another no start issue
06-20-2017, 10:28 AM
#1
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Join Date: Aug 2002
Location: London, ON, Canada
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another no start issue
Hi there,
I have a friends 95 TA that I agreed to help get started for him. He's done some work on it, but gave up after not being able to get it going. He replaced the original opti as well as the injectors, battery and coil.
Car will start and run for maybe 3-4 seconds - usually only when gas pedal is to the floor sending clear flood and it won't always start.
Fuel Pressure tested - 42lbs key on - goes up slightly while cranked, maintains pressure for several hours after
Coil ICM tested good
Water temp sensor in water pump tests good
Have spark at plugs - new plugs and wires all around
I was only getting 0.2 volts at the PCM on pin A25 which is the fuel enable circut for VATS, the service manual says should be 2.5v. I have scan 9495 as well as several tuning programs. I reflashed my ECM and disabled the VATS requirement in the ECM for testing.
No stored DTC codes in scan9495. I have a log file I saved while trying to get it started last night, I can send it to anyone who might want to take a look.
Fixed a broken ground strap near coil/icm.
I've tried starting it with the MAF disconnected - no change.
Noid light pulses when put on injectors - scan9495 shows injector pulses when the car tries to run as well, with the current opti on there.
4 different optisparks - the original one was replaced after the water pump failed dumping water on it - car hasn't started since.
New Chinese #1 failed - no AC voltage on ICM pin C when cranking
New Chinese #2 failed - all voltages/tests were correct per service manual and shbox.com tests - this one wouldn't start car at all - just would crank.
Bought a used GM Opti owner claimed was good - currently on car and sitting in above state, it also passes the the voltage tests.
The car has sat for sometime, roughly 9 months. Gas gauge does show 1/3 of a tank of fuel, I haven't flushed it.
Kinda at a loss what to do next. I suspect at this point, the optispark is the likely cause, but the owner of the car is a little gun-shy when it comes to buying another one. There is a person on ebay that sells optiparks with the good sensor which have been tested on an oscilloscope to confirm they are working correctly before shipping them. Anyone tried one of those before? The only other thing I can think of doing is replacing the cap and rotor on the GM unit with the ones off a Chinese one to see if that helps...I suspect probably not, but nothing to loose at this point.
Thanks for your time,
Kevin
I have a friends 95 TA that I agreed to help get started for him. He's done some work on it, but gave up after not being able to get it going. He replaced the original opti as well as the injectors, battery and coil.
Car will start and run for maybe 3-4 seconds - usually only when gas pedal is to the floor sending clear flood and it won't always start.
Fuel Pressure tested - 42lbs key on - goes up slightly while cranked, maintains pressure for several hours after
Coil ICM tested good
Water temp sensor in water pump tests good
Have spark at plugs - new plugs and wires all around
I was only getting 0.2 volts at the PCM on pin A25 which is the fuel enable circut for VATS, the service manual says should be 2.5v. I have scan 9495 as well as several tuning programs. I reflashed my ECM and disabled the VATS requirement in the ECM for testing.
No stored DTC codes in scan9495. I have a log file I saved while trying to get it started last night, I can send it to anyone who might want to take a look.
Fixed a broken ground strap near coil/icm.
I've tried starting it with the MAF disconnected - no change.
Noid light pulses when put on injectors - scan9495 shows injector pulses when the car tries to run as well, with the current opti on there.
4 different optisparks - the original one was replaced after the water pump failed dumping water on it - car hasn't started since.
New Chinese #1 failed - no AC voltage on ICM pin C when cranking
New Chinese #2 failed - all voltages/tests were correct per service manual and shbox.com tests - this one wouldn't start car at all - just would crank.
Bought a used GM Opti owner claimed was good - currently on car and sitting in above state, it also passes the the voltage tests.
The car has sat for sometime, roughly 9 months. Gas gauge does show 1/3 of a tank of fuel, I haven't flushed it.
Kinda at a loss what to do next. I suspect at this point, the optispark is the likely cause, but the owner of the car is a little gun-shy when it comes to buying another one. There is a person on ebay that sells optiparks with the good sensor which have been tested on an oscilloscope to confirm they are working correctly before shipping them. Anyone tried one of those before? The only other thing I can think of doing is replacing the cap and rotor on the GM unit with the ones off a Chinese one to see if that helps...I suspect probably not, but nothing to loose at this point.
Thanks for your time,
Kevin
06-20-2017, 03:32 PM
#2
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Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 70,650
Re: another no start issue
If you pulse the injectors one at a time, does the pressure drop as expected? Thinking they may be plugged, with one or more stuck open. Probably a good idea to drain the old fuel and add a few gallons of fresh.
You should be able to upload the Scan9495 file in a new post. Click on "Go Advanced" at the bottom of the message box, scroll down to "Additional Options", click on "Manage Attachments". ".csv" is an allowed extension.
Given your knowledge of the LT1, I'm assuming you have the Opti indexed correctly to the cam dowel pin.
You should be able to upload the Scan9495 file in a new post. Click on "Go Advanced" at the bottom of the message box, scroll down to "Additional Options", click on "Manage Attachments". ".csv" is an allowed extension.
Given your knowledge of the LT1, I'm assuming you have the Opti indexed correctly to the cam dowel pin.
06-21-2017, 09:46 AM
#3
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Join Date: Aug 2002
Location: London, ON, Canada
Posts: 19
Re: another no start issue
Thanks for the reply. I've uploaded one of the log files from the other night. Haven't had a chance to work on the car since then, but draining the fuel is on the to do list now.
