Sunday, August 12, 2012

Nissan Maxima GLE 3.0L, V6, the engine cranks like it is out of time. It bucks the starter and backfires


VEHICLE:  2000 Nissan Maxima GLE 3.0L, V6, MFI, DOHC, Eng Desg VQ30DE, Bosch L-Jetronic

MILEAGE:  108,000
Customer Concern: Intermittently the engine cranks like it is out of time. It bucks the starter and backfires. When the engine does start, it runs fine.

Tests:
1. Try moving the negative battery cable from the engine to one of the starter mounting bolts and see if the problem is corrected.
2. If no help, make sure all of the transmission to engine mounting bolts are clean and tight and that none are missing.
3. A last resort would be to unbolt and pull the transmission back from the engine and clean/lightly sand the entire mating surfaces of the engine and the transmission really well and bolt the transmission back up to the engine.


Potential Causes:
Battery Negative Cable
Engine To Transmission Mounting Surface

Confirmed Fix:

Repositioned Battery Negative Cable: Moved the battery ground cable to the lower starter bolt and cleaned the transmission case bolts.

Tech Tips:

The Position of Crankshaft (POS) counts off the rear Crankshaft Position (CKP) sensor should be 180 any time the engine is cranking or running. The Engine Control Module (ECM) marks number 1 off the front CKP sensor and counts 180 off the rear CKP sensor. The fact that the engine always runs fine once it starts, indicates the rear CKP sensor itself is fine - it is the magnetism of the starter affecting the rear CKP sensor while cranking that is the problem.

Nissan Maxima GLE 3.0L, V6, the engine cranks like it is out of time. It bucks the starter and backfires

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