hard starting when hot or after short stop

[masspydr]

82 spider very rough start when cold sometimes feels like too much power, once double start 'ouch',very low rpms till l push gas not a nice smooth start.after short trip or long crankes but doesn't start, have spark , hear fuel pump after sitting 10 -20 min starts smoothly but doesn't do this all the time. should i change fuel pressure regulator, fuel pump ? any ideas ?.the car also runs a little sluggish lately please help thank you in advance

[micbrody]

I have had this same problem since I got the car in 2014.
In simplistic terms: there has to be a mismatch of fuel:air ratio when hot start up.
In complicated terms: at start up:
Fuel delivery is determined by temperature of coolant thermo probe (at the front T of coolant line). The ECU also looks at position of AFM swing arm. Together it determines how long to keep injectors open when triggered by distributor.
In addition to above: there is a non-ECU contributor to fuel at start-up: the TTS/CSI. (Thermo timing switch/cold start injector.). The TTS is located in an awkward spot below fuel injector rail, near the oil cyclone ? Separator——(I don’t remember it’s name).
In any event the TTS energized the CSI when temp at start-up. Depending on temperature, CSI might fire few secs to no squirt of fuel.
To balance the extra fuel that might be needed at start-up, the auxiliary air valve (AAV) has a rotating shutter that is “fully open” on super cold days, to barely open on hot days/or when engine is hot. The mechanism for closure is two fold:
There is a bimetallic “spring” that operates shutter. The valve is literally mounted to coolant system at front top of engine. The ambient temperature of engine coolant is transmitted to the bi-metallic spring causing closure. However, there is also an electrical connection that is constantly heating this spring when car on. The net effect is within a minute or two, the valve is completely closed, regardless of engine temperature.

As for problem spots:
Any of these components can cause this issue if not working properly. There are ways to check all of them.
If I were u: I would first pull AAV and clean it and then test it in freezer and hair dryer. There are posts describing this).
You can also pull the CSI and check if it’s firing when car hot.(have car reach operating temp/two fan cycles. Pull valve/plug hole with tape; point injector in glass bottle; start car. It shouldn’t squirt at all (I think , or just for a 1/10th of a sec) at hot start up. If it continues to squirt during entire cranking, then CSI stuck open (which means during normal cruising, fuel rich burn); or the TTS not working correctly.
The thermo probe at coolant T is very important for smooth , efficient running of engine. Check the resistances at different temperatures (either installed; or removed). I don’t have the resistances memorized , but there are posts about it ).

I have done all of these procedures; and even adjusted shutter on AAV; but I still have intermittent problems at hot start up. However: since I “fixed” AFM by repainting board (still not officially successful .....but trending towards it.....see my post about it), I have noticed significantly less hot start problems. If I crank slightly longer on hot days (keep key in start position maybe 0.5 second longer), the car seems to start. However, at immediate startup , the RPMs drop to almost stall; but then recover after a few seconds. So I still have an issue......but “assuming” I had a flaky AFM at startup , my adjustment of AAV might need to be revisited.

[masspydr]

Wow,what a wealth of knowledge !!!.I will look into all the things you suggested ,it might take a while I'm not a mechanic but learning every time she brakes down.thank you for all your help ,greatly appreciateted

[RRoller123]

http://www.njfiats.org/joomla/images/st ... BoschL.pdf

[masspydr]

again thank you to both of you !!!!.l now need some mechanical help, more copy paper and more toner

[micbrody]

Have you had any luck finding and fixing problem?
I still have issues. If first start of the day, it starts right away. If I drive it to operating temperature , and turn off for 15-30 minutes, it starts right away. If I drive it to operating temperature; and then it sits off in sun for a few hours, I have the problem.
I have adjusted everything that can be adjusted (I think), including the AAV.
When it doesn’t start, the following occurs: starter turns; engine seems to “catch” but then immediately dies . Immediate restart takes at least 10 full seconds of cranking; or I can get it to start by pressing on gas pedal (though it doesn’t immediately start when hitting pedal ; but does shorten the start time to 3-5 seconds .
I still don’t know what to do next. Any suggestions anyone?

[masspydr]

I was told to disconnect cold start valve and it starts everytime now l have a spare one from doner car . I’m going to install Saturday and hope that the problem

[micbrody]

Not a bad idea to try ; and just reconnect when it gets colder . But the engineer in me wants to understand the source of problem.

In any event, I will try that

[NSFIAT]

I had cold start problems last year - very rough, ran very rich until up to temp. It ended up being a broken connection in the coolant temperature sensor (located in the coolant T). Swapped that out for new and it ran fine.

[masspydr]

I’m also going to replace the temp sensor at the t it’s one thing we don’t have to worry about in the future, I’m sure they’re are going to be other things,the car is 36 yrs old !!

[micbrody]

Update:
I disconnected electrical harness to CSI.
The first cold start was very very difficult; long crank time; eventually needed to pump gas pedal to start.
However, the afternoon start was immediate. Another two starts last evening were great.

This morning I expected another poor morning start; however it immediately started ??!!

I’m going to check resistance from harness to t-temp probe all the way to ECU. (I had previously done this without issues). I have also previously tested the temperature probe out of car and resistances checked out. The other possibility is the ECU has a fault; though I would expect car to continue to have chaotic performance after start; and engine is totally smooth after start .
Since startup CSI is totally independent of ECU, the two components involved are the CSI and TTS.
I tested this previously to see if CSI fired and eventually shut off on cold start (detached from plenum and observed in glass bottle). And it did start and stop; however what I did not test was the response relative to cold start temperature of TTS; maybe that’s the flaky component. I have an older replacement one; looks like a bitch to change out.
I will try to find temperature criteria that TTM fires

[masspydr]

Update changed the cold start valve Sunday,a used one from a doner car and it now starts all the time !! Took a look at the temperature sensor wires were completely cracked,exposed wires !! bought a new replacement connector and installed it.
I’m now worried about all the other wires and connections in the engine bay,it seems most of the wires are brittle!!

[Nanonevol]

Nice! This thread looks like it was a "two-fer".

[micbrody]

Update #2:(I’m thinking out-loud......)
With CSI still disconnected, car has started immediately and easily at all times up to 12 - 24 hours between starts.
If it has not been started from 12-24 hrs or longer, it does has a long, difficult crank time.
I’m thinking as long as there is residual pressure in the fuel rail, and it’s at last 70 degrees, the car starts great. After 12-24 hours, pressure has dissipated; and injectors need some crank time to fully and efficiently produce fine fuel mist. Thus: connected CSI might be helpful in adding extra fuel at cold startup when fuel rail not up to pressure.

[micbrody]

Masspyder:
Congrats on solving issue.
Can you clarify a few things:
1) did you fix connector AND replace CSI before starting car? In other words: car start great only with CSI exchange (but before connector repair)? And if it did, roughly what was temperature of car coolant? (Room temperature ; or on hotter side because car recently ran)
2) the temperature connector that you fixed: was it the one at coolant T? Or the one that goes it tight space below engine (Thermo timing switch )?