Zetec SVT problems

[breezy7]

I have been having problems with the SVT engine in my Caterham. The car starts and idles fine but seems down on power and gives a bucking effect at higher RPM that makes the car undriveable. There are no engine codes other that the usual evaporative emission ones, the spark plugs look OK and the engine pulls 14-15 inches of vacuum. The vacuum gauge drops to near zero and then returns to normal when blipping the throttle. I don't have a compression gauge but the vacuum readings indicate to me that I haven't lost compression. I also don't have a gauge for checking fuel pressure but talked with Caterham USA today and they haven't seen problems with Zetec fuel pressure.

 

I did a have the intake manifold off this winter to make connections to a new mechanical oil pressure line but it all electrical connections and vacuum lines look OK. If I had a leak at the manifold the vacuum readings would be off. Maybe I've been staring at the manifold too long and am missing something. If someone could post a picture or two of their manifold that may help.

 

Any suggetions on what else to try?

 

 

If I can't figure it out ( and its not looking good right now) I'm going to talk to my local Ford deal and hope they can hook up and read more whats going on then me just looking at fail codes. Curious if they will want to work on it. Anyone taken their 7 to a dealer?

[Off Road SHO]

14-15 inches doesn't seem like enough vacuum to me. Shouldn't it be at least 17-21?

 

Tom

[MHKflyer52]

Hi breezy7,

 

Take and start your car and let it idle, then take a can of either and spray lightly around the intake flange. If you have a intake leak your engine RPM will increase with the either and you should be able to narrow down the location of the leak if it is an intake leak or leaking vacuum house. Some people use WD40 for the same thing but I find that a little either goes a long way and does not leave everything coated with oil.

 

Might also want to check valve timing to make sure the valves are opening and closing at the correct time especially intakes as your timing could be to advanced or to retarded but then the car would not idle very well but worth the check.

 

Hope this helps.

Edited May 3, 2011 by MHKflyer52
corrected wording in RED

[slomove]

.... I also don't have a gauge for checking fuel pressure but talked with Caterham USA today and they haven't seen problems with Zetec fuel pressure.....

 

I find this a pretty poor statement from Caterham USA. The fuel pressure has nothing to do with the engine and clogged filters or a bad fuel pump may bog any engine down when giving it some throttle.

 

Not to say that must be it but I definitely would not discount the fuel supply (filter, pump or regulator). Hooking up a small pressure gage temporarily with a (pressure-proof) extension line into the cockpit could answer this question while driving. I have a cheap Volvo regulator and the pressure does not change more than 1/2 psi under all conditions.

 

Another possible (but rare) culprit may be the ignition coil. When running WOT the plugs need more voltage to spark. I find an intake leak unlikely because that would show at idle and rather decrease at WOT.

Edited May 3, 2011 by slomove

[Birkin42]

Hi breezy7,

 

Take and start your car and let it idle, then take a can of either and spray lightly around the intake flange. If you have a intake leak your engine RPM will increase with the either and you should be able to narrow down the location of the leak if it is an intake leak or leaking vacuum house. Some people use WD40 for the same thing but I find that a little either goes a long way and does not leave everything coated with oil.

 

Might also want to check valve timing to make sure the valves are opening and closing at the correct time especially intakes as your timing could be to advanced or to retarded but then the car would not idle very well but worth the check.

 

Hope this helps.

 

I would assume "ether" not "either".

I would assume a spray starter fluid is the most convenient source for this?

I agree that this is likely a great place to start as it directly relates to the work you did on the car. I assume the car was running fine when it was put away?

[breezy7]

Problem turned out to be bad plug wire. By chance I was holding the inductive pickup to my timing light in my right had and touched the #4 plug wire with my left hand and the timing light lit up. If I touched but not clamped the pick up to the wires at the rear of the engine the light worked but moving forward the clamp had to be installed to make the light come on. Seems that the wires have broken down and losing some of the spark. I did a quick bandaid fix and a trip around the block showed the car running great.

 

Off Road SHO: I found different numbers for what the vacuum should be, anywhere from 12 inches to 21 inches. The scale on the face of my vacuum gauge did show the reading a little low but checking my daily driver I had similar numbers to the Caterham plus the reading needs to be adjusted for elevation above sea level which I had not done. I think the way the gauge reacts is important even though a very low reading would be a concern.

 

Slomove: My concerns to CATUSA were that the filter could be clogged or the pump output low and starving the engine for fuel at higher RPM. Ben was not in the shop today, I have always talked to him when calling there. He is very helpful and spends the time with me whether I am buying something or just need help or information.

 

Mike

[Ian7]

Glad you found your problem, but be aware that the stock fuel pressure regulator on a zetec is a fragile unit on anything bnut a stock Focus.

We fail them seasonally on our Zetec-powered F2000's. When they go bad on our cars they pass 100psi or more, when 60 is plenty.

[breezy7]

Ian : Where is the regulator, have a picture? Is the SVT set up the same as a standard Zetec?

 

Mike

[Ian7]

No pic, but on our cars its the 2" dia black unit on the end of the fuel rail;

 

more I think of it, might not be a stock street car part, as its adjustable and unlikely Ford would risk letting the avg owner play with such things.....

[11Budlite]

I'm not positive, but I think the SVT uses a returnless system that doesn't have a fuel pressure regulator on the fuel rail. I think there's a FP sensor instead that sends a signal to the ECU to regulate the fuel flow.

 

Here's a link that describes it better: http://www.aa1car.com/library/returnless_efi.htm

[glenntwincam]

11Budlite is corrrect . SVT uses single line (returnless) system. there is a fuel rail pressure sensor on the fuel rail that signals the ecu along with the throttle position sensor . then correct voltage is sent to fuel pump via the fuel pump control module to regulate fuel flow.

Edited May 4, 2011 by glenntwincam

[RossD]

A normal Focus Zetec has the same type of returnless fuel rail. The older Zetecs from the Contours/Mystiqes have the 'usual' return style, IIRC.