well i got code 33 map high voltage something like that. i didnt figure that would cause idle issues at start up.. btw its not all the time but sometimes when i start the car it idles low then ses and after a few seconds after i put it in gear and go the light goes out and runs perfect .weird ???

 

Is your car converted to OBDI?

 

yes sir!

 

Just a little help, just got done reading on some stuff in a haynes manual, just happen to see that code 33 is a MAF (mass air flow) sensor. Check it out it might be something as simple as that. let me know how you make out.

 

code 33 is map sensor in my manual.it does mention idle and voltage so when my car upon startup (sometimes) idles a little low you would think the map voltage droped for some reason but its a high voltage code make sense???

 

DTC 33 = Manifold Absolute Pressure (MAP) sensor circuit (signal voltage high, low vacuum)

If the MAP sensor is indicating low vacuum, the PCM gets confused and assumes the engine is under load. Good possibility its causing start problems. It isn't unusual to get a low vacuum code with an aggressive cam, but you shouldn't necessarily get that code with the CC 306. Check the engine vacuum (or read the MAP sensor) and see what kind of readings you are getting at idle. If the MAP is over (I think the threshhold is) 68kPa, you will get the DTC 33 code.

For "omatter67".... recheck your Haynes, and if it says DTC 33 is for the MAF sensor, get your money back for the manual

DTC 48 = Mass Air Flow (MAF) sensor circuit

 

but its not all the time problem? other than what u listed what are some steps i can do at home to diagnose the issue till i can get back to the shop and on the scanner.

 

The code sets becuase the MAP reading is more than 68kPa when the TPS is less than 4% open. If you can't observe the MAP reading with a scanner, you could put a voltmeter on it, and use the table of volts vs. kPa in my online scanner writeup to see what the MAP sensor is indicating. If you don't have a scanner or a voltmeter, you could hook up a vacuum gauge. Vacuum = Barometer - MAP. In very rough terms (you would have to know the barometric pressure to get the exact number), if you have less than 10"Hg vacuum at idle, for a period of 5 seconds, you will get the code.

Low vacuum could be due to low idle speed, vacuum leaks, incorrect ignition timing (tune), incorrect valve adjustment, misfires.... and probably a few other things I can't think of. Or maybe a CC306 in a stock displacement engine can't pull enoiugh vacuum at idle.

You mention it sets when the idle is "low". Ask the person who did the tune what the idle speed is supposed to be. Generally, the PCM is prgrammed to run a higher idle speed until the coolant warms up. If yours isn't doing this, it might be a cause of the problem.

 

pcmforless tune. its idle is fine i was just saying every once in a while on a cold start it will idle kind of low then the ses light will come on after a few seconds of being in gear everythings normal light goes off. this happens like i said every once in a while on a cold start.

 

And the programmer can control the cold idle speed.... there's a table in the PCM of idle speed vs. coolant temp. One thing that would throw off the idle could be the coolant temp. Have you checked the coolant temp sensor to see if its indicating the correct temperarture.

 

If you are having periods of particularly low idle the MAP code may result from that. The PCM is seeing MAP values that are out of scale from what it's tables say it should expect and throws the code. Whatever is causing the low idle is the actual concern. The MAP sensor is only monitoring the condition.

 

i want to bring this thread up again, i'm having a similar problem with my car. my car liked to be hard to start before my cam swap and it's doing the same thing after.

it will turn over multiple times and i'll have to hit the key at least 3 separate times to get it to start. it finally started messing up on the road today while i was driving, i got it to Advance and scanned it and the only code i got was 33 MAP sensor voltage is too high.

i pulled off my MAP sensor, which i replaced during my cam swap. i crossed the part number in the computer and it gave me the wrong number according to Advance Auto's online catalog. i replaced the MAP with the other part number and it hasnt made anything better.

once the car finally starts it revs up (probably from so much gas in the chamber), settles down idles VERY low and it's missing badly. if i touch the gas it bucks and dies. injuneer you mentioned the values the MAP reads when the TPS is below 4% open, if my TPS was bad could that do it? i'm out of ideas, sorry for the long post.

 

If your TPS sensor was wrong, it might show only 4% TPP when the throttle is actually further open than that. As the throttle opens, vacuum goes down (MAP goes up). Not something I'd expect to see, but you could look at a scan and compare TPP % to MAP for a wide variety of conditions.