another idle question

[a911]

Ive been searching for an hour here but didnt found similar problem. So sorry if its another dumb q.
The car have problem at maintinig idle at 800rpm. Sometimes it does ok sometimes engine die. When revs drops it looks like it catches idle too late and revs drop to 100-200 or even engine die. Sometimes it picks ok at 800 and stays there. Or idle speed varies btw 600-1200.
Otherewise car is runing strong and have no other issue. I dont think its oxigen sensor as it dont have any other problem related to this faliure. Or am i wrong.

[kqw]

Check the torque on your manifold, 12 bolts. Use an 8mm allen socket with a swivel head and 6" extension to get to all the bolts.

The torque is 18 ft/lbs.

[scottb]

Mixture

[a911]

Originally posted by kqw
Check the torque on your manifold, 12 bolts. Use an 8mm allen socket with a swivel head and 6" extension to get to all the bolts.

The torque is 18 ft/lbs.

thanks i will check that. Is that a possible to have a prob. i got and solved with this? will try anyway.
Its not big issue but it doesnt look good if you stalled in lights.

[a911]

Originally posted by scottb
Mixture

what do you mean by that? Its 88 carrera so i dont think you can adjust this or? Still learning so bear with me.

[450knotOffice]

Actually, you can adjust the mixture on the Carrera but it's a job for a pro with a CO meter. I wouldn't touch it.

-Scott

[scottb]

I had a problem with the idle on my 84. It took it to my local mechanic, and they adjusted the mixture. I don't know the details, sorry. I think there is an adjustment for air/fuel ratio, but I don't know the details. Once my mixture was adjusted, all of the idle problems went away.

[a911]

Originally posted by scottb
I had a problem with the idle on my 84. It took it to my local mechanic, and they adjusted the mixture. I don't know the details, sorry. I think there is an adjustment for air/fuel ratio, but I don't know the details. Once my mixture was adjusted, all of the idle problems went away.

Is that afecting only idle problems? Why sometimes pickup is, as it should be, and sometimes dies or runing idle? If the mixture would be incorrect wouldnt there be other issues like not runing strong or bad gas mileage...

[Jeff Alton]

You could also have a bad ISV. Worth a look.

Jeff

[nhromyak]

Does the idle change at different warming-up temperatures?

1) Intake bolts

2) When it is idling put your hand on the ISV, is it "clicking or thumping"?

3) Check idle circuit for engagement. Check throttle linkage for kinks or stickiness. Check the leads/sensor to make sure they close the circuit when the accelerator is off.

3) Clean the ISV

4) Jumper the ISV connections (using a round relay) on the side of the firewall under the plastic fuse/electrical panel , check idle, and adjust as necessary.

5) Check CHT sensor. See Bentley for approximate ohm readings.

6) Check IAT sensor. See Bentely for approximate ohm readings.

7) Disconnect O2 sensor, you should get a solid idle with the O2 disconnected. If not, check O2 for Millivolt swings (DVOM needed here). R & R if not swinging or "slow" (this is relative hard to judge).

8) Get your CO checked.

That's all I can think of at the moment.
Good luck.

[kqw]

Intake manifold bolts....Simple fix....

Also, ......As Nick mentioned.

[a911]

Originally posted by kqw
Intake manifold bolts....Simple fix....

Also, ......As Nick mentioned.

THANKS all for help.
Today i cleaned ISV and waiting overnite to dry. As i watched into engine i tried to tightened mainfold. Since i dont have torque wrench yet i just try the first bolt and it didnt look tight. I could tighten it without too much force so my guess is that it really need torque wrench for tighten properly.
When cleaning ISV it didnt look too dirty and valve moves free.
Will have to buy some ohm meters to check and also torque wrench.
I love that you can do some stuff on your own car. I never did that, but i always have wish. Im really scared to do something wrong but i will do everything real slow. Got haynes manual and Waynes books so that is big help. And also this site and you all.
But it took me half an hour to find out what ISV means. Damn im stupid..........LOL

[nhromyak]

I think stupid is going too far.

I don't think I knew what an ISV was for the first two years, I had my '85.

I guess I should have written it out. Heck, I forget what it stands for now.

Idle Speed Valve? LOL

[OldTee]

Most probably you have a vaccum leak as discussed above. Get a spray bottle ($ store for $1) and use water. Spray the injector bases and look for bubbles, also check intake rubber boots, check the blow off valve under the air cleaner. Leaks kill CIS and adjusting the mixture without this step is a waste of time. Also check the vaccum hose at the distributor. Your 88 may not have one. Don't use brake cleaner to check for leaks. Good luck.

[nhromyak]

Originally posted by OldTee
Most probably you have a vaccum leak as discussed above. Get a spray bottle ($ store for $1) and use water. Spray the injector bases and look for bubbles, also check intake rubber boots, check the blow off valve under the air cleaner. Leaks kill CIS and adjusting the mixture without this step is a waste of time. Also check the vaccum hose at the distributor. Your 88 may not have one. Don't use brake cleaner to check for leaks. Good luck.

His '88 is motoronic, not CIS. Different injectors, and different runners.

I would use water, but you could get some Fuel-Injection spray/cleaner (this can eat paint though) and spray at the manifold intakes. At idle, if there is a leak the RPMs will change, I forget if they will go up or down. If they change, that one is leaking.

NOTE: some Carb Cleaners, as opposed to Fuel-Injection cleaner will KILL the O2 sensor, so be careful.

[a911]

Originally posted by OldTee
Most probably you have a vaccum leak as discussed above. Get a spray bottle ($ store for $1) and use water. Spray the injector bases and look for bubbles, also check intake rubber boots, check the blow off valve under the air cleaner. Leaks kill CIS and adjusting the mixture without this step is a waste of time. Also check the vaccum hose at the distributor. Your 88 may not have one. Don't use brake cleaner to check for leaks. Good luck.

huh now you are scaring me. I thought there is simple solution.
Maybe i shoul get even older car with less sensors and other things that can go wrong.