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

[Austin]

When you’re talking about an engine that has banks it’s either a v6 or a v8. 4 cyl. is one bank. look at a 6 or 8 like a V the left 3 pistons are one bank and the right 3 pistons are another bank. As far as driving with out o2 sensors, your car will run like absolute garbage, if not at all. I wouldn’t recommend it, o2’s are the brain of the car calculating the correct amount of fuel and air.

[Julian]

Just a few things from reading this thread.

1. The hesitation– does it happen while driving, at idle or both?

2. In your initial post, you showed the codes you pulled. One is P2122– Autozone site shows it as this:

Trouble Code: P2122

Throttle/Pedal Position Sensor/Switch -D- Circuit Low Input

Possible Causes:

Poor connector

Faulty APS1 (accelerator position sensor 1)

Open or short in APS1 circuit

Faulty PCM

I’d start with checking connections. Also, make sure the battery connection is good– those things caused me a lot of different grief 🙂

May try cleaning as suggested as well. You said it sat for a few months.

[Paul]

Thanks for the information/tips guys, i will give those things a bash and report back. For the throttle cleaning, how delicate do I have to be in regards to the cleaner I’m using and wiping it away ? I dont have any cleaner at the moment, any idea if this stuff is good for the job ? Wynn’s Fuel Injection & Carburettor Cleaner 500ml

I did intend to clean the battery terminals, but when I checked them, they looked immaculate anyway so left them, may still do it anyway now though (I do have a nice tool for it).

A very brief check of the connections, everything looked fine but it was only brief, I will give them another look (the connector to the pedal is a git to get out without removing the lower fascia).

I also tried taking off the O2 sensor last night, but the damn thing feels rusted on, its a tough bugger, so I left it until I had more time to sink my teeth into it. Using Torque App I checked to see what loop the engine was currently running in, on start, it was open loop, and not long after that (10-20 seconds) it went into closed loop and stayed that way (from a cold start). All normal from what I see. Wouldn’t a faulty O2 sensor cause it to go into open loop at all times ?

Edit – Another thing I will mention, sometimes (its rare) the car requires a long crank before it fires up. I can recreate this by holding down the accelerator pedal all the way, then starting the engine. As soon as I let go, the car fires up no problem. On my dads Focus, car starts immediately even with the pedal pushed down, and of course the revs fly straight up 😛

1. The hesitation– does it happen while driving, at idle or both?

I mainly see the hesitation from pulling away/reversing from idle, and stopped at lights/roundabout etc. I have noticed sometimes that, there’s a spot where if i very lightly press on the accelerator, the revs actually drop, if i hold it at that point, it does slowly rise back up.

[Paul]

Had my cousin look at the car, hooked up a real fancy OBD scan tool (I geeked out hard :P), some error codes were found, 1 to do with a steering angle sensor and a couple of others, but nothing that would have affected my issue (and he mentioned they were most likely caused by the battery going flat). Everything checked out great with the engine.

Performed tests on various sensors, absolutely everything was working correctly within their expected voltages etc, including the O2 sensors. He checked the battery, which was working perfectly also.

Basically couldn’t find anything wrong with it, so he cleared the codes and said to just give the car a bloody good run, possibly blasting any dormant crap that may be inside from being stored for a couple of months. He mentioned a quick first step to replace the spark plugs (and other service items) to see if that has an affect, and luckily he can get me them cheap because of his job. He mentioned that sometimes pedal sensors can go bad because valeters have been spraying what they use to clean around that sensor area, and it can get inside and cause issues.

After the codes were cleared, the engine fired up the fastest I have ever seen it, so for now i think I’m going to give this puppy a great big blast on the road and see how it goes 🙂

[EricTheCarGuy]

That sounds like a good plan. Just a tip. Do not try and remove an O2 sensor with an O2 sensor socket. They are split to make room for the sensor wire and as a result they’re not as strong as a traditional socket. I recommend you cut the wire and use a regular 6pt socket (usually a deep well 7/8″) with a 1/2″ breaker bar to remove it. However, if your’s doesn’t have a problem I’d leave it be. Sounds like it might just need to be run as you suggested.

Keep us posted.

[Austin]

glad it’s looking better, sounds like you as i said before you just need a good intake cleaning. By the way i know you said the car hesitates or doesn’t start when pushing the accelerator all the way down. That’s because not on all models, but most when you push the accelerator all the way to the floor it puts the car in “clear flood mode” and kills the fuel so it wont start. (This is used if somehow the engine gets flooded and you need spark but no fuel to burn off whats left.) anywho, keep us posted with progress!

