FAQ
TL;DR: Uneven running and “CHECK EXHAUST SYSTEM” on Renault Clio III 1.2 16V often trace to valve clearance or a clogged catalyst; one user’s emulator fix has been “working flawlessly for a year and a half.” [Elektroda, sebap, post #16791376]
Why it matters: This FAQ helps Clio 3 owners quickly diagnose misfire, exhaust warnings, and LPG-related issues with clear next steps.
Quick Facts
- Valve clearance spec: intake 0.25–0.32 mm, exhaust 0.35–0.42 mm; incorrect settings cause rough running. [Elektroda, Przemo9826, post #16792518]
- “Ignition loss is the norm with gas not properly tuned” on this engine; LPG setup quality matters. [Elektroda, milejow, post #16792213]
- Clogged catalytic converters trigger exhaust warnings; emulator install reported flawless for 1.5 years. [Elektroda, sebap, post #16791376]
- Typical emulator outlay mentioned: approx. 150 PLN; factor labor separately. [Elektroda, Sztampura123, post #16791368]
- Example vehicle data point: 180,000 km total, 165,000 km on LPG; misfire and exhaust warning reported. [Elektroda, Sztampura123, post #16789173]
What does “CHECK EXHAUST SYSTEM” mean on a Clio 3 1.2 16V?
It flags abnormal exhaust readings. Common triggers include catalyst restriction, misfires, or post‑cat oxygen sensor disagreement. A clogged catalyst can cause power loss and warnings, so check it early. If misfires occur, the ECU may blame the exhaust due to out‑of‑range sensor data. [Elektroda, leonov, post #16789252]
How do I fix uneven idle and misfires on cold start?
Verify and adjust valve clearances to spec. Multiple owners report rough running and warnings disappearing after a proper adjustment. Renault valvetrain setup is sensitive; choose a mechanic experienced with these engines. “Renault are specific cars,” one contributor notes. [Elektroda, ving, post #17195707]
What valve clearances should I set on the D4F 1.2 16V?
For the camshaft with the groove, set intake to 0.25–0.32 mm and exhaust to 0.35–0.42 mm. Incorrect settings cause misfires and poor drivability. Recheck after tightening. Follow the stated procedure precisely for reliable results. [Elektroda, Przemo9826, post #16792518]
Could my LPG installation be causing the misfire?
Yes. “Ignition loss is the norm with gas not properly tuned in this engine.” Poor calibration or installation quality often leads to misfires and dashboard warnings. Have a qualified LPG specialist recalibrate or inspect injectors and maps. [Elektroda, milejow, post #16792213]
I replaced the ignition coil and still have misfires—what next?
Check spark plugs and HV leads, then measure and set valve clearances to the specified ranges. If misfires persist, evaluate catalyst backpressure. These steps address the most common non‑coil causes observed by owners and techs. [Elektroda, Przemo9826, post #16792518]
Is my catalytic converter clogged, and what are the symptoms?
Clogging causes uneven running, loss of power, and exhaust warnings. One member solved the sensor fault pathway with a catalyst emulator, but noted that a clogged unit still needs physical removal or replacement. Diagnose backpressure before deciding. [Elektroda, sebap, post #16791376]
Can I remove the catalyst without triggering a fault?
If you delete the catalyst, the downstream oxygen sensor will detect it and set a fault. Owners use a post‑cat lambda emulator to prevent the error after removal. Choose a model intended for Renault sensor signals. [Elektroda, sebap, post #16791176]
How much does a catalyst emulator cost and is it worth it?
One owner cited about 150 PLN for the emulator hardware. It can suppress post‑cat sensor errors after catalyst removal. It does not restore flow if your catalyst is physically clogged; address the root cause first. [Elektroda, Sztampura123, post #16791368]
Has anyone run a catalyst emulator long‑term on a Renault?
Yes. A contributor installed one on a Scenic and reported it “working flawlessly for a year and a half.” This suggests decent reliability when correctly fitted and wired. Use heat‑resistant connections and protect from moisture. [Elektroda, sebap, post #16791376]
I removed LPG but the car still runs rough—why?
LPG can mask or aggravate underlying issues. After removal, persistent misfires point to valve clearance, ignition parts, or catalyst restriction. One owner still had problems while running on petrol after de‑installing LPG. [Elektroda, Sztampura123, post #16793828]
Quick 3‑step diagnosis for CHECK EXHAUST plus misfire?
- Read ECU codes and note misfire cylinders. 2. Inspect plugs and leads; replace if aged. 3. Measure valve clearances and reset to 0.25–0.32 mm intake, 0.35–0.42 mm exhaust. Re‑test idle and load. [Elektroda, Przemo9826, post #16792518]
Can tight valves really cause rough running on this engine?
Yes. One owner suffered repeated breakdowns after a shop set the valves too tight. A different mechanic corrected clearances and cured the issue. Tight valves hurt compression and cold drivability. [Elektroda, masz74, post #17106057]
What is a lambda (oxygen) probe, and why does it complain after cat removal?
It measures oxygen to verify catalyst efficiency. After removing the catalyst, the downstream sensor sees similar readings to the upstream one and flags a fault. That is why owners mention emulators after cat delete. [Elektroda, Sztampura123, post #16791166]
What if the problem appeared 13,000 km after an overhaul on LPG?
That timeline suggests wear‑in or a setup drift rather than immediate assembly error. Re‑check valve clearances and ignition parts. Also ensure the catalyst did not degrade from prior misfires. The owner reporting this drove 13,000 km post‑repair. [Elektroda, Sztampura123, post #16793828]
Which ignition parts should I verify before deeper engine work?
Confirm correct spark plugs and gap, and test high‑voltage leads under load. Replace aged parts first. Many misfires blame coils, but plugs and leads often share responsibility on this engine. Reassess once basics are fresh. [Elektroda, Przemo9826, post #16792518]
Edge case: Could a bad installation be the real LPG issue?
Yes. A member blamed misbehavior on “grandfather’s installation” and poor assembly. Bad component placement and wiring create persistent faults regardless of fuel. Inspect for workmanship before tuning maps. [Elektroda, sebap, post #16793909]
