Need Ramjet High/Low Idle Help (1 Viewer)

[centerlineseal]

We have a 350 Fuel-injected Ramjet in front of an h55f five speed with about 135 miles on it.

Fuel pressure varies between 35 and 40 psi at both idle and higher rpm, but with gauge on manifold under the hood, we cannot tell what fuel pressure is while driving.

We are experiencing intermittant but persistant bump to a high rpm (2,000 to 2,200 rpm) when lugging or putting a load on the motor while in gear at a low rpm. Stated otherways, we see this rpm bump to 2,000 rpm, without footpedal input, intermttantly in 2nd, 3rd, & 4th gear when we lugg it (at about 800 to 1,200 rpm.)

It feels as if the computer is forcing the bump in rpm and is a bit unsettling to have the rpm increase with no footpedal input.

Any ideas?

Another problem, also intermittant, is at idle-down when coming to a stop, foot off gas and with clutch pedal in (disengaged), the motor will occasionally idle down well below the 750-800 rpm range and almost, almost die, then recover to normal idle.

Again, any ideas.

Thanks

 

[inkpot]

Howdy! Had similar issues with a 350 TBI. Changed out TPS, and the air pressure/temperature thingy, whatever it's called. I think we even changed out the Idle Control Solinoid. I'd look over the comparable items on yours. Does it give you any codes? John

 

[Sharp38]

First, you might want to contact GM Performance Powertrain Contact Center. Their phone number is 866 453-4123. They will take your information, assign you a case number and give you a bunch of to-do's to try to fix your problem. They are a bunch of good guys.

A few things they will tell you. Make sure your grounds on the engine are are three differenct posts. Don't stack them up on one bolt. Move them around. I would be sure to check your timing and make sure that it is at 10 degrees with the diagnostic tool in place. That can easlly affect your idle down problem. The say that the IAT sensor needs to be removed some distance from the TB input to make sure it's not getting some influence from the TB temperature. I have mounted mine in the front of the air cleaner supplied with no problem, but you may want to check. Make sure you don't have exhaust leaks near the O2 sensor.

Don

www.wolfcreekrodworks.com

 

[centerlineseal]

Thanks Inkpot. We'll be checkin' the codes tomorrow.

Any ramjet guys out there with some thoughts?

 

[centerlineseal]

Sharp38 - Don,

You da man! Thank you kindly. We should be OK with the IAT as it's located quite aways from the TB (10-14"). Will check our ground situation and O2 sensor for leaks, but its a brand new, commercial exhaust system. Will recheck timing as well and after such, we'll make the call. Again, thanks for your prompt help!