Talk Morgan Forums Thread Like Summary - Help diagnosing Zetec running problem please

Hi,

I’m appealing for help please, as a very disappointed retiree from the Lands End Trial!

After thoroughly enjoying the first 8 hours of the trial with everything running well, my car began to lose power, and over the next 20 minutes it gradually worsened until I had just enough power to drive in first gear to the next village, and despite best efforts at the roadside, I had to retire and return home courtesy of Green Flag (who were superb btw).

My car is a 2000 4/4 1.8 zetec with Omex/ Jenvey TB’s and Librands exhaust. It was modified in 2017 and has since done over c20k, and ran absolutely fine for the first 8 hours / 150 miles or so of the trial. It starts and idles smoothly with no sign of misfire, and has enough power to move around in first/ second gear up to 1500 - 2000 rpm, but any more and the engine ‘bogs down’, as though choking for lack of air or fuel, best shown and heard in the youtube video link below:



I have several classics and modern classics and am fairly good with most things mechanical etc, however this one has really stumped me because I can’t get to the cause and it’s driving me mad! I am really hoping someone will watch the video, recognise the fairly distinctive symptoms and poor running, and even better recall what they did to fix it!

I have run through the usual checks, and so far tried new spark plugs, new coil pack, new leads, fuel pump and filter checked, confirmed fuel pressure at 45psi idle and under load, cleaned TB’s, checked Omex software for anything ‘obvious’ eg TPS (but I am not a tuning expert….), none of which has made any difference. The symptoms seem very distinctive, as seen and heard in the video, and are consistent. It doesn’t appear to be a sudden failure, and feels more air or fuel related as I can’t pick up any misfire on anyone cylinder. It fails smoothly, rather than losing power due lumpyness you tend to get if a cylinder is not behaving for fuel or spark reasons etc.

Next on list is compression test, possibly injectors change, drain and refill with new fuel….but not convinced the symptoms in video are what would expect even if had poor compression or valve issue..

So - hoping someone may watch the video and recognise the problem and solution so I can get going again, wondering how I missed something so simple…..

All help and ideas gratefully accepted.

Thanks
Steve

Thanks everyone for your thoughts, I am delighted to say the Gold Star goes to….Doug!

Just removed my cat and one core is intact, the second had broken down and was firmly wedged into the exit forming a nice plug.

New one ordered, may use the Omex log approach to work out why it degraded after just 20k miles…

Thanks again everyone!

My son’s escort once had a similar issue and that was a clogged up exhaust. ( cant recall whether baffles had come loose or whether it was a clogged cat.) Not sure it was as bad as yours sounds but might be worth dropping the pipe off to see if it makes a difference?

Still seems like fuel starvation though. Have you tried bypassing fuel pump relay/controller if there is one. This is not the main power relay (although worth replacing with Durite one) but the one near tank located under spare wheel area as here. If present its loom connector can have positive and ground feeds jumpered to bypass temporarily as below.

Contaminated fuel maybe? I agree, it doesn't seem to be ignition or mechanical.

Could the tank be pulling a vacuum & not getting air in to replace the fuel?

The answer is almost certainly waiting for you in your Omex ECU software, plug in and record a log, then methodically analyse the log from the comfort of your sofa.

As you're running ITBs the tuner would have set the ECU up to run Alpha-N, alpha representing the angle of the throttle butterflys (TPS) and N being engine speed (RPM) to give you a calculated approximation of engine load. You should therefore start by studying your TPS and crank position sensor signals in your log, if you're seeing erroneous signal data check your TPS and trigger wheel security and the condition of the trigger wheel, as well as the crank sensor itself and it's spacing to the trigger wheel.

When studying your log, also look at your ignition angle to confirm the idle timing and that the ignition timing is advancing as per your ignition table. I would also expect you'll be running a wide band lambda sensor, so you'll be able to view your lambda feedback in your log and easily establish if the engine is genuinely running lean? Also look at your injector durations (opening times) in your log to make sure they're moving up and down in line with engine speed and throttle position following your fuel table.

Finally, and if everything checks out as good in your ECU log, the trigger wheel condition/security and crank sensor to trigger wheel spacing are also good, whip the timing belt cover off and check your belt tension, then check your valve timing to make sure the belt hasn't jumped a few teeth, the Zetec is not an interference engine.

Fault finding is all about methodical diagnostics, don't just guess the issue is fuel starvation, let the data reveal the true fault, and the good news is our Omex ECU makes this easy.

Good luck with it

Dave.

Great news

However, as you rightly say, why it degraded after just 20k miles is the important question here?

If the engine has been running excessively rich the unburnt fuel will have built up in the cat, and when that fuel lights off it'll create a rather effective kiln which will soon break down a cat matrix, I've seen catalytic converters glowing cherry red when this happens.

The Omex logging feature will help you confirm or deny an excessively rich condition 'lambda feedback', it'll also immediately show if your lambda sensor itself is working? Keep in mind an excessively rich condition will quickly contaminate a lambda sensor leaving the ECU to fall back on the open loop fuel table, which itself may have been calibrated on the rich side.

Also, check the 'fuel cut on overrun' feature is active, typically this is only active above 2,000rpm to avoid drivability issues, but if its never been activated at all you can end up flooding your cat when you lift off the throttle, especially if the fuel table has been calibrated on the rich side in the decel/low load cells.

It's definitely worth spending some time investigating the route cause of the issue, and before you cook another expensive cat