mystingray1

So I have finished installing my aftermarket TPI fuel injection system that sat on the shelf for 12 years, it starts great and idles pretty decent but beyond that it is pretty sh.,ty the instantI I start to crack open the throttle body it starts to shake like it would if you pulled of a major vacuum line the more I open the thotlle body the more it shakes and then pops in the exhaust it is really struggling to pull up the rams it seems to me that the injectors are not adding fuel beyond an idle for some reason or another has anyone seen this before? Is my used ecm bad? I would think at idle with no load on the engine a proper functioning TPS would be crucial, I am just wondering if the ECM is not receiving a good signal from the TPS, my engine is sound and the timing is fine, it starts and idles just fine but beyond that it is not good??? Not in a position to drop 300 on a scan tool at the moment

mystingray1

I forgot to mention that this conversion was done on my 81 corvette

Pwnage1337

What aftermarket system are you running? is it MAP based, MAF based?

Is it an aftermarket computer or just aftermarket hardware (runners, intake base, etc)

mystingray1

I am running the FIRST injections TPI system, it is MAP based and uses a used stock MAP TPI computer

Pwnage1337

Have you had the chip in the TPI computer modified at all to compensate for the massive flow change you just made by changing to an aftermarket intake?

The computer will need to be tuned to run correctly

mystingray1

the prom was set up for my application and the system

Joe C

do you have this off-idle issue with both a cold and warm engine? I had a similar problem once - ran fine, cold, but with temperature, crap. turned out to be tight valve adjustment on #1 cylinder. thermal expansion would not allow the valves to fully close at temperature. not sayin' that's your problem, just sayin'

I would start with the timing. if your distributor is not indexed properly, you could experience this condition - starts and idles fine, but when any advance starts to kick in, it throws the ignition timing outside the normal timing window.

are all ignition components in good condition? proper firing order? initial timing set with ECM distributor harness connector disabled?

with ihatebarkingdogs - a vacuum gauge can provide a lot of valuable information.

start with the basics - IMO, start with the timing. baby steps, and when satisfied everything's dead nuts on the money, move on. good luck.

ex-x-fire

Fuel pressure! What is it at?