Sputtering when taking off 1999 Express Van

nicefighter80 · February 9, 2015

1999 Chevrolet Express Van

5.7L Automatic

118k Miles

Has started to sputter when taking off, unless to take off quick, then its fine.

The van idles fine, its only when taking off from a stop sometimes it act like the trans skips a tooth on the

a gear and it sputters then its fine over 10 mph.

Any ideas?

Doug_Scott · February 10, 2015

Have you checked for any codes in the system? When EFI first started appearing on a large scale, one of the first things I was told about diagnosing issues with EFI. There are sensors in the system that effectively replace parts or systems that are common between EFI and Non-EFI. For example, throttle position sensor can be used like the accelerator pump in the carburetor. The MAP sensor can also give information to the system so it can emulate an accelerator pump. Reason I bring this up is to get you to consider what you would look for if this was a carburetor engine.

Hesitation and or stumble can be an tip in lean issue(accelerator pump on carb), as well as needing more heat in the intake air stream. Older cars had a shield on the exhaust manifold that would heat the air going into the engine. This lean issue can be many things, so check for any vacuum leaks,

You really need to see about error codes and report any you find here.

nicefighter80 · February 10, 2015

It does have a check engine light on, and the I believe the codes are for o2 sensors. It's my fathers van, and those codes have been there for the last 2 years, but it has only recently started to do this stumbling.

Doug_Scott · February 10, 2015

You may find that the truck is not going into closed loop now. If the O2 sensors are failing, and setting codes it is time to get that looked after. Do not just replace them, get the codes and follow the troubleshooting flow charts for them. Far cheaper to learn than it is to just replace.

gmtech4 · February 11, 2015

You may find that the truck is not going into closed loop now. If the O2 sensors are failing, and setting codes it is time to get that looked after. Do not just replace them, get the codes and follow the troubleshooting flow charts for them. Far cheaper to learn than it is to just replace.

What he said ^^^^^^^