ICV/TPS??? Idle & rough running issues.....

Post Sat Nov 09, 2019 3:11 pm

Ok, so very long story short, my 327 touring is back on the road!
Nothing on this car is standard, so I can understand answers/advice may not be perfect here.
(2.7 conversion by Ant, aggressive cam, maf conversion, bbtb and more!)

Usually, it would be pretty lumpy at idle, (thanks to the cam), but would be at the normal kind of idle speed, wouldn't stall, etc, and would really take off above 3000/3500 rpm ish!

A long time back, before the car came off the road, I had a problem with a sticky throttle and I replaced the throttle body (bbtb) - I'm pretty sure the chap that fitted it for me then, had a play around with the adjustment screw, as it was idling badly and running a bit rough then.
Fast forward to now - I'm not exactly sure what has been poked at over the last couple of years while it's been knocking around a garage and a couple of bodyshops, but currently...

The car won't idle when cold, without some throttle input, for quite a while.
Once the car is nicely warmed, the idle mostly sits around 1500rpm!!! (I think that's been set so they could say it was running!).
Under load, the car misfires and even backfires at times. Before it comes on cam, it's not too bad - less throttle is better, with more obvious misfire with more/full throttle. Once above 32/3500 rpm 'on cam' it sounds really rough, misfiring, down on power and again worse the more throttle you give it, with some smoke from the exhaust if you give it some!!!

It's going into the garage on Monday for this (and a few other bits), but I'll have a poke tomorrow if I get time.

Again, I know it's difficult because nothing is standard... I know there are some wires under the bonnet which have never been connected since this engine went in, but I don't know which, or for what.
However, I have noticed that there is nothing at all plugged into the ICV. Surely there should be some kind of connection there, even if not the standard loom?
There is a 3 pin plug dangling, that looks like it should go there, but doesn't quite reach, (could be caught somewhere) - and I found another 3 pin plug that looks like it would fit, just hanging, on quite a long cable!!!

Should one go to the ICV?
One, or neither to the TPS?
Would it even run without those connected??

I'm assuming no harm in trying both connected to the ICV and see what happens?

Also, seen on the wiki about resetting the throttle body closing point to 0.0015in, but 'setting accurately requires an exhaust gas analyser' - I'm assuming the second part wouldn't be accurate on a modded car? It runs rich and emissions are questionable, when all is well!!!!! Can anyone expand on that???

Obviously, open to any other suggestions please!!!

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Post Sat Nov 09, 2019 3:59 pm

Iirc there should be 3 plugs under there,

One goes to the TPS, one to the ICV & the third I haven't a clue.

The longest should go to the ICV the next to the TPS & the third (shortest) just hangs there.

I had a similar problem with my 2.7 m20.

Mine turned out to be the CPS & TPS were both knackered. Also my injectors (green top m50 injectors) needed a good clean.

As for the throttle stop.

I adjusted mine so that when it was closed it was just 0.0015 of the stop (took some doing to get it that close).
I also gave the ICV a good clean out.

Fingers crossed you can get it sorted.

Post Sat Nov 09, 2019 4:00 pm

I always thought the gas analyser was used when setting the AFM?

Post Sat Nov 09, 2019 4:10 pm

Ah, thanks.
So the TPS is hopefully connected.
I'll try the long one on the ICV when I can and leave the short one hanging!

Haven't even considered the CPS to be honest!
Injectors were good, back when this problem started (it feels like it could be overfuelling at times, if anything!)

No idea on the gas analyser - as I say, emissions are not this cars strong point anyway!!!

Post Sat Nov 09, 2019 4:21 pm

Good luck with it.

When these cars have problems they are a proper ball ache,

I've just found out mine needs the fuel pump replacing

it's one thing after another.

Post Sat Nov 09, 2019 4:27 pm

Ha ha, cheers.
I'm forcing mine back into daily use for a while and quite a bit of mileage, so it has to be sorted asap really - it will get what it needs, while I can afford it!!!!!
If it doesn't get sorted by the guys I'm going to on Monday, I'll be seeking out a specialist who knows these inside out!!!

Post Sat Nov 09, 2019 4:30 pm

miniblob wrote: ↑
Sat Nov 09, 2019 4:27 pm
Ha ha, cheers.
I'm forcing mine back into daily use for a while and quite a bit of mileage, so it has to be sorted asap really - it will get what it needs, while I can afford it!!!!!
If it doesn't get sorted by the guys I'm going to on Monday, I'll be seeking out a specialist who knows these inside out!!!

