Acceleration hesitation ?

[Paul]

Got myself a second hand Ford Focus 2007 1.8 Hatchback, and its great bar something I’ve noticed, mostly when first starting a car and pulling off.

It seems like there’s a delay from when I press the pedal, and the revs rising up, and sometimes the revs just shoot up very quickly even with a very light press on the pedal.

I had this confirmed today when my brother tried using it, and he immediately noticed a delay too without me even mentioning it.

From what I know of the car, it had been put in storage for a few months until the owner wanted to finally sell it. The battery died so had to be charged up. When I got the car, I pulled some codes from it, many seemed to be regarding the battery dying, but a couple had faults regarding the Throttle Position Sensor. The codes are –

Fault log report generated by Torque for Android
=================================================

Vehicle VIN:
Vehicle Manufacturer:
Vehicle Calibration ID:

Current Fault Log
——————
U1039: null

Pending Fault Log
——————
ECU reports no pending faults

Historic Fault Log
——————
ECU reports no historic faults
Other discovered fault codes
(possibly pending, current or manufacturer specific)
—————————————————-
B2103: null
U1900: null
B1318: null
U2200: null
P2122: Throttle/Pedal Position Sensor/Switch D Circuit Low Input

End of report.

Anyone able to give me a few simple ideas to start off with before I start digging into it deeper ? I have a few ideas, such as the TPS (which is attached to the pedal AFAIK, and are only available in together) being faulty, maybe a sticky butterfly valve, vacuum leak, or spark plug related (I checked the ones currently sitting in the car, they look absolutely fine from what I can see).

Any ideas where to start with this ? I’m starting to look like an idiot stalling the damn car as I haven’t given the acceleration enough time to catch up with me

Topic

[Bill]

There are many issues with the throttle body on those cars. I have replaced a couple myself. Did you get any kind of warranty with the car?

[Austin]

Get ahold of a scan tool that can read live data, preferably one that can plot graphs. You can find them pretty cheap now days. You need to be looking at your TPS, KOEO (key on engine off) bring up your TPS. Now what you’re looking for is consistency. While watching the data stream, slowly push the pedal to the floor and then slowly release it. What you’re looking for is a slow steady climb up when pushing the pedal to the floor and then a slow steady decline when letting off. Faulty TPS most times (never say always) will have divits, as in when your slowly pushing the pedal (going up) it will spike down for just a second and then continue going up. The graph should look like a hill and then a V will happen and then continue to look normal. Or if your doing it by looking at percentages looking for up up up then drop for just a second then up up up again. That’s what your looking for, if you see this, replace the TPS.

P.S. be-ware there can be multiple TPS, Some on the pedal, some on the Throttle body itself. Check all of them, its an easy test that doesn’t take long.

P.P.S. Other than that as you stated above you can be looking at things such as old plugs, as you said sticky throttle blades, plugged cat, it goes on and on. Also you said something about the battery being charged and not. If the battery is disconnected with out a memory saver, it wipes adaptations. This will cause power loss, stalling at stop lights, things like that. A car will re-adapt quite quickly but there are battery issues were you’re disconnecting terminals, etc. Unlikely since this is a reoccurring issue, but if you are disconnecting to work on it, etc dont rule it out. But since you’re lucky enough to have a code, it points you in a direction and I would start there. Report back and good luck!

[Paul]

Thanks for the replies 🙂

Did have that idea with the TPS graph, wasn’t sure how to do it but figured it out with the Toque app I’m currently using. The only option i could find however was throttle position sensor (manifold), rather than at the pedal. Even so, the graph looked normal, no spikes or dips, very smooth curves under slight pressure, and a big quick raise with quick heavy pressure.

I will have to hunt a bit more to see if I can find a reading from the accelerator sensor, and if so see how that goes.

[Paul]

Here are a quick couple of graphs from my lunch break with the car. Could be normal for all i know, certainly the engine off graph looks fine to me, but with the engine on it goes up and down quite a lot while idle (which could be normal ?). What do you guys think ?

