Ryan 99 Posted August 12, 2006 My rebuilt mi16 idles at around 2200. If you squash the hose to the idle valve, or unplug it completly then it drops to around 1700. I've hooked the valve up to a battery and it does open and close fully. I know thats not an ideal test as it's pulsed to vary the opening, but it does confirm that the valve at least does something. The engine runs fine otherwise, although I haven't taken it much over 3k yet. Could this possibly be the ECU coolant temp sensor? Also does the AFM idle screw control the idle speed, or just the fuelling? Share this post Link to post Share on other sites
j_turnell 137 3 Cars Posted August 12, 2006 Sounds like an air leak does the revs take a while to go back down when blipped? Share this post Link to post Share on other sites
Higgy 0 Posted August 13, 2006 When I put my spare Mi in it idled very high. I re-used all the electronics from the old engine apart from Throttle Position Sensor. I then swapped the whole throttle butterfly assembly over from the old to new engine and it runs fine. So maybe your butterfly is open slightly causing it to rev? I have not got round to looking at the throttle assembly to see what was wrong with it though. Share this post Link to post Share on other sites
jackherer 543 Posted August 13, 2006 I have not got round to looking at the throttle assembly to see what was wrong with it though. the spindle wears, most of mine are like that Share this post Link to post Share on other sites
Ryan 99 Posted August 13, 2006 When I was building the engine I stripped the throttle body down and cleaned up all the parts, so it's possible that something could be slightly out of place. Surely worn spindles or a butterfly opening by a fraction of a degree wouldn't cause it to over-rev by 1100rpm though? Share this post Link to post Share on other sites
Higgy 0 Posted August 13, 2006 (edited) You would be surprised the little amount of air it needs, especially when there is no load on the engine. Mine was idling at 3k rpm. And as I said, I swapped the throttle over and it now works fine. There seems to be 2 makes of throttle. Webber and (i think) AVO or something like that. The 1990 engine had AVO and the 1989 Webber (which was the fauly one). Edited August 13, 2006 by Higgy Share this post Link to post Share on other sites
Ryan 99 Posted August 13, 2006 Are the 2 versions otherwise identical (butterfly size,etc)? Share this post Link to post Share on other sites
Higgy 0 Posted August 14, 2006 Are the 2 versions otherwise identical (butterfly size,etc)? Not sure, but just looking at them the butterfly it looks the same. However the Webber one has alot more parts on the casting, which dont looks utilised on the Mi. Maybe this throttle body was used on another engine? I did take a load of comparison pics, I'll hunt them out and upload them. Share this post Link to post Share on other sites
Ryan 99 Posted August 14, 2006 However the Webber one has alot more parts on the casting, which dont looks utilised on the Mi. Maybe this throttle body was used on another engine? I think the XU9JAZ engine used the same one, but with an extra vacuum take-off for the dizzy, and a solenoid valve screwed into the bottom for the aircon. Share this post Link to post Share on other sites
jackherer 543 Posted August 14, 2006 You would be surprised the little amount of air it needs, especially when there is no load on the engine. Mine was idling at 3k rpm. And as I said, I swapped the throttle over and it now works fine. There seems to be 2 makes of throttle. Webber and (i think) AVO or something like that. The 1990 engine had AVO and the 1989 Webber (which was the fauly one). The two types of MI16 TBs are Weber and AMC. A similar TB is used on 405 SRi/BX GTI 8V engines but the butterflies are smaller. Share this post Link to post Share on other sites
pug_ham 244 3 Cars Posted August 15, 2006 I've just stripped a Weber Mi16 TB tonight, the car was suffering froim an ever increasing idle speed & it turned out that the cam was sticking so it wasnt closing when the pedal was released. This TB had previously been messed with & the butterflies weren't opening staggered like they should but both together so a sticking throttle cam was making it rev higher. There is some play in the spindle for the top butterfly but I think its going to be staying like that unless we can find one without any play. I think the XU9JAZ engine used the same one The XU9JAZ uses a similar one to the standard 8v TB so it is nothing like the twin butterfly style fitted to the Mi. Graham. Share this post Link to post Share on other sites
jackherer 543 Posted August 15, 2006 I'm considering fitting a VAG TB, not because I think it will make any extra power (it wont...) but because I hope it will make my car idle at a sensible RPM (if I ever get it running again that is) http://www.205gtidrivers.com/articles.php?data=e2-vagtb Share this post Link to post Share on other sites
