Can a bad MAF cause an LT1 to be hard to start? It seems to crank a lot longer when the temperature gets warmer outside.
-
1994 Formula
3.23's
Moroso Cold Air Intake
G2 High Flow MAF
Flowmaster Exhaust w/ High-Flo Cat
1LE Intake Elbow
Cross Drilled/Slotted Rotors
NGK TR55's, Accel High Performance Coil, Accel Extreme Wires -
no.
At startup the PCM uses its fuel tables instead of the O2s and the MAF. I can never remember if it is called open or closed loop. I'm guessing it is closed loop.
Try checking your fuel pressure and clean up the TB. Then new plugs, wires, coil...Tracy
2002 C5 M6 Convertible
1994 Z28 M6 Convertible
Current Mods:
SLP Ultra-Z functional ramair, SS Spoiler, STB, SFCs, Headers, Clutch, Bilstein Shocks, and TB Airfoil. 17x9 SS rims with Goodyear tires, 160F T-Stat, MSD Blaster Coil, Taylor wires, Hurst billet shifter, Borla catback with QTP e-cutout, Tuned PCM, 1LE Swaybars, 1LE driveshaft, ES bushings, White gauges, C5 front brakes, !CAGS, Bose/Soundstream audio, CST leather interior, synthetic fluids
-
No.... the only difference between cold start/open loop and warmed up/closed loop is the absence of feedback from the O2 sensors. The MAF sensor is still used... it works fine on cold startup, and provides accurate engine airflow information. The PCM takes that airflow information, and calculates the injector pulse width the same way it always does... hot or cold.
The difference on cold start is the use of enriched A/F ratios based on coolant temperature.... just like the "choke" in a carbed car, the PCM provides a richer mixture when the coolant/engine is cold. And on cold start/open loop, the PCM uses the long term correction factors from Cell 16... but "learning" in Cell 16 (and all cells) is disabled until the PCM enters closed loop.
So.... for hard starting in warm weather, I would check the coolant temp sensor in the water pump housing. You also need to look for possible loss of fuel pressure due to a leaking check valve in the fuel pump or leaking diaphragm in the pressure regulator, although I can't think of a reason these problems would be worse in warmer weather.Fred
381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motorComment
Comment