Iron Indian

In reference to this thread... https://ls1tech.com/forums/generatio...d-problem.html

I'm chasing my tail trying to solve this issue. I have no codes or anything to go off of. However i know sensors can fail without producing a code.

With that said, anyone ever have hot start issues because of a bad MAP or O2 sensor?

Thanks.

1 FMF

iTrader: (1)

you should be able to rule out O2 sensors since they are a feedback sensor when the engine is running, they should have no impact on engine starting and running at idle for at least the first 2-3 seconds. And are front O2 sensors even used on a Speed Density tune? I thought SD was synonymous with open-loop ?

the MAP sensor on an EFI engine i suspect somewhat the same regarding the engine firing and at least running for 1-2 seconds. a handheld obd2 scan tool that shows PID data will show the value the MAP is reporting, and prior to starting should be 101 mpa.
And then since it's a SD tune, doesn't SD completely rely on manifold pressure instead of the MAF sensor? So if it was a MAP sensor problem I would think it would be evident once the engine's running, i can't see how the MAP sensor would not work prior to running then magically start working after the engine is running.

only time i've had a hard start issue was on a carbureted engine. And the cause for that unless something like valves or rings are worn, is fueling and timing.

if this is just starting to happen, what else has changed? Has the weather changed drastically now when the problem started happening versus when it didn't happen?
Problem with SD tune, unlike MAF tune, is it is more affected by ambient temperature, and would guess the tune is bad for lack of better description... maybe the SD tune was done in hot summer and now that it's winter that change is causing the problem?
Problem with any tune unfortunately is most DTC's get deactivated/deleted, and without being told first hand by whoever reprogrammed the computer it would be false to think i have no codes therefore should not be a problem happening.

to diagnose you might try a squirt of starting fluid when hot to see if that remedies the situation, if so it might suggest a lean a/f problem during that hot start condition. And opening the throttle blade a little more when cranking, in addition to blocking off around 75% of the throttle body with a piece of cardboard to mimic a choke when cranking, to see if either gives any more indication.

RPM WS6

iTrader: (3)

A marginal IAT sensor plus heat soak issue perhaps? Or was that deleted as well?