I'm getting a DTC 33 .. high MAP. Any idea's what could cause this? Just put the HOT cam in my car...

 

Hi Glock,
It means Manafold Absolute Pressure... a DTC 33 HI MAP it is probably that you disconnected your MAP sensor, and that if you started the car without it connected it was reading say 5 volts it would send a voltage high code. Your cam should have nothing to do withit, I'm supercharged going abouve 100kpa and it never sets a code, you may want to check the wires and be sure its plugged tight into the intake manifold.

hope this helps..


Mo

 

Ok, thanks!

 

hi MAP means low vaccum in the manifold... Cutis, you should see around 50 Kpa on your scanner at idle with that cam.. maybe 45 Kpa (100kpa is sea-level). This could be an indication of a vaccum leak.. or a valve not clsoing all the way..

 

Ahh.. ok. What about low idle? With the cam it takes higher idle to produce the vaccum required for brakes to work and everything... Right now i'm idling at only 700 (stock) and the cam needs about 850. I'm getting 70Kpa pressure right now, which is kind of high.

Hope it's not a valve not closing all the way! I didn't touch the valves... just the cam. That cam better not have a high circle on one of them :mad

Thanks Blu!


[Modified by GlockLT4, 9:32 AM 1/23/2004]

 

your cam and mine (both using 1.6 rockers) are almost identical.. I idle at 750rpm and get 48-51 Kpa at idle and 55-65kpa at idle in drive with the A/C on.. don;'t forget these are WARM idle numbers.. with the engine up to temp..

70Kpa is way to high!! you should double check all your vaccum lines, the intake manifold and TB gaskets and the IAC gasket.. what are your IAC counts at idle? If all of that checks out.. check your valves.. I know you had a little bit of a prob. adjusting them.. the easiest way to adjust them is after you;ve been driving the car around and the engine and oil are nice and hot, remove the alt. and belt.. loosen the little black cinch clip that goes from the rubber hose to the AIR tube check valve at the exhaust manifold.. grab yourself a 7/8" and 1" wrench and remove the check valve from the exhaust manifold tube.. and just move it aside (i keep it disconnected to the rubber hose.. it spins easily inside the hose once the cinch clip is loosed). Next remove the brack booster vaccum line from the intake manifold and the little ported vaccum line below it (the one that goes to the AIR bypass under the ASR motor and to the EGR (on LT1's only - so you wont have this). Next spin the valve cover bolts off and remove the valve cover..

for the passenger side its a chip shot.. you can just remove the valve cover without taking anything off except the PVC breather tube.. spin those nuts and take that off..


now find the little /\ (triangle) on your hub/balancer (this is TDC) for #1.. once your found it mark a stripe on the balancer with white-out so its easier to read.. next bump the key on the starter quickly (so the engine dosent start) - do this a few times till the white-out strip is on top... keep an eye on the #1 valves.. ]if they start to open as the mark approches the 12 oclock position you are 360* out and #6 is at TDC.. I'll discuss this later]now if the valves dont move as the mark nears 12 o'clock you are at #1 TDC and can adjust the #1 intake and exhaust valves and the Inatke valves on a few cyl and the exhaust on a few cyls.. (i'll post those tonight as I dont have my book right in front of me.. but if you have a helms manual it details which valves to adjust in this position.. next, spin the crank (again bumping the starter) 360* and you can do #6 cyl intake and exhaust.. and the remaining intake/exhaust valves of the other cyl's that you didnt do before..) I'm not sure the correct procedure for the LT4 roller rockers adjustment.. but for stamped LT1's you use your index finger and thumb to spin the pushrod.. tighten down the rocker arm until the pushrod stops spinning between your hands freely... this is called zero lash.. when you hit that point give it one mire full turn and your set. This is out of the GM helsm manual for the '93 corvette with the LT1. Hope that somewhat helps.. :cheers:

good luck..

 

Well, it's down to 60Kpa with it idling.. i'm going to have to see if what you said will work.

For now i'm more worried about the ticking noise.... might be a lifter that isn't pumping up.

 

Ok, here's what i'm getting.....

 

Glock,

I just looked at my logs... at 875 I am seeing right at 30KPA and that is supercharged I agree with the upper responses it seems like you may have a vacuum leak somewhere, your sure your intake sealed ok? It's hard to belive you cam is causing that much of a change... Everything else looked quite normal in the pic

Mo

 

yeah, i agree... i must have a leak somewhere. Time to start searching.

 

You may also check your throttle body as well I had problems after i pulled mine off the gaskets did not want to seal.... Just a thought

Mo

 

few things.. your TPS looks a bit high, as does your IAC counts.. (I am assuming that your car is in park with the A/C) if the A/C is on, or the car is in drive that could explain the 60kpa..

Also, you need to set your IAC motor now that you;ve had it unplugged.. to do this slightly depress the accelerator pedel and turn the car on with it slightly depressed.. keeping it depressed let it run (around 2000 rom would be plenty) for 5 seconds.. and then turn it off (all while keeping you foot and pedal steady in the slightly depressed position... then let the car site with the key off for 10 seconds and then restart it.. this could make a difference.. I'm suprised the IAC is so open considering the MAP reading..

curtis please keep in mind all my experiance comes from working on my '93.. which as you know is speed density.. MAF might be diffrent.. but not too much.. if after all that yoiur still getting 80 IAC counts allow the blades of the TB to close more by adjusting the stop postition screw..you want to shoot for 40 IAC counts at a hot idle.. anything over 50 is out of range with the car in park and the A/C off.. accorsing to my helms manual..

 

I'll check that.... Also, to note.. i adjusted the idle screw on the TB trying to get my IAC counts down to get the A/C to not kill the engine... it seems that i'm having to screw it out a lot more than when i did that to my 383...

 

Yeah, no park/drive on the LT4 ;) ... i adjust the screw and still have the high IAC counts.... I'll try doing the adjustment with the gas pedal.

 

Try adding some timing to the closed tps spark advance vs. RPM table

400 - 20*
800 - 20*
1200 - 28*

 

:withstupid:

oh yea.. forgot about the no auto's in an LT4 (i'm just used to working on mine.. hehe)

 

Got the IAC counts down to 40's ... had to screw out that bolt a LOT!

 

Alright, i'll give that a shot.

 

Ok, I adjusted my idle spark advance and bumped the hot idle up to 900 from 850... brought some vaccum back, but not that much.




[Modified by GlockLT4, 5:24 PM 1/24/2004]

 

curtis - that idle speed sounds extream... my 383 LT1 with an Auto (and the attached bullpoopie torque converter) idles great at 750rpm in drive, with the AC running with similar Compression ratio and cam as what your running (but alas..more cubic inches..) 900rpm seems high.. I still think you have a vaccum leak someplace.. lets talk about your IAC counts and throttle blade position.. did youg et that squared away..