I am beyond frustrated now. Going on 6 weeks with this problem. When the ambient temp outisde is below about 55 degrees, car wont start in the morning. has fire, but no pressure at Shrader valve. New pump, filter, TPS sensor, idle control valve, ECM temp sensor and pigtail, new fuel rail seals, new injector upper and lower o rings, new fuel regulator, plugs, wires, cap rotor, ignition module, coil wire, water pump, thermostat, battery.JUST REPLACE ECM YESTERDAY!!!!!. Wouldnt start this morning. Put a floor heater once again on the passenger floor board and came back 10 minutes later and she fired right up. She will start every time today until tomorrow morning!!!!! I AM COMPLETELY STUMP NOW as to what it could be. I could really use some more ideas, cause I am out of them. Please MSG me back, or text me or call me 702-510-6117.

 

I am by no means an expert, as a matter of fact I'm a newbie in EFI and just starting to get my feet wet. But here's my 2 cents. It seems your issue relates to the fuel pump not being energized. When this happens, try switching the fuel pump relay with the fan relay. I think they are identical. If it starts, well, you know where to put your money. I don't think it's the VATS, cuz that only cuts off the injectors. Maybe someone else can chime in.

 

I am having the exact same problem when the weather is cold or the colder the more difficult it is to start the car, what I do is put ignition switch open, thenthe ses light Begins to flash after a few minutes and stabilizes after about half an hour to an hour that's when the car turns well like any problem. I can even burn out if a want.


seems that the problem is the ecm but not what they have exactly
i discovered that the ecm has to be warm for the ses light stays on and the car turn well

Note .-The colder the longer needs the switch to be open so the light stays on and stabilized. And whit the switch open the ecm starts to warm up. Sorry for the english using Googletranslator.

 

I think its something witht the VATS. I have changed ECM and also changed VATS Module that is located next to the ECM. Still has same issue. I have been putting a floor heater in the car cabin at night or in the morning. Once the cabin ambient temp is warm, car fires right up. Something with the vats is blocking the fuel to the injectors. My vats has been bypassed by the previous owner. i have no chipped key and there is a wire running from under the column and over to the starter. i need to check connections under the column and look for a bypass module. maybe that is bad. BUT, there is no question, ambient cabin temp is the key, and you are right, the colder it is, the longer it takes. if i dont put the heater in the car at night, it takes 30-60 minutes to warm up enough to start. If i put the heater in before i crash for the night, I go out and it fires right up. I have pulled the A11 pin on the ECM. No corrosion and connection is tight. Same as the F12.

 

Yea the ambient cabin temp is the key for me too, i still loking for a solution if a have any luck y told you, i appreciate if you do the same, loking for solution in this manual https://rapidshare.com/files/4611333...ice_Manual.pdf its for firebird but works whit camaro too.
hope help you too.

 

Never heard of this before am am interested in helping to solve it.
This would be the 1227730 ECM or newer variant.
The ECM triggers the fuel pump to run (Pin A11 output) with each distributor reference pulse as the engine cranks. If the FP relay fails, the oil pressure switch should bring the pump online once pressure is established.
There is also a pin "G" in the ALDL connector that you could check voltage to see if the pump is attempting to run. You could also jumper power there to get the pump to run.
I would think distributor pickup coil is bad or doesn't like the cold but heating the inside takes that possibility away.
Very odd that heating the interior (or the ECM) solves this...

 

VATS will stop the injectors from firing but will not stop the fuel pump.
You should have pressure at the rail if the pump is running.

Edit: Distributor ref pulses are connected to "D8" with refernce to "D9" pins on the ECM.
Confirm they are in good condition and tight.

 

i agree with what JP said, if it was VATS the fuel pump should still run when cranking.
also, if it was a VATS problem, with the starter part of the VATS bypassed, the motor should start and run for 1~2 seconds.
VATS problems or not, at key on without cranking, the fuel pump should run ~2 seconds. turn the key off for more than 10 seconds and the pump should run again for ~2 seconds at key on.
you can use a test light to check for power at key on at pin G in the ALDL.

thinking out loud here, there may be a problem with the bulk head connector.
does the SES light come on?

