Engine stalls

mrvette said:
That looks like the oddest position for a MAP sensor, down next to the headers, and what are all those vacuum hoses doing there?? I can see one smaller hose to the map sensor, but I seeing larger ones also... why??

looks like some green wires going under that bracket, and for some reason the MAP sensor looks as if the mounting tab on the outer end was broken off....that's weird....

what I would do is get another sensor, and just let it hang off the port with a short hose to the plenum, and do what necessary to get the wires hooked up correctly.....

wonder if it's heat related?? too much heat for the poor sensor, that's certainly a funky location that I see no reason for it to be THERE.....:club::amazed:
Click to expand...

Actually the sensor is connected to the back of the engine the exhaust is at least 20 inches away.

But I will order a new one from Summit that I posted above.

What you see as hoses are wires from the Dakota Digital shiftier indicator.
 
BangkokDean said:
mrvette said:
That looks like the oddest position for a MAP sensor, down next to the headers, and what are all those vacuum hoses doing there?? I can see one smaller hose to the map sensor, but I seeing larger ones also... why??

looks like some green wires going under that bracket, and for some reason the MAP sensor looks as if the mounting tab on the outer end was broken off....that's weird....

what I would do is get another sensor, and just let it hang off the port with a short hose to the plenum, and do what necessary to get the wires hooked up correctly.....

wonder if it's heat related?? too much heat for the poor sensor, that's certainly a funky location that I see no reason for it to be THERE.....:club::amazed:
Click to expand...

Actually the sensor is connected to the back of the engine the exhaust is at least 20 inches away.

But I will order a new one from Summit that I posted above.

What you see as hoses are wires from the Dakota Digital shiftier indicator.
Click to expand...

I looking at the exhaust pipe dia, and it's damn close to same as distance to the sensor.....very odd perspective to have it at 20" distance, and I still think about that missing tab and it's location....

:eek: And at any rate, just for grins, I put the Fuel regulator on a long vacuum line, like to put FP reg in the rear near the pump, and use return line for vacuum.....well that didn't work out at ALL....... I wonder about anything longer than a ~6' line to the MAP......I"d put it up snug to the plenum when you get the new one, see what happens, and maybe then mount to the firewall, NOT down there....
 
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mrvette said:
BangkokDean said:
mrvette said:
That looks like the oddest position for a MAP sensor, down next to the headers, and what are all those vacuum hoses doing there?? I can see one smaller hose to the map sensor, but I seeing larger ones also... why??

looks like some green wires going under that bracket, and for some reason the MAP sensor looks as if the mounting tab on the outer end was broken off....that's weird....

what I would do is get another sensor, and just let it hang off the port with a short hose to the plenum, and do what necessary to get the wires hooked up correctly.....

wonder if it's heat related?? too much heat for the poor sensor, that's certainly a funky location that I see no reason for it to be THERE.....:club::amazed:
Click to expand...

Actually the sensor is connected to the back of the engine the exhaust is at least 20 inches away.

But I will order a new one from Summit that I posted above.

What you see as hoses are wires from the Dakota Digital shiftier indicator.
Click to expand...

I looking at the exhaust pipe dia, and it's damn close to same as distance to the sensor.....very odd perspective to have it at 20" distance, and I still think about that missing tab and it's location....

:eek: And at any rate, just for grins, I put the Fuel regulator on a long vacuum line, like to put FP reg in the rear near the pump, and use return line for vacuum.....well that didn't work out at ALL....... I wonder about anything longer than a ~6' line to the MAP......I"d put it up snug to the plenum when you get the new one, see what happens, and maybe then mount to the firewall, NOT down there....
Click to expand...

OK I see your point. I will move it up away from the heads. I will also try using a different vacuum point. So far no one has told me what the MPS sensor does? Does it control the timing? You see the LPG injection is a separate computer but it does not control the timing.
Many thanks, Dean
 
It's a manifold absolute pressure sensor, it reads manifold absolute pressure and the ecu uses that for fuel calculations, it's a sort of load factor like the lv8 on MAF systems. The timing is dependant on RPM & MAP YES!!! It, like the fueling map is a 3d graph of rpm vs map
 
Twin_Turbo said:
It's a manifold absolute pressure sensor, it reads manifold absolute pressure and the ecu uses that for fuel calculations, it's a sort of load factor like the lv8 on MAF systems. The timing is dependant on RPM & MAP YES!!! It, like the fueling map is a 3d graph of rpm vs map
Click to expand...

OK thanks. I will move the MAP sensor and also where it gets the vacuum from.

This is what these ports are used for right now.



