Hey guys im having an issue with my 2001 heads / cam bolt on vert. Getting a p0103 code for maf high frequency input. I tried replacing maf with no help, code still pops up. The car drives okay, but once you clutch in coming to a stop the rpms drop to like 300 and you have to Rev it to keep it running almost. My buddy checked the voltage going to the maf and it's reading 12v? Does this mean that I have a faulty pcm? Any help would be greatly appreciated!

Previous owner said he ran 5 gallons of 110 race fuel in it and the car never ran right since.

 

What color wire are you reading the 12 volts on ??....MAF has 3 wires and 2 for the IAT sensor....with sensor unplugged you should have 12 volts on the PINK wire...5 volts on the YELLOW wire and close to ground on the BLACK/WHITE...if you read 12 volts with positive lead of DVOM on PINK and negative lead on BLACK/WHITE your power AND ground are OK if you read battery voltage (12 volts) !!...with the connector plugged back in you should read less than 5 volts with key ON probing the yellow wire to ground with the DVOM...can't remember the exact number (mine was 4.95 volts) but it should not be 5 nor 0 volts !!...if your DVOM has a frequency setting that is a good way to check the MAF sensor with engine running !!...you should be around 3000khz at idle....this is my MAF sensor using a scope...it is a digital 0-5 volt square wave !!

THIS IS WHY YOU ALWAYS CHECK THE WIRING BEFORE REPLACING PARTS ESPECIALLY SENSORS !!!

 

I'm not a betting man, but if I were to bet I would put my money on it being tuning related. The tune might be a little off on some aspects such as throttle cracker or idle advance recovery/advance error adjustment.

 

Using a good scan tool you can look at MAF counts or voltage. (as the PCM is seeing)

 

I had a similar issue, come to a stop and engine would stumble and die..start right back up. ran fine in every other way. turned out it was a hole in the PCV hose about 6 inches from Throttle Body.. caused a very lean condition

 

Did you just aquire this car? Who tuned it? Your profile shows a 2001 Z06 and 2002 Z06 not a vert. If it was tuned in SD that would explain the P0103 code which can be Changed in the diagnostics part of the tune to not reported. The idle problem with a cam change can be tuned also. Adding timing to the idle area will give the motor more torque to compansate for the "idle lope" and help prevent stalling.

 

A MAF codes means that you need to re tune your 'LTFT" fuel corrections
LONG TERM FUEL TRIMS
Only some one with tuning software such as HP tuners or EFILIVE can properly data log your fuel trims and correct them
Ideally the LTFT's at P/T need to read "0" or slightly negative
This needs to be sorted out 1st
2nd
A car that wants to die when in P/N and revving it up OR when "in gear" and coming to a stop and wanting to die
In your tune this is called the "THROTTLE FOLLOWER"
To eliminate dying in gear go to the
IDLE section in your tune
Then go to the throttle follower
In the Follower tables Go to the "decay rate " IN GEAR" Start by SUBTRACTING 20% to this entire table If you went too far you will get the opposite affect and will get a hanging idle --then simply back off some % on that table
If it still dies ADD more % to this table
I would try this 1st this is the most common issue for your troubles But it is even more comlex too fix there are more steps to correct the dying

 

I don't see how 110 octane could hurt anything, but it's a little disconcerting that the previous owner seems to be describing a motor that previously ran OK and now doesn't. That might mean something went wrong mechanically, even if it was unrelated to the race gas. (What was he doing while running that race gas?)

That said, any time someone says they have an idle problem I wonder if they've got a vacuum leak - the kind of thing fishslayer143 was describing. Leaks are pretty common, they generally just screw up your idle, and though they can be tricky to track down, they're usually easy to fix.

That said, there's also a pretty good chance it could just be your tune. The MAF code does seem to indicate a tune problem, and I don't know of a way to address that without a wideband O2 sensor and a data logger.

My car had a similar idle issue after an intake and cam swap a couple months back. I've almost got it cured, but not quite. The most helpful changes were:

1) Too much spark advance at idle. It was around 28 degrees, is now about 19.
2) Not enough desired airflow (aka base airflow). It was around 9..5 grams/second, is now about 17, I'm about to try 18.

(I'm a little grumpy about paying hundreds for a tune and still having to fix this stuff myself.)

The base airflow problem likely would have been obvious if I had a data logger, so I'm trying to create an open-source one now and I hope to have it working by Christmas. Ho ho ho!

 

Found out car was tuned SD, changed out o2 sensors and problem is solved. Thank you so much for all your help guys. I've had 6 or 7 of these cars that's why my profile says 01 and 02

 

Your tuner needs to go under "Engine diognostics" and under DIC's change P0103 to "No Mill Light" or I expect your problem will return.

 

I was gonna say maybe he used LEADED Race Gas which will foul the O2s, glad it's fixed!

 

That's a really good point!

I should have thought of that before writing that 110 wouldn't hurt anything.

 

Yea, the guy was not too bright. He did use leaded 110. I'm glad the car is running great again though!