Low Idle Speed & Surge On Warm Restarts (ISU0314AP)

Publication date: 1998-11-01
Reference number: ISU0314AP

LOW IDLE SPEED & SURGE ON WARM RESTARTS

TECHNICAL INFORMATION TIP

Reference Number(s): ISU0314AP, Date of Issue: November 1998

LOW IDLE SPEED & SURGE ON WARM RESTARTS

YEAR(S): 1988-94

MANUFACTURER: Isuzu

MODEL(S): Amigo, Rodeo, Trooper, Trooper II

DATE OF ISSUE: November 1998

ISSUE & TIP

Any Isuzu Rodeo, Amigo or Trooper equipped with 4ZE1 (2.6 liter) engine may exhibit a low idle speed and surge on warm restarts. The intake gaskets are prone to leaking, especially near the number 4 cylinder and cause the MAF sensor to deliver the wrong input to the ECM. Additionally, a very low idle speed on a warm restart may be due to a thermostat with the wrong temperature range.

The TVSV on top of the thermostat housing is designed to open and boost the idle speed in the event of overheat, thus increasing the water pump flow. Too high of a temperature thermostat may increase the base idle speed with the overheat TVSV, and if the air bypass screw is adjusted at this time, the next restart idle speed may be after the overheat TVSV has closed, causing a very low idle speed.

To inspect, fully warm the engine and restrict the vacuum hose running from the TVSV and the intake ducting. If the engine slows, chances are a thermostat with the wrong temperature range was installed. Always inspect for basic overheat conditions, just to be on the safe side.

Courtesy of Import Service Magazine.

REFERENCE NUMBER

ISU0314AP

NOTE: This information has been obtained from sources generally believed to be reliable. Use your own judgment before relying on this data. Neither the suppliers of these Technical Information Tips, nor lemon-25 Repair Information Company, LLC, guarantees or assumes responsibility for data accuracy or completeness, nor is liability assumed by the suppliers of these Technical Information Tips or lemon-25 Repair Information Company, LLC, for any claims or damages resulting from the use of this information.