engine surge while coasting

[jmforem]

I have a 2005 S, with manual transmission.
When the engine is cold, say colder than roughly 35deg (cold winter mornings), when the car is moving and I press in the clutch and coast, the engine revs up then down, then up, then down, over and over.

The peak RPM in this up/down cycle is around 2500 rpm. When I come to a stop, the rev'ing up & down stops and it idles at normal RPMs.

It did not do this the first couple of years I had the car. And this winter it seems to be getting more severe (high rpm peaks) the longer it goes on.
Any ideas?

[dorman68]

Sounds like a bad intake manifold gasket. Toyota has a tsb for this on the 1zzfe engine. The vacuum leak tends to be worse when the outdoor temperatures drop. A new gasket is a cheap and easy fix for the DIY.

[jmforem]

Thanks Dorman68. Do you know what the TSB number is? I searched through the titles, and none jumped out as being the one you mentioned.

[dorman68]

Originally Posted by jmforem

Thanks Dorman68. Do you know what the TSB number is? I searched through the titles, and none jumped out as being the one you mentioned.

tsb - EG045-07

Title:
M.I.L "ON" DTC P0171, P030#,
AND/OR P0133 ENGINE RUNNING
LEAN IN SUBFREEZING AMBIENT
TEMPERATURES

Models:
'03 - '08 Corolla & Matrix (1ZZ-FE)

October 27, 2007
Introduction
Following a cold soak in subfreezing ambient temperatures, some 2003 - 2008 model year Corolla and Matrix vehicles equipped with a 1ZZ-FE engine may exhibit a M.I.L. "ON" with one or more of the following Diagnostic Trouble Codes (DTCs) as the result of a vacuum leak at the intake manifold.
^P0171 - System Too Lean (Bank 1)
^P0300 - Random Multiple Cylinder Misfire Detected
^P030 # - Cylinder (1-4) Misfire Detected
^P0133 - Oxygen Sensor Slow Response (Bank 1 Sensor 1) Please use the following procedure to repair the vehicle.

Applicable Vehicles
^2003 - 2008 model year Corolla and Matrix vehicles equipped with the 1ZZ-FE engine

[jmforem]

Thanks Dorman68.
Erik

[dorman68]

Originally Posted by jmforem

Thanks Dorman68.
Erik

Sure!! Glad to help out!