ETA No Warm Start

[jeffnhiscars]

I'm the first person to admit I don't know everything, but I do know most of the usual suspects. Th one part of th suggestions that I'm not getting though, is the thermal context of the problem and I'd much rather sit here and contemplate with your input rather than start swapping parts.

Please add some science to your suggestions as to why a widget would work hot or cold but not warm. Much obliged

[YosemiteSam]

Take a look at the spark system. You may have corrosion somewhere. Specifically check in your wire connections to the cap, on the coil out terminal, at the spark plugs, the inside of the cap and the rotor, and the engine ground cable. If you get just the right amount of corrosion there what can happen is that the coil can overpower it when it is cold, but since resistance increases with temperature it can become too much for the coil to spark through once the engine warms up. If this happens, the PCM continues to spray fuel so you would get lots of fuel smell out the tailpipe.

[jeffnhiscars]

Take a look at the spark system. You may have corrosion somewhere. Specifically check in your wire connections to the cap, on the coil out terminal, at the spark plugs, the inside of the cap and the rotor, and the engine ground cable. If you get just the right amount of corrosion there what can happen is that the coil can overpower it when it is cold, but since resistance increases with temperature it can become too much for the coil to spark through once the engine warms up. If this happens, the PCM continues to spray fuel so you would get lots of fuel smell out the tailpipe.

I put some time in on this when it was in it's no start mode. The couple of plugs I removed were virtually new, clean and were not wet. I did not test for spark as it's just me at the moment but I will later. I also measured fuel pressure and it rose above 2 bars whOch pretty much rules out fuel pump and fpr

I also swapped the 3 relays from my cabrio and they are fine. I'm not 100% sure I have spark but all connectors are squeaky clean and you would expect some dampness after crank no fire so I'm thinking the injectors aren't firing.

does that take me back to ecu or cps and if so why would either of those function when hot or cold but not warm ?

[YosemiteSam]

I put some time in on this when it was in it's no start mode. The couple of plugs I removed were virtually new, clean and were not wet. I did not test for spark as it's just me at the moment but I will later. I also measured fuel pressure and it rose above 2 bars whOch pretty much rules out fuel pump and fpr

I also swapped the 3 relays from my cabrio and they are fine. I'm not 100% sure I have spark but all connectors are squeaky clean and you would expect some dampness after crank no fire so I'm thinking the injectors aren't firing.

does that take me back to ecu or cps and if so why would either of those function when hot or cold but not warm ?

Based on the fact that it only happens when warm I would focus on things in the engine bay. Definitely check spark, I would try and check for injector drive. One other thing you can do is take a multi meter and measure the voltage from some unpainted metal on the engine block to the body ground on the passenger side strut tower. This should be close to 0 volts all the time, if it is more than 1 or 2 volts when the engine is hot this would indicate an engine ground issue.

[ForcedFirebird]

I've had the CPS only act up when warm. Next time it happens, put a multi-meter on the CPS and see if it's out of range.

[jeffnhiscars]

Based on the fact that it only happens when warm I would focus on things in the engine bay. Definitely check spark, I would try and check for injector drive. One other thing you can do is take a multi meter and measure the voltage from some unpainted metal on the engine block to the body ground on the passenger side strut tower. This should be close to 0 volts all the time, if it is more than 1 or 2 volts when the engine is hot this would indicate an engine ground issue.

Ground confirmed to be 0. When founding a plug to the head I do get sparkalthough it seems weak and looked to be co,omg from the base of the center electrode rather than the tip but that could be cause I'm grounding the plug to the valve cover (not ideal)

I've had the CPS only act up when warm. Next time it happens, put a multi-meter on the CPS and see if it's out of range.

Being an eta I assume the cps is buried underneath the brake booster. If I can test it on the other end where does that terminate ?

The cps needs a signal to tell the ecu to fire the injectors correct ?

[ForcedFirebird]

If the holder is still there, the plugs for the CPS's should be at the back of the valve cover - right up against the firewall. When people change the CPS's, the tend to let the connectors dangle, though.