The PCV is connected to the port on the left side of the intake (where you had told me to use)

I have been reading the posts on third gen f-body site and I see some people have had the same problems and one found a bad ground on his coil and others suggested Idle Air Control valve replacement or cleaning.

My IAC is new but I will remove it and see what it looks like.
 
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The IAC valve has some passages at the end of the pintle (cone shaped pin at the end). Check that those passages are clean, some tend to get bits of carbon and other goo that plugs up the system.
 
TimAT said:
The IAC valve has some passages at the end of the pintle (cone shaped pin at the end). Check that those passages are clean, some tend to get bits of carbon and other goo that plugs up the system.
Click to expand...

Will do, thanks Tim
 
BangkokDean said:
Twin_Turbo said:
It's a manifold absolute pressure sensor, it reads manifold absolute pressure and the ecu uses that for fuel calculations, it's a sort of load factor like the lv8 on MAF systems. The timing is dependant on RPM & MAP YES!!! It, like the fueling map is a 3d graph of rpm vs map
Click to expand...

OK thanks. I will move the MAP sensor and also where it gets the vacuum from.

This is what these ports are used for right now.



The PCV is connected to the port on the left side of the intake (where you had told me to use)

I have been reading the posts on third gen f-body site and I see some people have had the same problems and one found a bad ground on his coil and others suggested Idle Air Control valve replacement or cleaning.

My IAC is new but I will remove it and see what it looks like.
Click to expand...

Your pix there and asking about power brakes booster I assmume, it's too small, you need a 3/8 hose/pipe/connection for that, and on the left rear up/under of that plenum, you have a hole drilled for a fitting and 3/8 ID hose to the booster, NOW, if that hole in the plenum is open to atmosphere, I be surprised the engine runs a ALL, the F body dizzy makes it much easier to spot, and yes, 5 to 5 is the fuel pressure reg, and so to connect it to one of them ports in back as shown, but the MAP sensor has to go to another one in that set of 3 in that location.....the other was intended to run vacuum accessories, such as HVAC flow controls....if unused, plug/cap it....

:thumbs: I still convinced we can fix this via remote control, no matter HOW remote you ARE.....:bump:
 
Thanks Gene, I only have two ports on the right side of the Pentium as shown in the picture. The port you mentioned in the lower Pentium is what the MAP is connected to. My power booster located on the right side is from ford and has a really small connecting hose 1/4 inch, plus to connect to the port for left side booster is difficult due to the dizzy being so close to the fire wall, there is no room. The break booster works just fine as is, see the picture of my booster.


Now I have ordered a new dizzy and MAP sensor that should be here in 3 weeks time so I will take your advise, when the old dizzy is out mount the MAP sensor in a different location away from the back of the heads. My fire wall has nothing but the booster connected to it and I really don't want to drill any holes in it so the MAP sensor will have to be located some where on the back of the intake. My coil is mounted just on the right side of the dizzy with a plate made to bolt to the intake. It sits really nicely there, so I might mount the MAP on the other side but will have to wait till I do the dizzy change. When I do this I will post pictures.
 
Does the L98 TPI require a crank position sensor?

TT asked this question,"You DO have the correct prom in it right? For an automatic and not a manual? IAC steps, stall saver etc. are different for a manual."

I really don't know if I have the correct prom? this is what I have below. Now if I need a different one where do I buy one?




 
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AUJP is the GM code for the programming of the prom they shipped, but I note the typical silver tag with AUJP on it is replaced by a white tag, some of the early chips were photo sensitive and used light to erase the program.....but mostly those have been replaced these daze and so they unplug from the Cal Pak, and get inserted into a lap top set up to burn chips.....I had a retired GM engineer stop by one day on his way south, and it was great to watch, just wish I understood WTF I was looking at....oh well.....

I would not be so quick after that program chip at this time.....

also to check the Idle motor for continuity in the green and blue pairs....one is for opening, the other for closing the valve...it's a stepper motor....so at the computer end plug, check for that the motor is in fact wired right....

and that the wires did not get flipped around somehow....reversing the pairs may well cause screw ups in operation.....I have never done that, so I have not demonstrated that for myself, :crylol:
 
mrvette said:
also to check the Idle motor for continuity in the green and blue pairs....one is for opening, the other for closing the valve...it's a stepper motor....so at the computer end plug, check for that the motor is in fact wired right....

and that the wires did not get flipped around somehow....reversing the pairs may well cause screw ups in operation.....I have never done that, so I have not demonstrated that for myself, :crylol:
Click to expand...

