Random CEL when I hit large bumps - SOLVED!

[2mAn]

Hey Everyone.

As seems to typically be the case when you are working your way to a solid reliable M20, its two steps forward, one step back (sometimes the reverse too!)

The car is once again amazing since the 5 speed conversion, but a new issue has popped up. I dont believe them to be related, but I think my more "spirited" driving has revealed the new weakness.

Here in LA, for whatever reason there are areas on the road that seem to be the equivalent of speed bumps for E30s and a few times Ive driven over these at the speed limit, the CEL will illuminate for a second and then turn off.

My buddy who swapped the manual over mentioned that the injector harness connector was pretty bad, but he covered it in di electric grease. Im guessing that I need to get back in there and really clean it out, especially because its on the harness side, not the injector harness itself.

Anything else this could point to? I will finally have some free time to work on my cars again. Im hoping to finish up my Datsun in the next few days so I can get a few more things done on the E30 that Ive been wanting to get done. The list shrinks but theres always new things that pop up

Thanks in advance
Simon


*****UPDATE*******
Problem solved...



Thanks for everyones help, it was the connector just like everyone mentioned. Im sure the CPS was a good move still

[MrBurgundy]

Does the car buck or hesitate in any way when this happens?


Sent from my iPhone using Tapatalk

[2mAn]

Does the car buck or hesitate in any way when this happens?

for just the split second that its shaking from the bump

edit: Now that I think about it, my CPS also was bad and he put a good, used one in

[MrBurgundy]

I was dealing with a similar problem, but my car would buck really badly when the CEL came one.

It ended up being the CPS. The routing for the wiring was incorrect, so when I would hit a bump, the engine would yank on the wiring and cause it to lose connection.

Hopefully you'll find it quickly, because these kinds of problems are usually a PITA

[2mAn]

I think I should just buy a new CPS, but I dont know which one to get. Is this one of those "Buy OEM or you'll regret it" situations? If not, whats a good one thats worth it.


Pelican says BMW is NLA

https://www.pelicanparts.com/catalog/SuperCat/0193/BMW_0193_ELSENS_pg3.htm#item12

Bluntech only has VEMO (?)

https://www.blunttech.com/products/7846038

[MrBurgundy]

I’m running a vemo.

It’s been almost two years and I haven’t had a problem.

My catalogues only list that one, so I didn’t have any other options


Sent from my iPhone using Tapatalk

[2mAn]

Ok thanks, I will check out the harness and look into the CPS

[MrBurgundy]

Look at your tach when it happens and see if you notice anything obvious.

[2mAn]

Random CEL when I hit large bumps

Well... now the CEL is always on. I figured ok let me spend my Saturday night changing the CPS.

Old ones looked bad




New one from ECS tuning arrived quick


Figured this would be quick and easy... but I always get nervous with these feelings because....

It didn’t change anything.

It sounds like it’s running on 5 cylinders though. Ian suggested a stomp test so I’m about to go do that.

Stomp test
1-2-5-1

I guess it’s back to the injector harness again

[vtechnik]

let me know if you need any pigtails or injector wiring from my eta

[2mAn]

So we cleaned up the harness and it was pretty dirty but it didn’t make any change. So while it was running I pulled each spark plug wiring to see if there was any change and 2,4,6 showed no change...

Ideas?

[36brua]

If the X20 connector was /is corroded only cleaning that pins may not be enough
The corrosion can extend into both of the harnesses causing poor connections pull back the rubber boots and have a look
You may need to replace some wire and repin

[IceWhite]

So we cleaned up the harness and it was pretty dirty but it didn’t make any change. So while it was running I pulled each spark plug wiring to see if there was any change and 2,4,6 showed no change...

Ideas?

This is a clue.

I hope this helps. C191

[2mAn]

If the X20 connector was /is corroded only cleaning that pins may not be enough
The corrosion can extend into both of the harnesses causing poor connections pull back the rubber boots and have a look
You may need to replace some wire and repin

This is a clue.

I hope this helps. C191

Definitely does. Its about what I expected. And what a surprise that the one thats giving me issues is the one right smack dab in the middle.

Whats the ideal fix here? I dont want to eliminate the connector

[ForcedFirebird]

Pretty sure I suggested that in a recent PM.

The c191 uses the same pins as c101. If you get a pin release tool, you can easily re-pin the connector provided the plastic case is on ok shape. Most of the time I see them with some sort of aftermarket connector. This connector have been a problem spot for s few years now. :/