please help, my ls is going nuts!!!
08-19-12, 08:36 PM
#17
A MAP (Manifold Absolute Pressure) sensor measures the vacuum or boost, in a turbo or supercharged application. The amount of air is then calculated using the volumetric efficiency of the engine and temperature of the air. In reality it is a referred to a table in the ECU program. The MAP sensor allows you to calculate the mass of air and from that you can determine the mass of fuel you need to inject. Older fuel injected cars tend to use MAP.
A MAF (Mass Air Flow) or AFM (Air Flow Meter) measure the mass or volume of air. These work in various ways including measuring the cooling effect of the air as it passes a heated element, vortex shedding. Older methods include a vane which is pushed by the air flow. There is usually some compensation for temperature. As you basically measuring the mass of air it is more direct measurement and you can easily calculate the mass of fuel required. Most if not all new cars run MAF/AFM.
Can you swap them?
Not with your standard ECU. Aftermarket ECUs may be able to use either.
Which is better?
Most high horsepower guys seem to like MAP as it eliminates a restriction in the intake path. You can also exceed the range of a MAF/AFM in big horsepower application both at the top end or at idle. From an engineer's point of view I think that the MAF/AFM is a more precise method. From an emissions and efficiency point of view a MAF/AFM is normally the better approach.
MAF/AFM Tubes
Some people sell larger diameter intakes which you transfer your MAF/AFM to. The change in tube diameter actually changes the calibration of the MAF/AFM. Basically it can make you car run leaner which under full throttle applications may improve horsepower at the risk of engine damage.
MAP to MAF Converters
These are also available which allow you to run a MAP sensor in place of your MAF/AFM sensor.
Last edited by Lavrishevo; 08-19-12 at 08:42 PM.
08-21-12, 01:43 AM
#21
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89.99 at advanced autoparts for the cardone reman. just the black box and vane, that slides into the housing.
i can say after i cleaned it the AIT code disappeared, but 31 is still evident. it was in the plans to be replaced anyway, so i figured it was worth a shot, but now i know, thanks for the insight.
now, i know that the 1uz uses the same coil and ignitor as the 20v 4age blacktop. however ive never had one fail on me....ever. so im intrested to know, whats the best way of testing the coil on the 1uz?
the engine is acting like, either the timing isnt advancing with rpm's, or the spark is getting weaker as velocity and fuel is increasing in the chamber, so im pointing at the coils at this point. i had a car previously, that had the same type issue. ran fine, till it got to operating temp, then once warm would stall, couldnt put the engine underload, etc. basically the same behavior.
i can say after i cleaned it the AIT code disappeared, but 31 is still evident. it was in the plans to be replaced anyway, so i figured it was worth a shot, but now i know, thanks for the insight.
now, i know that the 1uz uses the same coil and ignitor as the 20v 4age blacktop. however ive never had one fail on me....ever. so im intrested to know, whats the best way of testing the coil on the 1uz?
the engine is acting like, either the timing isnt advancing with rpm's, or the spark is getting weaker as velocity and fuel is increasing in the chamber, so im pointing at the coils at this point. i had a car previously, that had the same type issue. ran fine, till it got to operating temp, then once warm would stall, couldnt put the engine underload, etc. basically the same behavior.
08-26-12, 02:27 PM
#22
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ok, so i replaced the MAF.......nothing. even bought a junkyard spare, tested before install, specs out....nothing. skimmed the harness back off the MAF connector all the way back into the main harness, all wires solid and in tact.
bought a coil.....tested on both sides, not it.
put in a CTS, just because theyre only $20....didnt help.
changed plugs, just because, didnt help.
now no matter what, it will not give me a CEL, no matter what i try to do. how likely is it, that the 93 ls400 ecu's go out? the check engine light will not come on sometimes, and other times it acts as if its got a short in it, rapid flashing, no certain tempo.
also , ive looked pretty good without tearing the engine further apart, where are the main harness grounds attached to the engine? im about to trace grounds, just to see if i have a weak or bad ground somewhere causing irratic behavior.
bought a coil.....tested on both sides, not it.
put in a CTS, just because theyre only $20....didnt help.
changed plugs, just because, didnt help.
now no matter what, it will not give me a CEL, no matter what i try to do. how likely is it, that the 93 ls400 ecu's go out? the check engine light will not come on sometimes, and other times it acts as if its got a short in it, rapid flashing, no certain tempo.
also , ive looked pretty good without tearing the engine further apart, where are the main harness grounds attached to the engine? im about to trace grounds, just to see if i have a weak or bad ground somewhere causing irratic behavior.
08-27-12, 12:45 AM
#25
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please read all of the post before commenting........thanks. im a 15 year mechanic, im not completely retarded. just new to this platform. the cel is steady on and blips irratically when the car is idling at 2000 rpms or running irregular, along with the trac off light. it just wont pull codes thru the CEL.
as of 10:30 pm tonight, i was messing around with the harness on the driver side (US) and plugged everything back in, started the car, idled and revved normal, no CEL, ran for about 15 minutes. i shut it off, and went to start it right back up.......2k rpm redline, and intermittant missing........w/ CEL and TRAC OFF light on.
on the driver side of the harness, you have......
