OK, the car is running (and it scared the sh*t outta me in Asda carpark earlier doing a nice slide.. ).. but..

 

When pulling away (or revving the engine under the bonnet), as the throttle opens off closed, the revs dip right down, then race up to catch up to the throttle position..

 

This makes pulling away..... interesting!

 

I've checked the TPS (now set at 0.45v closed), but it could be the idle control valve not set properly? When I pulled the yellow plug off, there was no change in RPM, shouldn't it drop a little?

 

At idle, I can hear a hissing, but it could be coming from the AIV's, would that be right? (The hissing goes away if I pinch the vacuum line that goes to the stock boost sender & AIV solenoid (I think that's correct?))...

 

Ideas? suggestions?

 

Thanks in advance

Aaron

Its funny you should mention that Aaron cus I get a drop in revs too when I press the accelerator from idle. Only very slightly mind but enough to grab my attention.

 

Is this normal on standard setup people?

One other question on the above;

 

When adjusting the throttle cable, should it be adjusted so that the throttle is a tiny bit open, when the cable is released, or should it be adjusted so that the plates are resting as closed as they can be on the spring tension? (the latter is how mine is now).

 

Thanks, Aaron

 

P.S. Cos, I dont think it's normal m8..

Az,

Have a look at EF & EC-87. Sounds like your symptom.

Andy - thanks m8, that sounds like it..

Bugger it's a right git to get to at the back of the plenum too!

 

I do recall that when I pulled the AAC plug, there was no drop in engine speed, and turning the screw did nothing

My car does that too. But only when you touch the pedal. If I tap my foot on it really light lightly, I can almost stall it.

However, it doesnt do it really when I pull off.

It's worse in an auto stuart - because you can't bring the revs up before pulling away (well.. you can but it's not great for the gearbox.. )..

 

I'm wondering if it's a big vac leak, meaning that the AAC is never active, perhaps? Maybe that hissing sound *isn't* normal that I have at idle..

 

Need to compare it to someone elses car I think

Originally posted by SRRAE:

My car does that too. But only when you touch the pedal. If I tap my foot on it really light lightly, I can almost stall it.

However, it doesnt do it really when I pull off.

 

 

Thats exactly what mine does too. Sounds like it either meant to be that way or that over time, a hesitation builds up. I used to have a similar problem with my Astra Belmont CDi but after consulting a specialist, he said that this was a characteristic of the Jetronic 2 injection system and could be sorted by grounding pin7 on the ECU loom connector. And it worked. Not sure if the same applies here.

 

Cos - it's definitely not normal.. But yeah it's something that sets in over time I imagine as stuff perishes/goes out of adjustment..

 

One thing I noticed earlier today is that I dont have the hesitation when the car is cold... (Or rather, I dont have it when the air regulator is open, I think is what it is)..

I think the same applies with mine too. I feel some further research coming on.

If I hadn't failed miserably on getting the wires for the fuel pressure sender into the engine bay today, and then had the (switched) power to the radio (which also controls the auto-mirror relay thats wired in on my car) die, I'd have done some

 

Bloody cars eh!

 

aaronjb this is a symptom I see a lot of and in general a good tb clean can put right,also the butterfly openings need to be checked that they are the same a .5 mm feeler gauge is about right and ensure the little air bleed hole in front and below the butterflys are clear.

 

Jeff TT

 

Jeff - everything in there is clean and clear, looks like the day it rolled out of the factory (I've only just put it all back together remember.. half a can of carb cleaner went on that lot )..

 

But it could be the TB's not opening synchronously, I did notice today that if I really gently press on the throttle quadrant, the right throttle bar moves about 1 or 2mm before the left follows it..

 

In fact, the right one seems to move before any resistance is felt on the throttle quadrant..

This is a typical symptom of the throttle bodies not being synchronized.

 

Check also for vacuum leaks.

As you say, the AAC valve can be closed completely because of an air leak.

 

The best method to check for air leaks is to blow up your engine....with air of course ;-)

Check out the Tech section of my home page for that.

 

Keep on fighting m8!

Maciej

I was thinking that plastic explosive would work better Maciej

 

I went around the engine today systematically removing, and plugging vacuum lines, and none of them made any difference, so I think I can safely say it's not that..

 

It's also not the PRVR solenoid, since it's still there with the vacuum line to the regulator removed & plugged.

 

I also don't believe it's the AAC valve, because it seems to be operating correctly and in-spec (I've nudged the idle up a bit though - I think I set it a little low, idle when warming up was terrible)

 

I think you're right on the TB's not being synchronised..

 

I had a very close look at them today, and I noticed that the passenger side doesn't actually sit on it's end stop - it's 1 or 2mm off it, while the drivers side does..

 

Whats the best way of resynchronising the TB's? Should I adjust the end stop on the drivers side so that it matches the passenger side, then adjust the end stop on the passenger side so that the TB bar is actually resting on it?

 

Or should I adjust it with the screws where the throttle bar meets the TB bars (where those needle bearings are, I mean..)?

 

Cheers

Az

Hi Guys,

 

I had the same problem

 

Dropping of you engine revs on gentle depression of the accelerator from standstill is either due to an air leak in the PCV lines or blocked PCV valves. The lines are standard rubber tubing and start wearing away after about 60k. The PCV valves should be changed every time you do the timing belt, so every 60K also.

 

Start the engine and listen carefully around the top of the engine near the rear for air leaks, alternatively dismantle the air pipes, clean and examine them one at a time and find the leak.

 

When fixed or plugged, the hisitation resolves.

 

Good luck,

 

Amer.

Amer,

 

I can't speak for the others, but I'm 99.999% sure it's not an air leak in my case (unless it's say between the upper & lower plenums, but that is unlikely).. Given that I just rebuilt my engine, all hoses replaced with silicone, new PCV valves (tested for leaks before they went on), new PCV hoses etc..

 

I've also been all round the engine, systematically disconnecting and plugging all vacuum lines, and not one made a difference to the problem..

 

Hence I'm looking at the TB synchronisation, which does appear to be off (the right side isn't sat on it's end stop, and does seem to move a mm or two before the left side).

 

Thanks though,

Aaron