[jeffnhiscars]

If the holder is still there, the plugs for the CPS's should be at the back of the valve cover - right up against the firewall. When people change the CPS's, the tend to let the connectors dangle, though.

The leads to these 2 plugs to to the trans so one should be the cps. I also see that red wire doesn't look healthy. May be time to do the motronic upgrade without the head.



There's also this sensor at the crank which I did not expect to see on an eta since that doesn't look like a trigger wheel. The gap is also quite large. This looks to be a tdc sensor. No clue

[e30sh]

There's also this sensor at the crank which I did not expect to see on an eta since that doesn't look like a trigger wheel. The gap is also quite large. This looks to be a tdc sensor. No clue

That is for the factory diagnostic tool.

Since fuel pressure is good and the plugs are clean, My guess is the thermo time switch which tells the cold start valve to fire. Starting fluid is your problem solving friend. lol

[jeffnhiscars]

That is for the factory diagnostic tool.

Since fuel pressure is good and the plugs are clean, My guess is the thermo time switch which tells the cold start valve to fire. Starting fluid is your problem solving friend. lol

Except the cold start valve isn't supposed to fire when the engine is warm and that's when it won't start. Cold start is fine. Hot start is fine.

[jeffnhiscars]

I checked the resistance on the cps at the connector and it read ok however the plug fell apart in my hand. I jury rigged it to go back together and itnstarted but the engine stumbled and died then wouldn't start again. Since this is very similar to the warm no start problem I can easily see how a bad connectors performance is temperature related so I'm going to replace both sensors (as has been suggested anyway) and see where that leaves me.

I hate buying new parts when I'm so close to the motronic swap but then I really don't want to ignore a problem that might be from something I won't be touching with the upgrade. THAT would be a can or worms.

[e30sh]

Except the cold start valve isn't supposed to fire when the engine is warm and that's when it won't start. Cold start is fine. Hot start is fine.

It's coolant temp based....~140 F and below it fires. If it's been sitting 30 min, the coolant temp drops off.

I had this exact issue with my ETA years ago. Hot or cold started fine. Sitting a bit warm and it would long crank. While it was in long crank mode, I squirted a little staring fluid in it and it fired right up. Changed the thermo time switch and the DME coolant temp sensor at the same time and it cured it.

[jeffnhiscars]

The thermotime switch is silly expensive especially when I'm this close to the motronic swap (1.3 doesn't use this part) but I'll check it out once I replace this crumbled cps connector (the plug itself is $5 from the dealer).

If the injectors fire even if the cold start valve is actuated is a faulty CSV really going to cause a no start on a warm engine....in Florida and isn't it an on off switch I can easily test for continutiy rather than resistance ?

[e30sh]

I went used on the TTS and new on the sensor. A new Bosch / VDO coolant temp sensor was ~$20.

Any chance you have any cracks in the ICV or throttle boot rubber parts? That would lean it out a bit.

SSquid can make you a chip for Motronic 1.0 if you want to retain all your new parts vs. switching to 1.3.

[jeffnhiscars]

I went used on the TTS and new on the sensor. A new Bosch / VDO coolant temp sensor was ~$20.

Any chance you have any cracks in the ICV or throttle boot rubber parts? That would lean it out a bit.

SSquid can make you a chip for Motronic 1.0 if you want to retain all your new parts vs. switching to 1.3.

I posted earlier that I installed a NIB CTS so that's not it. I also have an SSSquid chip in it and I'm switching to 1.3 as part of a 731 head swap so keeping 1.0 long term is off the table. I'll buy a cps for $41 no problem. Throttle body boot is brand new as are virtually all the rubber parts in the engine bay

As for the thermotime, my test log shows the engine started with a temp reading at the tstat housing of 145, but not at 118 so the tipping point seems to cover that 140 set point you mentioned. I'm also getting cold resistance at that switch of .33. I thought it was an on off so should have read zero but may be mistaken and unless that switch does more than tell the cold start valve when to fire I still don't see why it would cause a warm nonstart