12-19-2020, 04:18 PM | #1 |
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Stalling at every cold start & 7mpg
Current mods are:
Catless downpipes Full 3in IPE exhaust VRSF Intercoolers methanol injection without Jb4 map0 gapped ngk plugs DME stage 2 tune bcm with jb4 upgraded SSP clutches afe cold air intakes stage 1 turbos Cold start delete Probably something Im missing but nothing out of the ordinary. The roughest cold start I've ever seen. The RPMs fluctuate by 5-600 rpms up to 1200 then drop back down to 600 continuously over and over until the engine stalls. 0 codes on the car but I've been getting around 6-8mpg and my cold start will always stall the car unless its being driven right away or revved. Its been getting worse with colder climate, but completely disappears after 1-2minutes of driving. I've always been averaging between 6-8miles per gallon in city driving. Rarely go over 5k rpm in Manhattan, but I always try to use the entire RPM range every drive. I believe the idle possibly has to be adjusted? any ideas on how to do this? Last edited by m6NYC; 12-19-2020 at 05:28 PM.. |
12-21-2020, 10:11 AM | #3 |
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I had at one point thought the same since BMW has an extended warranty on their injectors until January 2015. My car was produced February 2015 and has the updated index injectors however the car is showing 0 codes whatsoever and that is throwing me off.
I will looking into this though. Thanks for mentioning it |
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12-21-2020, 01:44 PM | #4 |
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Here is a video of the RPMs oscillating. Usually it jumps from 600-1200rpms continuously. Seems to have gotten worse after my cold start delete.
https://vimeo.com/493476826 ANOTHER UPDATE: performed the smooth running test through ISTA+ and not surprisingly the flow rates of all 8 injectors are within range. Had they weren't, I would've received a code.[/U][/I][/B] Last edited by m6NYC; 12-21-2020 at 03:23 PM.. |
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12-21-2020, 07:08 PM | #5 |
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Drives: BMW'16 M6GC
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I dare to assume that irreversible changes have occurred in the cylinders. What is the consumption of engine oil?
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12-21-2020, 09:11 PM | #6 |
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I'm a F10 M5 guy lurking around and saw this post. Have you tried cleaning the MAF sensors? I had a similar idling issue (not the fuel consumption issue) that was quickly resolved when I cleaned my MAF's.
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12-21-2020, 09:22 PM | #7 |
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12-21-2020, 09:23 PM | #8 |
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I have already tried cleaning the maf sensors unfortunately with no resolution
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12-21-2020, 09:32 PM | #9 |
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https://vimeo.com/493590712Updated video of it stalling.
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12-22-2020, 12:52 AM | #10 |
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Mmmmm.. very strange that it's not throwing any codes. Aside from the MAF it could be related to the battery.. there was a thread running around a while ago with same symptoms, rough cold start and all that jazz.. ended up being a bad battery to everybody's surprise.
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12-22-2020, 04:46 AM | #11 |
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replace MAF or injectors, i was having leaky injectors before without any codes & checked them with ISTA showing all good, replaced later and all fine now, good luck
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12-22-2020, 12:56 PM | #12 | |
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I just re-cleaned the MAFs this morning and replaced/recoded a new oem battery this past February. Also added a bottle of seafoam fuel injector cleaner to full tank of gas last week with no resolution or improvement. Could you explain the symptoms you were getting with the leaky injectors? I had the car parked and not driven for almost 5 days and it stalled 4-5 times idling but it was also 10-15 degrees F which is the coldest it has been in New York this season. I was looking for the obvious lack of power symptoms you would see with failing injectors but its hard to notice any power dips with 780wheel horsepower. |
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12-22-2020, 07:28 PM | #13 |
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A sure way of ruling out injectors is pulling plugs in the morning to see if they are wet and smell of gas.
Leaky injectors, will give you a rough cold start (like yours) and in about 40sec the car will run fine, will pull hard and nothing will seem off. The issue is while trying to figure it out, you could be diluting your oil with that fuel and ruining your bearings. |
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12-26-2020, 04:09 AM | #14 | |
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what Spacecpe said above + you will hear little ticking sound coming from the exhaust sometimes at idle
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12-30-2020, 02:50 PM | #15 | |
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Seems like this issue was going on for a good amount of time unfortunately. The surging idle was hidden by the high revving cold start and the white smoke/unburnt gas smell was removed by the catalytic converters. Only when I removed the Cats and cold start did I start to notice this issue. I wouldn't be surprised if this is the cause of the infamous rod bearing issue with the E60/63 M5 M6 since it throws no warning issue and can continue for a relatively long amount of time until it progresses to the point of throwing an error code. Couldn't really hear any ticking from the exhaust at idle, I did hear a very very slight surge in rpms as that continues to happen even when warm. The surge is barely noticeable and less than 50 rpms. Last edited by m6NYC; 12-30-2020 at 03:04 PM.. |
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01-01-2021, 09:54 PM | #16 |
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Honestly with the rod bearing issues on this platform, I'd make injectors a regular maintenance item, maybe every 40k ish, new injectors. Every 10k plugs, every 15-20k all O2 sensors. And im sure everyone wouldn't have any issues
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03-04-2021, 10:12 PM | #17 | |||
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Found out my smaller axillary coolant tank was slowly leaking, always seems empty. Turbo coolant lines were clean. My stock plastic intercoolers had a crack and was leaking coolant into the engine. Replaced them both with VRSF Charge Coolers and my problem is solved. Also the AFE Cold Air Intakes were throwing off my fuel trim causing a 6-7miles per gallon. Reverted those back to stock with charcoal filter delete and my problems are solved! |
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03-04-2021, 11:22 PM | #18 |
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Awesome to see that you solved the issue.
So both the charge coolers and their reservoir were leaking? That's a first for me.. how many miles? Huge thank you for the update. Hate when people don't update their threads. |
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03-05-2021, 12:25 AM | #19 | |
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My passenger side Intercooler was the issue. It had a small crack only visible when I separated the upper and lower plastic housing from the metal center frame prior to throwing them out for how much trouble they've been causing me. I kept finding my smaller axillary coolant tank empty every 2 or so weeks. So I checked the usual turbo coolant lines but they were completely bone dry. Luckily for me, I had purchased the VRSF Intercoolers back in October but was too lazy to install after reading about nonretrofitting hardware. That couldn't have been anymore true. It was a pain in the ass to find 6 screws with correct threading as the stock hardware off the original intercoolers were made for plastic threads and not metal. 56k miles, driven like its stolen, daily Last edited by m6NYC; 03-05-2021 at 12:35 AM.. |
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