77 Bus - 2.0L FI - difficult to start

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buginu2
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77 Bus - 2.0L FI - difficult to start

Post by buginu2 » Fri Feb 14, 2014 10:29 pm

Symptoms -

Engine difficult to start when cold. It requires cranking for several 10 second attempts before it catches briefly and then dies. Several more attempts to start. It starts briefly and then immediately dies. This start - run a few seconds - die cycle repeats until the engine CHT gets to about 200F. Starting the engine and giving the engine some gas occasionally "muscles through" the urge to die. Once running and warmed up - engine runs fine.

Troubleshooting steps taken -

Removed AAR - cleaned, opening and resistance check according to procedure on website - all good.
CSV - removed CSV from plenum and checked for fuel spray - no spray.
Swapped out CSV - still no spray
Checked voltage to CSV - found voltage, but also found that one of the two wires to the CSV was pushing back out of the connector and not making contact.

Engine would now start without much cranking (the CSV is now working) - however it would run for a few seconds and die again.

At this point I suspect either vacuum leak or FI injector harness has a fault.

Removed all hoses, AFM, vacuum lines and checked them for crack/leaks - none found.
Removed the FI harness - it is brittle and cracked. Considering the earlier find with the CSV connector I carefully disassembled the wiring harness, checked continuity of all the wires, checked for worn insulation. Found a couple wires with worn insulation - fixed the insulation and then re-covered the harness.

Reinstalled the harness, hoses, AFM, vacuum lines.

Engine starts immediately. Adjusted the timing, but idle was not stable. I think I hear a vacuum leak. Determine that the CSV casing is leaking air. Swap the old CSV back on to the engine.

Engine starts, idles smoothly.

Tomorrow morning is final test - I will start it up early in the morning.

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Amskeptic
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Re: 77 Bus - 2.0L FI - difficult to start

Post by Amskeptic » Sat Feb 15, 2014 6:57 am

buginu2 wrote:Symptoms -

Engine difficult to start when cold.

Tomorrow morning is final test - I will start it up early in the morning.
I look foward to hearing of your results. Please be aware that the physics of the air bypass idle speed adjusting screw makes for some whistle in the intake plenum. This is normal.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

buginu2
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Re: 77 Bus - 2.0L FI - difficult to start

Post by buginu2 » Sat Feb 15, 2014 3:04 pm

This morning - 8:30am - high 30s.

Left the bus outside all night instead of the garage. Started after about 5 seconds cranking the starter. Idled fine - perhaps a bit low. Engine did not die. Engine performed great in both highway and city traffic - nice to have it running well again.

Conclusion -

1. The initial CSV replacement was not needed - the connector was pushing the wires out the back therefore the CSV never had power to it.
2. The wire to the TS2 had a cut in the insulation that may have grounded it out. Fixed insulation while recovering the FI wiring harness.
3. The replacement CSV may have created a vacuum leak. The plastic portion of the CSV moved slightly within the metal part. When I put my fingers near the CSV when running the vacuum leak sound changed.

Colin - regarding the air bypass screw - yes I agree! It does sound like a vacuum leak. That was something I considered. The sound was obviously coming from the area of the CSV and brake booster boot.

A bit concerned of the impact that cranking the engine and pushing on the throttle to "muscle through" the engine's to die may have had. Suspect a good amount of fuel ended up in the oil. I will do an oil chance and valve adjustment (even though it has hydraulic lifters) this weekend.

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