E30 M30 electrical issues

[medi]

I have an 1989 325i E30 with an M30 out of an e34 motor with M20 and im running my stock m20 harness, now the issue is when first start the car the car runs good and after it gets warm or around 5 min of driving it starts bogging like crazy especially sometime when i give it throttle and then i take it out of gear and rev it and it goes back to normal for a couple more minutes i don't know whats wrong but i think i may have connected a wire wrong does anyone have any idea what it could be or have a write up of where all the wire connect to because my dumb ass didn't mark the wires when disconnected im pretty sure everything is hooked up correctly but who knows thanks for your help

[bmw335isturbo]

I would take some time and look over the wires you had to make longer first Then check your plug conections make sure their are no loose pins.

[medi]

ill give it a try once again

[Massive Lee]

Coolant temp sensor.

[medi]

should i buy an m20 one or m30 one?? i disconnected the old one on the car and the car ran like shit and connected it again and it was fine it only when i barely hit the gas when in gear

[redhatpat]

should i buy an m20 one or m30 one?? i disconnected the old one on the car and the car ran like shit and connected it again and it was fine it only when i barely hit the gas when in gear

If you're using an m30 DME then use the m30 sensor.

[JoeMadoo]

Funny I am having that exact same problem that started last week. It's such a pain to drive more than like 2 miles. I bought a new coolant temp sensor when i did the swap. Anyone have any idea's?

If i let it idle until it's warm, it starts to bog down until the whole car is shaking and the idle goes down to about 500. From there it will either stall if i give it gas or have full power for a few secs when i floor it.

It's basically like the gas pedal is an on/off button on a video game.

[JoeMadoo]

someone please give us some idea's!

[bimmer_adam69]

haha funny you say that...that was my e28's problem, after a tune up (except the 02 sensor)guess what it was...

THE 02 SENSOR!....ok boys, unplug the o2 sensor and go for a drive, i know you'll get less fuel economy for 20- 30 min. but its all worth it in the end

if this doesnt fix your problem then someone help these guys! cuz im doing this swap on sunday with the m20 harness!!!!!!!!:p

[JoeMadoo]

i'll try that tomorrow, thanks alot man!

[medi]

how did that work out because i haven't had a chance to do anything with the car since i thought my starter went out, i took it off and went to auto zone and got it tested and its good so it must of been a bad connection now i have to put it back on and see if it works. but i changed the coolant sensor and it ran good for a couple days but as when i would drive the car and i take it off gear an leave it in neutral while coasting the idle stays at 1500, 3 sec after i stop it goes back down. now the thing is i am using an ecu off a 735 auto car and a throttle position sensor off an e24 535 5 speed and ran fine for like a week with that idle issue and now the bogging came back only when i barely hit the throttle basically costing the car in gear, i bought a new throttle position sensor for a 1990 e34 535 and still didn't install it but it seems to have the same part number as the one i got off an e24 but i bought it because it thought maybe the old one i had on there had the ecu with 2 row of pins and the one i bought might be the one but now im confused since its the same part number and if i install it i can't return it could it be the o2 sensor like you say i don't know until i get it running this weekend and i'll let everyone know

[AlpineBlanco80]

same problems here! Bogging after warm up... did u guys find the gremlins, im using m20 harness and m20 tps. m30 ecu. the car runs like shit.also the cluster lights dim at idle and brighten up as soon as i give it gas... HELP!

[Jean]

I had very similar thing happen to my m10 and it was a failing fpr. so give that a try if you have a spare nearby.

[AlpineBlanco80]

na i think its sumthink electrical ima start with thealternator prob the volt regulator, maybe the icv cuz it buzzes really bad, ima check all the grounds maybe add more, ima also hook up the 02. its just frustrating to drive it like this.

[Doughnut]

Yeah, my m30b35 powered e30 has all the problems above too...

Accept I don't think mine is as bad