Runs Great COLD !

Hello Folks, I have a 1999 Ford Escort ZX2 2.0l Vehicle with 71,000 miles. I bought it used with 22,500 miles on it. So far, The only cost to me has been a new set of tires.
The other day, upon taking my son to work, and then returning... round trip 5.6 miles everything was A-OK. However, upon picking him up everything changed [in the blink of an eye]. I drove there, cut the engine off for apx. 2 mins, He got in then I restarted it, and I noted the gas pedal felt different when backing up. When traffic cleared, I tried to merge with them, ONLY to FEEL,what Seemed to be Engine bogging, or double firing with NO Power to accelerate. The only way I could stay up with traffic was to put the "Pedal to the Medal," TO SLOWLY ACCELERATE !
NO Engine Codes came on, and the vehicle Runs Great "STONE COLD."
THIS HAS "NEVER" HAPPENED BEFORE, and I haven't got a clue what the problem is !
I am calling on All Experts, to help me Solve this Mystery. Thank-You, Nitrojc.:runaround:

Vacuum leak. It could be a hose off the intake plenum, the vacuum booster on the brake pedal or the PCV valve and it's related components. Runs good cold because the injectors are very rich in that mode.

You say the car smelled bad after you turned it off. What did it smell like. Gas? Rotten egg smell? Overheated? Burning oil?

Hello Dave, Isn't it very unusual for a vehicle to run great warm, or cold, and then "All of a sudden" Develope some kind of vacuum leak ... "out of the clear blue?" I am not questioning your trouble shooting, Figuring it to be some kind of vac leak, but wouldn't there have been a little "red flag" prior to this blaten problem I now have ? The smell, after turning it off, I think may be between rotten eggs, and burning oil. Next time I go out, I will try to determine which one. In the past, when the car ran perfect ... there were times when for no reason at all, I could smell a "Raw gas" odor at times, and then it would go away !
Do you think there could be other problems that would cause this terrible warm engine non-performance ? Thank-You, Nitrojc.

Right you are. A vacuum leak wouldn't happen if the car was parked and off and then all of a sudden be running badly. I'd say it is an ignition problem or a plugged catalytic converter. But, a converter wouldn't be all right one moment and plugged the next. It wouldn't run all right when it was cold. Usually a rotten egg smell comes from the cat when it is over taxed. That with a gas smell indicates the cat isn't burning what's left of the after the firing occurs. Usually with an ignition problem the car won't start or it will miss after it starts, not have low power. You can check for a plugged cat by putting a vacuum guauge on the intake port. With the car running, a vacuum of less than 17 inches indicates it's plugged. There are many things that could cause low power. Incorrect ignition timing, MAF, restricted fuel filter, coil pack, slipped timing belt or a restricted air filter. You aren't getting any check engine light? What's baffling is that it runs good cold. With all of the above it would run bad all the time. Disconnect the Mass Air Flow (MAF) sensor up stream from the air filter. When it is disconnected the computer makes the mixture rich by default. If it runs ok the problem is a too lean mixture on a warm engine. Caused by what I don't know. Possibly the MAF itself. Hope you get it fixed. Let me know how it goes. Dave

Well Dave, There has been a change in the vehicle's non-performance problem. From running great cold ... To runs the same Hot, or Cold. However, the stumbling, and power loss has deminished slightly. Now, it seems to misfire under light acceleration, and No miss fire under wide open throttle. I believe now that the engine may have stabilized, and can be diagnosed. This kind-of-stuff can blow your mind. Hopefully, you, or someone can sort thru this mess, and Pin-point the problem.
Thanks Again, Nitro.:headshake

With the hot/cold ups and downs sounds like your EGR valve is not working properly with a dirty throttle body and posibily your catalytic converter in combination. Rotten eggs and gas not converting into clean emission gives bad smells(Bad CAT), but performance is usually not affected to your degree. On the other hand you have symptoms of a non functioning EGR valve and a dirty throttle body. A simple engine diagnostic test should clear the air.

