95 Aurora: Surging/Idle issue

[fortco]

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.

[erw38]

First thing that comes to mind is what plugs and wires did you put in it? I know northstar engines (aurora engines) are extremely picky when it comes to plugs and wires (moreso plugs). I would probably stay with AC Deco platinum tipped plugs (about $6 each) and the Delco wires (about $120). I know letitroll98 used Magnecor race wires (to great success), but since Delco has a lifetime warranty you might as well use them and have all your bases covered. Some people have reported bad things while using other plugs.

Second thing I would check is the EGR valve. It may have carbon building up on it and may need to be cleaned/replaced (try cleaning it first with throttle body cleaner).

Then I would try a gas additive in the tank, perhaps a new air filter, fuel filter.

Maybe your changes were good and actually helped the car run better and therfore it is now showing all its problems. Hopefully this will help you.

Good luck ;D

[fortco]

Just checked, here's the new stuff in it:

Plugs: NGK-Ridium-TR55IX
Wires: Carquest-7mm-Triple3-Silicone-C2

wow, so basically what I have already spent should be replaced to eliminate that as a potential problem?

Do the coilpacks/etc need to come off to get to the back plugs, that looks tight?

Thanks

[erw38]

I have actually heard good things about those plugs. I have read one guys post and he claims that the plugs are a godsend.

www.automotiveforums.com/vbulletin/search.php?searchid=524960


Trh clicking on that link and you can read the threds on the topic.

Try the cheap stuff first. Look for vacuum leaks (free)., air filter, EGR valve, PCV valve, fuel cleaner (chevron techron or equivlent) (I like berymans B12 others here like lucas or something called BG44k (never heard of it)).

P.S. If you ask me, the symptoms actually sound like a vacuum leak.

---------------
*edit*

I bet you that your mechanic neglected to put back on a vaccum cap somewhere. Check all the hoses (esp the hoses near the items he replaced). Also, this is a guess so don't kill me if I am wrong, but check the lille plug on the air filter box (the plug is called the Idle Air Control valve)

Good Luck and let us know what happens. Then you can post some pics of your car!

[Letitroll98]

Hi fortco,

Fun owning an Aurora, huh? We all have a love/hate relationship.

The NKG plugs should be fine. They are the only acceptable replacement for AC Delco that I've heard of. Others may exist, just haven't heard of any other brand working.

I don't know anything about the carquest wires, but being that you can go wrong easier that right in this area, it may possibly be something to look at. Basicly the wire must suppress Electro Magnetic Interference and Radio Frequency Interference (EMI and RFI) resulting from the voltage spike delivered from the coils. These can only be fully understood by reviewing Maxwell's equations, but simply put, they screw up your ECM brain and MAY lead to the problems you described. However I would suspect a dirty EGR or something simpler like fuel filter, air filter, dirty throttle body, etc. But do check the manufacturers specs on the wires and make sure they at least claim to suppress RFI and EMI.

Yes, you have to remove the coil pack to get to the plugs and wire in the back. There are only four bolts and four little wire bundles to unhook. However one of the back bolts can't be reached by humans so you have to remove one of the coils individually. This can be either the far right one that I did, or the second from the right that looks like the one I should have removed. There are two little bolts holding the coil on, but you have to loosen the bracket on the firewall to get to the back bolt on the coil. This is all very frustrating to mechanically dislexic people like me. For good mechanics its probably a breeze.

Best of luck and don't lose hope.

[R4D30N]

it's possible that he didn't hook up a sensor of some sort, and it's not getting lean enough air.

[fortco]

Thanks for all the info guys.

I failed to mention, I have already done the air filter and PCV.

Sounds like I am ok on the plugs, wires are questionable.

Sounds like many other possibilities: vacuum hoses, EGR, dirty TB, fuel filter.

I'll have to start into it more or decide what to do with it.

Thanks!

[erw38]

Radeon,

Wouldn't that be the IAC? The engine would be tinking it wasn't getting enough air, therfore thinking that it was sufficating and choking on its own gases?

[Letitroll98]

Some stuff from the NKG website:

"When a spark plug fires, it creates a great deal of radio frequency interference (RFI). Uncontrolled, this can show up as static in the radio or other electronic devices, or much more seriously, in electronic ignitions, fuel injection, and engine management systems. This interference with EFI and engine management systems can cause "cross talk" between wiring harnesses resulting in poor running, misfiring and decreased performance."

"In fact, using a non-resistor plug in certain applications can actually cause the engine to suffer undesirable side effects such as an erratic idle, high-rpm misfire, engine run-on, power drop off at certain rpm levels and abnormal combustion."

I think the replacement plug you should be using from NKG is the PTR5C-13 Laser Platinum, not the Iridium IX (TR55IX). Although their website claims their ignition wires suppress RFI, there is no mention of EMI suppression. And your symptoms seem to mirror the description in their website, albeit for resistor plug usage. hmmmm.

[fortco]

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. 95 Aurora with 51k miles.

Thanks...fortco

[erw38]

FPR? Try replacing it with a new one. Only about $60.00 or so. 15 minute replacement. It cured my surging/hard starts/dying issures with the car.

[JimW]

Thats FPR for sure. Everything else sounds like simple maintenance. All that "other work" to try and fix the problem will only benefit you now. Once that FPR is replaced (which should have been the first thing) that car will be fine.

[miklar]

This has been a very interesting detective story. I hope it is finally resolved with a happy conclusion. I look forward to learning the culprit of all this grief and frustration! Good info. to have in the event it happens to me too. By the way, what is an "FPR"?

[omegaic]

fuel pressure regulator.

[TXOlds]

Mine was doing the same thing. I took it in for the recall, which I say was done with pleasure by the local GM dealer. They put a new FPR valve on, new fuel filter, I had the tranny flushed, it has just over 55K on here now, and had the horn fixed. It is running great! No more hard starts or power surges.