surging problem fixed. but not really. i need a lil help

[richardkeith97]

so my 85 eta had that surging problem everyone has. i unplugged my 02 sensor and the ploblem is gone. BUT!!! now i have the worse gas mileage ever. do i just need a new 02 sensor? i don't think the 02 sensor is bad becasue my car passed inspection. i heard something about a idle computer under my dash ? does my car have this? would this be a good thing to replace?

[jlevie]

Unplugging the O2 sensor causes the DME to switch to open loop mode using default (rich) maps. Open loop mode can mask any number of other problems.

The useful life of an O2 sensor is not more than 100k. If that applies in this case it needs to be replaced. That may or may not help with the surging problem, which can be caused by any or a combination of:

Intake leaks
Bad ICV
Bad ICM (on this car)
Bad or mis-adjusted TPS
Mis-adusted throttle stop
Bad AFM

Additional contributors can include:

Bad DME temp sensor
Cold running engine (bad or missing thermostat)
Bad Time-temperature switch (on this car)
Bad Cold start valve (on this car)
Fuel System pressure/delivery problem.

Solving the problem is a matter of eliminating possibilities.

[richardkeith97]

the cars only got 75,000 on it so i wouldn't think it would be the 02 sensor. i replaced the tps thinking it was that and didn't make a difference. i'm not to keen on prefix's. what is the DME, ICV, ICM?

[richardkeith97]

ICM idle control modul? is that under the dash right next to the ecu?

[richardkeith97]

it also does it a little when its idling but is worse when i give it gas and am more noticable going up hills. temp of the car doesn't matter

[jlevie]

DME - Digital Management, Engine (aka ECU)
ICV - Idle Control Valve
ICM - Idle Control Module

[Liam]

Replace the o2 sensor they only last about 30k in these old machines (If I remember correctly the mandated replacement interval was every other Inspection II).

Anything that can cause the car to run too rich or lean will cause surging... Also an incorrect throttle plate and or TPS adjustment.

Basically... The ISCV and ISCR can't be diagnosed with a bunch of other shit wrong with the car.

EDIT:

Old BMW guy slang: ISCV: Idle stabilizer control valve... ISCR: Idle stabilizer control relay.

[satin-325ix]

having the same problem as richardkeith97.. have you figured this out? help help help. its annoying. i thought it was my o2 sensor and i replaced that. i also thought it was bad gas. but i dont think thats it anymore. im lost.

[satin-325ix]

i also checked the engine code. it still comes up with 1221 which is the o2 sensor.

[jlevie]

A 1221 code is a lambda fault. It can be caused by a bad O2 sensor, or by anything that results in an abnormal A/F ratio. See my post above for the list of things to check.

[Invisible Saddle]

how did you pull codes on eta?? I have an '86 eta and everyone states you cannot pull codes from them. I know the stomp test doesn't work.

[richardkeith97]

its notan 02 sensor. if it was the 02 sensor then your car would run fine and get terrible gas mileage. if you 02 sensor went it would be the same as unplugging it and it would go into loop mode. i sprayed some carb cleaner around the motor and their are no leeaks anywhere. i'd say its either the ecu, icv, afm or icm. i sprayed my icv with carb cleaner and put it back in and it made it better. i have an icv and an icm on their way to my house. i'll let everyone know what happens when they get installed. hopefully this weekend if they get here. i really think its the icv becasue it the winter it was really bad until the motor warmed up. i think theirs stuff inside it and in the winter it would freeze.