down on power / hesitancy

[recomdos]

Hi all,

Recently detected a bit of a surging/hesitation feel through the rev range whilst driving my 98 A3T. The car also feels like it’s down on power. Build up is slower and in situations where my wheels would spin (such as in the wet) they don’t at all. Furthermore I am sure fuel consumption is down.

So from my past of reading such issues on this site I knew it could be down to a multitude of reasons – great!

In April I did a bit of DIY servicing – cleaned the Throttle Body and MAF. I also had my lambda probe replacing. The probe I bought (as advised by the local motor factors staff) was a cheaper alternative to the OEM one. When I popped round to my mechanic and asked him to swap it, he said the cheaper ones were indeed cheaper for a reason, and not as good as the OEM. Anyway we fitted it as I needed the car on that day.

Ran a vagcom this morning and low and behold the following few errors:

16515 - Oxygen (Lambda) Sensor B1 S1: Signal too Low
P0131 - 35-00 - -
17967 - Throttle Valve Control part (J338): Fault in basic settings
P1559 - 35-10 - - - Intermittent
17973 - Throttle Actuator (J338): Lower Stop not Reached
P1565 - 35-10 - - - Intermittent

Lambda probe – again!! Great! I monitored some of the measuring blocks (007 & 008) as advised through advice from helpful forum members. At 80+ degs the results I logged showed the voltage initially fluctuating from 0.0 to + 0.3ish, this as I am led to believe meaning the car is running lean – this would equate to my fuel consumption.

I cleared the codes, and the voltage sat at 0.0 – it didn’t budge at all. So maybe it is totally duff? This may need replacing again (this time for the OEM part of course), but I also have worries about the Throttle Valve Control part / Throttle Actuator. When I cleaned the Trottle Body I did not do a Throttle Body Alignment – I just let the car do this (as I read on here somewhere with the procedure).

The hesitation through driving seems to be around the 3k mark. Sitting still and reving the engine is fine, but when letting off the accelerator at 1800 revs there is a little bit of a jolt.

I’ve cleared the codes but yet to take her out for a drive. Should I try performing a TBA with vagcom? Obviously I need to monitor this lambda probe and indeed replace it if it continues to prove to be duff, but would these problems be the direct cause of power loss also? It didn't seem to be affected like this in the past when I first replaced the probe.


Any other ideas / suggestions?

Apologies for the long winded post – but I figured it may be helpful for other simpletons like me searching for similar info in the future.

Thanks
Rob

 

[jojo]

Have you tried driving around with the MAF disconnected Rob, the hesitation around 3k revs and running low on power seriously suggests your MAF is duff.

 

[recomdos]

heya Jojo

I've not tried without the MAF yet - though this was was my intial thought when it first felt out of fettle - until I vagcomed it. I think I'll have a go at that tomorrow night, and see how it feels.

how keeping matey?

Rob

 

[jojo]

heya Jojo

I've not tried without the MAF yet - though this was was my intial thought when it first felt out of fettle - until I vagcomed it. I think I'll have a go at that tomorrow night, and see how it feels.

how keeping matey?

Rob

I'm still about mate, MAFs are quite sensitive, you could damage it just by cleaning the damn things, my experience was less power, hesitance after 3k revs and almost like a miss fire everytime you stepped on it.

 

[recomdos]

drove it to work this morning and it felt pretty much back to normal ...I say pretty much as I think I'm just being overly conscious about looking for faults. will see what it's like on the way home.

keep ya posted

Rob

 

[HTC]

If there is no signal from the lambda then you'll probably be running on a safe map. I would have thought the check engine light would have illuminated.

Measure to see if you get any voltage when the car feels good. Could be a faulty sensors. If it's on and off then it's usually something electrical.

 

[HOUCH]

Hi there just wondering if you found anything at fault as I think I may have same problem, Felt like was down on power and using more fuel, changed maf and didnt feel much different not in limp mode still hear turbo winding up and dumping when lifting off gas no warning lights etc, thought maybe just in my head but came back from hols last week and didnt get that "this is quite quick" feeling that normally get from not driving of few days (Do you know what I mean?)

Cheers Houch

 

[recomdos]

Hi

Well I haven't found anything conclusive. Though it's been pretty much back to normal since that 'blip'. I've driven it without the MAF for a couple of sprints and the power was similar, but there was no hesitancy/jerkyness. Still getting reports of a faulty lambda / intermitent fault. Was wondering if it's a coilpack. It's in for a service this week and I've asked my mechanic to pop on the diagnostics at their end, they're also doing a search for any loose pipes / splits.

I will report back if I find anything, though it may just be a bit of trial and error in fault finding. As I say it's been ok as of late.

Rob

 

[Clach]

Loose connection to the injector amplifier maybe, check the connections on the back of the coilpacks, and the main unit attached to the airbox...