I am kind of leaning to a bad injector or 2 under hot condition, bad coil causing a short and shutting down signal from ECM. I did replace the coil and the CTS is new. Car starts great when cold.

 

I used to have an old pre-computer Porsche with the Bosch mechanical injection system. They were notorious for their hot start problems because the cold start injector that dumped gas in the intake manifold for cold starts was disabled by a hot coolant temperature switch. It had exactly the same sort of hard hot start symptoms you describe. Does the 87 system have a cold start injector?

 

Cold start switch was checked out & not leaking it is disconnected now. Also the cold start injector is not controled my the ECM so it has no affect on injector signal.

 

Have you floored the car on a hot restart to see if it will start? If it does start it points to too much fuel in the intake manifold, either through injectors, FRP or ?

 

floridaman, did you check injector harness using FSM chart A-3? "cranks but will not run."

if you want to stimulate more replies, you might explain specifically what you have done in case someone sees an error in the process. anybody can overlook something, my experience says.

 

See if it starts up hot with a blast of starting fluid. The answer could help eliminate a few of the variables for troubleshooting purposes.

 

When hot no injector signal from ECM thus no fuel under those conditions. You should not have to floor a C4 on start up.

 

Explain what would that would eliminate I already know it's not getting fuel when hot. I really don't want to use starting fluid

Thanks

 

Well the fact it runs fine from cold start I really didn't check the harness except to make sure all injectors were tight. Taking to Jon today from FIC he said it might be the EGR solenoid shorting out so I took that off line no difference. So I'm still looking

 

if it were my car I would use the starting fluid -or a squirt of gasoline. for one, it overcomes a low A/F ratio, which can then be the focus.

I would first define what my root cause is believed to be.

fuel -rich, lean
spark, and timing

injectors can give rich or lean, as can several other sensors.

if you have not verified an injector signal, it is pretty simple. follow the FSM chart a-3. if you get the blinking light on a simple test light, that is the end of that. or, hold one injector while someone cranks the engine, you can feel the click. this is a shortcut but is better than no check. this is not a simple problem. the FSM devotes 4 pages to it, plus another couple on the HEI, chart C-4.

you can unhook TPS and crank it. if that is no, hook it up, then do same with MAF. as you may know, the ecm will use a default value for the sensors. you're looking for a clue.

 

Joe the help is nice but my trouble is no signal from ECM under hot condition only on restart only. When running the signal is strong. Because the car sat for 1 1/2 years. I changed the fuel pump & FPR I didn't like the fuel pressure I was seeing. I had a cracked connector on the CTS so I changed that I had a spare ICM so that was changed out also. I changed out the IAC because a plastic part inside was bad. I had no iead how old the coil was so that is new also. Injectors Bosch lll's ohm out hot @ 17ohms. Something is causing the ECM to shut off pulse for fuel on hot starts. I will find it just takes time to run through the systems.
Thanks

 

we aren't communicating, dude, so I will politely back out.

you have no evidence whatsoever that you have no signal from ECM! the only way you discover that is by following the FSM, the "cranks but won't run" section. your method is classic "après hoc, ergo propter hoc," which is a common fallacy in reasoning, "after this, therefore because of this."

saludos.

 

I would get a can of circuit cooler. They when I saw a no start condition I would use the spray to cool down the electronics along the way.

This works great when there is a consistent hot problem with electronics. You can even get the tube to shoot right at one component on a circuit card and isolate it.

So if you have an old Distributor cap, drill a hole in it and put it on then when the car is hot and no injector signal you can slide the red tube into hole in distributor and cool everything down in there.

You can also cool down all the connectors one at a time while someone else cranks it.

If necessary take the computer out of the case and spray it down.

Once you find it and you will find it then be a little more diligent with the spray and you find the exact problem.

I think you get the picture.

good luck

 

Joe I have tested the injector harness with light I get no signal when hot that would be my evidence, is all I can say,when it's running I get a signal therefore there is a problem. The FSM dose not fully address a fail to start when hot believe me I have read it many times

 

Cap, rotor & coil are new

 

Thst is why i want you to check it, when you floor the car it goes into clear flood mode and turns off the injectors. I am not convinced that you are flooded and that is why it will not start. Once you rule that out we can move on.

 

try getting it warm, and switching in the cold temp sensor you already took out.
Just put some tape on the connector lock so it can come off easily, and then plug in the old sensor, and before it can get hot, try starting it.
If it starts, it might be the ecm's cold/hot computations.
If it still doesn't start, it could be the 4 pin plug on the distributor or pickup inside the dist.

 

It is not that the cold start injector is leaking. Is it getting a signal to richen the start under hot start conditions.

 

It doesn't work that way. There is a thermal element in the cold start injector switch. It turns off when the coolant temperature is over 95 °F or if you crank for more than 8 seconds (its power comes from the ignition switch START terminal). It is not connected to the ECM in any way.

 

There are three ways to get no injector signal:

1 - VATS. Most of the time the engine will not crank. I say "most" because some people bypass the VATS starter relay. The ECM needs to see a 30 Hz square wave from the VATS module or it won't fire the injectors. The ECM looks for the VATS signal when the ignition is first turned on and it is not checked while the engine is running, so VATS will not cause your engine to die once it is running, despite what some people say.

2 - No DRPs (Distributor Reference Pulses). These come from the ignition module in the distributor and will be present any time the engine is rotating -- either cranking or running. The exception is if the ICM overheats. If that happens it goes into a failsafe mode where it won't send DRPs to the ECM or fire the plugs. Usually this causes the engine to die while driving after it gets hot. The THERMAL (not dielectric) grease is VERY important to keep the ICM as cool as possible to prevent this from happening.

3 - If the TPS is telling the ECM to go to flood mode. This can happen if the gas pedal is depressed, if the TPS is bad or the wiring is bad. These are not likely, given that the car runs OK until it gets hot. The TPS circuit in the ECM has a failsafe mode also. It goes to the idle position if the wire is broken or the TPS is disconnected.