mak567

installed gm stage 2 cam engine will only stay running by throttling the gas .dtc p0101 for mass sensor and the motor is running very lean.could the timing chain be off a tooth? would platinum plugs cause this issue?swapped known good mas. no change.any input would greatly be appreciated.

mak567

could the cam need a tune? from what I have heard should be drop in and go

Darkman

iTrader: (2)

The P0101 code has two main causes associated with an engine that has just been worked on. One is having the inadvertently moved the MAF wiring harness too close to ignition or other wiring in the vicinty. The other is having inadverently created any vaccum leaks downstream of the MAF. So check the wiring and look for vaccum leaks as a start.

mak567

even though its hard to start I have to throttle the pedal to get it to start.

mak567

would timing being a tooth off advanced create this problem or would I be getting other codes?

sreve

iTrader: (3)

You mean one of these?

https://sdparts.com/details/gm-perfo...parts/88958722

227\239 yeah it's gonna need quite a bit of tuning.
Let me guess , you reused the stock hi-mile springs and pushrods.

chevybayboy

iTrader: (6)

When I installed my cam the tv2 I needed a tune it would run with my foot slightly on pedal and if I stayed on pedal for about a min I could let off and it would run, been when I started driving low rpms it would Buck or cut off coming to a fast stop.. got a base tune and it ran great until I blew bottom it but that was my fault

Darkman

iTrader: (2)

It is unlikely that the cam timing being off by tooth would cause the code. The code sets when the PCM encounters a reading from the MAF that differs from what the PCM "expects" based a calculation it performs using the manifold absolute pressure sensor reading, the intake air temperature sensor reading, the engine coolant temperature reading and the engine rpm level. Now, I can't say that it is impossible, because to the extent a valve is open at the wrong time it could presumably affect the intake manifold pressure reading.

If you have already checked the wiring and for vacuum leaks you might trying the code to see if it resets.

mak567

No have new springs and pushrods!!! and what does that have to do with my issue?

sreve

iTrader: (3)

No have new springs and pushrods!!! and what does that have to do with my issue?

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Quote: could the cam need a tune? from what I have heard should be drop in and go

The fact that those are some unrealistic expectations
The po101 code is a sanity check between the map and maf
idle map is in the 35kpa range stock, with that cam untuned it is likely
about twice that. Tuning can bring it down some although a massage of the diagnostic enable table is probably in it's future.
It's starting problems and idle is because base running air is way low along with
cracker ,follower ,breakaway friction and decay rates timing tables need massaged also. Long story short this is gonna need a lot of tuning

ls1 1990 VN

Get your car tuned, like fitting a set of tyres & expecting the air to already be in them.

Darkman

iTrader: (2)

Typical Catch 22. The tuner tells you to not show up for a tune until all the mechanical issues have been eliminated, and the no one wants to help you with potential mechanical issues unless and until the car is tuned.