I'm doing the same with mine lol but it's all done apart from the fuel pump & mot.

Gonna be fun in this weather.

Post Sun Nov 10, 2019 8:24 am

As if by magic.......
Connected up the icv to longest wire before I set off home last night - turned the key and it fired straight up with a steady idle (albeit very high)!!!
Seemed to run slightly better too, although still misfiring obviously.
Due to all someones messing about it now has a warm idle of about 2k rpm, but it's an improvement at least!!!

Driving home, I was thinking I don't remember seeing anything connected to the maf either. Surely there has to be???
So when I got home and had a look, I found the connector for that and plugged it in.
Couldn't tell any difference on the driveway, but I'll have a poke around and see what else these idiots missed out when getting my car 'running' and then take it for another drive!!!!!

Post Sun Nov 10, 2019 8:36 am

always good news when it's a simple fix,

as for the high warm idle, that could be the ecu relearning it's base settings, plug the maf back in & take it for an Italian tune up, that should help it,

as for the "garage" that did the work i'd steer clear of them, or go have a "word" or two.
lets hope they aint messed anything else up.

Post Sun Nov 10, 2019 8:39 am

also, check the inlet side for any vac/air leaks as they could be contributing to the high idle.

Post Sun Nov 10, 2019 9:19 am

As I said, I'm sure someone has messed about with the throttle body adjustment, so that'll have to be reset next!!!
Will have another poke around now it's daylight and take it for a spin.

I know the guys that own the place and they're good, but they've had a lot of crap young guys working there - finding it hard to get decent staff at the mo apparently.
Don't mind as much as I didn't pay for 'getting it running' and various other things he's sorted for me.
They're very good to me for other jobs on normal cars, cheap labour, lend me vehicles, etc - but that said, if this isn't sorted Monday, I'll take this one somewhere else to sort the running!!!!!

Post Sun Nov 10, 2019 9:41 am

when it comes to adjusting the throttle stop you could try following this guide

https://blog.bavauto.com/11511/bmw-thro ... iy-how-to/

seems to cover it,

as for the garage, i know what you mean but you can't always guarantee that it'll be the same person each time working on the car,
but as you say if they've had a lot of crap young lads working there it's hard to know where to start looking first.

it's folk like that that ruin the reputation of good garages,
like i said plug the maf back in, take the car for a good spin & take it from there, hopefully there's no more problems for you.

Post Sun Nov 10, 2019 3:49 pm

Thanks mate, not seen that guide so I'll have a look through it!
Did also see somewhere in the wiki about adjusting it for throttle pedal/cable travel as well - maybe someone played with that too, as adjusting the throttle body (just randomly at the mo) has lowered the idle a bit, but it's still about 17/1800 rpm!!!

Maf connector doesn't appear to make any difference, which is a bit odd!

Misfire I reckon is unrelated anyway!

I'll tell him to get someone decent on it tomorrow, reset the throttle body, check the throttle travel, etc and go from there!!!

Post Sun Nov 10, 2019 6:21 pm

no worries bud, good luck with it lets hope they can get it sorted at last.

Post Mon Nov 11, 2019 6:47 pm

Had it in their workshop for a bit today - now idle's about 1200 and drives slightly better......
There was a lot of oil residue in the inlet manifold that they cleaned out and sorted a couple other bits for me, but they reckon there's an air leak, on the intake side, which they ran out of time to track down!
It's a bit more acceptable now, so going back in next monday for more!!!

Question for you steve_k - had your 2.7 got a MAF conversion, or standard AFM?

Reconnecting my MAF sensor didn't appear to make any difference, but I'm not sure it was ever connected - and the chap who has worked in my car previously didn't think it was ever connected!!!
Not sure how it would run/what the point is, if it's not connected though!!!

Post Mon Nov 11, 2019 7:48 pm

miniblob wrote: ↑
Mon Nov 11, 2019 6:47 pm
Had it in their workshop for a bit today - now idle's about 1200 and drives slightly better......
There was a lot of oil residue in the inlet manifold that they cleaned out and sorted a couple other bits for me, but they reckon there's an air leak, on the intake side, which they ran out of time to track down!
It's a bit more acceptable now, so going back in next monday for more!!!