The injectors that were swapped in appear to be Ford 24# units. Doing some research on those, I found that at the GM fuel pressure of 43psi, those injectors run effectively at 29#. Would this be to much for a stockish LT1?
The injectors that were swapped in appear to be Ford 24# units. Doing some research on those, I found that at the GM fuel pressure of 43psi, those injectors run effectively at 29#. Would this be to much for a stockish LT1?
06-21-2017, 08:19 PM
#4
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Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 70,650
Re: another no start issue
Ford injectors are typically flow rated at 2.7 bar (39.15 psi). When operated at 3.0 bar (43.5 psi) they flow:
(43.5 / 39.15)^0.5 X 24.0 = 1.054 X 24.0 = 25.3 #/HR
The factory Multecs are nominally rated at 24 #/HR, but are actually programmed at 24.9 #/HR. Either way the difference is fairly small, and the long term fuel corrections, based on O2 sensor feedback should be able to adjust. Then there's the differences in offsets, but bottom line, should not be a big problem that would prevent startup.
I'll try to take a look at the data log tomorrow.
(43.5 / 39.15)^0.5 X 24.0 = 1.054 X 24.0 = 25.3 #/HR
The factory Multecs are nominally rated at 24 #/HR, but are actually programmed at 24.9 #/HR. Either way the difference is fairly small, and the long term fuel corrections, based on O2 sensor feedback should be able to adjust. Then there's the differences in offsets, but bottom line, should not be a big problem that would prevent startup.
I'll try to take a look at the data log tomorrow.
12-06-2017, 12:33 PM
#5
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Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 70,650
Re: another no start issue
Sorry I missed the data log. Not much to see, but it does show some problems.
First, what were you doing with the throttle? Three times you opened the throttle 100%, but there is no indication you attempted to start the engine. What were you doing?
Log shows fuel is enabled.
There are two attempts to start the engine.... RPM indicates the engine is rotating, signs of the sensors responding. But generally, doesn't look good.
In both cases, your system voltage is low... 10+/- volts in the first attempt, 9+/- volts in the second attempt. The second was was so low, appears the PCM was not able to control things.
In the first attempt, appears you still had the MAF connected. MAF indicates 2.45 grams/sec air flow, throttle is closed, MAP is abnormally high at 67 - 80 kPa. almost like the engine isn't sucking the air in. Would be consistent with bad rings. The injector pulse width is low, not sufficient for cold start.
Second attempt is a disaster. Appears that's where you unhooked the MAF. But the system voltage is so low that the PCM doesn't seem to be fully functional. MAP stays in the range of 94 - 98 kPa, even though the throttle is closed. No vacuum. When you disconnect the MAF sensor, the PCM defaults to speed-density to calculate air flow. The unreasonably high MAP causes the system to calculate a large air flow, and it sets the injector pulse widths in the range of 18 - 62 mSec. Way too much fuel.
When the battery is so weak, it affects the electronics and the fuel system.
Not surprised it didn't start.
First, what were you doing with the throttle? Three times you opened the throttle 100%, but there is no indication you attempted to start the engine. What were you doing?
Log shows fuel is enabled.
There are two attempts to start the engine.... RPM indicates the engine is rotating, signs of the sensors responding. But generally, doesn't look good.
In both cases, your system voltage is low... 10+/- volts in the first attempt, 9+/- volts in the second attempt. The second was was so low, appears the PCM was not able to control things.
In the first attempt, appears you still had the MAF connected. MAF indicates 2.45 grams/sec air flow, throttle is closed, MAP is abnormally high at 67 - 80 kPa. almost like the engine isn't sucking the air in. Would be consistent with bad rings. The injector pulse width is low, not sufficient for cold start.
Second attempt is a disaster. Appears that's where you unhooked the MAF. But the system voltage is so low that the PCM doesn't seem to be fully functional. MAP stays in the range of 94 - 98 kPa, even though the throttle is closed. No vacuum. When you disconnect the MAF sensor, the PCM defaults to speed-density to calculate air flow. The unreasonably high MAP causes the system to calculate a large air flow, and it sets the injector pulse widths in the range of 18 - 62 mSec. Way too much fuel.
When the battery is so weak, it affects the electronics and the fuel system.
Not surprised it didn't start.
Last edited by Injuneer; 12-06-2017 at 12:37 PM.
03-20-2018, 04:06 PM
#6
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Join Date: Aug 2002
Location: London, ON, Canada
Posts: 19
Re: another no start issue
Just wanted to update this post. Fred, to answer your questions, I'll be honest it was 9 months ago and my memory is a little foggy but the battery was weak during those tests. I usually kept it on a charger to keep the voltage up. I did spring for a new battery but it didn't change anything.
I did a compression test on 7 of the 8 cylinders and found 4 and 6 were both under 80psi. Best cylinder, 8, was at 180psi. I pulled the motor out around Christmas time and just got around to tearing it down. Stuck rings on both 4 and 6. I'm hoping I can free them up by soaking them, but I'm not overly optimistic about it. The rest of the other internals seem ok.
I did a compression test on 7 of the 8 cylinders and found 4 and 6 were both under 80psi. Best cylinder, 8, was at 180psi. I pulled the motor out around Christmas time and just got around to tearing it down. Stuck rings on both 4 and 6. I'm hoping I can free them up by soaking them, but I'm not overly optimistic about it. The rest of the other internals seem ok.