How would I know if my cold start injector is or is not working? What are the symptoms of a failure?

you can unplug the connector, and then check for 12v at the plug on a "cold start" to see if it is getting power.
its only supposed to be active during cranking, and with coolant temp below - um, not sure what the temp is.
the temp switch is on the top of the intake manifold, near the pulleys

quote Originally posted by donuteater306: ...What are the symptoms of a failure?

I am curious about this too....mine 87 GT is very "cold blooded". When I start it in the morning it starts easily but hunts for idle and will almost always stall unless I fiddle with the gas pedal (to keep it running) for about a minute...after about a minute it will be able to idle....it also wants to stall when attempting take off from a stop sign until it is fully warmed up

Now see, mine isn't THAT bad when started cold. Mine will start easily but occasionally the idle will come down, stumble and stall. Immediately restarting, it will idle normal.

Mine is a 5spd. The 1st time i release the clutch to drive off when the engine is cold, it feels like the engine will load-up and it stumbles, just once. From then on, everything is normal.

quote Originally posted by donuteater306: Now see, mine isn't THAT bad when started cold. Mine will start easily but occasionally the idle will come down, stumble and stall. Immediately restarting, it will idle normal. Mine is a 5spd. The 1st time i release the clutch to drive off when the engine is cold, it feels like the engine will load-up and it stumbles, just once. From then on, everything is normal.

I just got this thing from my old man....it had been sitting in his garage for at least 6 months....I am slowly working the bugs out of it. I love being back in a Fiero....I had an 86 SE back in the mid 90's that practically drove the wheels off of. That being said ...I too am knocking the rust off my Fiero knowledge with the help of this site (thanks everyone)

quote Originally posted by 92wastheyear: I am curious about this too....mine 87 GT is very "cold blooded". When I start it in the morning it starts easily but hunts for idle and will almost always stall unless I fiddle with the gas pedal (to keep it running) for about a minute...after about a minute it will be able to idle....it also wants to stall when attempting take off from a stop sign until it is fully warmed up

the cold start injector is ONLY active during cranking. once fired, it should be off.
most cold running issues are due to the 2 temperature sensors, one in the air filter can (IAT), which measures the air temp, and one on the intake manifold (CTS), sticking out towards the pulleys, which measures the coolant temp.

quote Originally posted by Pyrthian: the cold start injector is ONLY active during cranking. once fired, it should be off. most cold running issues are due to the 2 temperature sensors, one in the air filter can (IAT), which measures the air temp, and one on the intake manifold (CTS), sticking out towards the pulleys, which measures the coolant temp.

Excellent....thank you. These two sensors are pretty inexpensive too

Thank you for your help. I changed the IAT sensor a few years ago but have never replaced the temp sensor. Tho I hate to throw parts w/o diagnosis...even inexpensive ones. I guess i'll order a couple Delco sensors and see what happens. Cant hurt. Thanks again.

quote Originally posted by Pyrthian: the cold start injector is ONLY active during cranking. once fired, it should be off. most cold running issues are due to the 2 temperature sensors, one in the air filter can (IAT), which measures the air temp, and one on the intake manifold (CTS), sticking out towards the pulleys, which measures the coolant temp.

Well ....I followed Pyrthian's advice and picked up IAT and CST sensors at the local Rip-off artists auto-parts store and spent the afternoon installing them. It was warm out so I can't really test the cold start part of it but I was amazed at how much better it idled, shifted and ran on my test drive. I had thought it was running ok before....it wasn't missing or anything....but after this the difference is amazing. It now idles at 950rpm like clockwork regardless of the load ...in park...in gear....with a/c on...with it off. Much Much better. Thank you Pyrthian and thanks to donuteater306 for allowing me to semi-hijack his thread.

Ted

Good deal! These things are great when they're running well.

As always when amateur mechanics get to work there are some unexpected things that come up. I am going note a few for future generations and historians

1. I like to call this section :"Buying an IAT:Naming Convention Blues" Pyrthian described it as follows "...... in the air filter can (IAT), which measures the air temp" which by the way is a great description since I was able to locate and identify it easily by first googling IAT (I especially liked this gem: "IAT stands for Air Intake Temperature Sensor and it is located in the intake tube"...dyslexic much?) and then looking at the air cleaner. Ok so far so good...I then searched to see what was available online. Keep in mind that I haven't seen this part nor taken it the old one out of the car. This is what I found

Notice the same part number on the Napa site....geez. Same part .....2 different names...awesome. Needless to say I wasn't inspired with confidence when I went to the store....then the guy at the counter couldn't find it ...then he handed me a part and asked if "this" looked like the right part (since I hadn't pulled it ahead of time....I answered "I don't know"). Anyway...When I got back home I immediately pulled the old sensor and yes ....it was "this" was in fact the right part...and if I had pulled it first I guess I would have known that ....the problem is that I loath to pull out a part until I know for a fact I have the replacement in hand....too much bad crap can happen when you remove an old part and then have to put it back. The installation of the new part went like a charm.

2. The CST ...or Coolant Temperature Sensor. This was not too big of a hassle to identify ....they just called it a "Coolant Temp Sensor" and plopped it down in front of me with some confidence.

