MIssfire under Boost - Lateral-g Forums

mdprovee · #1 02-06-2023, 09:41 AM

Hello and hope you can help. I have a 383 SBC with Fast XFI 1.0, Holley Stealth Ram, and P-1SC Procharger. I have a MSD 6AL box and MSD Coil. I dont know alot, and have been chasing a problem. It just started within the last year. It runs great from idle to when boost starts. Once the boost kicks in (about at 4-5 PSI), the motor starts to misfire and cut out. I have replaced the cap and rotor, plug wire and gone thru several sets of plugs. Any ideas I can check? Thanks for your help.

Mike

**camcojb** · #2 02-06-2023, 11:48 AM

What happens to the A/F and fuel pressure when this occurs? Does your fuel regulator have a boost reference line? Do you have the proper MAP sensor? Plug gap?

mdprovee · #3 02-06-2023, 03:32 PM

To be honest I do not know what happens to either of those, as I don't have a guage for them. Something I will be working on. This system has been working for the last 10-12 yeas and recently started to give me heartburn. The spark plugs are gapped to .030".

**camcojb** · #4 02-06-2023, 05:05 PM

Quote:

Originally Posted by mdprovee

To be honest I do not know what happens to either of those, as I don't have a guage for them. Something I will be working on. This system has been working for the last 10-12 yeas and recently started to give me heartburn. The spark plugs are gapped to .030".

You should be able to see if it's going lean or rich by datalogging it. I would start with that.

ADY · #5 02-07-2023, 06:20 PM

A friend used RPM (https://www.rpmeng.com/dyno-tuning-rohnert-park) in Rohnert Park a couple years back for TBI/EFI tuning help. Had good feedback and not too far of a drive from Suisun City.

mdprovee · #6 02-08-2023, 09:40 AM

Thanks, going to try and see if I can get some datalogging done this weekend, and will check on RPM.

mdprovee · #7 06-09-2023, 10:07 PM

Quote:

Originally Posted by ADY

A friend used RPM (https://www.rpmeng.com/dyno-tuning-rohnert-park) in Rohnert Park a couple years back for TBI/EFI tuning help. Had good feedback and not too far of a drive from Suisun City.

Its been a while and life got in the way of fixing the car. Took it to RPM and they were amazing. Made a appointment and they got the car right in. It was a rusty distributor. After replacing the distributor, they did a little tuning and it is running great. 475 horsepower to the wheels.

Thanks for the referral.