car jerks at randomly need help

[StereoInstaller1]

BTW: OP, please post engine/vehicle data..."my e30" is pretty vague.

Anyway, take apart the injector power plug and clean it. It is one of those things that even if you don't need to do it, you need to do it.

The harness is directly below the throttle body. It screws together and they get all nasty and stuff. Use CRC "Electrical cleaner" to make it all better.

Luke

[mkcman17]

yep, its an Eta, 23.1 is down from 27 in the winter when I dont use ac.

phew okay good! driving mostly feather-footed i'm getting barely over 20 w/o ac in my stock b25. i was gonna be real disappointed if you got that from an 'i' motor!


oh and taping up my intake boot changed everything. no more lag, more punch, and seemingly a smoother idle and rev down.

[scottinAZ]

phew okay good! driving mostly feather-footed i'm getting barely over 20 w/o ac in my stock b25. i was gonna be real disappointed if you got that from an 'i' motor!


oh and taping up my intake boot changed everything. no more lag, more punch, and seemingly a smoother idle and rev down.

Get a new boot. taping is putting a band aid on the problem. Many issues can be tied to a bad signal from the AFM, most are due to bad boot, but others are due to a crappy signal from the sensor. Yours is a bad boot.

[mkcman17]

Get a new boot. taping is putting a band aid on the problem. Many issues can be tied to a bad signal from the AFM, most are due to bad boot, but others are due to a crappy signal from the sensor. Yours is a bad boot.

i'm actively looking for one. i guess i should pony up and buy a new one, but mine is the one only found in models produced between 11/88 and 1/89 so it's harder to come by..

[StereoInstaller1]

i'm actively looking for one. i guess i should pony up and buy a new one, but mine is the one only found in models produced between 11/88 and 1/89 so it's harder to come by..

Hit up Blunt, best place to get parts.

In the meantime, how about the OPs issue?

[scottinAZ]

Hit up Blunt, best place to get parts.

In the meantime, how about the OPs issue?

my advice doesnt change, AFM or possible boot issues. wont affect the tach unless its really bad.....

[StereoInstaller1]

If the tach freaks out, almost always a bad main relay.

[88e30dippin]

so the car is a stock 1988 bmw 325. its got the s-eta motor. m20b27 i believe. all stock besides 325is throttle body and 93 m50 vanos injectors.

i took the advice and cleaned the icv and afm. now my car jerks more. idk what this issue is but it just got worse. my throttle response is awesome. after cleaning, now it does a weird thing where after driving on the highway and it does the jerk thing, when i come to a stop the idle freaks out a little. jumps from 800 to 500 jerkingly like its about to die then goes back to 800 again. so could it be the relay that stereoinstaller1 is talking about or the icv?

[StereoInstaller1]

Unlikely that would be the main.

AFM is what I would check first.

Swap with a known smooth car, only thing I can say is I don't know if it is the same as M20B25

[scottinAZ]

I think the AFM is different between the types, so that does make it a bit more challenging. I would pop the black cover off of the AFM and check operation of the wiper. If the tracks are shot, adjust the height of the arm on the shaft up SLIGHTLY and this will get you to new carbon track. DONT GO TOO FAR as that will cause more problems than it solves, TRUST ME. Hope this helps

[88e30dippin]

okay i will be giving the arm idea a try. hopefully it works. i have found a good used 325i afm and icv for 60 bucks for both. if i can get a for sure on the m20b25 and the m20b27 afm being different, then i will not buy the 325i afm. i will search for a b27 one instead to be sure that i have the right afm.

[88e30dippin]

i have replaced the oem 88 325 seta afm with a different afm and now it runs better and doesn't jerk (but its only been a day since i put it in so idk if it will jerer k still). but my check engine light is on. it came on after i put the afm on. i will look at the model number and post it up here incase im using the wrong year afm on my 88 325 s-eta.

[88e30dippin]

i replaced the oem afm that was bad with an 87-93 525i afm. would it give me issues?

[88e30dippin]

i haven put in a 325is afm in today. car runs great. no check engine light but i have the sputter thing still. i might have a bad crank sensor. im going to replace it and find out. if that doesn't fix it then my last try is the icv.

if that don't fix it what else could it be?

[mkcman17]

okay, my problem has come back worse now. it seems like when i'm starting it cold, it will get stuck under about 1200 rpms until it's at full operating temp. it's really getting bad...esp if i have to cruise around driving like a goon for 20 until i get it hot enough. any help here? i have never experience any sputtering after full warm up, only when starting after sitting for more than a few hours. basically, it'll rev up to about 1200, then sort of revlimit itself out there.