Stanza Issues - Possible Limp Mode/IACV

[StanzaGal]

Hi all!

Ok, have an issue that is baffling me. Have a 90 Stanza that's been a real champ for many years. Has about 270k miles on original motor.

Now the car bucks/surges at over 3000rpm rendering me useless on the interstate (can't go over 60mph). It also high idles and seems to be running rich, but idle is steady.

Have taken off the IACV a couple of times, cleaned it (and throttle body) and it ran great for a few days, then went back to the bucking bronco.

Replaced the IACV last week, ran great for about 4 days, then again, this morning, back to the bucking/surging.

When letting off and on the accelerator, it tends to buck as well.

Have recently replaced the TPS, MAF, O2 Sensor, and many other items as well.

Now, why after cleaning/replacing the IACV will it run fine but go right back to the surging/bucking?

No check engine light, will be checking the ecu for codes asap as well when time permits.

Any ideas? Possible knock sensor? Limp Mode? etc...

 

Thanks!

Tina

[zerow]

Hi all!

Ok, have an issue that is baffling me. Have a 90 Stanza that's been a real champ for many years. Has about 270k miles on original motor.

Now the car bucks/surges at over 3000rpm rendering me useless on the interstate (can't go over 60mph). It also high idles and seems to be running rich, but idle is steady.

Have taken off the IACV a couple of times, cleaned it (and throttle body) and it ran great for a few days, then went back to the bucking bronco.

Replaced the IACV last week, ran great for about 4 days, then again, this morning, back to the bucking/surging.

When letting off and on the accelerator, it tends to buck as well.

Have recently replaced the TPS, MAF, O2 Sensor, and many other items as well.

Now, why after cleaning/replacing the IACV will it run fine but go right back to the surging/bucking?

No check engine light, will be checking the ecu for codes asap as well when time permits.

Any ideas? Possible knock sensor? Limp Mode? etc...

 

Thanks!

Tina

 

Tina,

First off, Welcome to Ratsun!

I would have to ask - Did you clean or replace your EGR valve? Its a common thing for cars at 270K miles to have a sticking or completely plugged EGR valve. It would partially describe the symptoms you describe. Its a simple remove and clean with carb cleaner and a small conical wire brush (like a battery terminal post cleaner) I have had two cars that this was the problem, especially the newer one where the EGR has a plug on it and its signal goes to the ECM.

 

Good Luck, and its a good starting point for a repair. Let us know!