×

Sale ends todayGet 30% off any course (excluding packages)

Ends in --- --- ---

Idle surging

General Tuning Discussion

Forum Posts

Courses

Blog

Tech Articles

Discuss all things tuning in this section. News, products, problems and results. 

= Resolved threads

Author
209 Views

I have a 94 Camaro racecar with a LT1 small block chevy I am struggling to identify an issue. At idle I get significant surging once the car has warmed up and is in closed loop. When I take it out on the track I will get misfires under high load (5th gear and 5,000 RPM). At the end of a long day it will cut out completely and not refire until it has fully cooled.

So far I have:

- measured fuel pressure which is reading 31-32 at idle and 40s at WOT per the stock parameters

- fogged the intake with no visible vacuum leaks

- checked all spark plug wire connections

- Checked grounds

- Checked exhaust manifolds for leaks

- Replaced my MAP sensor

I've attached my HP Tuners log. I'm pretty new to all this but it seems like there is an asymmetry in my bank1/bank 2 fuel trims that is consistent each time I test and the MAP seems to fluctuate strangely.

Any advice would be greatly appreciated

Attached Files

Hi

Regarding the misfires worsen with prolonged use, I would look at the ignition side of things first. In particular ignition coils.

D

Just to confirm, which gen' "LT1" is this - sometimes the earlier "LT-1" is also written as "LT1"?

If the former, the OEM coil, or HEI, is weak at higher rpm, and upgrading is a must.

If the later, as seems to be the case, how have you got the fuelling routed, if it's looped, and the rails, fittings, etc are a little undersized for the requirements, you will get a pressure drop along, and between, the fuel rails.

Thanks guys!

I have the newer “LT1” which predated the LS1 in the 90s. I upgraded the ignition from the Optispark to coil packs which are all new. My fuel pressure sensor is at the rail.

Any thoughts on how I could troubleshoot ignition vs. fuel related issues? Is the asymmetry in fuel trim suggest an issue on the fuel side?

thanks!

We usually reply within 12hrs (often sooner)

Need Help?

Need help choosing a course?

Experiencing website difficulties?

Or need to contact us for any other reason?