87vette

I have an 87 L98 and I'm curious as to when or how often these things need to be replaced ?

RRT vette

The only way I know to check it for leaks is to pull the CSV out..loosen and manipulate the fuel line so as to check it visually when the system is primed. It ohms at around 4-6 ohms as the other 8 injectors are around 16 ohms. There is a fuse for the circuit behind the DIC (5a). There is a thermal switch located in the front of the intake manifold and only activated below 95* during cranking. The system is powered by the starter solenoid.

ultraviolet70

Have you ever replaced the other injectors, if so and their a newer design you can actually shut the cold start injector off (via a new chip).

RRT vette

Correct.

87vette

No I never replaced them.

tonymax2

According to Dave McLellan, the cold start injector only activated below -20 deg F. If you never start at temps this low you don't have to worry about it.

RRT vette

The thermal switch is what contols the "on" time for the CSV. As the engine temp increases the signal to the CSV decreases until the engine reaches 95*F and the CSV is no longer active. The CSV is not activate at engine temperatures above 95*F, but is at any less temperature.

scorp508

Totally incorrect.

Mike_88Z51

To answer your original question, when it stops working properly.

Actually, the cold start injector (CSV) is a modified fuel injector similar to the other 8 fuel injectors. Unfortunately no one makes them anymore, so you cannot easily replace it. It can be tested as RRT vette says by following the Cold Start Troubleshooting Chart in the Factory Shop Manual. He is also correct about the injector operating at 95* F and below. I think tonymax2 is misremembering what he read about Dave McLellan, for I know that my CSV works above -20*F quite often, and I have personally tested it above that value.

Since you cannot buy a new one, it is probably best to remove the cold start injector and have it serviced by a quality injector service shop like Cruzin Performance when you need to replace/service the other 8 injectors. That is what I did at 75k in my 88. I noticed a significant difference in startup response and overall engine performance when I had all of mine done.

tonymax2

Maybe so! My '89 manual doesn't include it so I have no way of tracing the circuit to see what's it connected to. Ask Dave the next time you see him. Reference p134, "Corvette From the Inside".

scorp508

The guy's brain has probably forgotten more C4 knowledge than most of us will ever kno. He can't get it all right all the time. Somewhere around here I have the details as to the length of fuel spray the CSI gives in seconds vs. temperature at startup.

Electricblue80

sounds to be correct.

CALI C4er

I have an 88. I installed superam and new injectors about a year ago. That's when I threw the cold start injector away. It starts fine. I live in California and probably don't need one. I believe they were used for a few years and then discontinued.

87vette

Didn't know they were no longer made. Thanks for the responses.

Mike_88Z51

The cold start injector is connected directly to the cold start switch and has no electrical connection to the ECM or the other injectors. Double check what's on page 134. The error is in the book or Dave's recollection. My guess is that Dave dictated what is in the book and it was incorrectly recorded. Here is why:

The 88 Factory Shop Manual page 6E3-A-22 states:
The system is controlled by a cold start fuel injection switch which provides a ground path for the valve during engine cranking when engine coolant is below 35*C (95*F).
The cold start injection switch consists of a bimetal material which opens at a specified coolant temperature. This bimetal is also heated by the winding in the thermal switch, which allows the valve to stay "ON" for 8 seconds at -20*C (-4*F) coolant. The time the switch stays closed varies inversely with coolant temperature.

I think someone has confused -20*Centigrade with -20*Fahrenheit.
The switch does not work ONLY at -20*C, but reaches its maximim ON time at that temp.

The cold start circuit as used in 87vette's L-98, was only used from 85-88 in Corvettes. By 89 the ECM was more capable and the programming more sophisticated, so the cold start circuit as we know it was eliminated and the starting program in the ECM adjusted to enrichen the mix at cold start.

You can eliminate the cold start valve in the 85-88s and start time isn't significantly affected during most starts. Even in deep winter I would guess it won't make more than a second or two difference in start time.

If it starts to malfunction it can make starting much harder due to a bad switch or leaking 9th injector. Some guys have reported swapping the mem-cal chip from an 89 auto into an 88 auto and eliminating the cold start circuit with great results. I would guess that the 87 auto might be able to do the same. The manual tranny guys cannot do this as the 85-88 manual was a 4+3 while the 89+ manuals were 6-speeds, so the mem-call chip programming is far too different.

For me, the easiest option was to pull the 9th injector and have it serviced when I replaced my original 8. I plan to do this every 75k.

scorp508

There was a more recent addition to the $32b definition files for Tunercat/Tunerpro etc. that adds some more cold cranking fields for 87/88 to help tune around the CSI removal. I don't know if they're in there for $32 as well.

Da Mail Man

....well, the time has come. i have both a cold start injector (csv) and the temp switch for same....i removed the clip/plug that is on the temp switch at front of engine and did a continuity test of the in block temp switch.

.......each pin (2) is shorted to each other and to ground..this appears to be normal as the car is cold and the switch terminals would be normally closed (grounded) to provide a ground path for the csv to fire when cold........so, i assume it is good.....

i also checked the temporary ground i put at the csv to ground it should the switch had been bad, and it had continuity back to the temperature switch........teh make-shift ground it did nothing to help my starting problems.....so, assumably, the csv is bad.......

.......will be removing the csv momentarily to replace it....so, anything i should know before i dive in?..any proceedure as there is not one in the helms?....how much crapola has to come off..thanks!

RRT vette

You might want to get new fuel o-rings to replace the old ones, if they look bad.

Da Mail Man

......none of that helps if i can't figure the proceedure for pulling cold start injector......the helms is useless......if i have to pull the plenum, game over as i won't do that......

RRT vette

If I remember correctly there is a bolt that holds the flange down. Take the CSV connector off, loosen and remove the bolt, loosen and remove the fuel line that goes to the back of the fuel rail (close to the brake booster vac...there will be gas shed). Once all that is loose, just pull the CSV out with a little effort.