Smithlaaa

I've had a consistent problem with an engine management light for the last 3 months, I've had 2 different mechanics look at the problem and not one has been able to fix the issue so I'm desperate for some expert advice or somebody who may have experienced the same issue!!

It all started 3 months ago when I had a coil pack break down on me, engine started to run like a bag a crap and had coil pack replaced along with new leads and spark plugs - problem solved and car back to driving normal.

About 4 weeks later, my engine management light came on but with no real symptoms other than the engine felt like it may stall when idle but very infrequent, other than that the car drove fine. Had the EML fault code read by a mechanic and he recommended replacement lambda sensor, I replaced the sensor and reader came back with a different code:-

- P103 - Mass Air Flow Circuit (High Input)

Next recommendation was to replace the MAF, which I did, issue still not resolved and the problem is now getting worse and worse by the week.

The car now runs really rough at idle most of the time (stalls quite frequently but not all the time). When idling, the engine begins to "hunt" and the revs increase/decrease every second along with headlights and dashboard bulbs dimming in time with the engine "hunting", it tries to sort itself for around 15 seconds and then finally stalls - I start the car up again and no initial problems, when engine gets hotter after another drive the same issue re-appears.

I've had two more suggestions made to me for replacement parts but the expense is starting to get too much, it may be time to ditch the car but I want to try and rescue it one more time as I do love the car, somebody has suggested either Idle speed control valve or catalytic converter? When you listen to the back end of the car whilst the engine "hunts", you can hear the exhaust pipe making a slight popping noise, other than that there's an occasional misfire whilst driving but relatively fine to drive with no serious issues - only at idle.

Any suggestions?

(P.S. - Also replaced Throttle Position Sensor in an attempt to resolve another issue - no luck!).

Cheers,

Craig

oldford

What fault code is present at this moment?
Did you use an original maf sensor or aftermarket?

Smithlaaa

The same fault code is present, P103 - Mass Air Flow Circuit (High Input). I didn't really specify whether I needed an original or aftermarket MAF to the parts shop, I believe it was an original ford part as the top plastic housing of the MAF sensor itself had Ford logo imprints and a ford part number.

I forgot to mention that when the original mechanic fitted the MAF the plug didn't fit correctly and he therefore had to cable tie the plug into the clip housing itself, there was good contact on the pins but the plug edge seemed to be too thick for the clip housing, hence the cable tie. The EML disappeared (as usual after being cleared) for around 4 hours of driving, then the same light re-appeared.

I noticed today when parking up and leaving the engine running that when the engine begins to "hunt", whilst watching the exhaust and catalytic converter from underneath the car they seem to shake in time with the engine hunting, the best thing I can describe it as is if there's too much pressure, the car eventually stalls as usual.

oldford

The fault code P0103 is normally set when the voltage on the signal line is very high.
Depending on the actual system this is usually around 4.5 or 4.6 volts.
That kind of voltage normally cannot be reached when the enige is idling.
So, you're probably looking at some wiring fault or a defective ecu.

The plug for the maf sounds suspicious and is a good place to start investigating.

Smithlaaa

Oldford, cheers for the input so far - much appreciated.

Stuck a multi-meter on the battery last night and running at between 12v - 12.5v within engine off, when engine idling it was running @ 13.8v - 14.1v, looks normal to me? What do you think?

Interestingly, I pulled the MAF plug when engine was idling and started to "hunt" quite violently, it stopped immediately and engine was rescued from stalling, engine began to compensate from lack of air flow measurement and ticked over @ a higher rate but no more "hunting".

How do I go about testing power input to MAF plug? I can't probe the back of connectors as I'm guessing that could damage rubber cable bungs, right? I don't have a wire-piercing probe so would I make a small incision in the wire and test, then cover with electrical tape?

Cheers.