FAQ
TL;DR: 5 likely causes are cited; "The best thing to do is to ... check the injection angle, fuel dosage." For a VW T4 1.9 TD that smokes cold, start with timing, glow plugs, fuel‑air leaks, then injectors. [Elektroda, arekkwiatek2, post #19825804]
Why it matters: Fast, correct checks stop cold-start smoke, prevent excess soot, and keep your Transporter reliable.
- Timing on this engine is set mechanically "on the clock," not via VAG diagnostics. [Elektroda, Anonymous, post #19825843]
- Cold black smoke points to advanced timing or over‑fuelling; blue smoke indicates late timing. Also check glow plugs and air in lines. [Elektroda, arekkwiatek2, post #19825804]
- "Suction" means a cold‑start lever; some versions use a temperature actuator that enriches only while cold. [Elektroda, ciuqu, post #19825979]
- Edge case: a sheared key/"wedge" on the shaft can shift timing and cause smoke. [Elektroda, arekkwiatek2, post #19826119]
- Suggested order: check glow plugs, set timing "on the clock," then bench‑test injectors if needed. [Elektroda, Anonymous, post #19825843]
Quick Facts
- Timing on this engine is set mechanically "on the clock," not via VAG diagnostics. [Elektroda, Anonymous, post #19825843]
- Cold black smoke points to advanced timing or over‑fuelling; blue smoke indicates late timing. Also check glow plugs and air in lines. [Elektroda, arekkwiatek2, post #19825804]
- "Suction" means a cold‑start lever; some versions use a temperature actuator that enriches only while cold. [Elektroda, ciuqu, post #19825979]
- Edge case: a sheared key/"wedge" on the shaft can shift timing and cause smoke. [Elektroda, arekkwiatek2, post #19826119]
- Suggested order: check glow plugs, set timing "on the clock," then bench‑test injectors if needed. [Elektroda, Anonymous, post #19825843]
Why does my VW T4 1.9 TD blow black smoke only when cold?
Cold black smoke signals over‑fuelling or advanced injection timing. Blue smoke points to late timing. Check glow plugs and air in the fuel lines. “These are old armoured engines,” but they need correct timing and preheat to burn clean. This thread lists five likely causes: injectors, early/late timing, air‑in, and glow plugs. [Elektroda, arekkwiatek2, post #19825804]
What color smoke means late injection timing on a 1.9 TD?
Blue smoke on cold start indicates late injection timing. As one expert wrote: “Blue if the injection angle is too late.” Black smoke instead suggests early timing or excess fuelling. [Elektroda, arekkwiatek2, post #19825804]
Does this engine have a choke? What is the manual/automatic “suction”?
There is no choke on diesels. By “suction,” owners mean a cold‑start lever that increases fuel for starting. Some versions replaced the lever with a temperature actuator that enriches during warm‑up. Inspect this linkage or actuator if enrichment doesn’t release when warm. [Elektroda, ciuqu, post #19825979]
Can VAG‑COM/VCDS set or read timing on a 1.9 TD mechanical pump?
No. On a mechanical pump, you don’t set timing with VAG diagnostics. That guidance applies to electronic TDI systems. Use a mechanical measurement method instead. [Elektroda, dizba, post #19825826]
How do I check and set injection timing “on the clock”?
Use a dial gauge method. 1. Mount a dial gauge to the pump’s timing port. 2. Set the crank at the timing reference and read the gauge. 3. Loosen the pump, adjust to the specified reading, then tighten and re‑check cold. As one poster said, “the injection … only on the clock.” [Elektroda, Anonymous, post #19825843]
My van smokes black at idle for a bit, then clears—what does that suggest?
That pattern suggests excessive cold‑start enrichment. Check glow plugs first. Then set the injection timing on the clock. If it still smokes, move to injector testing on the bench. [Elektroda, Anonymous, post #19825843]
Could glow plugs alone cause this cold smoke?
Yes. Weak or faulty glow plugs reduce combustion quality when cold and create smoke. The symptom often clears as the engine warms. Test and replace bad plugs before deeper fuel system work. [Elektroda, arekkwiatek2, post #19825804]
Should I suspect air in the fuel lines?
Yes. Air in the lines to the injection pump can cause rough starts and visible smoke. Inspect and bleed the fuel lines. Eliminate leaks before adjusting timing or injectors. [Elektroda, arekkwiatek2, post #19825804]
Is my 1997 T4 likely to have a manual cold‑start lever?
The 1997 example in this thread uses a manual cold‑start control. If yours is manual, ensure the lever returns fully to the off position as the engine warms. [Elektroda, serwispcv24, post #19824935]
Could timing slip due to a sheared key (“wedge”)?
Yes. These engines can shear the shaft key (“wedge”), shifting timing and increasing smoke. If symptoms persist after adjustment, inspect the key and timing alignment. [Elektroda, arekkwiatek2, post #19826119]
When should I consider injector testing?
After verifying glow plugs and setting timing, test injectors if smoke remains. Perform an “on the table” bench test to evaluate them properly. [Elektroda, Anonymous, post #19825843]
What is the recommended troubleshooting order for this issue?
Start with glow plug checks. Next, set the injection timing “on the clock.” Finally, bench‑test the injectors if the smoke persists. [Elektroda, Anonymous, post #19825843]
Why do some advise VAG while others say mechanical timing?
One poster noted the next generation used a VP37 TDI pump with ECU‑supported timing. That explains VAG advice on some models versus mechanical timing on this 1.9 TD. [Elektroda, arekkwiatek2, post #19826119]
I replaced glow plugs and filters; what should I check next?
With new glow plugs and filters fitted, proceed to check the injection setting. Verifying the injection angle and dosage is the logical next step. [Elektroda, serwispcv24, post #19826890]
