Engine hesitates until I get past 2000 rpm.

[mattd1979]

My engine hesitates until I get past 2000 rpm. Has anyone else had this problem with their G50? This just started today. It's like the engine is at 70% power until I get past the 2000rpm mark and then it's all there. Like flipping a switch.

Matt

[OwnerCS]

Matt - Not on the G50 but something similar when I tested a bad MAF on the I30. Basically the car had difficulty running at lower RPMs.

[mattd1979]

Well, the problem mysteriously healed itself for now. I guess I'm going to have to wait until it gets worse in order to pin point it. I replaced the MAF recently but it with a third party new MAF from Car Parts Warehouse. My buddy has a 91 that had the MAF go bad on his and he bought his from there and hasn't had a problem yet. So, I thought I'd give it a shot. If the problem starts back, I'll have him bring his over and I'll swap to see if the problem moves to his car. The part is under warranty so if it is bad then I can have them send out another. I got tired of replacing a MAF with a used one almost every year and decided to try a new one, but couldn't afford to spend what it would cost for an OEM new MAF and so this is where I am now. I will say this, I have noticed more of an improvement with this MAF in response and power then I have with any of the used MAFs that I had bought.

[OwnerCS]

That's good to know.. Thanks for the info.

[mattd1979]

It was Car Parts Warehouse that I bought the MAF from, not Rock Auto. I corrected it in my last post.

[Skibane]

A bad knock sensor can also do that.

Basically, the ECM makes a worst-case assumption that you're running crap for gas, and reacts by reducing power output enough to minimize the risk of engine damage due to preignition (or "spark knock"). As engine speed increases, preignition tends to become less severe, so the ECM gradually restores power output at higher RPMs.

I'm pretty sure the ECM also takes ambient air temperature into account when deciding how much to reduce power output - The reduction gets a lot more drastic in hot weather.

[mattd1979]

I hooked up my ECUTalk adapter to pull the codes and got a code "55" all clear.