LS1 Throttle Response issue

[gjkrv8]

Hi Everyone,

Please excuse my way of explaining this I am a novice.

Also - apologies in advance to Ford boys.

I am going for engineering Mon 8th Dec and have done a little bit of "testing" and find I have a fairly decent flat spot with regards to throttle response.

Essentially when you increase the throttle gradually its not that bad, but increasing medium to fast causes it to cough and splutter a bit. Cruising is ok.
i.e. Down on power a fair bit when you accelerate (i.e. coughs a fair bit).

Note: My engine is a Ls1 5.7L with Cable Accelerator (EURO II Emission) and stock tune from sideshow

I have double checked all electrical connections etc - not that its still not one of them.

I double checked Fuel pressure during idle and acceleration and its a constant 60psi. (I thought it might be a fuel delivery/volume issue rather than pressure).

I was (and am still) a bit suspect of my spark plug leads as they have been on and off a few times during the build and one of them physically looks a bit suspect.


I decided to remove one injector plug at a time, and I found one of the spark plug leads was not on the plug properly. This improved things a little but the flat spot is still there.

(One thing I did notice was that unplugging some leads had more effect than others - although only slightly)

I double checked the other plug leads and they “seemed” to be on ok.

I am still suspect on the plug leads and am going to get a new set tomorrow – not a bad thing to do when you are building a new car anyway I’d say.


I double checked that the MAP sensor plug is plugged in properly, I haven’t checked its operation with a Voltmeter yet though. That might be my next step if the plug leads dont fix it. i.e. 5V at engine off - 1 to 1.5 during idle and about 4.x when accelerate (I'm told).

I have also double chekced that I have blocked off both the Brake Booster vacuum inlet and dash instrument vacuum inlets - any others I have forgotten - I cant see any.


Any suggestions? (other than getting a tuner to hook up and see what/if any codes are coming up)?

Thanks

rgds

Gregg