Ok here is the million dollar question. The car will not start when it is hot. I first got the car there were times it wouldn't start hot or cold. Took it to the Pontiac dealer and he tested a ton of stuff. Found that the car would start with a battery charger on it. Tested the system and found that the injectors were not getting ground from the computer all the time. Once the car starts it will run forever. He cleaned the ground on the right rear of the block, thought we had it. The car starts when its cold but will not start when it gets hot. I think the injectors are loosing signal from the computer. Does anyone know what tells the injectors to open and at what rate when the engine is hot? Something has to tell the computer when and how much to open correct? Im ready to shoot the car. Only has 1600 miles on it. Any help would be great, Thanks.
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No start when hot.
- Thread starter jeffc89
- Start date
Just went through the same thing. My car has 8k miles. GM dealer charged me $400 to check everything with no results plus $100 in parts. I purchased a used ECM from a member on this site and installed it. Problem solved!!! I then installed a Turbo Tweak chip from Erick and the car has never run better.
Bruce Busse
Bruce Busse
I wouldn't think you would have two bad ECM's.
A little background for you might help. I took the car in for a high idle when driving. I got tired of going 45 MPH without my foot on the gas and the fans would not shut off when you shut the car off. I took it to a dealer that would allow me to be in the shop. The mechanic had thirty years as a corvette specialist. He attached a Tech 1 analyzer to the car and found the temperature to be 137 degrees when hot. Diagnosis, new thermostat. Installed new thermostat, still 137 Degrees. Installed temperature sensor, still 137 degrees.
Checked voltage to sensor, found intermittent voltage (0-5v). Opened the wire loom and found a broken resistor of 470 ohms in the line. According to the service manual this was not supposed to be there. It did appear to be a factory install although I can't be sure. I told the mechanic to remove it. After he made the repair the car ran perfect and the fan problem was gone. This is when the no start problem started. He checked fuel pressure, fuel injectors, coil pack, spark and other things with no answer. He started the car with carb cleaner through the vacuum port on top of the intake manifold.
Drove the car home and the same results, no start when hot. I researched this site and the GN site and decided to try a crank sensor. It did not work. That is when i tried the ECM and it worked.
I don't know if any of this is relevant but food for thought.
Bruce
A little background for you might help. I took the car in for a high idle when driving. I got tired of going 45 MPH without my foot on the gas and the fans would not shut off when you shut the car off. I took it to a dealer that would allow me to be in the shop. The mechanic had thirty years as a corvette specialist. He attached a Tech 1 analyzer to the car and found the temperature to be 137 degrees when hot. Diagnosis, new thermostat. Installed new thermostat, still 137 Degrees. Installed temperature sensor, still 137 degrees.
Checked voltage to sensor, found intermittent voltage (0-5v). Opened the wire loom and found a broken resistor of 470 ohms in the line. According to the service manual this was not supposed to be there. It did appear to be a factory install although I can't be sure. I told the mechanic to remove it. After he made the repair the car ran perfect and the fan problem was gone. This is when the no start problem started. He checked fuel pressure, fuel injectors, coil pack, spark and other things with no answer. He started the car with carb cleaner through the vacuum port on top of the intake manifold.
Drove the car home and the same results, no start when hot. I researched this site and the GN site and decided to try a crank sensor. It did not work. That is when i tried the ECM and it worked.
I don't know if any of this is relevant but food for thought.
Bruce
I replacede the MAF sensor and still starts cold will not start hot. I have an ecm coming tomorrow and temp sensor. I think the only thing left is the throttle positioning sensor. Besides that I don't know what else to change. But it is driving me nuts. It sucks to go to a show and not start.
TURBO1
Super Cool Member
I'm sure when you had it at the dealer, they checked for codes right? Was there any stored? Has the fuel relay been checked or swapped. Fuel pressure checked? Cold for a base line reading, then hot for comparrison? It could really be a number of things, always start with the basics first. I've seen so many times, working in the automotive field, people replace parts that don't need repalced & spend alot of money in the process & overlooked the simple stuff, thinking it was more than what it really was, like a bad relay, blown fuse, loose/and or corroded ground connection or connector,etc.
Have you noticed anything else when this happens thats not normal for your car?
Have you noticed anything else when this happens thats not normal for your car?
WS6
Stay thirsty my friends
The fastest way to hate your car is start throwing parts at it with no results. And your salvation,unfortunately, will not be at a dealership or run of the mill garage for that matter.
Get yourself the TTA service manual supplement and start reading it, it has lots of "no start" trees to use. Then read http://www.vortexbuicks-etc.com/ and then go to turbobuicks.com and read some more.
All these web sites,including this one, are filled with very knowlegeable folks. But it will be worthless if you don't have some basic knowledge of the early feedback ECM's and drivetrains.
Just reading your posts it seems your on the road to hating your car because it's costing you allot of money. Stop buying parts and start doing some research. When you have you can better isolate your problem by association and we can help you better.
...
Get yourself the TTA service manual supplement and start reading it, it has lots of "no start" trees to use. Then read http://www.vortexbuicks-etc.com/ and then go to turbobuicks.com and read some more.
All these web sites,including this one, are filled with very knowlegeable folks. But it will be worthless if you don't have some basic knowledge of the early feedback ECM's and drivetrains.
