Hesitation/ boost
 

When i am driving my car it will sometimes hesitate under boost. It usually occurs at about 3,000rpm, but it has also done it to me at around 4,500rpm. I have a cat back & a down pipe. Any ideas?

DUCK! The search police will be upon you soon!

MANY threads on this. 3K hesitaion normal, many cars do it, some don't, some cars respond to extra grounding, or spark plug change, or fuel filter change, or O2 sensor change, or fuel type change, or... anyway, the only SURE FIRE way to solve it seems to be replacing the ECU with an aftermarket programmable one, which is spendy.

The 4500 hesitation is less common. Do you have a boost gauge? What are the boost numbers at 4500 when the hesitation occurs?

Could this be the 3000 rpm hesitation? Maybe?

boost can be from 1psi up to 12psi when it hesitates at 4,500rpm. But one thing, You mentioned something about the hesitation responding to extra grounding? I added another ground to the engine ground on the plentum. I also added another ground to the engine ground on the a/c bracket. Is this ok or should i take them off?

I checked all the previous threads on this topic, and the only definate answer was to get the PFC. Is this dangerous to the motor? Has anyone let this problem linger and has it lead to a blown motor or something of that nature?

The hesitation is harmless. The only thing it will damage is your mental state. Additional grounding is a good idea - search for grounds by Damian - he did a very nice write-up once.

The 4500rpm dip sounds like the onset of the secondary turbo. (The 8 in the 10-8-10 boost pattern occurs at 4500rpm). Could be a leaky to the turbo precontrol actuator on the vacuum or pressure side, or maybe a slow/leaky check valve (?). Search around for boost transition issues - each type of leak has a characteristic effect on the boost pattern.

Dave

thanks