Ignition box problem?

[406shark]

Tonight I ran the engine at different rpm ranges and recorded them. Then I installed my MSD plug wires, cap and rotor. Again ran the engine the same and recorded. I overlaid the graphs and they match up almost exactly the same. I have RF noise, but after looking back at my logs from the past couple of years... the same noise was there in all of them. That's not the problem.

I just can't figure out what is causing it to this... it worked great over the past. This all started my first pass of this season. Can't figure out what could change to cause these problems.

Over the winter that only thing that was done was to install a round tube front half chassis to cut weight. Same engine, same transmission, same rear. All of the same accessories are the same. Everything is even wired the same as it's been for years.

Driving me crazy!

[Kevin Johnson]

WAG

If you are using a battery, the plates could be shifting/shorting while the vehicle is moving/vibrating/accelerating etc.

[Old as Dirt]

take apart your grounds.. clean and re- install.. they are important..

[406shark]

WAG

If you are using a battery, the plates could be shifting/shorting while the vehicle is moving/vibrating/accelerating etc.

I did install a new battery this winter... https://www.summitracing.com/parts/xsp-s1200

It's supposed to be a good choice for a racing environment... at least that's what they advertise.

I'm not sure that it even uses normal plates?

[406shark]

take apart your grounds.. clean and re- install.. they are important..

I'll take a look at all the grounds tomorrow night.

I use a floating ground system on my truck. Always have since I built it 7 years ago. I'm a big proponent of good grounds. I even have 6 gauge grounds running from cylinder head to cylinder head back to main ground block.


Thanks.

[tenxal]

Was the MSD box physically on the car when the chassis welding was done? Welding can raise havoc....TIG more than MIG, though both can potentially kill an ignition box and/or coil.

[406shark]

Was the MSD box physically on the car when the chassis welding was done? Welding can raise havoc....TIG more than MIG, though both can potentially kill an ignition box and/or coil.

The Mallory 685 box was mounted in the truck during the chassis work.

That's why after the converter didn't fix it, I installed a Daytona Sensors CD-1 ignition and coil. Still have same problems.

[tenxal]

My bad for not reading all your posts on this.

[fdicrasto]

One question for you. Do you have jet extensions on the rear jets?

[406shark]

My bad for not reading all your posts on this.

No problem... any help is appreciated.



Jeff

[406shark]

One question for you. Do you have jet extensions on the rear jets?

Yep.



Jeff

[406shark]

take apart your grounds.. clean and re- install.. they are important..

Spent last night making sure all the grounds were clean and tight. No change on the data logger as far as noise is concerned. Plan to take it to a 1/8 mile track that has tnt on Saturday. Probably not going to change anything, but there's only one way to find out.

I am going to do at least one pass with the 2 step bypassed... going to go against the brake without it and let it leave at stall.

I'll update after the track outing.


Thanks again to everyone that gave some suggestions.



Jeff

[fdicrasto]

Is the problem only at launch, high G-force,hard acceleration and once past that it acts normal? I believe that is what you have described with the exception of the starting issue. Does your data logger show afr info at incremental intervals?

[406shark]

Is the problem only at launch, high G-force,hard acceleration and once past that it acts normal? I believe that is what you have described with the exception of the starting issue. Does your data logger show afr info at incremental intervals?

The biggest problem is the launch. I don't log AFR.

Here is a picture of a log screen showing RPM and driveshaft speed.




I had the 2 step at 4500 rpm... as you can see it only went to 3850-3900 rpm... then dropped slightly, then stayed low at the launch for over 1 second before climbing.


Jeff

[406shark]

The problem continues...

I checked the trigger wires coming out of the firewall. They were bundled with the coolant fan and water-pump wires coming through the hole. The cluster of wires was running really close to a couple of the plug wires (about 3/4 - 1" away).

I cut the zip tie and unplugged the trigger wires. I rerouted the trigger wires to run down toward the mid-plate, then flow around the passenger side of the distributor and plugged it back in. Now the trigger wires are at least 3" away from any spark plug wire.

I made 4 passes today.

First pass - set the 2 step at 5000 rpm and let it rip.
Second pass - disconnected the electric water pump and coolant fan.
Third pass - hooked those back up and unplugged the 2 step wire from the quick connector.
Fourth pass - removed the alternator belt

It did the exact same thing on all 4 passes. RPM went to about 3900 rpm... stayed there until I was about 60' out... then took off and ran great. It did run the highest MPH it's ever been here in Minnesota... 134.12 was the highest with the other 3 at 133.83 - 133.96.

Another racer said he had a spare distributor I could try. Pulled my distributor and walked over to his trailer. He had an old Mallory distributor with a crab cap and a 3 wire pickup in it. It wouldn't work with my setup. Mine, like most use the ford style 2 wire pickup assembly. Oh well... he was having worse luck than me today. He broke the input shaft on his glide.

The only thing I can figure is something in my distributor is bad... either that or PTC didn't fix my converter properly? Everyone at the track today said they thought the converter was the problem. I was talking to a bunch of the guys today trying to get feedback.

Still open to any ideas.



Jeff