Hey everyone, I'm going to be tuning my stock L98 up soon and had a couple questions:
1) What plugs should I get?
2)Should I take the plugs out when the motor is hot or cold(Just saw a conflicting post on this the other day)?
3)Is there any small(cheap) upgrades I can do ie. rotor/cap,Timing etc?

The only mods on this engiune is open airbox and frisbee removed, other than that its bone stock and 160,000 miles(still runs strong though).Thanks for all your input. Rick :cheers:

 

1. I run AC Delco Rapidfire #5
2. COLD!!!!!!
3. You could cutback the electrodes and re-gap the sparkplugs. They won't last as long though.


Depending on how long its been sine the last time it was done you may also want to....

1. Air Filter
2. Fuel Filter
3. PCV Valve
4. Distributor Cap
5. Distributor Rotor
6. Sparkplug Wires

 

Fuel filter and PCV valve, where are they and how difficult to replace?Thanks Rick

 

PCV valve is super simple. On your driver's side valve cover you'll see a small hose connecting into something towards the left side of the cover. That is the PCV valve. Yank it out, pop it off, and pop on the new one. Good to go.

The fuel filter is located along the passenger side fuel rail behind the front right tire. You'll need to get the front of the car up on ramps to do it, and its a little more messy.

 

I use AC Delco plugs with cut-back ground electrodes; in your case gap to .035". The engine can be warm but not hot; cold is best.

Use some anti-sieze on the spark plug threads to prevent siezing.

Remove the inspection plate on the passenger side inner wheel well for access to #2 & #4 plugs. Remove the AIR tubes and A/C strut for access to #4 & #6.

 

While youre in there, you should remove and clean the Throttle body and IAC, and you may want to do the TB bypass now. All that means is that you disconnect the two coolant hoses leading in and out of the TB, and mate them together with a small pipe and 2 clamps, or you can get some heater hose from a hardware store (5/8") and route it that way.

I run AC Delco Rapidfires, GM cap and rotor, MSD 8.5mm plug wires.

Stock timing is 6*, i run 8*

 

1. I use Bosch Plat.s and like em, but many people seem to hate them. I hardly ever hear bad things about Delcos, so next time I'll probably go with those. Before putting them in, do the cutback mod. It seems that most people agree that this shortens the life of them, but gives a nice small gain (5-10 hp?). Plugs are cheap so its probably worth it.
2. Since you live in FL. do the throttle body bypass. They ran coolant through the trottle body to prevent the blade from freezing over, but it causes the incoming air to heat up. I doubt you'll have a problem with freezing, so do this one also.
3. If you have time, you should also relocate the IAT sensor to a coolor place (ususally the air box). This will make the ECU see colder air coming in, so it will richen the mixture to your advantage, and also advance the timing a little. Has anybody tried bypassing the IAT sensor with a variable resistor so you can control the IAT input from inside the car? I have a 98 Grand Cherokee 318ci and I know a lot of people do this and see nice gains on Jeeps. I put a resistor in the place of my IAT sensor to tell the ECU that I am getting 32 degree air (forgot the ohms) and I really noticed a difference. Probably more than my K&N CAI and Flowmaster exhaust combined. I would like to be able to control in from inside because sometimes I notice the enging pinging w/o high octane gas.
4. You also might want to remove the screens in your MAF sensor. I've heard that this is worthless, but I think more people agree that it works, and it's free.
5. If you haven't done it yet, you should def. rebuild your throttle body I would do this before any other mods because it only costs a few bucks for new gaskets (I reused my old ones) and a few bucks for tb cleaner and it will improve your idle and some people notice a large hp gain because it was so dirty. Just take it all apart, clean it really well, take out IAC and clean the tip (don't get cleaner on anything but the pintle tip), reinstall, set min. idle sped and TPS voltage. If your tb is real dirty or your tps voltage is off, you'll notice better idle and more power.
6. I can't recommend a good cap, wires, etc. because I have never done this.

If you don't know how to do any of these, most are in the tech section, or just search and you'll find plenty of info. Good luck on wakin' that L98 up!

edit: wow, 5 people posted just while I was writing this. This forum is great!


[Modified by WardVette, 6:12 PM 1/28/2003]

 

Be real careful when by passing the coolant lines. Wet air conditions the throttle plates freeze open. I speak from first hand knoledge. It will get your attention.

 

That's great advise (that's why I haven't done it here in the App. mtns.) but he lives in Florida. I know it still gets cold every once in a while in Orlando, but probably not enough to cause it to freeze open. I don't want anybody to get hurt over my advise though, so anybody else agree, disagree?

 

You should be ok with the TB bypass in Orlando, I don't think you'll have to worry about TB plates freezing there.

You may want to think about pulling the radiator and cleaning all the leaves, roadkill, cig butts, etc out of there. Vet's are excellent street sweepers :jester You'll be amazed at what you'll pull out of there.

There is a good writeup in Tech Tips here on the forum that explains how to do it. :thumbs:

 

I'm in SC, never had problems with TB bypass, it must get REALLY cold for something bad to happen there. I have driven mine in single digit/low teens.

A 90 has no MAF, its a Speed Density setup.