This was the first tune-up for my 14 year old GTA 305 TPI with 75K miles on it. Accel rotor and cap (old one was horribly corroded), new Bosch wires, and new AC rapidfires. The gaps on some of the old plugs was over .045 - 75K miles on original AC Delco's. They were all real badly worn out. I Seafoamed the engine a week earlier and these plugs were still dirty.

Before tuneup - miss under heavy load, tach bouncing around

After tuneup - tach rock solid, but no power and misses heavily under any load. Can rev the motor up to 5500 out of gear and it sounds great (no missing without load).

I know why, and I need an opinion. I was going to put in an MSD coil due to the fact that the rapid fires have a lot higher resistance (.045 gap + platinum). But when I saw the stupid OEM rivets holding in the stock coil, I said forget it and took the MSD coil back.

I think, due to the high resistance of my spark plugs, the system is missing heavy under load. So I have three choices.

1. Get the MSD coil that hopefully has enough energy to jump the rapidfires.

2. Regap the rapidfires to .035 to make it easier on the OEM coil

3. Chuck the rapidfires and install regular plugs.

If I get the MSD coil, can I just have it lay on top of the stock coil (without removing the stock coil) to see if it fixes my problems?

Are the Bosch 7mm wire up to handling the spark of the MSD coil without letting it jump somewhere else?

Thanks,

Don

 

i have both the stock coil and the MSD one...i keep the stock one in my car because i have recently had problems with the MSD coil. when i put the stock one in, i just let it set on top of the valve cover and it is fine. i also use rapidfires and they work fine on the stock coil. your plugs should be gapped to .35 anyways...that is the factory gap.

i would get rid of 7mm wires and get a set of 8mm or 8.5mm wires and use them instead. are you the original owner of the car?

 

I've only have this car sine May '04. It' definitely hasn't been loved until now.

Rapidfires come out of the box .045. I know stock gap is .035, but with the MSD coil I thought I could increase the gap. You say fix the gap to .035 no matter which coil I go with?

I went with stock wires since I have a mostly stock engine. Only the Accel cap and rotor and the rapidfires are out of the norm.

 

i run .035 regardless of which coil i am running. i have them both in the car at all times, but only one hooked up and when i have the msd coil hooked up, the stock one is inside the car with me.

 

1. How hard was it to remove the stock coil?

2. What are the problems you are getting with the MSD coil?

I was going to use the MSD OEM replacement one for remote mounted coil, since I have a TPI. But if your MSD coil is having problems, I'd like to know before I spend $50.

Thanks for the help,

Don

 

1. Take the coil out of the car...then you have to drill the rivets out of the bracket and that is all. The new coil has bolts or screws, cant remember, that hold it in place.

2. The wires on top of the coil are not seating properly causing the car not to start sometimes. It is like they are rattling off the coil. Not a big problem though.

 

That is where I ran into trouble. I couldn't figure out how to take the coil off to drill the rivets. I was going to dremel the thing while on the car.

The OEM coil has a catch/lock thingy that holds the wires on. The MSD is missing this?

 

IIRC, there are a couple of screws that have to be removed in order to pull the coil bracket off. the primary connecter (gray one) is the one i am having problems with. as of now, i have the msd coil hooked up and no problems, but it occasionally messes up on me.

 

Cool. Couple of screws should be no problem. I think I'll re-gap the plugs first to see if that solves things. It's the cheapest thing to do.

 

New update:

I went outside to check the firing order. From what I can tell (it's dark) it looks good.

But here is something else that worries me. The motor is HOT for taking about a 15 minute drive over two hours ago. The motor seemed hot when I came back.

Would this be caused by all of the fuel dumping into the exhaust from the car missing? The top of the TPI manifold was very warm for it being 9:21pm and maybe 70-75 degrees outside. I drove the car at 7pm, it was about 82 - 84 at that time.

 

1. what is the temp guage reading
2. what t-stat are you using
3. stock manifolds or headers

 

Sorry, I didn't think to check the temp gauge while running. Very unscientific - just hand on the intake manifolds, and I noticed it seemed to be putting out a lot of heat after taking it for a test drive.

Stock / OEM everything on the LB9 except for plugs and Accel cap and rotor.

The car ran fairly cool before the tuneup. I think once I get the plugs regapped like you said everything will be fine.

 

Honestly, you've already answered your own problem. IMO, you should perform all three steps you mentioned in your first post for a few reasons.

Platinum plugs are unnecessary, especially on a stock engine. Overgapping the plugs is also unnecessary, even with a high output stock replacement coil. Get the MSD coil and replace the plugs with the same Delcos that you pulled out. Bosch wires have pretty crappy boots and connectors (IMO, again), and the 7mm ones are just not adequate. Go with the 8mm set for sure if you're getting a high output coil, and if you have the money, go with MSD or similar higher quality wires. Wire size should be determined by the ignition components, not engine modifications.

 

EDIT: I just realized you have TPI.

You can go .045 gap with an aftermarket coil but it is not necessary. I run stock .035 with my MSD coil, wires, and other goodies. I thought the coil was in cap for TPI? There shouldn't be any brackets.

 

Shifty,

The coil is on the passenger side, mounted on the intake manifold with a bracket.

CaysE,

I think I will first re-gap he plugs to .035 I've spent a lot of time reading post on this and it seems like the best route to take. If this doesn't work, then I'll look at a new coil and wires.

One of the biggest problems with reading through post that I searched on, is that people say they are going to try something like re-gapping their plugs, but they never reply back if it fixed the problem or not. I'll just have to try it out and see for myself.

 

I drove the car yesterday to get it back up on the ramps so that I could pull the spark plugs. The engine fires up real fast and idles good.

This makes me doubt I could have switched plug wires, right? If I have two wires swapped, I'd expect it to be very hard to start.

Now to just wait for the rain to end....

 

You'll be waiting till Friday, my man.

 

Did you check your timing ? also IMHO msd makes good products but if you are using there remote coils ALWAYS carry a spare

 

Mr. Kidd,

No, I didn't check the timing. Good idea, because replacing the cap and rotor probably changed the timing.

Does someone have a link to a high quality timing light with an advance adjustment?

I have the cheapy autozone one, but I'd like to get one to check total advance. I think I saw one on ebay with a tach built in too (it was digital).

Thanks,

Don

 

I hate it when people don't let you know what fixed the problem, so this is my follow-up.

5 and 7 wires were crossed, but I had already started re-gapping to .035

I'm not sure if the .045 gap would have been bad to run, but since I have a stock ignition, I'll keep the gap stock.

Runs like a bat out of h@ll now. I just can't believe this car had gone 75K miles and no one saw fit to give it a tune up. We'll, there loss is my gain. It runs incredibly good now, and I'm going to see if the gas milage has changed - I was getting around 18 - 20.