1995 Aurora: Surging/Idle issue

I recently purchased my first Aurora, 1995 with 51k miles.

After driving about 200 miles, I notice intermittent oil leak. Oil pan gasket replaced by local mechanic. He replaced by dropping transmission, not a cheap bill. Oil leak has now stopped.

After receiving car back, it ran extremely rough, at idle/acceleration/etc, basically all the time. Local mechanic replaced 1 bad coilpack, and I had the original plugs and wires replaced. I had NOT noticed this constant roughness issue prior to taking in for oil leak, but I had only driven it about 200 miles prior. It ran noticible better after coilpack, plugs, wires replaced.

Not long after this, I have yet another issue:
The car will intermittently "surge" at idle (sometimes large surges), run rough at idle, and a hesitation when starting to go.

This is not constant, sometimes it idles fine, but most of the time this issue exists. I cannot really pickup a scheme to it (i.e. when hot, etc). It will sometimes do it when first starting for the day, other times not. Other times it will do it after being driven for awhile, sometimes not.

I have just had the "recall" done also. It made no difference on this issue, but the safety problem is done.

So, any ideas? We have had the car for 2 months now and I have had nothing but problems and bills.

If there is an obvious solution to this, great. We are thinking about just getting rid of it, if it going to be a guessing game, more expenses, and headaches. We'll take a huge loss by unloading it, but it is to the point where my wife will not even drive it, given the unpredicatability.

I'd like to keep it, and figure with 51K miles, there should be a lot left in it. But so far, it has not been fun. :)

Thanks for any suggestions.

Though it may not be the case here, a leaking pcv valve hose (the elbow connector on top of it) will cause this symptom. It would be wise to check your vacuum hoses as well, since at this advanced age they tend to be rotted and leaky without regard to how many miles are actually on the vehicle.
I had replaced the elbow with a different type of hose which fit and within 6 months it had become swollen and popped off (due to oil contact) causing the same idle problem you mentioned. I would definitely suggest a trip to the dealer for the part if that's the issue you're facing.

Hello there;

The other problem, coukld be the Idle Control Motor.
Mounted on the left side, next to the throttle cables.
This is a sign that it may be going.
Should you park and stop the acr and hear clicking that is the problems.

This part control the idle and if you are having a surge while driving thus could be the problem.

The part is about $ 90.00 (Deal Only) of GM Parts for Less on Line.
And 1 hour of labor to repair. I have all the books on my 1995 with 140,000 miles.

The car is great, different, and comfortable, just sometimes a pain to repair.

Any questions, write me at [email protected]

btw, I have changed the PCV and AirFilter also.

sideshowbob:
I will check PCV and vacuum hoses. Nothing was noticibly visible, but I wasnt looking for that. I changed the PCV and didnt notice any hose probs, but I will look closer.

cmdrgala:
I havent noticed any clicking noises related to ICM. Thanks for offer on books, I will keep your email. Maybe ICM is bad without clicking?

Thanks!

My egr valve sticking open caused something like this in my 95. It was a near stalling that was followed by a surge over and over. It rapidly degenerated to where it would usally just die unless I kept the engine off idle a bit.

You can look for carbon inside the throttle body area in general, but the egr valve is the first thing it interfered with on mine. A can of throttle body cleaner could just fix your troubles.

I agree with the EGR valve. If you have been running with
a poor spark for a while, you could easily have carbon
built up. It is not too hard to get to. It is the black small
canister looking part on the back corner of your manifold,
just behind where the throttle plate is. It has a 5-pin
connector on top, and two screws holding it into the manifold.

I got in there and pulled it out and cleaned it with a spray
cleaner, and also the ports. It made a big difference.

Looking at the shop manual, page 6E3-B-6, I also see that
the fuel pressure regulator is a primary cause of idle problems.
The diaphram cracked on mine a while ago, letting the vacuum
adjust line "suck" fuel up to right behind the throttle plate.
This really messed up the fuel mix when the engine was at
a low RPM, and it was having trouble modulating the IAC to
keep the idle stable. Pull the vacuum line off of the top of the
throttle body and see it there is obviously fuel getting in there
from the FPR.

By the way, I recommend www.gmpartsdirect.com. OEM parts,
great prices!

Hope this helps,
GuMan :p

An update on my issue:

Intermittent surge/idle issues continued.

Vacuum hoses seem fine.

Cleaned EGR with TB cleaner. Stem and ports were pretty carboned up.

Cleaned Throttle Body, it was pretty gummed up. Cleaned both sides of plate.

Added Chevron Techron.

It ran perfect for about 150 miles.

Intermittent surge/idle issue started again.

