90 Lumina 3.1 idle surge / hesitation

[ibbobud]

Hello,

My 90 lumina euro 3.1 has idle surge after it warms up. fluxuates between 600 and 1200 rpm when in drive. When you first get on the throttle it wants to die. Once you get past that it runs smoothe while driving. Ive also notice that it trys to "buck" when its at lower rpm and bearly on the throttle while pulling.

i cant seem to find any vacuum leaks, has recient tuneup, had a egr code and that has been replaced.
Ive cleaned the throttle body also. Previous owner had intake gaskets replaced as well as fuel injectors, fuel rail, fuel pump.

Its really ignoying and unsafe now.. wants to die when i pull out and everyone throw a hissy fit behind me.

Suggestions?

[ibbobud]

New information:

I took a can of throttle body cleaner and tested for vaccuum leaks and found none. even checked the evap canister at the rear of the car.

Still geting a error 32 (egr) even after replacing the egr valve and making sure passages were clear. (intake passage was sucking, and exhaust passage was blowing, haha)

if i go on a wide open run i will get a error code 44 (running lean) yet sometimes i get a puff of black smoke (means rich?)

idle surge and hesitation only seems to be after it goes into closed loop (after its warm).

There is a small exhaust leak at the donut where exhaust connects to header.

possible bad o2 sensor?

[maxwedge]

low fuel pressure or the o2 sensor could cause this.

[ibbobud]

Originally Posted by maxwedge

low fuel pressure or the o2 sensor could cause this.

entire fuel system has been replaced including the fuel pump twice, fuel rail, fuel pressure regulator, one of the injectors, and fuel filter.

If i unplug the idle control motor while its idling it will speed up a little and settle down but idles about 1100 rpm.

[ibbobud]

I think im going to do a tripple threat to it this weekend and order a idle control motor, o2 sensor, and map sensor and change them all at once.

On the o2 sensor i have the following brand choices:

standard motor producs
Airtex/wells
bosch
denso

which is best? (some people have complained about the bosch...)

of the cheaper brands for the other parts, is there any difference between standard motor and airtex/wells?

[maxwedge]

Non oe is always a gamble for anything.

[ibbobud]

Well its off to the mechanic... Ive been fighting this issue for about 6 months.

I got someone who used to be a gm service tech and he texted me this morning said he needed more time cause "its acting strange"

Oh lord bless this car... it needs your help...

I will let you all know what happens.

[ibbobud]

Well i went and got my car back from the "mechanic" sense he didnt make any progress on it.

I tested the fuel pressure even though it just had a new fuel pump installed and here is what i got.

Key on engine off - 30psi (40 -47psi haynes manual)
Key on engine on - 25psi (3 - 10psi below above number in haynes manual)
Key on engine on fpr vac line disconnected - 35psi
Key on engine on return line clamped - between 50 and 60 psi (around 75psi haynes manual)

But after geting these low numbers i desided to test my guage on my gf's neon which isnt having any current fuel issues and the reading i got on her was 38psi and the factory specs is 49psi.

I believe my guage is possibly reading 10psi low. Im going to verify the numbers with another guage tomarrow and get back with the results.

[ibbobud]

new fuel pressure numbers.

key on engine off - 50psi
key on engine on - 39psi
vaccuum hose off engine on - 48psi

Looks like i move on to the o2 sensor

[ibbobud]

Went to the exhaust place this morning with a exhaust flange gasket (leaking) and a O2 sensor. They replaced both and ran test on the cat (tested good!). Now the car runs so much better!

I then reset the computer and took a 50 mile drive to confirm everything.

Idle surge and most of the hesitation has been resolved.

[goodol55]

Originally Posted by ibbobud

Went to the exhaust place this morning with a exhaust flange gasket (leaking) and a O2 sensor. They replaced both and ran test on the cat (tested good!). Now the car runs so much better!

I then reset the computer and took a 50 mile drive to confirm everything.

Idle surge and most of the hesitation has been resolved.

Hello, I have been having the same problems exactly with my 1990 3.1 Lumina Euro. I also have a leaking exhaust flange gasket, and this might be the problem as you say.

I'll let you know.

[Thorkild]

My 91 Lumina Euro 3.1 is doing the close to the same. When it goes into closed loop, it idles low, around 5-600 rpm and surges and sometimes stalls. I've been racking my brains at this, I'm no mechanic, and have thrown a couple parts at it, all to no avail. I replaced the IAC valve, EGR is newish, cleaned the throttle body, replaced the fuel filter, fuel pressure is fine. I'm going out now to check for exhaust leaks. It also jerks when driving around 40-60 mph, like it's trying to shift up and down at once. Did the flange gasket solve your issues?

[Tech II]

Should clean the IAC passageway, clean the throttle plate and bore, and do an "idle learn" procedure........

As for the jerking at 40-60, could be a misfire or TCC problem.....

Check vac line to f/p regulator for fuel.....

Check for codes?