Other VR4 niggles!

[Piers1989]

Ok so I got my RPM issue sorted with the IFS wiring being fixed - TY guys :)

Theirs another issue where under very light throttle (barley covering the accelerator), suddenly my AFR gauge drops to 22.4 (no fuelling) and you can feel the power has all been cut and the RPM drops to just above idle (as it does if you back off the accelerator).

This is much less smooth than backing off the accelerator, like it is instant lack of fuel. Never experienced a similar issue under load, but its irritating when tootling around at 30mph.

I'm guessing maybe the TPS is sending the ECU the wrong information, telling it there is 0 throttle so it cuts fuel? Or is there something else that could cause this? I did have a quick search but wasn't quite sure what to put in!

On a similar note, when stopping and starting (in traffic) there is a fair bit of "slack" in the drive train. Enough that you get a little clunk when engaging / disengaging power. Otherwise no issues with the gearbox etc. Do I recall there is a rubber component on the driveshaft that can be responsible for this (I think I read something about this in my first year of legnum ownership!)

Otherwise I have a few generic suspension knocks, but I'm sure the garage can resolve those without any specialist advice :)

Any help with the above though would be greatly appreciated!

[elnevio]

Do you have Evoscan? You could do a few runs and it can log the throttle position info the ECU is using.

Check the condition of the engine mounts regarding the driveline shunt, especially the front and rear roll stoppers.

[Nick Mann]

I would agree with Nev. Evoscan is a very useful tool. Your system glitch could be a few things but evoscan is likely to log the glitch so you can see if the air flow suddenly changes or the tps jumps.

You will get a thump from the torque converter going in and out of drive as it loads up the drive train. Many suggest that staying in drive and holding on the brakes is a better method. However I'd agree with Nev again that checking engine mounts might be a good idea.

[elnevio]

I would agree with Nev. Evoscan is a very useful tool. Your system glitch could be a few things but evoscan is likely to log the glitch so you can see if the air flow suddenly changes or the tps jumps.

You will get a thump from the torque converter going in and out of drive as it loads up the drive train. Many suggest that staying in drive and holding on the brakes is a better method. However I'd agree with Nev again that checking engine mounts might be a good idea.

I always opt to leave it in D (or 1) and put the handbrake on. Not a fan of leaving a foot on the brake pedal, especially as the VR-4's brakes get hot just by looking at them! :D Less chance of causing brake disc issues.

On another note, Nick has agreed with me twice in one post! I must be paying attention, but more likely just lucky today /dunce

[Piers1989]

Thanks guys,

I have another OpenPort 2.0 on the way so I will get logging :)

Relating to the stop start jolt, I'll ask the garage to check the mounts. In stop start traffic I generally leave it in D and just use the footbrake. It's like there is slack where you start touching the throttle then a moment later everything feels like it engages. On the flipside when you remove the load (say you've reached 5mph and the cars infront start braking, you can feel it "disengage" too.
I wouldn't do this after any form of spirited driving (would use P and keep all brakes off as long as possible) but I'm talking like leaving work for a job and getting stuck in roadworks for 10 mins.

Thanks :)

[Confused]

If you've done spirited driving, leave it in N rather than P. In neutral, the fluid is still circulated, including out to the cooler in the bottom of the radiator. In Park, it's not pumped around.

The injectors should switch off when you come off throttle and are moving - EvoScan will show you the injector pulse width and throttle position sensor signals. TPS should range from ~12% at idle to ~96% at full, so values outside of that range (especially 0%!) could indicate issues or it needing setting up correctly.

[Piers1989]

You learn something new every day - I'll keep that in mind, thanks :)

My interface arrived today - before flashing KS 1.03 and doing a quick blast with logging to make sure it isn't knocking I did a little dawdle to warm the car up and see if I could log the aforementioned "cut" in fuel / RPM.

I noticed it happen once on the drive just before I came home and think I pinned it down to here: https://drive.google.com/open?id=0B44Bync-fZCaY29PUWdaYjREVGs

Looks like it was reading consistently 17-18% but for 1 readout it dropped to minimum (12.15% seems to be the "off" setting). Pulse width was 2.56 on that cell, and the one above.

[Confused]

Odd, I would have expected 0% - that's what mine showed when my TPS was broken. 12.5% says to me that the the pedal was released, or the butterfly valve closed, as that's the normal rest value, as you said.

Is yours an Auto? Maybe the TCL or ASC kicked in and cut the throttle?

[Piers1989]

It is auto, but there were no flashing warning lights, and as you can see I was barley moving and just covering the throttle at the time!

It only ever happens under very light load (as in the least I can cover the pedal).

The issue is I regularly need to feather the pedal to keep the car at low speeds in 30 / 40 zones and when this happens it's annoying and passengers like to comment on how my car doesn't feel right!
I agree it thinks I have lifted off, but it is wrong. I don't know what I can do to rectify this though!