Replaced Fuel filter with GM part, intermittent surge/idle issue remained.

Now, surge/idle is consistent, happens all the time. And it has actually died a few times at stop lights because of the idle.

Sounds like the FPR might be the next thing to replace.

The wife wont even drive it now, way too many hassles for the time I have.

to recap prior stuff done: air filter, pcv, plugs/wires

ANYONE WANT TO BUY THIS THING. :)

Thanks...fortco

Replace the FPR. Its an easy replacement (about 15 minutes). About $60.00 or so. It will fix your problems.

We are talking about this Part #, right?
12570618

At gmpartsdirect.com:

This is under 95 Aurora, Sections:
"Fuel&Exhaust"
"Fuel Injection, Electronic, MFI"
"Pressure Regulator"
$63.69

I ordered a week ago and now find out its "special ordered" with no ETA.

Did you get it in yet? If not, cancel the order and but it from a local auto parts dealer.

FPR is a common if not all-fixing repair for most of the issues you are experiencing. You may also want to check your intake manifold bolts. I had the same issues only to find that these bolts were finger tight. I have had to tighten them a second time as well. Another common issue is the fuel pump but I would eliminate all other causes first!

FPR finally showed up from gmpartsdirect: 2 weeks

Installed, ran perfect for 5 miles, parked for most of day.

At next start, slight surging at idle, but not as bad as before.

Sat overnight, drove next day for 2 miles. Put in reverse, and it died.

Restarted, put in drive, died. Cycled through this multiple times with dying.

Gave some extra throttle to prevent dying when drive engaged, limped home. It ran, but was lacking massively on power.

FPR did not resolve anything. So, fuel pump next? Manifold bolts?

As mentioned before, anyone want to buy a 95 with 52k, make me an offer. :)

:disappoin Sorry you are having a crazy amount of problems with your 95 Aurora. It seems like the 95's have the most problems! My 97 went thru a bad phase like yours but lucky I purchased a warranty that covered most. The car is running great now like a dream except for a similar problem idle shut off at a red light. I would have your mechanic check out the CRANKCASE SENSORS there are 2...Check these out before putting down the money for a fuel pump/sending unit. That is my next step. The sensors are going to be checked out. They cost about 50.00 bucks each plus less than an hour labor per my mechanic. I had a fuel sytem 3 step cleaning, a $90.00 Radiator coolant flush {thats good for 5 years they said} and fill at Expressway, a cam sensor replaced, fuel filter also like yourself and these did not solve the problem. It shuts off twice on the way to work at red lights...then twice on the way home at red lights or idle. Max 4 times daily. Sensors are next then if this does not work, the fuel pump next. Otherwise the car is a dream to drive!!!!!!!Have your mechanic try to duplicate the problem in the shop. This idea is per another post. Good luck and let us know. Thanks. :smokin:

The TP SENSOR/IDLE LEARN procedure should be performed when:
The TP sensor is replaced.
The ISC motor is adjusted or replaced.
The throttle body is replaced.
The PCM is replaced.
The EEPROM is replaced.

The "TP SENSOR LEARN" procedure should be performed when:



The TP sensor is replaced.
The throttle body is replaced.
The PCM is replaced.
Before the "IDLE LEARN" procedure.
If"TP LEARN" is reset.

To perform "TP SENSOR LEARN":

Turn ignition to "ON" (engine not running).
Turn ignition to "OFF."
Wait a minimum of 20 seconds.
Turn ignition to "ON" (engine not running).
Turn ignition to "OFF."
Wait a minimum of 20 seconds.
Turn ignition to "ON" (engine not running).
Turn ignition to "OFF."
Wait a minimum of 20 seconds. NOTE: Make sure nothing is touching or obstructing the accelerator or brake pedals during the "TP SENSOR LEARN" procedure because this will prevent the PCM from performing the learn routine.

To perform "IDLE LEARN":

Start the engine.
Allow the vehicle to idle continuously until the coolant temperature is 80°C (176°F), then idle an additional 5 minutes.
With the transaxie in "PARK" range, briefly accelerate the engine over 1500 RPM.
Return to idle.
Apply the brakes and place the transaxle in "DRIVE" range.
Idle the vehicle for 2 minutes or until the Malfuntion Indicator Light (MIL) (Service Engine Soon) goes out.


give it a shot..it may help.

when i had a similar problem i changed plugs, wires, egr valve..which i didnt see that listed on yours..kind of pricey but mine was full of gunk.. still had the problem..changed fpr..got it home..ran ok for a while.,...then had the runaway idle problem..finally cleaned throttle body gunk out real good..and both sides of plate where the throttle position sensor is and the other side too..until you have a smooth operating valve....has run well ever since.