Ok, I had the LE 1 heads/cam installed on my car and the car has been running unbeleivably rich ever since than, even after a MadZ28 tune. I datalogged it and everything was fine as for sensors as far as functioning, but I noticed at idle (I hold the gas as 1600-1800 rpms and cuz the engine just floods out if I let the RPMS drop below 1,000) the MAP reading was at 22" HG while atmospheric pressure is 29" HG and when as I slowly increased the RPMS to 3300 the MAP readings went down gradually and it was at 13" HG.
I have also performed a vaccuum test before and they confirm this, although the vaccuum test wasnt all that easy to conduct being that the car wont idle by itself the vaccuum readings at 1600-1800 rpms were around 8-10" HG and around 2500 RPMS went up to around 14" HG.
The injector duty cyle with the stock 22 lb/hr injectors were around 18-20% duty cyle between 1600-1800 rpms, which seems very very high at idle.
The vaccuum seems to increase as does the RPMs, which is kindof the opposite of what I have read it should be doing, correct me if i'm wrong but, shoudn't LOW MAP = LOW LOAD (lower rpms) and HIGH MAP = HIGH LOAD (higher rpms) and since vaccuum is the difference between manifold absolute pressure and atmospheric pressure, shouldn't vaccuum be HIGH at idle and low loads and LOW at high loads? Just to clarify, the vacuum reading are definetly going up while I hit the throttle, and not when get off the throttle.
Things that I think might be wrong could be:
-intake manifold leak
-valve adjusted wrong, valves stick open
-improper valve timing
Based on what the vaccuum/MAP readings are showing, is there any way to narrow that down to something specifically or 2 out of 3 of those that might be wrong?
I have also performed a vaccuum test before and they confirm this, although the vaccuum test wasnt all that easy to conduct being that the car wont idle by itself the vaccuum readings at 1600-1800 rpms were around 8-10" HG and around 2500 RPMS went up to around 14" HG.
The injector duty cyle with the stock 22 lb/hr injectors were around 18-20% duty cyle between 1600-1800 rpms, which seems very very high at idle.
The vaccuum seems to increase as does the RPMs, which is kindof the opposite of what I have read it should be doing, correct me if i'm wrong but, shoudn't LOW MAP = LOW LOAD (lower rpms) and HIGH MAP = HIGH LOAD (higher rpms) and since vaccuum is the difference between manifold absolute pressure and atmospheric pressure, shouldn't vaccuum be HIGH at idle and low loads and LOW at high loads? Just to clarify, the vacuum reading are definetly going up while I hit the throttle, and not when get off the throttle.
Things that I think might be wrong could be:
-intake manifold leak
-valve adjusted wrong, valves stick open
-improper valve timing
Based on what the vaccuum/MAP readings are showing, is there any way to narrow that down to something specifically or 2 out of 3 of those that might be wrong?
ttt
Registered User
You want to send me a datalog? I can look it over for possible problems/solutions.
Registered User
I think you have it backwards with regards to the MAP, but right with regards to the Vaccume 
.. I guess it depends how you read the sensor.
The more you throttle the engine, the MAP reading should go higher, ie closer to reaching about 1.0 Bar.
At Idle (low load), the blades are closed so the vaccume is high, which means you get a lower MAP reading (0.XX something)
So.. Low MAP = High vacuum & higher MAP = Lower vacuum .
Your right, the vacuum should go down as you increase the RPM. I would guess that its running bad enough to not "want" more air at the lower rpm causing it to do the opposite....?
.. I guess it depends how you read the sensor.The more you throttle the engine, the MAP reading should go higher, ie closer to reaching about 1.0 Bar.
At Idle (low load), the blades are closed so the vaccume is high, which means you get a lower MAP reading (0.XX something)
So.. Low MAP = High vacuum & higher MAP = Lower vacuum .
Your right, the vacuum should go down as you increase the RPM. I would guess that its running bad enough to not "want" more air at the lower rpm causing it to do the opposite....?
Quote:
.. I guess it depends how you read the sensor.
The more you throttle the engine, the MAP reading should go higher, ie closer to reaching about 1.0 Bar.
At Idle (low load), the blades are closed so the vaccume is high, which means you get a lower MAP reading (0.XX something)
So.. Low MAP = High vacuum & higher MAP = Lower vacuum .
Your right, the vacuum should go down as you increase the RPM. I would guess that its running bad enough to not "want" more air at the lower rpm causing it to do the opposite....?
Thats what I was saying... when vacuum is suppose to be higher (idle), the MAP should be lower, hence LOW MAP = LOW LOAD. And at higher loads and RPMs, it should be higher... HIGH MAP = HIGH LOAD... Correct me if i'm wrong but Vaccuum is the difference between Manifold Absolute Pressure and the Atmospheric pressure.. EX: if atmospheric pressure is at 29" HG and your MAP is at 22" HG, that would suggest you have 7" HG of vaccuum and hence the car is probably under heavy load and there is little vaccuum due to the throttle blades being open...Originally Posted by toby360
I think you have it backwards with regards to the MAP, but right with regards to the Vaccume .. I guess it depends how you read the sensor.The more you throttle the engine, the MAP reading should go higher, ie closer to reaching about 1.0 Bar.
At Idle (low load), the blades are closed so the vaccume is high, which means you get a lower MAP reading (0.XX something)
So.. Low MAP = High vacuum & higher MAP = Lower vacuum .
Your right, the vacuum should go down as you increase the RPM. I would guess that its running bad enough to not "want" more air at the lower rpm causing it to do the opposite....?
The only problem is that is whats happening, but the throttle blades are closed and the car is at a high idle when it is at 22" HG of MAP and 7" HG of vaccuum and when the throttle blades are open more (higher load) (~3300 rpm) the MAP is at 13" HG and the vaccuum is at 16" HG of vacuum. Obviously, this suggest something is wrong, I got a few ideas of what if might be, but I was just hoping that this info would lead me a certain direction toward where the problem is, instead of the wide variety of it could be a intake leak, improper valve lash adjustment, bad ignition timing and bad valve timing..