2001 Ford Focus ZX3 hard start and stall problem.

intake air temp or IAT sensor~ combined with 02 readings can make it run iffy~needs to know how hot it is outside temp of the throttle and adjust making it too rich and chokin' the windpipe~ because of the age of the vehicle am going to suggest a new TPS as errant signals can make it run poopy (yes, I said poopy)~

Do you mean Throttle Position Sensor?

Sounds to me like the negative battery cable is full of corrosion at the point that it attaches to the rest of the car...get out a coarse wirebrush and really brush it shiny, both lug and the fender or chassis where it's connected to...this "brown power" has played hell with the performance of your ECU computer and will not behave itself until you get a NEW battery and clean with a wirebrush...as I have recommended~

yes....but scratch that....I hadn't fully realized the decrepitude of the system Ground.~ 'till you stop the connection from issuing varying voltages and varying available amperages, the "Brain Box" will be unstable...what I'm saying is with a NEW battery and sparky-fresh connections the world will start turning in the right direction~

TPS...the throttle position sensor is one of the principal devices where man meets machine through an electro-mechanical interface, that while supposed to be an optical device that would theoretically NEVER wear out, in reality crumbles like ALL plastics~

I already put in a new battery, and still no fix?

It seems more like a fuel thing to be honest, but I'm not sure.

yes...chokin' with excessive hydrocarbons...blackening your spark plugs...IAT and temp sensors should fix that, but look at the date of the batteries first charge as noted on the knock off labels on the top of the battery...five years and they will give you trouble~

that's because the other end of the black cable cannot make good~

you can make it good with a wirebrush on the spot where the lug attaches~

the ECU is watching Fox News....and NOT getting the full picture...please enlighten your brain power by providing reliable grounding~

Tennisshoes how do I perform a fuel pressure flow test?

I am having the same issue. There is no valve for fuel pressure testing on my 2001 focus zx3 (zetec engine). I plugged in a scanner to read the fuel pressure. When the engine is cold, fuel pressure is around 45 psi. It drops to about 40 when warmed up. At idle, if I rev it, it drops to about 28 psi. When driving, if I floor it, it drops as low as 6psi. I replaced the filter, but there was no change in fuel pressure. Obviously it hesitates and wants to stall when the pressure drops that low. If the car is cold, it performs better. As it warms up, it gets worse. There is no pressure regulator, either. Based on the research I did, the computer tells the fuel pump how fast to run. It seems that either the computer is giving bad info to the pump, or the pump can't deliver at the speed being called for, especially when the engine is warm. Any help would be greatly appreciated!

The fuel pressure regulator that connects to the very left side of the fuel rail is a $100 plus part that Ford doesn't have any of right now( supplier quality issue) I got one out of the junk yard off another Ztec engine. No more hard starts and rough idle or stalls. Tricky R&R , study the attaching clips carefully, have to remove fuel rail and that might be more "O" rings. Cyl pressure should be in the 200lbs range, mine were 195-203.. The eng check light said #2 cyl issue, misleading HUh?

similiar issue with my 01' Focus wagon. Tech' said it was an "airbox issue" did some adjusting...for free but 2 months later same stalling has occured. Drove 160 miles testerday and it was fine but today...same stalling. Did younsay there is a Ford call back?

I am having a similar is issue, I have had the oil cover gasket, plugs, wires, radiator hose, & battery replaced... and my car when I drive it for a certain amount of time go home, park, I go to turn it on it will cut right back off, and I know its not the fuel pump cause I replaced that and the filter less than a year ago, I know its not my alternator cause its not showing signs that it is bad, my mechanic said it was my fuel rail sensor thing, I just want to be for sure so I don't have to worry about getting stuck somewhere anymore, I need help more like opinions lol.

I had a similar problem in June/July of 2015 and the solution was simple however quite a nuisance to remedy. It's a fuel issue, I lowered the fuel tank, removed the fuel pump assembly and inspected the fuel strainer, the first line of defense in keeping foreign objects out of the fuel injectors. If you have run out of gas and used a Jerry Can it's likely how the debris got there in the first place. I found a moderate amount of black goo, sludge, grime, whatever you want to call it, crud. I simply washed the strainer off with "methyl hydrate" and ensured the tank was free of other contaminates. Since then I've haven't had any issues with fuel delivery unto to this point. However I have a new problem, I suspect it's a fuel issues again, this time I suspect it's a plugged fuel filter but I won't know until I replace it and cut the old one open with a hacksaw. For what it's worth I've truly enjoyed my 2000 Focus SE, the power train is a 2.0 Liter DOHC (Zetec) automatic transmission, FWD, no traction control or ABS brakes but it's fun for a small domestic car with reasonable fuel economy and ample trunk space for my audio system.

Hi my names Ana and I have a 2001 xterra and it experiencing hard cold start I live in Texas so not really cold .. It'll eventually start up n when it's warm it starts up no problems .. New fuel pump fuel sending unit fuel filter new fuel pump relay ... Tps is new as well as new water pump timing belt n distributor ... I'm at wits end to what the problem is .. Any help would be awesome .. Only codes are p0420 and knock sensor

I'm abdu i have ford focus 2008 me to I have starting problem I went garage and they ask me to change crank sensor. Spark plug and coil full pump .cump sensor .tampratur sensor air filter but still my car can't start still one's I trays to start its traing start like all most if I don't accelerated it is going back to off again and if it's off to much cranking if any one have idea pleas help

i have a 2001 focus se wagon. i have replaced the mass air flow sensor, fuel filter and fuel pump.... the car starts and runs until the engine gets hot, then it cuts off. i have been told it could be the computer. also the coil pack and or the crank sensor. im at a complete loss as to what the heck is really the problem is...

Change the coil. I changed mine to a cheap one and then car was hard to start below freezing. Would not start at all, actually. So, installed a new coil, that fixed it. These coils have sensor and trigger circuits in them besides the high voltage stuff. So, cheezy solder joint or bad components inside. Car run really strong now and starts every time.