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Zetec running rough/rich, missing


catsv7

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I recently purchased a pre-owned Caterham SV (2002 build?). It is missing under acceleration, backfiring under throttle lift, the tail pipe is black and there is the smell of raw fuel.

 

I have no build documentation for the car. It does have 2.0L Zetec with TWM throttle bodies and pectel ECU. The was in storage for ~7 yrs (guessing) and had sta-bil in the fuel tank. The fuel tank was drained and filled with fresh fuel and injector cleaner. The alternator is producing 13.5v.

 

I do not have a the pectel interface cable or Descpro software. I am looking for help/suggestions to troubleshoot the problem.

 

TIA

Greg

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I would send the injectors to RC for cleaning. They will also replace the filter screens and make sure they are all within spec. About $100 with a very quick turnaround. I would also replace the fuel filters and any rubber flex lines (if installed).

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Try cleaning off the spark plugs with brake clean and a wire brush, then run a tank or two of fuel injector cleaner. A bottle of combustion chamber cleaner may help too, if there is any carbon build up on the valves and pistons.

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If it is unknown that the car was ever set up and ran properly, I would not discount the possibility that the ECU setup is more or less screwed up.

But cleaning injectors and replacing the fuel lines would not hurt and if the problem does not go away a dyno session may be required.

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If the engine control unit is open loop and the car was tuned for a lower altitude it would run too rich. The recommendation for RC Injectors is a great one, my order of issues would be:

1. Is control program open or closed loop relative to O2 and where and how was it last tuned and does it only need a retune?

2. Since it is running rich it would seem to be getting enough fuel, but the fuel may not be properly atomized by the injectors.

3. Sensor that times injection pulses ( on the Ford ECU that is the cam position sensor)

4. Sensor that fires the spark plugs (on the Ford ECU that is the crank position sensor)

5. Plug wires and or coil.

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Is your pressure regulator working as it should ? if you don't know what your base line fuel pressure is supposed to be, it may be difficult to tell where you need to be. On my Zetec I run an AFR gauge to allow me to monitor how my fuel delivery is doing. By the way, I've been running the stock Ford ignition coils since day 1 and have never had any issues. I know some have but I haven't but my car only runs on the track as I don't drive it around town. If your camshaft position sensor isn't working properly, your ECU may go into a safe mode and provide richer than desired fuel to be safe. I know the engine won't run without the crank sensor but it will run without the cam sensor. Too bad these cars don't have an OBD-II port system to self diagnose these issues.

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"missing under acceleration, backfiring under throttle lift, the tail pipe is black and there is the smell of raw fuel"

 

iGNITION OR FUEL SYSTEM -- a thousand dollar question.

I'm leaning towards ignition. Cheap troubleshooting is to replace the sparkplugs - if not, then wires....I will start with that.

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  • 2 weeks later...

I just wanted to given an update. I hva been making progress bit by bit. I have replaced items in the following steps.

 

1. the spark plugs, ignition wires,

2. camshaft position sensor,

3. alternator, and crankshaft position sensor.

 

With each step I got a noticable improvement. Fuel injectors are working but probably need to be sent for maintenance.

 

Thanks for everyone's thoughtfull suggestions

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If your in open loop it doesnt mean your ECU has been messed with or that your ECU is bad , something as simple as a bad 02 sensor can cause your ECU to go open loop

The cam position sensor isnt what tells the injectors to fire , the cam position sensor doesnt have be hooked up ( non VCT ) for the engine to run perfectly fine

 

What ECU are you running , if stock do you have or know any one with a SCT XCAL3 or XCAL4 ? If you do I will be happy to look over some logs for you

 

When was your front o2 sensor changed last , for an over fueling / fueling / misfire issue that would be the first thing I would check/log

 

Tom

Edited by 1turbofocus
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catsv7: If you don't know, 1turbofocus (AKA "TurboTom") is one of the elite Zetec tuners/modifiers in the US, having done many 1000's over the years. He is currently assisting my mechanic in resolving my Zetec's problem with poor running and going lean over 3500 rpms.

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Greg,

 

Eric at Quicksilver Race Engines in Frederick Md redid my motor with the same basics. (301-698-9009) He might be of some help as they were a Pectel dealer at one time. I have a map on CD somewhere. If I find it and can copy it off I can send it to you if you think it could help.

 

FWITW: My car has always run rich and smelled. However, it has not had a cat converter since the addition of TBs pistons and cams.

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Thanks for everyone's help.

 

Progress has been slow on my part.

 

I finally got a interface cable to the Pectel T2 ECU. I tested the cable with the DeskproW software and confirmed that software recognized the ecu. I don't have a local contact with someone using a SCT XCAL3 or XCAL4. I have new O2 sensor but I have not installed it. I did check the exhaust back pressure just to make sure it wasn't horrible, it was bouncing on the gauge a lot at 2500 rpm, I had more than 3ft of tubing from the bung to the gauge, the average value was ~1 1/4 psi.

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  • 3 weeks later...

More progress ...

 

1. I replaced the ignition/coil pack .... no measurable change.

2. I got a new DMM and re-measured the fuel injector impedance .... they are all low at ~2.5 ohms and consequently a miss-match for the Pectel T2.

3. I plumbed in a fuel pressure pressure gauge, it was reporting ~54 psi at idle

4. I got a LM-2 and measured the lambda at idle as 1.25, I raised fuel pressure regulator setpoint to 57.5 to get lambda to a safer value of 1.15

 

I need to replace the injector with a high impedance kind .... any suggestions/experience?

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I would call Pectel and ask if there ECU cannot run both Low and High Impedance , I know for a fact some of them can just dont remember which ones it is

 

Your fuel psi is way to high , Zetec should be 39-41 psi MAX at idle with the Vac unhooked from your PSI Regulator , You never want to raise the fuel psi to aid in proper Air Fuel

I dont know all the mods you have but easy to get 30lb Inj from the SVT Focus or Mustang and those will safely get you to 190-200NA to the wheels

 

Tom

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1turbofocus et al,

 

I have contacted Cosworth and they confirmed that low impedance injectors are not compatible with the Pectel T2 (the ecu I have). I have 30 lb high impedance injectors "in the mail" so to speak. Thanks again for everyone's continuing interest and input.

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  • 2 weeks later...

Update from last weekend

 

I put in the new 30lb high impedace injectors, drained the old fuel, changed the fuel filter, put in fresh high octane fuel. Another Caterham owner with the same ecu, TB and engine setup as I provided ECU maps to try. Then ….

 

1. First, I started the car with the old maps … it ran worse than before, AFR at idle >22, running rough. Trying to accelerate engine motor just cause it to quit.

2. Second, I load in the new ecu maps. I was doing some basic checking of the maps and noticed the TPS table lookup was reversed from my map. Probably just a matter of method used to wire the sensor. So I created a new version of the map with the TPS table from my old map.

3. I loaded the revised ecu map into my ecu and started the car. It runs very well, no more rough idle, AFR at idle ~12. A short run up and down the street had smooth throttle response, and responsive, no more back firing on throttle lift and AFR’s ~13 at 35 mph.

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