I need help getting this car to run.

September 12, 2019, 08:57 AM

Mike Nitzsche

My new roadster. Been racing it since Memorial weekend. Had one issue fathers day that caused a big miss, pop, bang about half track, but found the fuel shutoff was closing by itself. Fixed that and have run a few race weekends without issue. After two flawless time runs Labor day weekend, it starts popping and banging in burn box and down track. Not so noticeable on two step. Idles and drives perfect. Free revs perfect. Seems to only happen under load. Sbc 406, Toilet injected, msd digital 7, hvc 2 coil.

Heres what I've done/ replaced. Ignition box, crank sensor, put msd tester on complete ignition. Replaced cap, rotor, wires, and checked rotor phase. no magnets missing from crank trigger. Replaced distributor gear. Valve springs are only a half season old, but checked pressures. plugs are new, but looked at all of them. Inspected all nozzles. I'm using the same fuel, from the same can in my Cobalt with no issues. Timing is spot on at 36 degrees. I just put a new Ron's twin gear pump on it. I went 15 pill sizes rich with no noticeable effect. I'm not confident it's fixed yet and need more ideas before I go to the bracket finals.

September 12, 2019, 09:03 AM

Mike Nitzsche

It's also not a tradition rev limiter activating. The motor feels like the crank is coming out the bottom when the popping and banging starts.

September 12, 2019, 09:08 AM

511camaro

I know you looked at them but put new plugs in it

September 12, 2019, 09:32 AM

rs72z

Just gonna throw this out, Check all grounds!

September 12, 2019, 09:50 AM

Mike Nitzsche

quote:
Originally posted by rs72z:
Just gonna throw this out, Check all grounds!

Already did and the ground wire comes from the battery directly to the stud that the ignition stuff hooks to.

September 12, 2019, 10:15 AM

57 Vette

I would be having a real good look at that HVC II coil. They are known to cause problems like this when they go bad.You can do a Sweep Test using a temp gun. I would just change out that coil to the MSD #8251 coil.

IHRA ACDELCO Canadian Nationals
Top/et Iron man Champion

Don Davis 57 Corvette Super Gas roadster

SDPC 582 Head Hunter on alcohol

September 12, 2019, 10:19 AM

Mike Nitzsche

quote:
Originally posted by 57 Vette:
I would be having a real good look at that HVC II coil. They are known to cause problems like this when they go bad.You can do a Sweep Test using a temp gun. I would just change out that coil to the MSD #8251 coil.

IHRA ACDELCO Canadian Nationals
Top/et Iron man Champion
Don Davis 57 Corvette Super Gas roadster
SDPC 582 Head Hunter on alcohol

Funny, several people I talked to said nobody ever has problems with those coils. I was going to replace it, but I was sticker shocked at the $250 price.

September 12, 2019, 10:55 AM

rusty

remember simple things ,
master switch
battery
also i had a bad solder joint on a 12v wire do that once

September 12, 2019, 11:24 AM

Dave Koehler

quote:
Originally posted by Mike Nitzsche:
I just put a new Ron's twin gear pump on it. I went 15 pill sizes rich with no noticeable effect. I'm not confident it's fixed yet and need more ideas before I go to the bracket finals.

99% of injection problems are electrical related.
Having said that I am wondering why the new fuel pump and more importantly what made you decide to go .015 richer?

September 12, 2019, 11:35 AM

57 Vette

quote:
Originally posted by Mike Nitzsche:
quote:
Originally posted by 57 Vette:
I would be having a real good look at that HVC II coil. They are known to cause problems like this when they go bad.You can do a Sweep Test using a temp gun. I would just change out that coil to the MSD #8251 coil.

IHRA ACDELCO Canadian Nationals
Top/et Iron man Champion
Don Davis 57 Corvette Super Gas roadster
SDPC 582 Head Hunter on alcohol

Funny, several people I talked to said nobody ever has problems with those coils. I was going to replace it, but I was sticker shocked at the $250 price.

You need to be talking to Pat Collins at TECH WEST about these coils.he gets back about 100 of these each year that have a internal short in them that normally takes the igntion box out with it.

IHRA ACDELCO Canadian Nationals
Top/et Iron man Champion

Don Davis 57 Corvette Super Gas roadster

SDPC 582 Head Hunter on alcohol

This message has been edited. Last edited by: 57 Vette,

September 12, 2019, 11:43 AM

Dave Koehler

Here is an electrical question.
When a fancy MSD coil is suspect is there any reason you can't use a common, cheap barrel shaped coil to test it?

September 12, 2019, 12:34 PM

Mike Nitzsche

quote:
Originally posted by Dave Koehler:
quote:
Originally posted by Mike Nitzsche:
I just put a new Ron's twin gear pump on it. I went 15 pill sizes rich with no noticeable effect. I'm not confident it's fixed yet and need more ideas before I go to the bracket finals.

99% of injection problems are electrical related.
Having said that I am wondering why the new fuel pump and more importantly what made you decide to go .015 richer?

Dave, I wanted a new pump because I don't have a spare and my old pump was used when I started running it in 2011. I found nothing wrong with the original black pump, but decided while I was trying new parts, I might as well get another one. I've ran injection for 15 years with 0 problems. The only reason I suspected a pump problem is because this popping and banging was exactly like earlier in the season when my fuel shutoff closed half way on it's own.

I wanted to make a significant change to the fuel curve to try and isolate fuel from electrical.

