sluggish bottom end on 320!!!

[mrLEE30]

Always thought that 320's were kind of sluggish as i have a 320cab and a 325 too, but the other day i drove a car for sale (320) and it was no where near as slow as mine!! so obviously thay are not as slow as i thought.

So the question is why is mine so slow. its an auto (as was the one i tested) and the engine runs fine. but up to 3000-3500 it is soooo slow!! from 3500 it begins to move.

Could the AFM be part of the problem?? i was considereing doing the 325 Throttle body change anyway, and while on that subject can i change the whole AFM,T body and inlet manifold or are the two manifolds different.


please help me!!!!!!!

mrlee

[Andy_magic]

I've got a 320i 2 door saloon that was a pretty poor performer.

I have gone throught the entire engine management system and fettled everything. the basic engine itself was sound.

I would go with the basics first and make sure all is well.

Plugs and leads

air filter

Check everywhere for vacuum leaks

Check the resistance of the blue temperature sensor, it might only look like a little part but it serves a major purpose. It tells the ECU what temp the engine is and adjusts the fuelling accordingly. I have had major drama's with my car, mostly down to this sensor. also check the wiring to the ECU on BOTH terminals, the multi plug under the inlet manifold can corrode and cause problems here. The ECU repsonds to resistance changes in this sensor to adjust fuelling. A bad ground or signal will cause the ECU to think the engine is colder or hotter than it really is, causing either underfuelling or overfuelling.

I bought a brand new sensor from BMW the other day and it showed 3k ohms out of the car, with the engine running and the temp guage showing just under the half way mark it read 300 ohms.

another thing to check is the thermostat, it should read just under half way for optimum running (as the ECU fuels according to water temp on non oxygen sensor cars)

I am in the process of writing a how-to on getting a rough running 6 pot BMW to run sweet as a nut.

[mrLEE30]

Cheers andy, where is the blue temp sensor?? or sould i check it from the ECU and if so what pins are they??

cheeers again mate look foreward to your how to article.

mrlee

[Andy_magic]

No problem, the blue temp sensor is on the thermostat housing next to the injector rail. It can be a bit of a job to change, you'll see what I mean when you look at it.

The best tool for the job is a cranked 19mm ring spanner.

The coolant temp sensor input on the ECU is pin 45, with the connector off the ECU and in your hand its the right most row of pins, 8 down from the top. This is assuming you have the ECU plug in your left hand and the wiring coming out of the top. The plug itself has numbering at either end or each row of pins so it's not hard to work out. I think on most cars it's the brown wire with a red trace.