jhiggins119

I understand that the factory spec for the L-83 is 450 after warmup. This forum indicates that 650 is probably better. My motor still is at 800-900 RPM's when warm. I will run at 35 mph on level ground. The car runs great, but I do not want it to move that fast at idle in drive. Should I retard the timing before looking for vacuum leaks?
Thanks for your advice.

bpassmore

Mine runs 550-650. I'd look for a leak or a sticking idle air control. I use carburetor cleaner through the idle control several times a year. Look for a leak. I run my timing @10*, 4* more than the decal.

7T1vette

Is your computer control system still operational? Is the CEL light 'on'?

If there is a fault with a temp sender, or if the computer doesn't think the engine is warmed up, it will cause the idle speed to run higher.

The idle speed [when warmed up] is 'programmed', so it doesn't need adjustment....unless there are other system problems.

jhiggins119

As a newbee, I do not have a service manual yet. Where is the idle control valve? Is there one for each injector or just a single?
Thanks bpassmore. Your expertise is a great help.

terry82

450 rpm is a little low .550 -650 rpm is factory .idle valves are at the front of the throttle bodys.You can see the electrical wires going to them .I would check vac lines and intake .Do your headlights work up and down okay?if not there is your vac leak.

jhiggins119

Thanks for your help.

jhiggins119

The CCS is still operational and no CEL light is on.
Thanks.

jhiggins119

The headlights work fine.
Thanks.

bpassmore

I agree with 7T1 about the temp switch, it is in front of the intake manifold, the early models had a round connector, the replacement (Later design) had a 2 pin connector, the early design are notorious for failure, one symptom is the fast idle when the engine was warm. By now most have been changed to the 2nd design. If it has not been converted it probably be a good idea to change it and the connector it can throw a lot of curve ball s to the ecm.

jhiggins119

Thanks. Can I buy one from a local parts store or will I need to buy it from one of the on-line Corvette parts suppliers?

terry82

if the temp sensor is bad .you will get a rich condition.but if you still want to replace ,you can find at most parts stores.

jhiggins119

It looks like the temp sensor was replaced since the two wires have been spliced to the sensor. I think it is running rich by the black carbon deposits, especially at start up, that emit from the exhaust pipes. The car has 47K miles on it. It has all new belts, hoses, spark plugs and totally stock except for the air conditioning converted to R134. I am in over my head when it comes to the fuel injection. I am going to check the timing tomorrow. The hood decal indicates that it should be set at 6 degrees. I hope I can find a tech that really knows the 82 fuel injection system.
Thanks.

terry82

timing is not your problem .and may not be the injection system .you need to check for vac leaks .

hugie82

There is an idle stop screw you can turn up if its dropping too low. Is the motor running good other than the idle?

Rmodeler

Get the high idle taken care of soon, because it can be a safety issue on slippery pavement. Don't ask how I know.

Wrecked82

OK, I won't.

wombvette

First the crossfire needs to be balanced. That should be done at the factory. If someone has monkeyed with it, you need to re-balance by the correct method. Assuming that no one has messed with that, then you need to set the minimum idle. That is the 450 rpm figure. It is set by blocking the bypass ports and adjusting the idle. After that is done, the computer sets the idle by signaling the IACs. That should hold the idle in the 650 range. Any idle more than 800 indicates bad adjustments or a vacuum leak.

You need to inspect if for tampering. Probably has been messed with.

74 LS4-454

some questions for you?

1-the 800-900 r's when warn is that in "D" or "P"?
2-if it is in "D", then what is the rpm in "P"? and vice-versa?
3-can you explain..."I will run at 35 mph on level ground"?
4-how many miles on the motor?
5-what have you done (if anything) to the engine?
6-have you read the "sticky", especially the "IDLING SECTION"?

I would not make any changes as of yet, unless as mentioned earlier, that the system has been tampered with....I would go through the "sticky" and eliminate as many possible solutions as possible before resetting the idle or re-balancing the TB's. JMO........Tom

jhiggins119

The timing was off the tab. I estimate it was 12-14 degrees. It is now set at 6 degrees and the problem is solved. The distributor clamp bolt must have not been loosened in years. It was a bear to get to and to loosen. Talk about "stuff" in the way! Finally with an offset L 9/16 wrench and breaker bar and tapping with a hammer, The bolt came loose. On to the next project of finding the rattle in the passenger door and adjusting the window glass.

jhiggins119

Timing now set back to 6 degrees and the problem is solved.
Thanks.