[Paul]

Thanks for the replies guys. I did actually get an O2 socket and tried to use it a couple of days ago …. but I never felt like a had a good grip on it so didn’t go ahead with removal, and I don’t think that’s the problem now anyway (phew !).

I’l be sticking to my plan of servicing it first before doing anything else, I have already been giving it a good blast (2 hour journey) … but sadly it remains the same. Trying my dads car again, the response from the pedal is a huge difference, instantaneous even.

I couldn’t help myself, so I went to have a quick look at the throttle body connector, just in the hope’s something might stand out. I unclipped the red connector and tried pulling it off, but the thing just will not budge. It looks like something that should slide off quite easily but its just not happening, it can wiggle but not retract. Here are some pics –

I’m not saying there is anything wrong, but I did just want to have a quick peek, didnt expect it to be seemingly welded on 😛

glad it’s looking better, sounds like you as i said before you just need a good intake cleaning. By the way i know you said the car hesitates or doesn’t start when pushing the accelerator all the way down. That’s because not on all models, but most when you push the accelerator all the way to the floor it puts the car in “clear flood mode” and kills the fuel so it wont start. (This is used if somehow the engine gets flooded and you need spark but no fuel to burn off whats left.) anywho, keep us posted with progress!

Ah that’s good to hear then, although any idea why my car might give the same impression sometimes when starting up ? Its likely the same issue I’m having that causes it but just thought id see if there’s any other potential reasons.

Will keep you guys updated, I’m not letting this one past me 🙂

Edit – And I just had 2 instances of the car performing a “clear flood mode” like start up, if I hit the pedal and let go very quickly, car fires up immediately.

Edit 2 – Couple more observations. Looking at the other side of the throttle body, i found what appears to be an adjustment bolt (not something i would touch unless i knew exactly what i was doing), and also what appears to be some gasket material sticking out ? Should this be ?

[Austin]

1. Have you gotten the chance to do any kind of maintenance like the blades of the throttle body and such yet?

2. Seeing gasket material can be a problem and it can’t. all gaskets are designed differently, i wouldn’t worry to much about, you can check by spraying some carb cleaner on it while the engine is running and listen for a raise in RPM, or watch your upstream o2s on your torque app while you’re doing it and look for them to go rich (higher voltage on the .1-.9 volt scale) if you see it or hear it go up then you know its getting through and the gasket needs to be replaced. If not then don’t worry about it.

3. On the TPS connector on your throttle body, that red tab is usually a lock, if you pull it straight out until you hear it click, then you can squeeze it like a normal connector, but it’s designed so that the tab has to be pulled out first. Unlocking it and pulling will not take it off, it must be unlocked and then squeezed.

4. The adjustment knob. I’m honestly not sure what it is without looking at a diagram, i would just leave it alone, even if it was an adjustment knob, it doesn’t need to be touched, you don’t want to deal with throwing calibration of the TPS off.

5. As far as the slow starting, try KOEO (key on engine off) for about 3 seconds before trying to crank it, when you put your key in before cranking it primes the fuel pump, see if that fixes it.

Glad it’s still looking better! keep us updated.

[Paul]

1. Not yet, I’m picking up some throttle body cleaner today and a toothbrush 🙂 The clips on the air hose are a total git. Easy enough to take off, but putting back on not so much, its a clip that needs to be stretched all the way over the lip and dropped in to secure it, not easy with a flat blade, and feel like i could be causing damage should it slip :S I will take pics of it later to show you.

2. Might give that a go, however i did notice a YouTube video of someone taking apart a throttle body, and that gasket had a lip sticking out of it, i guess to make it easier for removal, so more than likely not a problem.

3. The same YouTube video shown me how to unclip it, i was being silly. Pull the red tab out until it clicks, then hold down another tab on the outside of the connector, push up, then pull back and hey presto, out it came no hassle. Looked fine too.

4. Yeah, didn’t think this is something that should be touched. I believe its a “Stop” adjustment, so not touching it 🙂

5. I will give that a go 🙂

I have also been researching drive by wire systems ….. and found countless posts over the internet of many people having very similar problems to mine, in which their is a delay between a throttle press and a reaction from the engine. It sounds like it could be perfectly normal for my car …. so I’m going to check to see if my dads car is cable driven, which would make a lot of sense then. Some people mentioned ECU/Firmware upgrades that improve throttle response, so may look into that, but i don’t think Ford dealers typically like doing this ….. (I will also compare ECU version numbers between mine and my dads car).