When I went to pull the old part however, I found it was buried under some other stuff...I kept having to refer to various pics and diagrams to first identify where to look and then look at the right angle to actually catch a glimpse of it. I had to remove the connector blind because it was underneath everything by holding a thin screw driver with my left hand and pulling back the retaining thingy by feel and simultaneously trying to pull the socket out using just my thumb and index finger, which was all that fit in there...but I was successful..so alright. I also ended up un-mounting the ERG solenoid from its bracket and then removing the bracket itself to gain access to the sensor itself. Next I realized I would need a deep socket (3/4" I think) but I didn't have one ....I fished around in my tool box and found a spark plug socket that was almost the right size (using the new part as a guide) ...so I crossed my fingers and gave it a try and lo and behold it started to turn and I was able to spin out the old part!! Victory!! ....that is until I looked at the old part closely and realized that the threaded part was much bigger than the replacement's threaded part (the rest looked identical). [expletive deleted]!!!!! I almost jumped into my truck to head back to Napa yell at counter guy (I prolly wouldn't have yelled but still) when I took an even closer look and realized that what I was seeing was old sensor threaded into another threaded insert !! What the hell?! ....well regardless.... this was something I could work with. I did the whole 2 box wrench tango (I won't go into details but at least my hand didn't slip and smash myself in the nuts...so that is something) and separated the two pieces ...cleaned up the insert with a wire brush and threaded the new sensor and insert together (Box Wrench Tango II: Electric Bugaloo). Then used the spark plug socket again to thread it into the manifold until it was finger tight and finished it off with an open-end wrench. I replaced the ERG Solenoid and bracket. Finally, I filled and burped the coolant system and went for my test drive (I already recounted how that went earlier in the thread)....yay!!!

3. Minor detail...while I was wrist deep under the ERG Solenoid, I felt something loose laying there ...I fished it out and it was a (1/4" or 3/8") machine screw with a washer painted black...no idea where it came from. The extra parts god gave a gift again....only this time swear it wasn't something that I removed and forgot to put back!! Seriously

I found that removing the dog bone bracket helps clear the biggest obstacles in that area.

quote Originally posted by Hudini: I found that removing the dog bone bracket helps clear the biggest obstacles in that area.

I wonder why they went with that threaded insert?

quote Originally posted by 92wastheyear: I am curious about this too....mine 87 GT is very "cold blooded". When I start it in the morning it starts easily but hunts for idle and will almost always stall unless I fiddle with the gas pedal (to keep it running) for about a minute...after about a minute it will be able to idle....it also wants to stall when attempting take off from a stop sign until it is fully warmed up

Sounds just like how mine acts at cold idle, minus the stop sign issue. I have to catch it with the throttle twice, then it will be able to catch the stumbles by itself. As it warms up it gets stable.
When it started doing this, I noticed in WinALDL that the CTS was erratically reporting a very high temperature. It would read normal, and then suddenly say 300F. At the same moment, the engine would stumble. I think I was lucky to even see that happen, because the speed of the datalogging connection on this ECM is slow.
My electrical connector is completely rotted apart, so I'm going to replace that first. But the fact that it's temperature sensitive makes me think the problem is the sensor itself.
A high temperature reading comes from low resistance. So apparently my sensor, or something in the circuit, has an intermittent short when cold. Seems strange to me, I wonder if that's the typical failure mode?
My CTS is an aftermarket "BWD" that I erroneously bought about 1.5 years ago. There was nothing wrong with the old one, and now I wish I had kept it.

As far as the insert:
From what I've read, the original CTS used a "weatherpack" electrical connector. Later replacements use the "Metripack" connector. Some of these were sold in a kit that included the replacement connector. I wonder if the original CTS filled the larger opening, and the insert was added to fit the metripack sensors? That's just a guess. I've never seen the older style CTS.
From what I've seen happen to my metripack connector, I'm not exactly sold on it being an improvement. It's wrecked worse than any of the weatherpacks on the car, and that's saying something. The pins are also closer together, which doesn't help it's robustness any.
I think I really prefer weatherpack, and at minimum those connectors are easier to replace. But I guess the weatherpack sensors are unavailable so it's not an option.

=
The IAT can sometimes be fixed by cleaning. Mine was fixed after soaking in CLR, and has stayed accurate for about 2 years now (as seen in WinALDL).
Remove it from the car, check it's resistance and compare with a resistance vs temperature chart to see if it's working correctly. I think the same chart is used for the IAT, CTS, and the temperature gauge sender.
I've become cynical enough about the quality of modern aftermarket parts, that I would suggest not throwing away the old one until you try cleaning it. If it's factory, it's probably better made than the new one.

quote If it's factory, it's probably better made than the new one.

I have come to the conclusion that my car has been thoroughly gone thru at some point in the semi-recent past....all the weather stripping seems very new and pliable. Like I mentioned I got the car from my father ....but he bought it from a used car dealer. Dad also says he talked to the previous owner (who sold or consigned it to the car lot) and got the impression it might have been a barn find or some such. Regardless, I suspect that the majority of the parts and stuff are aftermarket replacements (but I still do have the parts that I removed btw). Your take about a change of design in the CTS sounds imminently logical. I wonder if anyone can confirm this