Cold Start Injector???

[jim's82]

Quick question... does the 82 Corvette crossfire have a cold start injector? My 82, since the day I bought it, has had a rough idle until the engine warms up. Has many new parts: ECM, IAC's clean injectors, TB's balanced, Coolant Sensor, TPS & many more. No codes either. The car runs better than ever once warm but barely tolerable when cold.... sounds like it's running on 7 cyl.'s & occassionally hunts idle up & down. Just recently, had a guy tell me that he was betting it was my Cold Start Injector that's causing it. If there is one on this car, where is it & what can I do to check &/or repair the problem? Thanks, Jim

 

[topless82vette]

no you don't have one, try checking your coolant temp switch its located on the very front of the intake manifold and has a two wire conector going to it, it should have a yellow and a black wire going to the connector, the computer uses this sensor for cold fuel enrichment, if it has the old round style sensor they were alot of trouble there wires inside the pigtail would fuse together, I am using a newer style one from a 85 up tpi car and it works great

 

[DDLS3]

Jim,

Your oxygen sensor plays apart in this too. Until the O2 sensor sees about 390 degrees in the exhaust it will not allow your system to go into closed loop operation. This may account for the rough idle and hunting that you are seeing before the closed loop picks up. The output voltage at the sensor leads should be between 0-1.0 volts when warm. The cold voltage should be around .5 volts. If the voltage is very slow to change (cold to warm) then the sensor is on the way out. If and when it fails to change voltage at all you should get a code 13.

 

[jim's82]

I didn't think there was but he was so confident that he was right I thought I'd better make sure. The coolant temp sensor was changed at the same time the intake manifold was re-sealed (about 6 months ago). The mechanic that did it said that the new sensor was an "upgraded one". I never took note of what the old one looked like but the new one has a round plug going to it. Everything that has been done to this car has improved the way it runs warm, in fact, it's running very good once warm. Nothing however, has improved the way it runs cold. I haven't checked the voltage to the O2 sensor yet but I will.

If the new sensor (Coolant Temp) is the replacement for the 82, do you think I might benifit from going to a newer one? If so, what year do I ask for & would anything need to be changed in the computer? Thanks again

The weather got VERY cold here last night, I think it was below 20, I started the car last night & it ran pretty smooth for about 20 - 30 seconds & then began bucking again. I'm pretty sure that's the coldest it's ever been when I've started this car. Is this kinda wierd or about par for a bad sensor?

 

[topless82vette]

jim

your original coolant sensor is a squeeze type removal one where the upgraded one has a tab you have to lift up to remove the connector to wire it in simply splice the wires, does your check engine light come on when key is turned to run position ? seems weird that it runs so poorly with no codes, either that or your dealing with a non ECM related drivability problem, I would run the car at night and crawl under it and look for plug wires arcing since many are in very tight areas, mine once had a problem with the magnetic pickup coil in the distributor and it didnt throw a code, I also found a slight miss in my engine related to leaks up near the headlights.

 

[jim's82]

I'll have to take a closer look at my coolant sensor to see which one I have. The check engine light is working & I'm not getting any codes. The only code I can get when I check it is "12". I'll take a look at the possibility of arcing but they're all new wires & routed as far as they can be from the block & manifolds. But you're right, some are extremely tight.

What's your thought on gas octaine? A friend of mine just suggested that my problem could be that I'm running high octaine & the car's not made for it. I switched to the highest ocatine (93 I think) right after I bought the car. I noticed a slight ping if the engine were bogged down a bit so I switched & never had another ping. Could the high octaine have a part to play in the rough idle when cold?

 

[jim's82]

I also found a slight miss in my engine related to leaks up near the headlights.

Hmmmm.... are you talking about a vacuum leak? I've checked for vacuum leaks everywhere under the hood except for up around the headlights. If it were a vacuum leak, would the engine smooth out after the computer kicks in?

 

[topless82vette]

jim

also has your car ever been timed correctly ? when we bought our it ran kinda poorly but not quite as bad as yours, always had a bad fuel odor from the exhaust, turned out our was cause from the timing and low coolant temperature,( I also never had a check engine light ), if you find a 4 wire connector off your distributor follow a tan wire and it should have a single connector this connector has to be unplugged for the car to be timed right and after its warmed up though, I used to time mine by unplugging the 4 wire connector and the car ran poorly till I unplugged the 1 wire connector, as for octane Ive run them all and my car runs very nice just on low octane, and have never had pinging from any other octanes

 

[jim's82]

Multi part question....

My car does have a new ECM but I have no idea if the PROM is the most currnet update. 1st question: How can I tell if I have the most cuurent PROM? 2nd) If not current, is it a very big job to change & apx. how much $$$ for new PROM? 3rd) Does anyone know if the PROM could be causing my cold idle problems? I read a "service bulletin" that stated "this new PROM leans the fuel callibration during cold engine operation & unlocks the torque converter at a lower throttle opening". I think it is mostly addressing spark plug fouling but I guess I'm hoping that if this is a relatively cheap fix & that this might be my trouble. Any thoughts? Thanks for all the great suggestions.