2003 focus zx5

Can you please tell me why my 03 focus zx5 will stall in reverse. I have had the tranny seviced. I can drive it and then let it sit for about an hour and then try to reverse in it and it dies. I have change the mac, tps, iac sensors. I am at a loss for why this is happenening. I also changed the pvc hose that runs from the back of the motor to the pvc valve

You will need to be able to replicate the situation to get it analyzed. My wag you need a new fuel pump.

This one is quite a puzzle. Stalls in reverse, but apparently runs fine in all forward gears.

hmmm … well, first thing, have you had the diagnostic codes read out from the ECM memory? If so, post the codes here. The only other things I can think of is that somehow a wire is getting pinched when the transmission is in reverse, it does put forces on the transmission a little differently than forward. Besides that, something weird happening with the egr system can cause stalls.

I know it is strange, because I drove it this morning and it is fine. My husband drove it yesterday to the dentist and it was fine. When he came out to leave it stalled in reverse. It started off doing this wierd shift as you were driving and the tranny service light would come on for a split second and then go off. The check engine light never came on. We changed the throttle body sensor as the car would also die at a stop. We would unplug it and plug it back in and it would work for awhile. Since we were having all these issues, I took it in to have the tranny serviced, fluid, filter changed and new gasket. Nothing wrong with the transmission. My husband decided to change the MAC sensor and this is when the car started doing the reverse issue and then the CEL came on. We took it and the codes read that the MAC, IAC, Throttle body sensor. So that is when we checked for vacuum leaks and found that one hose in the back real soft and we figure it was collapsing. So we changed it and cleaned the IAC sensor as it was so carbonized… This solved all problems except the stalling in reverse. Like I said it doesn’t do it all the time and if you give it gas while in park and as the throttle starts to drop you can put it in reverse and it will go. So I am going to put a new or go back to the old MAC as this seems to be when that issued started. By the way we did check for other vacuum leaks and no problems with the hoses. I am going to check the PVC also. If there are any other suggestions I would greatly aprreciate the input. Thanks to the repsonse.

I had a 2001 ZX3 that could only use 100% gasoline 10% gasoline was not allowed. In my reading on info I found that the the honeycomb in the muffler swells up with 10% gasoline. The problem was that it chugged. Never fixed it. traded it off. What does it say about what kind of gasoline % you can use in the owners manual. I did learn that the dealership was able to fix the car. Do not know what they did.

I’m not sure what a MAC is. Do you mean the mass airflow sensor, MAF? Or do you mean the MAP, manifold absolute pressure sensor? Also the term “throttle body sensor” is ambiguous as there are usually several sensors associated with the throttle body and incoming air flow. Please clarify. Do you mean the TPS, throttle position sensor? The IAT , intake air temperature sensor?

Your transmission may have a computer too, and may be posting codes. You may need a Ford specific scan tool to access those codes. A Ford dealership would have it.

Has the EGR system been tested yet?

Check the hose that runs between the air filter/MAF sensor and the throttle body. It may have a crack that opens up when the engine tilts a little bit in reverse. This will cause an erroneous MAF reading and may stall the engine.

You might want to consider replacing the idle air control valve . . . sometimes cleaning it just isn’t quite enough

The part isn’t very expensive

Actually, we found that when put in reverse foot on break stays running. Foot off brake touch gas pedal it dies. It will die while my foot is on the brake pedal and touch the gas when it is in reverse.

Sounds like it’s time for a tech to experience this with a scope attached to see what is dropping out (fuel or spark) and go from there.

We are happy to hear that you found the problem and posted the repair for us.

But it would serve everyone better if you posted this under the old thread instead of starting a new one. Then we would understand the relationship between this post and the original complaint.

Happy driving @Giz .


Well I told you all what the symptoms were with my car and that it started stalling in reverse. No one could figure this out as there were no codes showing and the fact that all the symptoms were pointing to the IAC sensor, TP sensor and the Mass air control sensor. Well we replaced all and the vaccum hose and PVC hose. This still didn’t fix the stalling problem in reverse, though it did fix all the other problems. So I got on google again and re-worded the problem. Got a site that was a few years old on the discussion, but it had the same symptoms as mine for the reverse stalling as it would jerk hard when it did this. The problem ended up being the trans sensor. WOO HOO the care is fixed. Runs great, no stalling in reverse. Just wanted to tell everyone the heahach is over. Thanks and I love this sire. It has been added to my favorites.

@Yosemite and @Giz, I merged the two threads.

@Giz, could you possibly tell us exactly which “trans sensor” fixed the problem? Thanks.

One of the various speed sensors, perhaps . . . ?