Just reading your posts it seems your on the road to hating your car because it's costing you allot of money. Stop buying parts and start doing some research. When you have you can better isolate your problem by association and we can help you better.
...
I love my cars wouldn't get mad at it. The mechanic at the Pontiac dealer has about 25 years in the field and is good. The first time this started he found that the injectors were not getting ground from the computer. We thought it was the ecm, took it out of my other TTA and still the same results. But the car would start every time with a battery charger. Just that little extra volts. He found the grounds to be dirty on the block, clean them and the car started every time. The car sat in the trailer for the summer, took it out to a local show and wouldn't start hot. Like 180-190. Left the hood open for a half hour and it started. I know it has to be a sensor that gets hot and looses contact in the sensor to shut the injectors down. I've been looking through the book and so has the mechanic. The person who I bought it from had changed the crank sensor. I've replaced the spark mod, because of a code in the computer. The fuel pump relay, cover was broke. And the MAF thinking once it gets hot it has a short. Also I just pulled both ground studs out of the intake, cleaned and dielectric greased all connections. Car will start run great let it get to 180-190 then it will just crank. Fuel pump turns on charges system but thats it. It has to be something stupid. What about the temp sensor?
WS6
Stay thirsty my friends
I believe ECM doesn't look at the temp sensor during cranking, whether it be the inlet air or coolant temp sensor.
No start - no spark, has injector pulse - Check the ignition module
No start - no spark or injector pulse - Crank sensor or module
I don't think it looks at the MAF during crank or start up either,it looks for the cam sensor signal and crank sensor. You'll need to get a FP gauge on the rail and check FP during and before cranking.
If it were me, I'd be sure I had 38-43psi of FP at the rail,key on. If so I'd be looking at the ignition module again, next I'd be adjusting the crank sensor and looking at the cam sensor adjustment or possible failure. Under 400 RPM's the ECM requires very little input to light off the car.
ECM failures do happen, but not as often as you'd think, and usually throw a code or more.
....
No start - no spark, has injector pulse - Check the ignition module
No start - no spark or injector pulse - Crank sensor or module
I don't think it looks at the MAF during crank or start up either,it looks for the cam sensor signal and crank sensor. You'll need to get a FP gauge on the rail and check FP during and before cranking.
If it were me, I'd be sure I had 38-43psi of FP at the rail,key on. If so I'd be looking at the ignition module again, next I'd be adjusting the crank sensor and looking at the cam sensor adjustment or possible failure. Under 400 RPM's the ECM requires very little input to light off the car.
ECM failures do happen, but not as often as you'd think, and usually throw a code or more.
....
No I don't think I have it yet. Fuel pressure is good. Spark seems to be good and injectors seem to be getting power. I swapped out the ecm the other day and the car didn't like that. Started the first time cold. Wouldn't start hot again, then wouldn't start at all. Had to put the old ecm in. Replaced the chip with the old ecm. Starts easier cold haven't had time to get it hot to recheck it. I'm just lost. I had some one tell me the spark pack could be going bad once it gets hot. Trying to keep it simple so I don't change all the parts but don't know where to go from here. Its just strange that a 1600 mile car would start like this.
72firebird
Super Moderator
it will actually be more common for things to break or not work right on a low mileage car. The systems on the car are made to be in use, when it sits for a long time without everything being cycled things begin to deteriorate or become used to the state that they're in.
New update. Replaced chip with as close to stock as I could get. Car starts a lot better now cold. Once car is hot still will not start. Decided to remove air intake off throtle body. Shot with starting fluid, car starts and idles fine. What tell the injectors how much/long to pulse on start? I don't think its getting enough fuel or when it gets hot something isn't tell the injectors to adjust for the start after the motors hot.
I remember this problem with my first TTA, it turn out to be when the sliced ignition wire for the alarm starter disable. Somehow the proper voltage was not being pass through during startup. A jumpstart would get me going quick, if not I had to wait till things cool down. Not sure if this is your problem, but it was mine. Good luck.
gplmaster
Active Member
Hi Jeffc,
I can sympathize with your frustration. I had this same problem a couple years ago. My car would crank an inordinately long time (3-4 seconds) before it would start cold. Then, once warm, it would not restart. My short-term remedy was to unplug the red connector next to the radiator close to the battery for 20 seconds or more to reset the computer. Then I would try to start. I would repeat this until it would start. Sometimes, I would have to come back after several hours and then it would finally start. My computer had been showing code 41 (cam sensor). So my local Pontiac dealer changed my ECM and crank angle sensor. They also installed a Casper's cam sensor I bought online. It worked well for about a year of occasional driving with the exception of its appetite for batteries. My car, if not driven for a month or so, will consume my battery - so I know there are other issues as well. Recently, my other car's alternator finally gave up at 341,000 miles, so in the meantime I am driving my TTA. My car is again having trouble restarting. This time, I can turn the key off, then to the on position where you can hear the fuel pump pressure up. There is a part in the car called an IAC Motor. I can hear it sometimes going through its routine like it threads itself forward or backward - kind of a winding sound. Since the weather has been much colder this week, my starting problem has lessened. Everything on my car is stock to my knowledge except for the Red Armstrong fuel pump with the pulsator left on. I had this done at my local dealer as well. I do have a vacuum leak since my a/c/heater is missing the vacuum tube required to operate it. I don't know how this affects my starting/running. Good luck - I would like to hear if you have a solution with your problem - maybe we have the same one?
