2008 Xfe Rpm Dropping Randomly/Bumpy Roads? - Chevy Cobalt Forum / Cobalt Reviews / Cobalt SS / Cobalt Parts
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post #1 of 14 (permalink) Old 07-13-2016, 05:34 PM Thread Starter
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2008 Xfe Rpm Dropping Randomly/Bumpy Roads?

So i purchased a 2008 Chevy cobalt ls xfe a month ago i have done everything trying to figure this one out. So my family mechanic fully inspected the car before i bought it and after it had a clogged cat which the dealer fixed at another shop. only problem no check engines nothing. my family mechanic look the car over 100% he topped my oil new fuel filter air filter spark plugs the works cause family yo. well im still getting this problem i think it has to be a cable no grounded good or something but, what happens is when i hit a bump or maybe its at random my tact for my rpms only dies goes to 0 and bounces right back up. Now my family mechanic drove my car for 30 mins but it didn't happen it was cooler out tho by 25 degrees idk... anyways I just let is sit all day and drove a mile down the road and it happened again bam rpms dropping. now before I had the work done it was doing the same and on the highway the car sometimes would drop rpms and die. Being that this is a 5 speed i don't want to hurt the car and fix the problem asap but i need help. when it happens and dies usually on the highway only going 2k . 2500 rpms and tact drops and car dies if i hold the clutch the car starts itself back up? just bam engines running fine again and it doesn't do it again. so i'm lost for words i need help bad i cant just pop the clutch and live with it. I have a kid on the way and i don't want to risk my life and others. If i cant fix it i will have to trade the car so please help

Last edited by BeforeDeth; 07-13-2016 at 05:36 PM.
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post #2 of 14 (permalink) Old 07-13-2016, 06:24 PM
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Coby 7 will respond and tell you which ground connection may be the issue. Have you checked your battery cables?

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post #3 of 14 (permalink) Old 07-13-2016, 06:29 PM Thread Starter
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Originally Posted by money_man View Post
Coby 7 will respond and tell you which ground connection may be the issue. Have you checked your battery cables?
Yeah i checked them there good aswell as boost post he responded to my post when i first got the car but i've had no luck
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post #4 of 14 (permalink) Old 07-14-2016, 03:53 PM Thread Starter
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I think i figured it out, the rpms havent dropped any i ran some sea foam spray through it and the air filter box was not secured properly at all the little clips it sits in it was on top of those i took it down the highway without a problem and some back roads i do still get a little jerk feeling when hitting a bump but i dont think thats a problem? my rpms stay steady now so i suppose it was the air box letting air into the engine when at a high speed hitting a bump it opened the box some. ill update further if it happens again but anyone else ever see that from a air box not being secure causing rpms to drop and car to stall?


Nvm Wasnt the issue or the fuel issue, saw rpms drop again and felt jerking idk anymore im about to sell this lemon i have never had such a pain in the ass problem to locate before

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post #5 of 14 (permalink) Old 07-14-2016, 05:43 PM
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Did your mechanic pull the BCM connectors and clan them and re-seat. Sounds like a Cobalt that sat on a parking lot for a while and corrosion set in. Just re-seat the BCM connectors and enjoy your Cobalt.....

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post #6 of 14 (permalink) Old 07-14-2016, 07:03 PM Thread Starter
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Did your mechanic pull the BCM connectors and clan them and re-seat. Sounds like a Cobalt that sat on a parking lot for a while and corrosion set in. Just re-seat the BCM connectors and enjoy your Cobalt.....

---------- Post added at 09:43 PM ---------- Previous post was at 09:41 PM ----------

Don't give up that easy!!!!!!!

So i got some pictures is this a tcm or bcm? i looked it over one was half way taken off i snugged it back on but all the pics i show have a tcm and bcm togther and this car only has this >.< your help is appreciated, Also is there suppose to be a ground on it because there is not

Saw this video and thought it might need to be grounded better but i dont even see a ground on it or on the casing :/




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post #7 of 14 (permalink) Old 07-16-2016, 04:24 AM
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The body control module is in the center console on the passenger side.

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post #8 of 14 (permalink) Old 07-16-2016, 05:43 AM
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In a manual car there is no TCM. The picture you show is of the ECM and it has no ground strap. It is grounded through the harness and goes to the engine block where it then goes to the frame with a strap.

This is the BCM module where you may want to re-seat the connectors.



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post #9 of 14 (permalink) Old 07-17-2016, 07:16 PM Thread Starter
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i unplugged and snugged back down and did a test drive, cant be for certain yet where does the bcm ground at through the harness or in the center console? ( i did see on the orange circle up the cable eletrical tape but idk if thats from manufacture or a mechanic but it dont seem to be cut anywhere... also zip ties on the harnesses i assume also from gm. i feel it is electrical problem......if it would just through a check engine code... What exactly is the 2 circles i have people telling me i need a new fuel pump when there 320 dollars i'm not about that life on a car i owned a month.
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post #10 of 14 (permalink) Old 07-18-2016, 04:20 AM
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BCM ground is under the driver's seat but your problem isn't a BCM ground because a lot more wouldn't work.

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