Rev hang after manual conversion???

[Simonr32 28]

Hi team. 

I have completed the manual swap on my m54b30 330ci.

I used a zf gearbox and a rhd lightweight flywheel and clutch.

When you rev the engine out, the revs seem to stick at high rpms for a second.  Making it feel strange when shifting . 

Have had the DME coded to manual aswell. 

Anyone had this issue ? 

[aja540i 1906]

I had the same thing on my e39 540i, apparently it can be coded out but I sold it before I got a chance to sort it. I originally had a light flywheel but swapped it for a standard DMF and it didn't make any difference.

[BM WORLD 1283]

15 minutes ago, Simonr32 said:

Hi team. 

I have completed the manual swap on my m54b30 330ci.

I used a zf gearbox and a rhd lightweight flywheel and clutch.

When you rev the engine out, the revs seem to stick at high rpms for a second.  Making it feel strange when shifting . 

Have had the DME coded to manual aswell. 

Anyone had this issue ? 

yup light flywheel will do that 

[Sammo 2544]

Weird, I swear mine does it too, not when i'm driving relaxed or flat out but when I'm accelerating and shifting around 75% pace... could be user error but 6 months later still does it at times. I feel like I have to be very deliberate with taking my foot right off before engaging the clutch.

Manual converted when I got it, ZF, assume standard clutch and flywheel but no idea really.

[KwS 2425]

My old E36 did that after it was converted to manual with light flywheel. Always thought it was because it wasnt re-coded, but maybe not.

[Eagle 1662]

I've read of clutch switches not being wired in properly causing hangs but that was more on M52TU engines, does your cruise control work ie clutch module wired in properly?. E46 manuals used electric fan instead of viscous i believe which may have some influence. When i did my manual swap i updated the DME to the latest as it was the first version ever released. Manual BMW's with DBW have never felt that great to me, reprogramming would probably improve that to some extent but its no cable.

 

 

[exextatic 111]

Check clutch switch is wired and operating correctly, and also remove the viscous and pusher fans, replacing with the proper manual puller fan.

[Simonr32 28]

Yeah so that was my next option to try. 

I have bypassed the clutch switch.  I think I need the signal sent from the clutch switch to pin23 on the DME.  Apparently this signals the DME to cut the revs when the clutch pedal is pressed. I have ordered the correct clutch switch. 

Will try this. If not it could quite well be the light flywheel . 

[tawa 150]

I'm keen to hear how you get on with that clutch switch, mine does it too and I've just been living with it (got a recoded ECU for it). Can't recall doing anything with a clutch switch...

[Herbmiester 925]

I will be in the same boat soon, so really keen to see how this gets resolved. 

[Simonr32 28]

I had my ecu coded aswell. Still no fix. I will hopefully get around to doing it in the next few weeks. Super busy atm. 

Will let you know my findings.  

[Herbmiester 925]

I have some info via a chap in the US who said that part of the issue with M52 cars is the ICV. His theory is that if the throttle shuts air can still get in via the ICV. He said Mustang drivers have a similar issue and restricting the airflow to the ICV solves the problem. He said dont cut it off but restrict the diameter of the tube that comes from the Throttle Body boot, start by reducing diameter by half. He glued in a smaller piece of rubber hose. He said also make sure that there are no air leaks like a torn throttle body boot and he disabled the flapper valve vacuum that went to his exhaust. Basically you cant have any vacuum leaks as this contributes a lot  to the rev hang issue. Now this is someone else's work not mine so just passing it on. 

[m325i 709]

#metoo in my old e36 328i conversion

[KwS 2425]

7 hours ago, Herbmiester said:

I have some info via a chap in the US who said that part of the issue with M52 cars is the ICV. His theory is that if the throttle shuts air can still get in via the ICV. He said Mustang drivers have a similar issue and restricting the airflow to the ICV solves the problem. He said dont cut it off but restrict the diameter of the tube that comes from the Throttle Body boot, start by reducing diameter by half. He glued in a smaller piece of rubber hose. He said also make sure that there are no air leaks like a torn throttle body boot and he disabled the flapper valve vacuum that went to his exhaust. Basically you cant have any vacuum leaks as this contributes a lot  to the rev hang issue. Now this is someone else's work not mine so just passing it on. 

Why would the ICV make a difference though? I dont think factory manual cars run a different ICV, does the ecu control it differently auto/manual?

[Dogballs 115]

FYI. I have done an E46 manual conversion, and wired the clutch switch at the time. The revs do not hang. I used a S54 std flywheel and pressure plate with the 6speed ZF 22 spline g,box. The std M3 flywheel is the heaviest of the *54 options.., so if anything would hang it would this config! - I suspect the lack of switch will make the difference.. 

I’ll be interested to see the result of getting it connected.

[Herbmiester 925]

6 hours ago, KwS said:

Why would the ICV make a difference though? I dont think factory manual cars run a different ICV, does the ecu control it differently auto/manual?

I am unsure just passing on what he said worked. Clutch switch seems like a solution to me.

[tawa 150]

23 hours ago, Herbmiester said:

I have some info via a chap in the US who said that part of the issue with M52 cars is the ICV. His theory is that if the throttle shuts air can still get in via the ICV. He said Mustang drivers have a similar issue and restricting the airflow to the ICV solves the problem. He said dont cut it off but restrict the diameter of the tube that comes from the Throttle Body boot, start by reducing diameter by half. He glued in a smaller piece of rubber hose. He said also make sure that there are no air leaks like a torn throttle body boot and he disabled the flapper valve vacuum that went to his exhaust. Basically you cant have any vacuum leaks as this contributes a lot  to the rev hang issue. Now this is someone else's work not mine so just passing it on. 

I had heard that too, gave mine a clean, and also run a wideband sensor, doesn't show any spikes in AFR as I'd expect if the rev hang was due to an air leak.

[euroriffic 609]

When I did my e36 328i touring I had the issue of the icv not catching in time and stalling when pulling up to intersections. Swapped the computer out for a manual one and was good as gold after that