 

SES light DOES come on. I have put in a new ECM and a new VATS module. Still has same problem. I am pretty sure I can hear the pump come on and the 2 second prime humm. I have pulled the A11 pin and made sure it is clean and tight connection. I have good continuity on the A11 wire from the pin to the firewall. I have put a floor heater in the passenger floor board. After 5-45 inutes ( depending on how cold it is outside) it fires right up. I have moved the heater to the driver floor board, and it starts. I then put in on the center console and ran it. I have found that as long as the cabin ambient temp is fairly warm, it fires right up. I have put in all new fuel pump, filter, fuel regulator, ignition module, TPS sensor, ecm temp sensor and pigtail, all new seals on the fuel rails, all new upper and lower O rings on each injector. I have changed the coil wires, cap, plugs, rotor. The 20 amp fuse by the battery is good as well. The PO had apparently bypassed the VATS, due to key is not chipped. I replaced teh steering column and put in a new key cylinder. Once I put the heater in the cabin in the morning and it starts, I have no problems all day long. If I go out to the car late at night when the outside temp has dropped, right back to the same problem. Additionally, I even tried putting some insulation up and around the ECM and VATS module overnight. That did not make any difference. I thought I was losing my mind, until I started hearing about other people with the same problem. I appreciate all the help, it's now beyond a pain in the A#$ problem.

 

Maybe this is a stupid question but when you say you changed the ecm did you changed everything including the module where the three chips are?,Or you are using a new ecm with your old chips?,I'm the guy whit the same problem, Somewhere in this page I read, that one of the chips may be the cause of the problem.

This day it took me 10 minutes to turn on my car, I been checking the wiring from the ecm, grounds, voltage, etc., but no luck yet, the A11 pin you said, according to the manual page 810. corresponds to MAF sensor ground. This is for V8 Fuel Injection TPI Engine 305 and 350.

I have a Camaro Iroc-z 1986 V8 305 engine TPI Fuel Injection. Whit no mods. Almost everything original.

 

And another thing, you might try removing the ecm in the night and the morning before try to turn on your car heat the ecm to see if the ecm need to be hot for the car turn on ok,or is another thing causing the problem. I do it my self but i don't have a heater.

 

I put in a new ECM, and swapped the PROM. I replaced the VATS module ( that is mounted next to the ECM). yesterday afternoon, it was cold when i left work and wouldnt start. i put the floor heater on teh drivers side floorboard 9due to the closest power source that I could plug into with the extension cord). It was down there for 4 minutes and it fired right up. I leave for work @ 5:30am, so i wont be able to test until this weekend, the theory of putting the ECM in the house overnight and replacing it in the morning. If it still doesnt start, I wont have time to plug in the heater and wait without being late for work. Now recently, I HAVE tested the theory of only putting it on the drivers floorboard, and it started in less time then putting it on the passenger floorboard. unfortuately, the past week, i have been just setting it on teh center console and running it on low when i crash for the night, so the entire cabin is warm and it fires right up. I am wondering what connections are on teh drivers side under teh dash that could cause it. i am not sure exactly how the PO bypassed the VATS. maybe they did it correctly with a bypass module or not. All I know it this point is that my key IS NOT chipped, and there is a seperate wire running from up under driver side dash, through firewall and over to starter. I believe i read that these both had to be done as part of the bypass process. Hopefully we can get this figured out soon

 

The box next to the ECM is either the DERM or cruise module. They are both located under the dash on the passenger side. The VATs module is located under the dash between the defrost duct and the firewall. Very difficult to get to.

Note that the VATs module also has a paper label with "Passkey II" on it.

If the PO used a resistor to fool the VATs module it may not even be soldered. If it just has the wires twisted around the resistor leads...

RBob.

 

I guess I will get back up under the column this weekend and see what I can find. I will follow that wire running to the starter and see where it is originating at and start there

 

I'm starting to believe that the problem is the PROM I'll try to change but here where I live is difficult to find. I hope be another the problem and not the PROM.

 

I am checking the connections under the column this weekend. Going to make sure they are soldered and not twisted together as RBOB has sommented on. I am leaning now to the problem being in THAT area. I seem to get a quicker response by the heater being placed in the drivers floor board. It wouldnt start yesterday after work. Was about 48 degrees outside. I put the heater ( which i keep in the car unfortunately) in the drivers floor board. I came back to it 4 minutes later and it fired right up. The ambient temp in the cabin in other areas, like back seating area and passenger side wasnt near as warm as teh drivers floorboard area was. I am not sure if there is a way to test the PROM. If there is let me know, and I will go and have it tested, so we can eliminate or pin-point that as being the problem. At least we are eliminating and narrowing down the possibilities.

 

with a fully complete and operational VATS that has a problem, it either won't crank at all, or it will start and die within ~2 seconds.
with the start relay bypassed, it will crank and start, then die ~2 seconds.
so i really don't think its going to be your problem.

gera_lopez21, your car uses a different computer system than what robster
has.
but this could apply to both of you.

when it won't start, have you tried putting a battery charger on it?
the reason i ask is because if the voltage to the ECM is too low, then it won't
start. even if it cranks over good, you still may have low voltage to the ECM
when cranking.
i forget what the exact voltage is, 9.4, or 9.6 but the ECM will shut down if
its too low.
a few years ago i ran into a problem with my car cranking fine, but not
starting.
using jumper cables, it would only start if the other vehicle was running.
even a small battery charger set to 50 amps was enough to get it to start every time.
the first time i had this problem it turned out to be a bad ignition switch.
then a few months later it happened again, it had a bad connection at the
main power wire in bulk head connector.
the third time, the ignition switch was bad again.
the original switch was over 20 years old when i replaced it.
when the replacement ignition switch failed, it was less than a year old. it may have failed because of the problem at the bulk head connector, or it may have just been a bad switch to start with.