I also read that some Ford throttle bodies have some sort of special coating on them, and that I shouldn’t use any throttle cleaner on them as it removes this. Typically these have labels on them saying not to do so, so I am going to check mine tonight to be on the safe side.

Might feel a bit guilty if this all ends up being “normal” for the drive by wire system my car uses :S

[Paul]

Here are the pics of the air tube clips, absolute nightmares to put back together. Anybody have any experience with them, and tips for easy un-clipping and putting back on ?

The only positive thing I can say is, these things are bloody tight clampers 😛

[Austin]

Id’e research the accelerator wire you’re talking about. I personally don’t know alot about them or id’e be able to tell you more. As far as those clamps go I can’t see them to well, they almost look like cv bands, which in that case can not be reused only replaced upon removal. If they aren’t I would assume you take a flat head or a small pry bar and flip the lock, they look like a bear, but like i said i can’t really tell by the picture. In any case, when you get them off, ide just say screw it and throw a screw clamp on there so you won’t have to worry about fighting it in the future if you ever need to get back in.

P.S. even if it is a normal condition, what you’re doing regardless is good maintenance so don’t beat yourself up over it to much. Plus in the end when you get it figured out whether there be a problem or not, you’ll A. be up on your research so if something does happen you have a better grasp of what you are looking for. B. have the peace of mind that nothing is wrong!

keep us posted.

[EricTheCarGuy]

OK let’s back the truck up for a second. What proof do you have the TPS is an issue? Any codes? If not, look elsewhere. Modern vehicles will set a code if there’s an issue with a sensor. If you want to see what the sensor is doing, hook up a scan tool and look at the live data. You have no idea how good you have it these days with that capability. Before OBDII you needed to do the type of testing you’re attempting. Now, just by looking at the data list, you can verify the operation of the sensor, it’s wiring and connectors, and the computers ability to interpret that information. What you’re doing now is throwing away that opportunity and potentially opening up other issues with your method of diagnostics. It’s not like you can poke around in the dark till you stumble on a solution. Diagnosis is a process, not a guessing game. Keep going like you’re going, and you just might break something else.

This article really does walk you through a process of diagnosis. I would urge you to read through it and then tackle this problem with a fresh approach.

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

[Paul]

Dont get me wrong Eric, I’m just pre planning for the worst case scenario (I typically do that), so I’m aware of potential costs/work involved, I haven’t got the money to start swapping out parts either so I’m forced into the diagnostic route 🙂 Although I do go a bit overboard with it sometimes.

Today I did the service, replaced oil filter, oil, spark plugs, air filter and pollen filter (this was a total sod to replace :angry:) and on first fire up, everything seemed gravy ! Idle was stable, and the throttle response genuinely seemed great, similar to my dads. I thought I had finally bumped this one on the head.

I then took it for an hours drive, and really it just felt the same. When I came to a stop, then tried to accelerate, I still had to overly apply pressure to the pedal for the revs to start rising, and there is still about a second delay for the revs to even move after the pedal press. Guess I’m back to square one again 🙁

The Torque app does show an uneven throttle position (apparently the reading is taken from the manifold), at idle its constantly fluctuating between a couple of percentages, which does not happen on my dads (he also has a Drive By Wire system).

I still have the option to clean the butterfly valve, which I will do when I find good enough pliers that pinch and click those gits back in to place without me damaging something (the only reason being that, sometimes the revs “jump” when I lightly hold the pedal, which makes me think the first few movements of the throttle are held back by sticky crap, or there is some electronic issue, but then I have no codes to support this :().

I will keep you guys informed, any ideas to take it from hear would be really appreciated 🙂

[John Hugon]

I hope the cleaning helps….but the throttle bodies are an issue with that car.

The air intake duct retainers can be removed by inserting a small screw driver under the clamp “pull over”, twist the screw driver and the clamp will pop open. To re clamp I use a CV boot clamp tool…Ford has a special tool for Removal and replacement…. of course.

[Paul]

[quote=”JTF” post=101834]I hope the cleaning helps….but the throttle bodies are an issue with that car.

The air intake duct retainers can be removed by inserting a small screw driver under the clamp “pull over”, twist the screw driver and the clamp will pop open. To re clamp I use a CV boot clamp tool…Ford has a special tool for Removal and replacement…. of course.[/quote]

Thanks, hopefully it isn’t the throttle body (expensive part ….), I will see what a clean can do for it.

It appears that it may use “CLIC” clamps ? At least they look very similar and there are a variety of tools for them.

[Author]

Replies