The harness was new plus the Idle motor I don't see how it could get switched as the plug only goes one way?
IMG_5980_zpsd524c848.jpg


IMG_5978_zps5413c8dd.jpg
 
I talking of the possibility of the pin outs on the wiring having been cross in the assy process, either by you or who ever assembled the harness....

not the plugging of the harness into the motor, that's keyed pretty good...but would be easy for anyone to push the rong color wire into the rong slot on the plug casting, OR when doing same on the computer end,

I made all my own wiring harnesses on several FI installs over the years, me shark has had maybe two wiring harnesses, only because I was trying another computer setup some years ago, but it was a NO go.....so I gave up.....and went back to same computer you have, and as was my original install....

:hissyfit:
 
DEAN, Talking to my son about this, and you maybe know, he has a '57 pickup his fiance' has from her father's farm yet.....and so he mentioned something....


DO YOU HAVE A SPEED SENSOR/SENDER on the speedo output?? that is a 4 pulse per turn magnetic sender unit, telling the computer the vehicle is stopped or WTF is going on with speeds......

if you do not have that input saying something, anything, even if it's complete bullshit.....the computer gets a messed up.....

I put my FI on the vette in '95, and had a fit with very similar problems that you have, and the solution for ME, upon advice, was to get a speed sensor onto the speedo cable, right there at the trans output purple/yellow twisted wires into the computer directly....wires twisted so to prevent other RFI/EMI from messing up the signal.... check your install for that.....


:shocking::shocking::shocking::crap::clap:
 
With no VSS inout the IAC will not reset but the ECM will think it's standing still all the time. You will never leave the BLM cell #4 (special cell) and that cell is also used for open loop fueling (WOT) Std sender for TPI is 4K ppm, not 4. You can alter it in the bin if needed. The speedo/cruise output on those later ECMs is 2K pulses per mile but you won't need that

still wondering if timing is set correctly, does it go in closed loop (jumper aldl pin a&b and watch the CEL, rapid flashing is open loop, slow = closed)
 
Twin_Turbo said:
With no VSS inout the IAC will not reset but the ECM will think it's standing still all the time. You will never leave the BLM cell #4 (special cell) and that cell is also used for open loop fueling (WOT) Std sender for TPI is 4K ppm, not 4. You can alter it in the bin if needed. The speedo/cruise output on those later ECMs is 2K pulses per mile but you won't need that

still wondering if timing is set correctly, does it go in closed loop (jumper aldl pin a&b and watch the CEL, rapid flashing is open loop, slow = closed)
Click to expand...

it was MY understand that at 60 mph, the cable spun 1001 rpm, and why THAT odd count, I dunno....lets just leave that to the mysteries of the universe.....:p

but for every speedo cable rev the sender was supposed to send out 4 pulses....the way I understood it, anyway....


methinks we on same page....


:shocking::clap:
 
Do these systems require a crank trigger? It looks like my digital gauges sending unit has a place to connect the VSS.

My friend that did the wiring thinks my problem is the coil in the dizzy.I guess I will have to wait till the new dizzy gets here in 3 weeks time.
 
No, the ignition module in your distributor sends the ecm the reference signal.

Coil in your distributor? you mean the pickup coil? either it's bad or it's not. the only thing that can produce intermittent errors and crapping out and then simply allowing a restart is the ignition module.


No one over there has a snap on red brick scanner? If not, order an aLDL to usb cable and some scanning software. Might want to use DataMaster free trial (I like DM the best) and hook your laptop to the aldl and do a scan & log whilst driving and letting it die. That is a hell of a lot more effective than guessing and throwing money at it. It might even be something as silly as a fuel pressure issue.
 
Twin_Turbo said:
No, the ignition module in your distributor sends the ecm the reference signal.

Coil in your distributor? you mean the pickup coil? either it's bad or it's not. the only thing that can produce intermittent errors and crapping out and then simply allowing a restart is the ignition module.


No one over there has a snap on red brick scanner? If not, order an aLDL to usb cable and some scanning software. Might want to use DataMaster free trial (I like DM the best) and hook your laptop to the aldl and do a scan & log whilst driving and letting it die. That is a hell of a lot more effective than guessing and throwing money at it. It might even be something as silly as a fuel pressure issue.
Click to expand...

Thanks TT, I think I found someone that has a scanner and has offered to assist. Now I need to find a list of codes.

The problem with it being fuel pressure is both systems have the same problem so that shows it is not fuel pressure. I do have a pressure gauge permanently installed on the fuel rails and it stays at 40 lbs. The LPG is pressurized. Keep in mind the stalling starts when hot and it does start right up.
 
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