Hard starting when warm
it might be your fuel pressure regulator has gone bad or the hose going to the MAP (manifold air pressure sensor) may be broken
I would check the idle air control valve (IAC).
could be leaky injectors,
Well I have a 2000 grandprix gt and it would not start after warm I change the t ps sensor idle air control map sensor low coolant sensor low oil level sensor crank sensor change them all my self did not solve problem with warm starting so I took my car put it on computer it was the ingnition control module after they told me problem went home hook it up myself problem solved starts any time now the icm is under you're coil packs and is common problem for grandprix
Looking for a Used Grand Prix in your area?
CarGurus has 2,724 nationwide Grand Prix listings starting at $1,491.
Search Pontiac Grand Prix Questions
Pontiac Grand Prix Experts
Related Models For Sale