Nothing left to check? VP 5.7GSI wont start - good fuel pressure, good ecm, wiring
05-24-2015, 02:48 PM
#332
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05-24-2015, 02:50 PM
#333
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Are you sure that the float and level of fuel in the cool fuel section is working properly - Do you have fuel in the vent line out of the cool fuel line going into the throttle body spacer ?
when engine running if you unplug TPS connector what happens to the engine running conditions and if no change rehook connection ?
next If MAP signal voltage is low - unhook connectors from ECT and TPS - since MAP and ECT and TPS share common circuits - did the engine change running conditions for the better - if not ECT and TPS most likely not the problem.
next install a vacuum to a correct manifold vacuum source - start engine what is your vacuum readings
Next with scan connected to the DLC - have ignition OFF , remove MAP connector at MAP sensor - jumper together harness terminals very carefully B and C - then turn ignition ON is the MAP sensor reading now above 4 volts - IF SO - checked for leaking sensor vacuum fitting or its plugged - if none of this and all okay - you have a faulty MAP sensor.
The MAP sensor responds to changes in manifold pressure - vacuum. The ECM receives all of this info as a signal voltage that will vary from 1 to 2 Volts MAX. (Actually 2 V is a tad on the high side) when the throttle plate is closed idle - idle is high vacuum and WOT is low vacuum. Signal voltage of MAP at WOT should be 4 to 4.9 volts.
If a bad MAP sensor or fails - the ECM will sub a default MAP value that will vary with RPM. MAP sensor is a 5 volt reference and is delived from J2-4 to the MAP sensor connector termainal C. J2-3 is the ground circuit for the MAP sensor A terminal. The MAP sensor B terminal will send Voltage to terminal J2-27 of the ECM according to manifold pressure.
These are good test to see if all of this is working correctly.
when engine running if you unplug TPS connector what happens to the engine running conditions and if no change rehook connection ?
next If MAP signal voltage is low - unhook connectors from ECT and TPS - since MAP and ECT and TPS share common circuits - did the engine change running conditions for the better - if not ECT and TPS most likely not the problem.
next install a vacuum to a correct manifold vacuum source - start engine what is your vacuum readings
Next with scan connected to the DLC - have ignition OFF , remove MAP connector at MAP sensor - jumper together harness terminals very carefully B and C - then turn ignition ON is the MAP sensor reading now above 4 volts - IF SO - checked for leaking sensor vacuum fitting or its plugged - if none of this and all okay - you have a faulty MAP sensor.
The MAP sensor responds to changes in manifold pressure - vacuum. The ECM receives all of this info as a signal voltage that will vary from 1 to 2 Volts MAX. (Actually 2 V is a tad on the high side) when the throttle plate is closed idle - idle is high vacuum and WOT is low vacuum. Signal voltage of MAP at WOT should be 4 to 4.9 volts.
If a bad MAP sensor or fails - the ECM will sub a default MAP value that will vary with RPM. MAP sensor is a 5 volt reference and is delived from J2-4 to the MAP sensor connector termainal C. J2-3 is the ground circuit for the MAP sensor A terminal. The MAP sensor B terminal will send Voltage to terminal J2-27 of the ECM according to manifold pressure.
These are good test to see if all of this is working correctly.
Engine idling after warmed up just checked vaccum 18 psi.
Cam timing is perfect checked today.
Distributor timing 8 BTC.
Yes the fuel vent line was wet, but not full with fuel. Should it not even be wet? if the fuel vent wasn't working correctly I would see that with fuel pressure issues I thought?
05-24-2015, 02:51 PM
#334
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It's on my engine now. What do u want me to check? Idle 18. U want me to check another rpm? I'm going to get a can of carb cleaner and check for leaks in 1 hour.
Edit: just did all vaccum tests that BUP outlined in that video. They all checked out. Even with it running this ****ty, the vaccum drops to 2psi then jumps to about 20 when you snap the throttle. This simply can't be mechanical or a vaccum leak.
