timing?
- Thread starter tyfoo
- Start date
TYRODD
My ass. Look at it.
The Manifold Absolute Pressure Sensor (MAP) is attatched to the same bracket as the EGR selenoid, on the drivers side of the intake, and directly in front of the distibutor coil. Its boxy in shape and has a single vaccum line, and a 3-wire harness going to it.
Trying to remember how to test it, Ill back with you later when Im not at work
.
Trying to remember how to test it, Ill back with you later when Im not at work
.
TYRODD
My ass. Look at it.
Okay, about the MAP sensor, the 3-wire harness going to it is comprised of a ground, a 5 volt constant, and a signal wire to the ECM-this one tells the ECM whats up. I cant remember what signal voltage is Ideal but if there is no trouble code present (33 or 34) then I doubt that its necessarily the MAP.
If you had a vac leak it could make the MAP do funky things, and a vac leak effects basically everything with our trucks. REALLY check your vac lines, not just visually, you might as well replace them all anyways if you havent already.
Got a FP guage? Would be a good Idea to check that out.
I cant imagine that it would be your O2 sensor as it doesnt change temp. enough in 5 seconds to do anything (its also in "open loop" at startup/cold start and the ECM takes no readings from the O2 then).
Have you thrown/pulled any codes?
If you had a vac leak it could make the MAP do funky things, and a vac leak effects basically everything with our trucks. REALLY check your vac lines, not just visually, you might as well replace them all anyways if you havent already.
Got a FP guage? Would be a good Idea to check that out.
I cant imagine that it would be your O2 sensor as it doesnt change temp. enough in 5 seconds to do anything (its also in "open loop" at startup/cold start and the ECM takes no readings from the O2 then).
Have you thrown/pulled any codes?
toolmann
Member
very doutful that your o2 sensor is a problem....i had/have a stumble & an o2 dident fix it-
the 50 bucks is better spent on vac.lines and beer.
believe it or not a bottle of Chevron Techron fuel injector cleaner damn near eliminated my stumble-im gonna run another can threw it to really clean that mother out...
T
the 50 bucks is better spent on vac.lines and beer.
believe it or not a bottle of Chevron Techron fuel injector cleaner damn near eliminated my stumble-im gonna run another can threw it to really clean that mother out...
T
toolmann
Member
yeah...i could smell it in the exhaust.my o2 sensor was reading pretty nutty too,jumpin' from 800 to 2 mvs.wasent the sensor tho-
after the Techron the stumble is waaay better.it still seems to run alittle rich but i dident correct my fuel press after i bumped it up a bit (to 48 psi) but i guess fats better than lean...
replacing the vac. lines would probably help...just about every one i touched when i was replacing mine broke...but i got 3x the miles you got...still wouldent hurt tho...
iv been havin'some issues with the truck cause i let a bone head work on it (in addition to me),but i got it straightend out now.its running strong & quite. i aint messin with it anymore xept to put in a Walbro,that the LAST "recommended upgrade" i need to do.....
....until something breaks,burns,leaks,cracks or xplodes.
T
after the Techron the stumble is waaay better.it still seems to run alittle rich but i dident correct my fuel press after i bumped it up a bit (to 48 psi) but i guess fats better than lean...
replacing the vac. lines would probably help...just about every one i touched when i was replacing mine broke...but i got 3x the miles you got...still wouldent hurt tho...
iv been havin'some issues with the truck cause i let a bone head work on it (in addition to me),but i got it straightend out now.its running strong & quite. i aint messin with it anymore xept to put in a Walbro,that the LAST "recommended upgrade" i need to do.....
....until something breaks,burns,leaks,cracks or xplodes.
T
TYRODD
My ass. Look at it.
Ive heard that using pour in FI cleaners are no good, except maybe a GM or BG type, others may swell FP seals.
The MAP is to the drivers side of the upper intake, its mounted on a black bracket. I think you may have it confused with the EGR valve-that big fuggly mess directly behind the throttle body.
If you really want to clean you FI system, use some GM top engine cleaner or some BG equivalent. Shoot, I would even remove the whole upper int., TB, rail/injectors and clean them by hand if you want to do it right.
Oh yeah, the ECM will throw a code when checking timing with the tan wire disconnected-this is normal.
The MAP is to the drivers side of the upper intake, its mounted on a black bracket. I think you may have it confused with the EGR valve-that big fuggly mess directly behind the throttle body.
If you really want to clean you FI system, use some GM top engine cleaner or some BG equivalent. Shoot, I would even remove the whole upper int., TB, rail/injectors and clean them by hand if you want to do it right.
Oh yeah, the ECM will throw a code when checking timing with the tan wire disconnected-this is normal.
still can't get the hick-up out
double checked timing notice with the wire under dash pluged in that the timing is @ 20 with it disconnected it's on zero
when it is at a idile the timming jumps when it kick-ups to about 5
any ideals?
hocked a fuel tester to the rail
turn the key on and got 40 psi
is this right?
so far
plugs
wires
cap
rotor
adjust tv
oil- filter
timing
clean egr
fuel filter
injector cleaner
checked hoses
double checked timing notice with the wire under dash pluged in that the timing is @ 20 with it disconnected it's on zero
when it is at a idile the timming jumps when it kick-ups to about 5
any ideals?
hocked a fuel tester to the rail
turn the key on and got 40 psi
is this right?
so far
plugs
wires
cap
rotor
adjust tv
oil- filter
timing
clean egr
fuel filter
injector cleaner
checked hoses
TYRODD
My ass. Look at it.
Okay, how does you truck run while your driving? Is there any tach flutter going on? What wires did you use? Even brand new wires can be bad. I also have 40# of pressure with the key on, so I wouldnt say thats bad, but what does it do with the engine running (FP guage)?
Id hate for you to start throwing more money at it, I did and I learned then on to make sure before I bought, I hated myself for doing that. :x
Have you checked your coil or coil harness? What about cleaning your upper intake/injectors?
Id hate for you to start throwing more money at it, I did and I learned then on to make sure before I bought, I hated myself for doing that. :x
Have you checked your coil or coil harness? What about cleaning your upper intake/injectors?
notice to night that when i put it into gear and sit there it runs good no hic-up or rpm hunting
once i put it in park or
at start up and put in gear kwick to take off. its rough and even dies once in awhile
is there a vacum that goes to the tranny?
is there a blow off valve in the vacum system and then closes when theres a load apliyed
once i put it in park or
at start up and put in gear kwick to take off. its rough and even dies once in awhile
is there a vacum that goes to the tranny?
is there a blow off valve in the vacum system and then closes when theres a load apliyed
TYRODD
My ass. Look at it.
Youre idle may change a little while in gear due to a diff. A/F ratio from the ECM while in gear.
There is no blow off valve to my knowledge
There is a vent line coming out of the tranny, I think it ends up near the Vapor Canister.
Still, any tach flutter while moving?
There is no blow off valve to my knowledge
There is a vent line coming out of the tranny, I think it ends up near the Vapor Canister.
Still, any tach flutter while moving?