-4 injectors
-egr valve
-fuel vsv
-charcoal canister vsv
-coil plug
-6 prong plug that contains the CAS, and a few other wires.
also note. when it runs normal, the injectors are silent. when the CEL comes on and the idle becomes choppy, or it revs high, the injectors become very loud. just to make sure im hearing the injectors, and not valvetrain noise, i stuck a screwdriver (old school listenin' stick) to each injector to confirm, that it is them that are so loud.
bad FPR maybe?
also note: speedo not working, have to rev past 2500 to bring tach online.
lets try this again, shall we?
ok, cant get anything from the CEL, however i opted again for the trac and abs codes. (also nothing from trans codes either.....)
-18 (abs light)
18 is only thrown once in the obd1 codes for this car..
No. 2 cam position sensor signal (CEL)
(but why be flashing thru abs?)
-24 (trac light)
24 is used 3 times in this vehicles obd1 system
1. Sub-throttle valve does not move even when the sub-throttle valve is controlled to fully open position by ECU. (TRAC)
2. Open or short circuit in 3-position solenoid circuit for rear left wheel. (ABS)
3. Intake air temp. sensor signal (CEL, odd as how i got this from the CEL the only time i was ever able to pull CEL codes)
-26 (trac light)
26 is used twice in this vehicles obd1 system.
1. Air-fuel ratio rich malfunction (CEL, and i know its running rich )
2. Sub-throttle valve does not move even when the sub-throttle valve is controlled to fully open position by ECU (TRAC)
-33 trac light
33 is used once in this vehicles obd1 system
1. Rear right wheel speed sensor signal malfunction (ABS)
-34 trac light
34 is used oncce in this vehicles obd1 system.
1. Rear left wheel speed sensor signal malfunction
-43 trac light
43 is used twice in this vehicles obd1 system
1. Malfunction in TRAC control system (ABS)
2. starter signal (CEL, im gonna call this one since i know that there is no starter issues, and i constantly have a trac light illuminated)
-44 trac light
44 is used once in this vehicles odb1 system.
1. During TRAC control, NE signals are not input to the ECU (TRAC)
-45 trac light
45 is used once in this vehicles obd1 system.
1. When idle switch is ON, main throttle position sensor signal is 1.5V or higher (TRAC)
-51 trac light
51 is used 3 times in this vehicles obd1 system.
1. Switch condition signal (CEL)
2. Pump motor is locked, Open in pump motor ground (ABS)
3.Problem in engine control system (TRAC)
-55 trac light
55 is used twice in this vehicles obd1 system.
1. Short in TRAC motor relay circuit (TRAC)
2. No. 2 knock sensor signal (CEL)
so the first number with "-", signifies where i got the code. the "(TRAC)" determines the particular codes corresponding origin. since my CEL isnt working, and some of these codes arent found in the particular bank they were flashed from, is it possible for the ecu to redirect these codes to other indicators, or in opinion, is my ecu fried?
not trying to be rude, but none the less thanks a mill for everyone of you guys input.......
also for "PureDrifter" i got you homie, im there too.......
this is my mag cover ae86...... http://s3mag.com/blog/?p=2994#more-2994 all built by me, from stock to what it is now, 7th corolla ive built......
heres another for ya, bike carb converted ae86 hatch gtsr5, who needs fuel injection? again all built by me......
note, my coupe in the back ground
i port heads, do head work, and build engines too......IF ITS A COROLLA IN THE PICS, IVE WORKED ON IT, BUILT IT, OR ITS MINE.....
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please do not mistake me for an idiot.
Last edited by shoob; 08-27-12 at 01:21 AM.
08-27-12, 01:35 AM
#27
Have you searched the history of your LS? Maybe pull the cover off the ecu to see if ya have any leaking caps. A few of the other guys have had erratic idle issues fixs can range from bad ecu to a streched timing belt.
08-27-12, 07:44 AM
#28
Good job dude, I'm 16 and own a 1992 SC400. Back when I was 15, I owned a 1971 Oldsmobile Cutlass, and a 1992 Ford Explorer. You know more than me if you've been building cars!
^^^^^Make sure, though, to see if the timing belt isn't stretched or something.....Would it not shoot various codes?
Stay in there shoob!
^^^^^Make sure, though, to see if the timing belt isn't stretched or something.....Would it not shoot various codes?
Stay in there shoob!
08-27-12, 08:49 AM
#29
Sounds like a bad ECU to me. Just read this thread for the first time and that's my hunch. Mechanical stuff breaks. There's no 'intermittent' with mechanincal so thats out of the equation. All these different symptoms have one thing in common - the ECU. As stated before, it wouldn't be the first ECU to go bad.
Do some research before you get it repaired or replaced. There's lots of good information regarding both on this site.
Do some research before you get it repaired or replaced. There's lots of good information regarding both on this site.
08-27-12, 12:52 PM
#30
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thanks for the input guys, im pulling it out today, and popping the cover off.....ive got various obd1 toyota ecus laying around, if i see something i can change, i might take a stab at it,