HELP PLEASE :-(...somethings not right!!!

[gillsl500]

Right I guys I jumped into my E30 cabby 325i auto box was cruising down the road and noticed that the revs were coming on as if I had put my foot down? Any ways thought nothing of it and carried on, happened a few times again before I parked up.

So later when I drive her back home the same thing is happening, only loads more obvious and almost aggressive?!

I'l be doing 35-40mph at just over 2000revs with my accelerator pressed accordingly and then suddenly the revs start shooting up to 3000revs and back down to 2000revs. At this point I remove my foot completely from the accelerator and this continues to happen two more times before it comes back to normal!

Guys can any body help diagnose a potential cause for this? I hope I've explained it clearly?

Many thanks

[mrLEE30]

moved to technical help.

First place i would look would be for large airleaks on the rubber inlet hoses between the AFM an the throttle body. an easy test for this is the spray carb cleaner around the inlet area carefully while the engine is running on idle, and change in engine pitch signifies an air leak as it allows the carb cleaner into the inlet and this affects the engine revs - normally raises them. BUT KEEP the spray AWAY from the sparkplug side - it highly flammable!

How does it idle once warm?

[gillsl500]

Cheers buddy, have to say my knowledge is limited so when you refer to the rubber in let, that's on the right hand side of the engine right? when looking at if I was standing in front of the passenger head light?

When it's parked up I've noticed no problems with idle although sones when cold she screeches a little and the car wobbles when idleing.

If any body has any pcs of the part I need to be looking for, that would be great?

Also can I use wd40 to do te test?

Many thanks for your help mate

[gillsl500]

Right guys I checked it out and noticed this, have no idea what it is but it definatly loose. In the pics you can see how it should sit and how loose it is...



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Hope this helps?

How could I seal this and stop it from being so loose?

Cheers

[Grrrmachine]

Familiarise yourself with the Intake side of the engine:

http://www.e30zone.net/e30zonewiki/index.php/Intake

What you're looking at is a Vacuum Booster hose (for the brakes) going into the Throttle Body. Loctite make other sorts of sealants beside superglue, and one of those will keep that hose in place. Plumbers' PTFE tape will also help a bit (since that's used on air fittings for compressors and the like).

[mrLEE30]

screeching is normally your fan belt slipping as its damp or loose (or both!) unless it does it all the time its nothing to worry about now,

as you see above we have a very good wiki section that helps you with the basics.

when i say the inlet hose if you stand on your passenger side of the engine you will see to the lower left behind the lights is the airfilter box, this hten goes to another box, this is the AFM or Air flow Meter, from here will be a rubber pipe going to the throttle body (what you have shown a picture of above) and from there it goes to the metal inlet manifold and into your cylinders. all this is the air inlet and control part of the engine, it is designed to monitor and contorl how much air goes into the cylinder where it is mixed with fuel from the injectors and ignited by the spark.

if you have a air leak it will be between to AFM and the Throttle body that makes the biggest difference, and normally the big rubber hose is split, so check this first. the carb cleaner trick helps to find a small leak as the engie is runnig and you spray the cleaner around the inlet hose, if there is a leak it wil such the carb cleaner in and affect the engine speed - otherwise a good visual check is OK.

As you have found there are many hoses going to and from this area so its quite hard to spot small leaks - hence the spray. note clean the spray off after as it can perish the rubber.

Try this first an then let us knwo what if anything you find

[BenHar]

I'l be doing 35-40mph at just over 2000revs with my accelerator pressed accordingly and then suddenly the revs start shooting up to 3000revs and back down to 2000revs. At this point I remove my foot completely from the accelerator and this continues to happen two more times before it comes back to normal!

This sounds like the gearbox flicking between gears.

Check the gear box oil?

Ben

[gillsl500]

Really appreciate all your help fellas

Actually come to think of it, the gears do flick up and down and that's where the revs appear to be affected? I've not much experience with auto boxes and only just thought about this?

Other than the gear box oil could it be somthing else?

Cheers

[mrLEE30]

^^^ OK now you mention that the gear change that is entirely a different matter, the way i read it was the engine surges even with your foot off the throttle.

OK start again.

1 check the auto box fluid. to do this you start the car, run it up to normal temp by driving. stop on level ground, keep engine running. handbreak on select each position on the autobox from R through to 1, pausing for a few seconds in each position. then retrun to P. open the bonnet and locate the dip stick (just below the windscreen next to the throttle body) remove and the fluid level should be between the marks. also rub some fluid between you fingers, it should not be gritty, smell it - it should not smell burnt, it should also not be foamy.

2. all this OK then chances are you have a stuck govenor or an electrical problem (i assume you have the later autobox with the rotory switch next to the lever that says S-E-123 - also worth asking oif this switch does anything? i.e. E is normal driving. S will not switch into overdrive with lever in D, and 1-2-3 hold the box in the gear you select with the lever)

Also check the conection to the control unit (located on the left in your boot).

That unfrotunatekly is about all you an do with limited knowledge, unless you want to have a go at draining the thing and changing the filter - and for this i suggest you invest in a Bentley manual - otherwise its a specialist.

[gillsl500]

Cheers for your help buddy, I've been at work, but will do as you said and see if we can pin pOint the Problem?

I'l post up soon as I've done it...once again thanks for you time and help mate