 

I have a charger whit 5,10 and 50 capacity and make no difference to start the engine, the key to the problem is the cabin temp, and why the ses flashes until either leave the switch open for a few time or rise the cabin temp, in my case i don't have a heater so i just leave the switch open for about 30 or 60 minutes depends the outside temp and the its star fine, but in the process the ses light star to flash randomly (not like a code just randomly), until it stay steady (after 30-60 minutes) and then is wen i can turn on the engine without any problem, same thing happens if i bridge the pins for the codes the ecm don't send the 12 code until 30 to 60 minutes whit switch open or the cabin temp is hot ( in the process the ses light star to flash randomly), Then the ses light Begins to send the 12 code and only the 12 code. That is why i thing the PROM is bad, but hope not.

 

That's a good point Denn Shah,
If the ECM does not get a good ignition switch voltage I would think the output for the fuel pump wouldn't turn on again. Current draw from the starter could be dropping the voltage at that pin.
You say the pump is priming during initial key on but not sure if its running during cranking?

If that is the case then the initialize of the program is ok and we should turn our attention to the ignition switch input at the ECM.
This is pin "A6" (Maybe jump power here when cold to see if that starts it.) Be sure to take it from a known source that is still powered when cranking.

Also verify with a volt meter if power is at "G" terminal referencing the "A" terminal for ground indicating the fuel pump is running during cranking. If any wiring changes were ever done to the car it is possible the power is not present during cranking if taken from the wrong place.
Do you know if the wiring has been changed or modified anywhere other than the VATS?

 

This is a strange problem and 2 guys are having it?

Like Denn Shah said battery voltage could be an issue. The colder it gets the less efficient a battery is, it may have enough to crank a starter but that draws down voltage needed for ECM and turning on relays. Have seen this and after fully charging a battery it was only 12.3 volts and it failed a load test. 12 volt battery in good condition and fully charged at 70 degrees up should read 13.2 volts, 2,2 volts per cell. IIRC a car battery is only 60 percent of it's efficiency at 32 degrees. That's why everyone finds their battery problems when it gets cold out.

But these guys or one has run a charger and does not seem to help, and both say cabin temps make the car start? Wierd...

VATS does 2 things when pellet in key does not match VATS module, one: won't let the starter engage, two: turns of injectors, so like guys said above you should here fuel pump prime when turning key on, but if resistance to VATS from key is not correct starter will not engage and injectors won't fire.

Also if you use the wrong key and VATS fails it will take four minutes to reset. On my B body anyway... it has a Pass Key light in dash, separate from Check Engine Light. What does the Camaro do/use? One guys says he gets a flashing CEL/SES light that will stop after long length of time if left on? He may have found that VATS/Pass Key module if failed gives up and turns on after 30 minutes if left key on i think he said...

One guy said the Previous Owner PO for the guy using translator. Ran a wire from VATS starter relay to starter eliminating that part of the VATS/PassKeyII system so the starter will turn over without pellet in key or resistor match, if he turned off VATS in the ECM then that system is eliminated.

Now if he used resistors in wires from VATS to simulate resistance of the key this may be why a heater under dash is making the car start! Here is why I think this...

I cut off the plug coming from ignition switch and use it and the wires to make a plug in resister, measure pellet in key resistance with DVM and wire in resistors to meet that resistance. Shrink wrap, plug in, done! I noticed when doing this I usually have more then one resistor tied in series to match exactly what key was. There is a variable, but I shoot for what the key is. Here's the point! Resistance changes with heat! I tie say two or more together and check, perfect, solder, check and they are different resistance? Cool down and now it's back to correct resistance. Solder them to wires on plug and resistance is changed? Cool down and back to same... shrink wrap and check resistance warm and it has changed, cools down and I am back at original resistance reading.

I think there are 15 different VATS key resistance pellets. Each has a upper and lower limit. I found heat changes the measured resistance. This may be why each key has a variable and the variable is built into the VATS module. There is no way to reset VATS module, when it is new you insert any of the 15 keys and it sets for that key for life.

I know, long winded but getting to the point... he changed ECM and used old Memcal so looking at it could see if it has had sticker removed to erase, reburn without VATS enabled? He didn't mention having an adapter to new EEPROM...

