Proper gap settings

Hey everyone. Could use some advice. I have a 96 olds aurora. I am battling a misfire problem. I wanted to get the bosch plus 4's out of the car because they might be causing my problems. I have new bosch wires on the car so I'm gonna see if new ac delco platinum plugs will work better. Hope these are the right one's for this car.

I need to know the proper gap setting on these plugs. Part number 41-950. Replaced the fuel pump recently but it only hid the problem for a few hundred miles or so. Always getting the p0300 code.

I pulled the bosch plugs after only 3,000 miles and they are all carboned up already. Car has lost alot of power and this cold weather has virtually killed it. Gas mileage is down alot and I can't seem to figure out the problem. I checked the coils and fuel pressure regultor and they looked good.

The oil does however smell like gas. I am wondering if the injectors are clogged or a few are bad. I was told there was a good bit of stuff in the gas tank. If these plugs don't help next step is a injection cleaning. Car has 79k on it.

I am wondering even after all the fuel system cleaners I have run witch temporarily seem to help. I need to have the tank dropped and maybe new lines put in along with a injection clean to get this car to run.

If anyone has the time to help I would greatly appreciate it.

Thanks Jeremy

I have a '96 aurora, at 81k miles I had a slight persistant misfire & gas mileage was poor. My problem was a dirty EGR valve. The book indicates that too much EGR flow can trip a DTC P0300 code. Might be worth looking into if you haven't already.

Thanks Apollo. Could you tell me where the egr valve is located. I'm pretty handy. I cleaned my throttle body a few months back and it was so black. Looks like it was never cleaned. What do you use to clean it and does it have to come off. Any other procedures for cleaning it.

Thanks again Jer

The valve is located at the left rear of engine,near the firewall.
Remove solenoid connector & the two bolts that hold valve in.
I don't recall what I used to clean the valve with,but obviously you want to remove carbon deposits around the pintle , in order for it to seat properly, however possible without damaging the valve. If its bad enough it may need replacement. Inspect and clean the mating part before installation. Good luck, hope it solves your problem.

The gap setting is under your hood or in the owners manuel, now get the bosh +4 plugs out of your car, they are JUNK! The bosh platnum are great as well, also if you want, put champion(sp) in there, just to see if problem goes away b/c that would be stock in there.

Gap on the AC Platinum plugs should be .060".

hello Jeremy,
The correct gap for the ACDELCO Platinum plugs is .050, even if someone did reply .060, they were wrong. Just replaced the plugs and wires in my car, as they were original and she runs like new again,
Additional problems with power or misfires could be the FPR, fuel pressure regulator, a bit pricey at $158., or the EGR valve, $185. approx,
a clogged fuel injector has created similar problems, around $59. for service.
It could also end up being a bad coil. Possibly 1 of four in the coil pack at the rear of the V8. Look for corrsion on the coil plug wire post as a clue.
If I hadn't just gone through this last night I probably wouldn't have bothered to reply.
Best of luck,
Finn

Thanks for all the suggestions. I gapped the plugs at 0.60. Hope that isn't to bad. I didn't see it under the decal. As I was putting them in I then faintly saw 0.50 it was worn out and I missed it the first time. Don't feal like taking them out. Will this be o.k.

Also I started at the back 4 plugs. Got the coil packs off on each end to access them. I then couldn't get to them. I think you need a wobble extension. I have 20 extensions and not the right one. Couldn't go to store because I have no car. Wife is at work with the other car.

Coils throw a strong blue white spark. The fpr is completely dry in the little black tube. I cleaned the throttle body but I have never checked the egr valve yet. Also alot of the time when I get my car scanned there is a secondary code for a oxygen sensor. Always the missfire code then the oxygen sensor I guess.

We clear it and it doesn't come back. The missfire code does. But the oxygen sensor has shown up more than 3 times this year. But the car just passed inspection and emissions. Unless I was splugged into another cars exhaust.

May change that out to some time. These cars aren't cheap and alot of people can't work on them. That includes me but I'm getting better on this engine. I'm used to small easy to work on 4 cylinders. This is my first V8 and I'm only 24.

Thanks again Jer

The underhood sticker on my '97 CLEARLY shows .060".

The' 96 Service Manual states;

Plug gap for the 4.0 liter engine is: 0.050
Plug gap for the 3.8 liter engine is: 0.060


The AC plug P/N for the 4.0 is: 41-900
The AC plug P/N for the 3.8 is: 41-921

I have a '96 4.0, the decal under the hood lists the plug gap at 0.050.

Indy are you sure you have a 4.0 in that '97! :smile: :smile:

Year to year difference I quess? May be emission related to California car. Sorry for any confusion to Jeremy.

I have a 97, for those of you who don't know - they only came with the 4.0 V8 (piece of crap).

On mine there is a sticker on the radiator support that clearly states .060 - BUT my OEM Service Manual States .050

I am now experiencing the random misfire problem & replaced my plugs with Delco 41-950, at first I gapped them to the label .060 setting - problem got horribly worse.

Pulled them back out & gapped - to the Service Manual .050 setting and much improvement is noted, and the car is almost driveable. I am still getting random misfires & ordered a set of Borg Warner wires hope this fixes my problem though I'm sure there will be more to it.