The zx2 doesn't have an EGR (Exhaust Gas Recirculation) valve. Instead it has VCT (Variable Cam Timing). In an EGR system a vacuum activated valve will pull some of the exhaust gas back into the intake side of the engine to be reburned. This cools the cylinder and does 2 things, helps create more low-end power and reduces the amount of emissions from the engine. VCT operates by retarding the exhaust cam. This means the exhaust valves will be open somewhat on the intake stroke. Not only will this pull air in from the intake, but it will, also pull in some of the exhaust.

Franco2112 is right about the symptoms. Instead of the EGR, the VCT is acting up. Sometimes it takes 50 miles or so for the DTC (Diagnostic Trouble Code) to show up on your check engine light. When it does it very likely will be P0340- Cam Position Sensor General Malfunction. The cam position sensor for the VCT gets it's signal from the exhaust cam. The position of the exhaust cam is probably off a few degrees because the timing belt has lost a few teeth and has jumped time. This is a very common problem on the DOHC Zetec engine. I would replace the timing belt. You have a non-interference engine so if the belt breaks there will be no damage to the pistons and valves. Worst scenario-paying the tow truck driver. This would cause the smell you describe due to too much raw gas entering the cat.

:rolleyes:HELLOOO DAVE, Yesterday, Bill my next door neighbor came over with his DTC Checker to help. I had already removed the [neg.] battery connector to reset the computer, and there Never was a Check Engine Light. I did not know it could take 50 miles, or so to show up. Anyhow, Bill checked the system for faults, and found none. Next, we took a test drive, and almost didn't make it back. He ran the DTC again, and as before No faults. I asked him about the spark plugs, and wires ..... So, he pulled the wires, the conductors looked OK. HOWEVER, THE PLUGS WERE COVERED WITH OIL Half way up the insulators !! How, and Where did the oil come from ? My Best Guess here is that caused the problem. Bill works for "Roush Engineering," and couldn't Explain it; because he's Never seen it before. Dave, Please give me "Your Take" here on this latest information. Thank-You, Nitrojc.

Nice catch. Oil is leaking past worn valve guides or piston rings into the combustion chamber. Causes hard starting, misfiring and hesitation. I'm surprised your not getting any engine codes. Fix this and new plugs it will run like new!

:nono:Nice catch. Oil is leaking past worn valve guides or piston rings into the combustion chamber. Causes hard starting, misfiring and hesitation. I'm surprised your not getting any engine codes. Fix this and new plugs it will run like new!
FRANCO with all due respect ........ I BELIEVE YOUR DIAGNOSIS IS "OVERKILL." However, I did find a loose machine screw on the valve cover, and tightened it up. If you read my posts from the beginning, this condition came out of the clear blue. What you have described would take a period of time to develope ..... Worn Valve guides, and, or Piston rings ! Remember this happened overnight, so to speak. Nitrojc.

You say oil was half-way up the insulators. Are you referring to the outside of the plug? Not the insulator on the firing electrode? I suspect the valve cover gaskets need to be replaced. Glad you found out what it was. They say you should seek the simplest causes of a problem first and you have. Good for you. Found it!

NITROJC, remember large caps means your yelling at me. Here on the forum we give all types of scenarios to help solve the problem. We don't get paid to help you, so there is no over kill. Hope you solved your ZX2 issue.

NITROJC, remember large caps means your yelling at me. Here on the forum we give all types of scenarios to help solve the problem. We don't get paid to help you, so there is no over kill. Hope you solved your ZX2 issue.

Franco, Don't take it personally I have always used "Caps," Especially when Drafting up "Blue Prints." I use them only for emphasis nothing more !

Dave, Your right on Target. Yes, the oil was half way up the insulator on the outside of the plug, and I did find one loose [finger tight] machine screw on the top center of the valve cover. I tightened it up, as I did, I felt the cover draw-in. I Vacuumed Up the oil mess, then blow tried the area with compressed air.
Next, I put everything back together, and Fired Her Up. SHE PURRED like a kitten. Then, took her out for a road test. Nothing, But POWER, was at my Command for the first time in a week ! Oh, what a great feeling, and I owe it all to these Forums. Thanks, So-Much, for your help. Jim.