In TECHMAIL, we answer your motoring queries…
I own a 2006 Mazda RX8 and have recently had the motor repaired/overhauled by a independent garage. Following the service, the vehicle struggles to start when the motor is hot. Initially, I thought it was the battery and replaced it; however, this did not solve the problem.
Whitney Hand – Via Email
There are two well-known reasons for a hot-starting problem on an RX8 engine: low compression and failed coil packs. The latter is the cheaper fault to fix, so we’d recommend you borrow coil packs to test whether this solves the problem before buying new ones.
Some rotary engines tend to lose compression when it gets hot, as the seals surrounding the rotor deform, especially when they are worn. The best advice is to conduct a cold and hot compression test to see if there is a marked difference and that the measurements are within specification. Remember that compression testing on a rotary engine is best left to specialists, because normal compression testing may show inconclusive results.
Some owners fit a “faster” starter that may solve the starting issue (in low-compression engines) in the short term, but that does not address the root cause.