Thought it would be a good Idea to start a new thread regarding the 2.4l TB seeing as all the info regarding the issues and possible solutions to this mod is a little scattered and hard to find in the previous and sometimes off topic posts.

So to recap, some of us have bought the TB off a 2.4l chevy cobalt to sit nicley on our 2.4l intake manifolds being that there 65mm diameter instead of the standard 58mm diameter.

Having established the 68m TB from the chevy cobalt ss worked fine on our uk version of the z22se engine it was a fair assumption that so to would the 65mm TB from the 2.4l engine but with the added advantage that it would bolt directly on with no adaptor plate or wireing loom alterations.

Assumption being the mother of all, we have since learnt that the 2.4l TB isnt quite as bolt on as first hoped and that it has a small teething problem. This being that it throws up an ecu fault p1514.

This appears to be a problem between the reported throttle position and the manifold absolute pressure sensor. As mark kindly explained, there would appear to be a table within the ecu program that compares the two and ensures that the manifold pressure is within +/-30kpa of what it should be at any given throttle position or engine load?

We know its not directly due to the size of the TB as Ffoeg sucsessfully ran the 2.0SC 68mm TB on a virtually standard engine with no problem.

Vocky has measured the potentiometer feedback from the 2.4l TB and compared it to the 68mm SS TB and the standard TB and noted that the feedback is a quite different. Ill have to look at the figures again and see if the full scale deflection is similar between each TB and if so a few simple resistors may help?

Meanwhile, Johnnys car is in with courtneys and they have found the same problem as the rest of us and as far as im aware they have EDS looking into it. Any more info Johnny?

It was first thought that perhaps you needed quite extensive engine work such as cams, manifolds and porting for the 2.4l TB to work due to the larger size and increased air flow, but again, as ffoeg ran the 68mm tb with just cams and no faults, I think we can put that theory to bed. I have a good cat back system and piper cams and a dbilas flowmaster and I still get p1514.

Last time I tryed the TB on at MPG, we monitored the throttle position feedback vie the tech2 and it all looked fine and what was intresting is that there is actually a calibration programe for the TB. We carried that out, which is mostly automated, but it made no difference. You can rev the engine up and down ok in neutral but as soon as you try to drive it.....p1514 lol. :roll:

Please add your ideas and findings to this thread as I think it will come in quite usefull to finding a solution. notsure.gif