Engine off, completely flat line when not touching pedal, very smooth climbs when playing around with it –

Engine on, running idle, didn’t touch the pedal, kept rising and dipping –

[Paul]

Some extra information, might be useful 🙂

Just tried the same test on my dads Focus 2007 1.6 Zetec, his throttle sensor doesn’t show any info until the engine is running, so could only do it with the engine on.

The graph shown a straight line, no dips or raises at all until I pushed on the pedal.

Slowly starting to think my sensor might be OK, but the butterfly valve could be a little stuck, or a vacuum leak is letting air in ….. or this is normal for my type of engine (Duratec).

Edit – And a little bit of extra info, I notice when I turn off the engine on mine, there is what sounds like a “whir down” noise, very obvious from inside the car, this doesn’t happen on my dads car, but again, not sure if its specific to mine, being a different/bigger engine.

[Austin]

okay, next thing i would do (because you think it might be a vacuum leak) sense i bet you don’t have access to a 3k smoke machine setup, get a can of carb. cleaner and start spraying down vacuum lines and around your intake manifold, throttle body, etc. While you’re doing this you need to look and listen for two things. 1. while you’re spraying you need to listen and see if you hear the engine RPM’s rise. If you do when you spray on a specific spot then you know the carb cleaner is getting through and being burned (hints the raise in RPM). The other thing you do when doing this test is to watch your UPSTREAM o2 sensors. If you do have a vacuum leak then when you spray the carb cleaner as formentioned above it will get into the chamber and burn, so what you’re looking for on the o2’s is for them to go rich. The lower the voltage, the leaner it is, the higher the voltage the richer it is. it will be on a scale from .1Volts – .9Volts when you spray it and see the voltage go up then you’ve found your leak and whats happening is the carb cleaner is going in and richening the air/fuel mixture (which is why you see the raise on the o2’s). good luck report back!

[Austin]

I would clean that butterfly in the throttle body first, easy to get too, easy to knock out. Whether that is your problem or not its good maintenance. normally on a vacuum leak you would have lean codes, and engine miss. but it is possible for it not to pick it up as far as i know, try it out. its an easy test, well go from there

[Rob megee]

It’s pretty easy to make a smoke tester. Search you-tube and you will find several ways to make one. I found that it works very well and is very easy to diagnose vacuum leaks.

[Akshat Goel]

Hi,

I advise you to use BitKar for troubleshooting the problem with your car. You can manage the maintenance and repair life cycle of your car, search for local repair shops,diagnose car problems etc.

Here is a link to the BitKar website – bit.ly/1n3yoDG

Link to download iOS app – bit.ly/Sv72N5

Link to download Android app – bit.ly/1u1vt12

[Paul]

Might have found something, going to investigate further, but sharing in case anyone has any ideas.

[Austin]

so is this saying you’re having issues with your upsteam o2’s? Have never used torque before.

[Paul]

Its an idea based on what Torque was reporting ….. but I would have thought a CEL would appear and some codes related to it, so its a bit strange (found a post from another forum saying that sometimes, a very small fault with the sensors wont flag up anything to trigger a CEL or Codes). Might just be a test Torque cant run on my vehicle so reports it as failed.

However i did find this while looking this morning …..

Connected to nothing, and not able to see anything that it would clearly connect to (maybe it doesn’t ? Breather tube ?), and its quite short. I have no idea what this hose is :S

Edit – Nevermind, a quick part number search suggest its a Water Drain tube, so I think its normal.

[Austin]

It’s probably water drain hose for the A/C condensation. Have you done a butterfly cleaning yet?

[Austin]

also if the plugs are easy to get to, take them out and snap a picture of them.

[EricTheCarGuy]

That’s the AC drain, nothing to worry about.

A faulty O2 can cause issues like this. By the look of it you might have a short in the heater circuit. More info on how O2 sensors operation and how to go about solving issues like this can be found here.

http://www.ericthecarguy.com/faq/solving-automotive-performance-issues

Start with that and check back with us. Good luck and keep us posted on what you find.

[Author]

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