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What should I expect cranking voltage to be? Fortunately the car has a voltmeter as part of its on-board self-diagnostics (the trip reset trick) so I
can read live voltages quite easily. Can disconnect ignition coil whilst cranking to get a decent reading.
In fact I can read a surprising amount of data off that thing including lots of engine sensors. I've only got a VAG scanner at the moment though
(my more generic OBD2 one hasn't arrived yet  so can't read off any more DTCs)
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britishtrident
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| posted on 27/11/12 at 09:01 AM |
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It is best checked with a DMM or other separate voltmeter including those LED gadget that are sold by Maplin, BM Bargain Stores or eBay.
It should be able to crank for 20 seconds without the voltage dropping below 10v most engines will maintain 11v during this test. If it shows below
9v something is wrong.
If the battery has a dead cell the voltage drops almost instantly to to 6v -- it may slowly rises.
If the voltage drops slowly to 8 volts or so it generally indicates it indicates the battery has a low charge, this can be for various
reasons.
[Edited on 27/11/12 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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PSpirine
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| posted on 27/11/12 at 09:46 AM |
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Thanks BT, I'll measure with my multimeter.
Pretty sure it doesn't drop down to 6v or anywhere near that bad (you can usually tell by the headlights..)
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ian locostzx9rc2
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| posted on 27/11/12 at 06:05 PM |
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Battery is weak if showing less than 12v should be approx 12.3v or above with ign on so will more than likely need a battery weak battery causes lots
of issues.Plus check for water around plug leads lots of cars going through standing water to quickly have had 2 cars in w/shop today one dryed out ok
the other one dryed out but shorted a coil out so had to change the coil pack. coil pack and leads very common on fords....
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