vteck kicks in at 2500rpm, yo

[Kershaw]

1987 325es. build date 9/86. ~210k miles.

my engine is not performing normally. but i dont think its vacuum leak or compression related. when the engine is completely cold, i can drive it for over a mile and it will act completely normal. it pulls nice and strong. after it warms up a bit (about the same time my heat starts working) the engine will stumble. if you keep a normal load on the engine, it'll start bucking. this can be stopped by either letting off the gas or giving it more gas. full gas and the car stops bucking and builds rpms, if i stay on the throttle, once i reach 2500rpm i get a huuuuge woosh of power. like a turbocharged engine suddenly reached spool and the power just takes off. sometimes, it'll even chirp 3rd when the power kicks in.

im really confused, and im tired of throwing parts at it.

i have replaced or inspected:
cap and rotor. (new)
spark plug wires. (new)
spark plugs. (new)
1 eta trans sensor. (new)
injectors are good. (all orange pintle caps are nice and shiny from gas exploding)
3.0 FPR from an i. (this actually helped quite a bit, made it from undrivable to barely livable)
adjusted the valves.
dme temp sensor. (new)


if its a vacuum leak, it would be inconsistent when it runs. if its compression, it would run better when hot. but nope. it runs great when cold. it does burn a decent bit of oil.

it used to stumble a bit, but then when i got on the highway it would clear up and act normally. now its all the time after it warms up. the FPR really changed how it acted, so i want to say its fuel related and not.. say a bad dme. but maybe it is. it has a 153 iirc.

im really lost here. its getting 25mpg and i commute 70 miles a day back and forth to work, so not getting 30mpg really hurts at the end of the week.

[lennon]

have you replaced the o2 sensor?

[jlevie]

The first thing I'd suspect would be intake leaks. The fact that the 3.0bar FPR helped tends to confirm that, though there could also be problems with the injectors. Things to do:

1) Have the intake smoke tested and fix the leaks it reveals.
2) Install a new 2.5bar FPR and then run the fuel system tests in the Bentley.
3) Replace the O2 sensor.
4) Check the AFM for a binding vane or bad spots in the resistance curve.
5) Clean the ICV and make sure it opeates. If the idle is unstable, the ICM could be bad.

With the car being an ETA it won't have a 153 DME.

[7pilot]

Sounds like a DME problem.
The ignition or fueling Maps in your DME are incorrect for the injection/ignition systems on the engine.
Or:
The engine may have a compression ratio that is too high for the DME to handle

m

[Danny]

I'm gonna say afm.

[slammin.e28]

Coolant temp sensor or O2.

Same problem on my e28 with the B34. I replaced the coolant temp sensor (advised to from another e28 aficionado) and it helped a little. Disconnected the O2 sensor and it worked fine, albeit very rich. Just disconnect the O2 and see what happens.

[Kershaw]

i already did the temp sensor so its not that. i'll get started on the rest of the things.

thanks.

[So Live]

Same issues with my 85 eta w/ 210kmi. Not sure of build date, have to check.

I did NEW
Cap + rotor
Plugs
TPS
2.5 Bar FPR
DME Temp sensor
Rebuilt injectors
Cleaned ICV

I did some AFM tuning and got it running pretty good with AFR's almost spot on.

My intermittent lack of powar problem started a few months after doing all these things (ran shitty all the time before). I never had an 02 sensor hooked up and there are a few random electrical plugs not plugged into anything... One 2pin (identical to the ICV connector) near the "T" for the cold start injector and theres a jumper or something right near the firewall...

And what are all the temp sensors in the thermostat housing? I have like 4 sensors in the tstat housing. I know the DME has one and the Cluster has one...

Hopefully we can both figure this thing out....

[Kershaw]

the cold start valve is another temp sensor. i would definitely run with an o2 sensor....

my issue turned out to be the o2 sensor in fact. i replaced it with a $40 1990 mustang gt 5.0 v8 o2 sensor and just soldered and heat shrunk the connections. bmw o2 sensor was $132, what a mark up. or that different plug must be gold plated.

here is a pic of my old o2 sensor. can anyone spot what is wrong? lol....



runs like a champ now. pulls strong. idles smoothly. its awesome. im very happy. thanks all.

[lennon]

called it!

[Kershaw]

yes you did. thanks.

[So Live]

You have the 3 wire o2 like me or the newer 4 wire? If its the 3 wire, what wires went where from the ford o2?

Thanks and good work getting your car running like you want it!!!!

[Kershaw]

i have the 3 wire o2 sensor. 4th wire is just a ground wire btw. you could ground it to the chassis.

the 3 wires are all the same colors. its exactly the same o2 sensor. 2 white wires doesnt matter, just heater wires. and black to black.