Idle stalling/shaking at stops — likely air-intake leak

Tags: #problem

Symptom. The vehicle shakes or stalls at stops, sometimes specifically at red lights. When the brake is released after stopping, the engine can momentarily stumble¹².

Likely cause. Most likely cause: an air-intake leak causing rough idle¹². Confidence: medium — reported by two owners without a confirmed fix documented in this batch; cross-check against the crankcase-ventilation-hose card, since a disconnected hose is a related and confirmed cause of similar symptoms elsewhere in this KB.

Throttle/idle runaway — inspection procedure. Symptom: engine accelerates to 4000 RPM on its own, doesn't respond to the throttle pedal, with a clicking sound from the engine compartment. Diagnostic steps: (1) remove the air-intake hose from the throttle body; (2) visually inspect the throttle-butterfly position — it should move freely; (3) check whether the butterfly is stuck closed (IAC/idle-control issue) or stuck open (mechanical jam); (4) look for carbon buildup or debris under the butterfly; (5) disconnect the battery terminals for 5 minutes to reset the ECU; (6) check whether the rubber fuel line inside the engine bay is cracked, causing a vacuum leak. If the issue persists after this inspection, a service visit for ECU diagnosis and possible throttle-body cleaning is recommended^{345678910111213}.

Diagnostic method — fuel-trim monitoring plus a quick spray test. Air leaks can be located using a diagnostic scanner by watching fuel-trim correction (долговременная коррекция топлива): if the ECU is actively compensating fuel delivery, that indicates an air leak. A faster field test: spray carburetor cleaner or WD-40 around suspected leak points on a running engine — RPM will rise noticeably if a leak is present at that spot, pinpointing the source^14151617.

Air-intake leak as the cause of hesitation at 1300-1400 RPM with AT engagement hiccups. A separate case: RPM drop and AISIN-transmission engagement hiccups specifically around 1300-1400 RPM during acceleration, root-caused to an air leak in the intake manifold gasket area — consistent with the general air-leak diagnosis already on this card. Diagnosis used a smoke generator to visually locate the leak point. Fix: replace the intake manifold gaskets and clean the throttle body. Problem confirmed resolved after the repair (Feb 2026)¹⁸¹⁹²⁰.

Hose on the DPF (сажевый фильтр) side of the intake manifold: are clamps needed? (Sep 2026). Vasily Egorov, fighting floating idle revs (плавающие обороты) for two days, was replacing the thin hose that runs from the DPF-side connection under the intake manifold and asked for photos of its routing ²¹. Romanych says this hose has no stock clamps because they cannot be reached to tighten ²². Vasily fitted washing-machine-type spring clamps as a precaution ²³; Сергей Елисеев says the new hose went on very tightly and clamps would have been superfluous ²⁴.

Long-term fuel trim and MAP at idle. After a rough idle and higher fuel use, an owner replaced the thermostat and cleaned the throttle body; the long-term fuel trim at idle fell from about 1.6 to 0.8-0.9. Another member says a vacuum leak shows up as a high long-term trim and suggests a carb-cleaner spray test; the MAP reading at warm idle should be 28-35 kPa, with 35 kPa the upper limit^25142627.

Related pages

• Intake manifold hose (gofra) replacement
• Crankcase ventilation hose and rough idle
• Front wheel hub bearing
• Side mirror assembly — folding motor failure
• Wiper system — normal behavior and malfunctions

Sources

This page is compiled from 27 community messages. Every fact carries a numbered reference to its original author and message.

Last updated: 2026-10-29