MSII v3.0 board, with MSII Rev 2.92000
Not running any idle control (aside from the idle screw on the TB), and have been working on tuning idle. I have it sitting well, from what I can gather, but I have this strange dip every 45 seconds or so. RPMs drop, and then come right back.
Attached is the MSQ and the Log file showing the dip. Any idea what is going on here?
Smooth idle then abrupt dip, then smooth idle returns
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Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.
If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0). For tuning/troubleshooting questions, please attached a datalog and your MSQ file to your post.
If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days
The full forum rules are here: Forum Rules, be sure to read them all regularly.
Smooth idle then abrupt dip, then smooth idle returns
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Re: Smooth idle then abrupt dip, then smooth idle returns
The battery voltage seems to dip just before the problem. That in itself shouldn't be a problem, but it makes me wonder about the supply to the MS and the grounding. The TPS output also appears to have a lot of jitter on it which would also suggest incorrect grounding.
Dave P, London UK.
Rover V-8
MSII V3
EDIS
Tech Edge Wideband
Rover V-8
MSII V3
EDIS
Tech Edge Wideband
Re: Smooth idle then abrupt dip, then smooth idle returns
Thanks for the quick feedback.
Everything is grounded to one spot on the engine block, but I may move it to see if I get any better results. I have noticed that the temperature seems quite jittery as well, maybe this could be the issue as well.
Everything is grounded to one spot on the engine block, but I may move it to see if I get any better results. I have noticed that the temperature seems quite jittery as well, maybe this could be the issue as well.
Re: Smooth idle then abrupt dip, then smooth idle returns
Sounds like you've identified your problem. The rule of thumb is:-gt eunuch wrote:Thanks for the quick feedback.
Everything is grounded to one spot on the engine block, but I may move it to see if I get any better results. I have noticed that the temperature seems quite jittery as well, maybe this could be the issue as well.
If you unplug the MS, would any sensor still have a ground?
If the answer is yes, it means the high current MS ground (for injectors etc) is being shared with that sensor. And the sensor input on the MS is attempting to measure tiny currents.
To explain further, any cable has some resistance. So there will be some voltage drop along it when drawing current. Now 0.1v won't matter at all to a 12v injector - but will to a sensor which may need to resolve amounts that small or even smaller.
So the correct way is to bring each and every sensor ground back to the DB37 connector, where they then ground to the MS ground plane. Which is in turn grounded to the engine block using separate wires.
Dave P, London UK.
Rover V-8
MSII V3
EDIS
Tech Edge Wideband
Rover V-8
MSII V3
EDIS
Tech Edge Wideband
Re: Smooth idle then abrupt dip, then smooth idle returns
So today I checked over my wiring, verifying grounds, etc.
I am running the Relay board, and that had been grounded well, however I was 'piggy backing' off that ground for my wideband o2 sensor. I had soldered the relay board, and the LC-1 grounds onto one wire, and then grounded that to the engine block. I have now fixed this, giving the LC-1 it's own dedicated grounding wire all the way to the block, where it is bolted to the same grounding bolt as the relay board.
Car idles quite well at this time, and maintains the idle nicely. Attached is a revised log, and MSQ. Does it seem better? Anything else I need to be concerned with? Next steps are going to be tuning via passenger seat while a friend is driving.
I am running the Relay board, and that had been grounded well, however I was 'piggy backing' off that ground for my wideband o2 sensor. I had soldered the relay board, and the LC-1 grounds onto one wire, and then grounded that to the engine block. I have now fixed this, giving the LC-1 it's own dedicated grounding wire all the way to the block, where it is bolted to the same grounding bolt as the relay board.
Car idles quite well at this time, and maintains the idle nicely. Attached is a revised log, and MSQ. Does it seem better? Anything else I need to be concerned with? Next steps are going to be tuning via passenger seat while a friend is driving.
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