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zetec pcm woes


debushau

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I have a US spec Caterham 7 with a 2.0 Zetec and I am becoming frustrated with a continual electrical problem that a persisted over the past few months that I have been unable to remedy.

 

When I originally put the car together, I had lots of problems getting the computer to switch on - in the end I think it was a case of not tightening up the screw on the connector and the computer came into life. This worked fine for a few months until the car began to cut out while driving just for an instant (this was the subject of a prior email). I tightened up this connector again and shook some wires and the car seemed to be ok again. After a week or two the computer refused to come on at all. After checking the connections for the umpteenth time, I opted to plug in a used pcm (direct swap - same model number). After hooking up the new computer, the car started again and all was well with the world until I visited the car last weekend (in its winter storage) and the same old problem - no characteristic "bleep" from the computer, the starter turns but no spark,fuel pressure is there.

 

I am trying to figure out what this might be - my guess is that the pcm is probably ok (and the original is ok too), perhaps it could be an ignition problem (though the starter turns?). The obd II code checker I have cannot connect with the computer. I have taken the cover off the harness connector are there are no loose wires apparent (though there are 50 or so and if one was pulled out a bit, I'd never know).

 

Any suggestions?

 

thanks,

 

Shane

 

 

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Shane,

 

I had a ton of electrical problems with my U.S. Zetec (standard Ford ECU) before I finally realized that I had to ground a few extra pins.

 

Two questions:

What ECU do you use?

Are all harness contacts to the spedometer, cam sensor etc in use, or do you have some dangling bits here and there?

 

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Magnus,

 

I use the 98BB-BXA ECU. There is a dangling speedometer sensor that Caterham said was unused, I think it's the speedometer to ECU connection - apparently Caterham just wire the speedo directly to the hall sensor so this piece of the harness is not used. That's about the only thing - apart from the usual evap canister error - but it's hooked up.

 

Shane

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I'll give that a go next time I go to its winter storage. You just spliced a ground into the ground wire leading to the connector? I guess since I'll never need the connector, I could just hack if off.

 

The car will, on occasion, fire and it worked just fine last summer for 3 months but since then seems to run only when it feels like it. I would be delighted if this is the solution.

 

If this is an issue Caterham USA should be aware of it - I had spoken to them last year and got the distinct impression that this dangling bit did nothing. Plus, I don't really understand why they use an auto box ECU.

 

Shane

 

Edited by - debushau on 13 Jan 2003 18:13:36

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I tried to ground the black lead of the speedometer contact after noticing that not all the GND pins in the monster connector to the ECU where actually grounded. These pins were, however, hooked up to GND of the speedometer contact. Grounding this point thereby grounded the pins as well. It took me ten hours with a Fluke and wiring diagrams to figure this one out.

 

You could probably just cut off the speedometer contact. I cannot remember if I did it or not.

 

I blamed the fault on the early revision of my harness, but we should drop a note to Rocky Mountain Sportscars if more people stumble upon this problem.

 

The reason for having a standard Ford ECU is that you can use the standard Ford intake system. I have this setup with racier intake cams in order to get 175HP. The whole thing is, however, a non-optimal solution since it restricts the airflow in a bad way. I'm saving up for real intake ports and a better ECU.

 

/Magnus F.

 

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