thecause17

Most of the guys in the 1st gen forum aren't fuel injected so I was wondering if any of you guys could help me out here instead. I have an '85 GSL-SE, that I have recently installed a low milage(15k) motor in. The car runs beautifully, but when I start it up, say first thing in the morning when the engine is completely cold, it won't idle right away. It has to warm up slightly before it'll hold proper idle, but once it does, it's rock solid at 750-800rpms. I have adjusted the TPS within specs a while back, and it solved some other issues I had, but this one is still there.

Now if the car has sat for even as much as say, 3 hours...I can go out, fire it up, and it's fine. But not when the engine is completely cold.

Any ideas? I'm not sure what the problem is....like I said, the car runs great, this is the only bug I have left in it.

rx7raca

thats the way my car is also, the reason mine is like that because i did the tb mod, which is removeing those coldstart plates/butterfly plates. if those are removed on yours then thats your answer.

on your car now, im guessing either the plates are stuck open or arent working the way they should be.
one question i have for you is when you start the car does it shoot up to 3k rpm? if not then this is reason for not idling.

it gets little annoying having to hold the idle manually but gets rid of those restrictive plates. plus i ported mine so its even better. play with those plates on the tb an see if they move freely.

if not then theres your problem

Amur_

Also, how long does it take for it to "warm up a little"? Are we talking 10 seconds or five minutes? (Yes, I am going somewhere with this.)

thecause17

Probably about 10-20 seconds before it will hold an idle on it's own....but if I take it out right away, it will stall a couple times when coming to a stop, or the idle will drop to appx 300rpms, then inch it's way back up to 750 again.

And no, when i start it, it does not jump up to 3k....

NZConvertible

Cold idle has nothing to do with the EFI, it's controlled by the thermowax (I presume GSL-SE 13B's are similar to FC's in this regard). It opens the primary throttle a bit when the coolant flowing through it is cold, then closes it as it warms up. Check it's operation.

thecause17

What's the best way to determine if it's working or not?

NZConvertible

I took my TB off and ran hot and cold water through the hoses so I could watch the thermowax rod extend and retract.

Amur_

Then I dunno.

If it takes 5+ mins for it stabilize, then I was going to suggest the water temp sensor. I broke this on my FC two winters ago and the ECU went into limp (hot) mode. Getting the car started and keeping it running for the first 5 mins in January was a bitch...

thecause17

If the coolant temp sensor was bad, then the guage wouldn't read properly correct? Mine reads fine. I do have one sensor that is broken, which is the coolant level sensor, would that cause a similar problem? It came apart, and it needs resoldered, I just haven't gotten a chance to do that, or replace the sensor all together.

Amur_

The coolant level sensor is not responsible for your problem. All it does is trigger the buzzer and the warning light.

I was thinking of the temp sensor that reports to the ECU (mounted below the filler neck and alternator,) not the one that reports to the dashboard gauge.

Raymr

Sounds like the thermowax as stated above. It's on the rear of the intake in a very inconvenient location. You might be able to check it with a mirror and light to see if it's holding the throttle open slightly when cold. There's a cam adjustment on it but I think you have to remove the UIM if it's similar to 2nd gen cars.