Edit: just did all vaccum tests that BUP outlined in that video. They all checked out. Even with it running this ****ty, the vaccum drops to 2psi then jumps to about 20 when you snap the throttle. This simply can't be mechanical or a vaccum leak.
Last edited by nunnink23; 05-24-2015 at 02:56 PM.
05-24-2015, 02:59 PM
#335
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[. What do u want me to check? Idle 18. U want me to check another rpm? I'm going to get a can of carb cleaner and check for leaks in 1 hour.[/QUOTE]
Watch the video I know its a car but the operating principle are the same. That test isolates the map
https://www.youtube.com/watch?v=B8EVhFc5Yqw
Watch the video I know its a car but the operating principle are the same. That test isolates the map
https://www.youtube.com/watch?v=B8EVhFc5Yqw
05-24-2015, 03:40 PM
#336
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https://www.youtube.com/watch?v=B8EVhFc5Yqw [/QUOTE]
I just tested both of my map sensors with a vaccum gauge and the diacom tool.
Here is the result for each sensor.
standard motor products MAP sensor:
0 psi 4.92v
5 psi 4.12v
10 psi 3.25v
15 psi 2.25v
20 psi 1.33v
Factory MAP sensor
0 psi 4.96v
5 psi 4.12v
10 psi 3.20v
15 psi 2.27v
20 psi 1.27v
05-24-2015, 03:49 PM
#337
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Here is what I want you to do before anything else. Very IMPORTANT. And follow this to a T.
You need a hand held vac like a mity vac to manually put 10 inches of vac on the MAP sensor - you can use the vac line to do so with the mity vac . start your engine - does it run better and stay running correctly now ? - if not - pull your mity vac off hook vac line back - start engine then pull the MAP vac line then put 10 inches of vac to the MAP sensor - does the engine run any better ?
Next test - put everything back together pull your mity vac- now hook your scan tool back up - fully warm up engine read scan MAP voltage write it down - then pull vac line off and plug vac port with a rubber cap or even black electrical tape very well. connect the hand held vac pump to the MAP sensor / vac line to the MAP and then apply 10 inches of Vac - then look at the MAP voltage while applying 10 inches of vac. Make sure it is 10 inches of vac. write that voltage number down. . next you take that number and subtract it from your first vac voltage reading.
If the voltage of your subtraction is greater than 1.5 volts - your MAP sensor is good if it is 1.5 volts or less the MAP sensor is bad or you have a connection problem within the MAP circuit.
Report your findings here. Do these these before anything else.
You need a hand held vac like a mity vac to manually put 10 inches of vac on the MAP sensor - you can use the vac line to do so with the mity vac . start your engine - does it run better and stay running correctly now ? - if not - pull your mity vac off hook vac line back - start engine then pull the MAP vac line then put 10 inches of vac to the MAP sensor - does the engine run any better ?
Next test - put everything back together pull your mity vac- now hook your scan tool back up - fully warm up engine read scan MAP voltage write it down - then pull vac line off and plug vac port with a rubber cap or even black electrical tape very well. connect the hand held vac pump to the MAP sensor / vac line to the MAP and then apply 10 inches of Vac - then look at the MAP voltage while applying 10 inches of vac. Make sure it is 10 inches of vac. write that voltage number down. . next you take that number and subtract it from your first vac voltage reading.
If the voltage of your subtraction is greater than 1.5 volts - your MAP sensor is good if it is 1.5 volts or less the MAP sensor is bad or you have a connection problem within the MAP circuit.
Report your findings here. Do these these before anything else.
05-24-2015, 04:10 PM
#339
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Apply 10 iches of VAC NOT PSI to the MAP sensor. You need a vac tester like mity vac hand held to apply it.
If this F in motor runs good with 10 inches of vac applied to the MAP while starting and running I want to f in know this.
If this F in motor runs good with 10 inches of vac applied to the MAP while starting and running I want to f in know this.
05-24-2015, 04:17 PM
#340
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Post 337 do all those tests. and I want to know what happens and the numbers - my feeling might be apply 10 inches of vac to the MAP this pig might run better. I want to know. Also do it both ways with the vac port un plugged and then plug it however forgot to mentioned this.