Question for you steve_k - had your 2.7 got a MAF conversion, or standard AFM?

Reconnecting my MAF sensor didn't appear to make any difference, but I'm not sure it was ever connected - and the chap who has worked in my car previously didn't think it was ever connected!!!
Not sure how it would run/what the point is, if it's not connected though!!!

i thought there could be an air leak, 1200 idle is coming down then.

as for the oil residue in the inlet, i'd check the condition of the pipe that goes from the rocker cover to the inlet, thats the main reason i use a baffled oil catch can in it's place,

one place to check for an air leak no matter how daft it sounds is the PCV tube which goes from the bottom end to the inlet, check the state of the rubber O rings top & bottom, mine was missing the top one, replaced it & the idle went back to normal.

as for my 2.7, mine uses the AFM from a 3L 944, can't remember where i got it from but it works perfectly.

as for your MAF not being connected i have no idea how it would run with it unplugged.

Post Wed Nov 13, 2019 2:32 pm

Pipe from the rocker to the inlet is on my list!
So how is yours set up - pipe from the rocker goes to a catch can, then just blanked off on the inlet?

Not sure about that tube from the block to the inlet - recall a pipe with a spring round it from the block, but thought it was metal and no idea where it goes - could that be the one?
I'll tell them to check that too!

Post Wed Nov 13, 2019 2:45 pm

On mine the pipe goes from the rocker cover to the baffled catch tank then back to the inlet.

The pipe on the underside of the inlet is the pcv tube aka the bitch tube.

Where it meets the inlet manifold there's normally a rubber O ring which seats the top of the tube,

Because mine was missing it was drawing extra air in.

Fitted a new O ring (25p from a local motor factors) & it seemed to fix the high idle.

Post Thu Nov 14, 2019 4:32 pm

Ah right, might look into a catch can then.

I'll def get them to check the pipe on the underside - cheers!

Post Fri Nov 15, 2019 12:14 pm

So something happened yesterday...... was on the motorway for some time, stuck in a 50 zone for 15/20 mins then sat at a steady 65 ish (where it seemed happy) for about 30 mins....
As soon as I came off the motorway, the car drove completely different!!!
Only way I can think to describe it, is as if a massive amount of weight had been lifted and it was suddenly revving really freely through the range, especially 'on cam' where it didn't want to rev before.
Idle has dropped right down and is hunting now, (between 700ish and 900ish), so obviously seems like an air leak somewhere.
There's still a little misfire occasionally, but it's a massive improvement, out of nowhere!!!

So what happened???
Obviously, it's great, but at the same time, I have no idea what it was and when it will happen again, (presumably only a matter of time). Still drove way better late last night when I was out and this morning.

Could it have been the TPS was stuck and the heat and vibration sitting on the motorway loosened it off?
Have I finally burnt through some old fuel or oil that was sitting somewhere?
Or cleared some other blockage somewhere???

Only other thing I noticed yesterday/this morning, is that the temp gauge is sitting quite low, so poss a thermostat issue there as well.

Not sure how many people will be reading this, but where does your temp gauge sit???
I'm sure all BMW's of all models I've ever had, have sat solidly on halfway.
I'm not 100% sure I trust the gauge, but it sits around the first line out of the blue, but dropped quite a bit below when sitting on the motorway for a while and doesn't get much over the first line, even sitting in traffic!!!

Post Fri Nov 15, 2019 12:56 pm

325i should sit at slightly above a quarter, so yours should be the same.

Paul

Post Fri Nov 15, 2019 1:13 pm

Hmmmm, thought I read that somewhere else recently... might be ok then.

Strange, I'm convinced all my BM's have always sat on the halfway line - and I've had a lot!!!

Post Fri Nov 22, 2019 4:26 pm

Forgot to update this..... on Monday they sorted a couple of air leaks on the intake side apparently - not exactly sure what else they did, but it runs a lot better now!!!

Only issue really, which I can live with for the mo, is the idle!!!
Fast idle again when cold - prob 13/1400 rpm.
Once it's warm, it'll sometimes sits about right, but mostly hunts between almost stalling at 600? ish and bouncing up to 900?ish. Or sometimes it'll randomly rise to about 1100 and stay there!!!!!!