Dodgy throttle response (video inside)

Post Thu Mar 28, 2013 7:17 pm

[youtube][/youtube]

After I posted a video in my build/repair thread of me giving it beans the other day it has decided that it doesn't want to play ball.

On sat the car drove perfectly, no issues at all, smooth, perfect response etc.
Monday night I decided to pop to Tesco, got most of the way there, the revs started to climb whilst in traffic and then the car stalled at a roundabout when I went to pull away. Once it had stalled it wouldn't start again. I had to wait for the RAC to collect me.

The engine had been running fine when cold and then started getting odd once warm. Once recovered we found that the plugs were soaked in fuel so it looks like it has been over fuelling and drowned itself.

Tonight I decided to run the engine (without going anywhere) to see how it was going to behave as I need to drive it tomorrow. It seems that now it is back to having some throttle issues I had before which I'd attributed to the TPS (as it was faulty and once I'd changed it the car was fine on Sat).

When I put in a little bit of throttle it seems to want to stall and then have a slow response to the small input (ie if I prod the throttle it'll stutter then pick up). If I gently ease on the throttle it'll pick up and move through the revs ok.
The video above is of my giving it a few gentle taps of the throttle with my foot and you can hear it isn't responding well.

The blue temp sensor has been changed and I did test the resistance at the sensor and ECU and they were fine I think.

Any ideas as to why it is doing this and also why it would flood itself when running after having driven perfectly two days prior?

I'm getting more and more fed up with the car as I just can't rely on it at all. When I think something is sorted it throws up another issue. It's fun when it works yes, but in all honesty I'm very tempted to just sack it off and lose the pile of cash I put into it as I can't be doing with having such an unreliable car.

Post Thu Mar 28, 2013 7:49 pm

I think you should check that the TPS is still correct and connected.

As that is the last thing you touched it is likely to be the cause.

Ben

Post Thu Mar 28, 2013 7:54 pm

I'll have a look in the morning (dark and cold out there now), I'd be surprised if it has moved. If it has and that's the problem...

I can understand if the TPS moved and it resulted in the dodgy pick up I got this evening but it wouldn't explain and idle that crept up to 2000rpm and flooded the engine really would it?

Post Fri Mar 29, 2013 8:36 am

Had a look this morning, the TPS is solid and actuates correctly but it is still picking up badly.

Post Fri Mar 29, 2013 8:43 am

I forgot to mention, it idles spot on and starts fine too.

Post Fri Mar 29, 2013 4:28 pm

Well I'm confused.

Risked it today, loaded the car up, hopped in, drove to the M5, idle was always ~800 rpm and the throttle was picking up a little dodgy but was ok. On the M5 it was fine until I hit near standstill traffic where it idled at ~1500rpm. Drove the ~120 miles back to my parents, got close and the idle was back to ~800rpm. It also was slow to respond to throttle input on the motorway.

Turned it off, turned it on and it fired and idled just fine at ~800. Took it out for a spin after it had cooled a bit and once again it ran perfectly, great throttle response etc.

I did reset the ECU this morning before I put the battery back in (it is going flat a lot as it is duff so was on charge last night). I don't know if that will have helped the car to learn the idle correctly? I will be fitting a new battery at some point this weekend when I can be bothered as the current/old one was flat when I got the car and I've repeatedly killed it by firing up the car when I was working on it and not letting it get a charge.
I will also have a look to see if there is a drain on the battery when the car is off but I'm fairly sure that is fine. I had the battery out of the car the other evening and it lost ~.5V just sat in the living room.

Post Mon Apr 01, 2013 1:18 pm

I checked the AFM via another guide (I don't have the battery connector for a 9V battery) which is the same process but running it off ignition position 2.

I'd been having some battery problems lately due to it being a rubbish old one that came with the car and was flat when I got it. I fitted a brand new one on Sat, drove it to get fuel and then drove 120mi on Sunday without issue, and then again today it drove fine.

Is there any chance that a battery that slowly loses charge (when completely disconnected from the car too) would cause odd running issues?

It's really annoying that it works right now as to be totally honest I don't trust it still and I expect that it'll not work when I really need it to run.