So I think he is going to find PO wired around the VATS starter relay AND put in resisters to meet ECM VATS requirement to enable fuel injectors (pulse).

The resisters wired in were not exact, but close, they work all summer and when cabin is warmed, but not when cold. My guess is the PO did not use exact resistor amount when he did this and because of temperature it is not within the allowed variable. That is why his car is turning over but not starting. But when cabin is warmed will start.

 

I'm totally chuffed to find out someone else is working on this problem. I've been helping a friend keep her 89 RS with 305 and TBI running for the last several years. The car sat for a long while as her mechanic charged her $1,000 she couldn't afford trying to find an intermittent no-start problem. I solved it by spoofing the VATS with a resistor. Every winter we go through the same problem described - no start when cold. I thought perhaps the resistor was the issue, and so replaced it with a circuit purchased from e-bay. Car starts and runs fine on a nice day. Cold mornings, nothing. I'm going to try a cabin heater and see what that does. When this thing gets figured out, please share the solution - it's more common than you might think!

To give you an idea of how much time and effort I've spent on this, I have named this Camaro "The Antichrist," because I lose my religion every time I see it.

 

gera_lopez21, from what your describing your problems are ECM related.

1, a bad connection at the ECM.
unplugging the harness connectors and reconnecting them may take care of that.
from what you have said, you have already done this.

2, a bad connection between the chips and ECM.
reseating the chips should fix it if that is the problem.
3, a bad ECM.
only fix is to either replace the ECM or have it rebuilt.
4, bad chips.
only fix is to replace the chips.

next time you try to start the car and the SES light is not working properly, lightly tap on the
ECM with a screw driver or wrench and watch the SES light for any change in what its doing..
you don't need to beat on it, just tap it a few times.
another test to try, again while watching the SES press on the ECM housing and see if that makes a difference.
if either of these 2 tests makes a difference, then you will need to swap out the ECM to either rule it out or to confirm it is bad.
if it still has the problem with a replacement ECM, then you will need to replace the chip again rule it out or to confirm it is bad.
unfortunately sometimes the only way to find a problem is to replace with known good parts.

 

Thank you, Denn,
Today I tried putting the key in the "run" position for several minutes as discussed earlier in this thread. Car started right up. I will continue with the diagnostics you provided to try and figure out the root of the problem, and I will post what I find. Thanks so much!!

 

UPDATE: 6:30 AM, 31 degrees. Will not start. Tried leaving key in "run" position for several minutes, with no success. Put an electric space heater inside the car and heated up the interior. Still no start, even after leaving it in "run" position. Makes me think the culprit is under the hood. If I can get another cold day when I'm not working, I'm thinking of using a hair dryer to heat individual components to see if I can target the problem. Any further ideas certainly welcome!!

 

I would think the vats bypass resisters used are changing value and are out of 4% tolerance spec when cold.

 

Cant you just ground the Green f10 at ECU and ground the the starter relay to completely bypass the VATS?

 

you cannot just ground f10 depending on the ecm it will expect to see a 30 to 50hz signal from a the passkey module or a modulator.

 

Looks like to me that the VATS module is just a three way relay but I haven't tested it yet. From the looks of it, the reason GM put the module in such a hard place to get to it is that if it was right under the dash you could bypass it with two paper clips. Then again like I said I haven't tested it yet but I will.

 

I already considered a resistor changing value. I installed a signal generator that provides the expected signal directly to the ECM. No more resistor, so that is not the problem. I am quite sure VATS is not the problem. It would not start this morning at 31 degrees, but fired right up this afternoon at 50 degrees. Thinking of moving to the tropics.

 

SOLVED --

See my thread: https://www.thirdgen.org/forums/dfi-...ml#post5130058

 

I'm glad you got your issue solved and shared the fix!

But I don't think it's the same as what these guys are doing with a heater in cabin... how would that warm up a distributor issue?

 

It's a peculiar issue, but it seems as though there are various issues that will result in no cold start. In my case it seemed to be a weak spark caused by a distributor issue that didn't trigger the injectors. All these weird issues seem to be the result of several marginal items acting together to result in a problem. Heating the ECM might be a part of the issue. In any case, it might be worth checking the condition of the dizzy. Good luck to all!

 

The dizzy issue would cause the pump to not run...(no ref pulse)
I thought your issue was that the pump was running but no injector pulse?
glad the dizzy solved it (Hopefully)

 

Crankshaft position sensor, from what all I've been reading as I have the same problem except mine won't even crank when below 50.

 

Revived a 14 year old thread that was already solved with suggesting a part that doesn't even exist on a L98.

 

No........just.......................................no.