September 12, 2019, 12:55 PM

markemark

quote:
Originally posted by Mike Nitzsche:
Heres what I've done/ replaced. Ignition box, crank sensor, put msd tester on complete ignition. Replaced cap, rotor, wires, and checked rotor phase. no magnets missing from crank trigger. Replaced distributor gear. Valve springs are only a half season old, but checked pressures. plugs are new, but looked at all of them. Inspected all nozzles. I'm using the same fuel, from the same can in my Cobalt with no issues. Timing is spot on at 36 degrees. I just put a new Ron's twin gear pump on it. I went 15 pill sizes rich with no noticeable effect. I'm not confident it's fixed yet and need more ideas before I go to the bracket finals.

Did you replace all this and re-try on the track?

September 12, 2019, 12:56 PM

Dave Koehler

Granted, every pump will be different in it's flow curve.
Did you work your way back toward your original main jet?

Something electrical to add to the pile.
Batteries can get old before their perceived end of life, seem fine but under load the voltage can drop to the ignition box.

I think MSD says it will run on 9 volts.
My experience has been that if the box sees less than 12.5v things can get funky. Even lower is worse of course.

September 12, 2019, 01:04 PM

rusty

quote:
The only reason I suspected a pump problem is because this popping and banging was exactly like earlier in the season when my fuel shutoff closed half way on it's own

check the lever for slippage

September 12, 2019, 01:11 PM

Mike Nitzsche

quote:
Originally posted by markemark:
quote:
Originally posted by Mike Nitzsche:
Heres what I've done/ replaced. Ignition box, crank sensor, put msd tester on complete ignition. Replaced cap, rotor, wires, and checked rotor phase. no magnets missing from crank trigger. Replaced distributor gear. Valve springs are only a half season old, but checked pressures. plugs are new, but looked at all of them. Inspected all nozzles. I'm using the same fuel, from the same can in my Cobalt with no issues. Timing is spot on at 36 degrees. I just put a new Ron's twin gear pump on it. I went 15 pill sizes rich with no noticeable effect. I'm not confident it's fixed yet and need more ideas before I go to the bracket finals.

Did you replace all this and re-try on the track?

Not really. Most of it I replaced at home after not finding anything. My problem is that I only have one race left and it's the finals, so not much time to try things....lol.

September 12, 2019, 01:13 PM

Mike Nitzsche

quote:
Originally posted by Dave Koehler:
Granted, every pump will be different in it's flow curve.
Did you work your way back toward your original main jet?

Something electrical to add to the pile.
Batteries can get old before their perceived end of life, seem fine but under load the voltage can drop to the ignition box.

I think MSD says it will run on 9 volts.
My experience has been that if the box sees less than 12.5v things can get funky. Even lower is worse of course.

Yes Dave, I did put the normal pill back in. After researching the faulty coil theory, its pretty solid, as other symptoms are the same as mine. I have a new coil on the way to meet me at the track.

September 12, 2019, 01:15 PM

Mike Nitzsche

quote:
Originally posted by rusty:
quote:
The only reason I suspected a pump problem is because this popping and banging was exactly like earlier in the season when my fuel shutoff closed half way on it's own

check the lever for slippage

Yes I did. The motor still shuts off like it did and I found no evidence that the lever is in a different position.

September 12, 2019, 01:22 PM

57 Vette

quote:
Originally posted by 57 Vette:
quote:
Originally posted by Mike Nitzsche:
quote:
Originally posted by 57 Vette:
I would be having a real good look at that HVC II coil. They are known to cause problems like this when they go bad.You can do a Sweep Test using a temp gun. I would just change out that coil to the MSD #8251 coil.

IHRA ACDELCO Canadian Nationals
Top/et Iron man Champion
Don Davis 57 Corvette Super Gas roadster
SDPC 582 Head Hunter on alcohol

Funny, several people I talked to said nobody ever has problems with those coils. I was going to replace it, but I was sticker shocked at the $250 price.
You need to be talking to Pat Collins at TECH WEST about these coils.he gets back about 100 of these each year that have a internal short in them that normally takes the igntion box out with it.

IHRA ACDELCO Canadian Nationals
Top/et Iron man Champion
Don Davis 57 Corvette Super Gas roadster
SDPC 582 Head Hunter on alcohol

September 12, 2019, 01:26 PM

Mike Nitzsche

quote:
Originally posted by 57 Vette:
quote:
Originally posted by 57 Vette:
quote:
Originally posted by Mike Nitzsche:
quote:
Originally posted by 57 Vette:
I would be having a real good look at that HVC II coil. They are known to cause problems like this when they go bad.You can do a Sweep Test using a temp gun. I would just change out that coil to the MSD #8251 coil.

IHRA ACDELCO Canadian Nationals
Top/et Iron man Champion
Don Davis 57 Corvette Super Gas roadster
SDPC 582 Head Hunter on alcohol

Funny, several people I talked to said nobody ever has problems with those coils. I was going to replace it, but I was sticker shocked at the $250 price.
You need to be talking to Pat Collins at TECH WEST about these coils.he gets back about 100 of these each year that have a internal short in them that normally takes the igntion box out with it.

IHRA ACDELCO Canadian Nationals
Top/et Iron man Champion
Don Davis 57 Corvette Super Gas roadster
SDPC 582 Head Hunter on alcohol

After reading some things, it sounds like my problem is the same as others that have had hvc coil failures. I have a new coil meeting me at the track tonight.