So I had warm start issues after a brand new rebuild. Some how that disappeared. I thought the engine was flooding. There was a lot of premix in there. Injectors could have been leaky or gunked up something.

Needless to say I was ecstatic. I was driving the car and it as running smoothly. Boosted right. On off throttle right. Idle right. Was perfect. For a good full day. Later that night I put a little gas in it. Drove it around. Then noticed idle woildnt return to normal. It would stay up around 1700 - 1900. It would run smooth. Rpm was steady. It was just high. I didn't touch a thing.

I researched this morn searching the forum. Came to conclusion it was either bad ground or vacuum leak. I cleaned up the ground tightened etc. but idle still high. I searched around the vacuum lines which are new and couldn't find anything visible. So I then I backed off the throttle screw. This worked. However rpm is still 1025 or 1050. I literallly backed it all the way off. Shouldn't the rpm go way down. Basically my concern is that I am just bandaiding an issue with vacuum. So my question is if there was a vacuum leak or something malfunctioning would adjusting the screw work in lowering the idle?

And shouldnt idle be lower with the screw all the way out. Engine has according to Dave a monster port? The car runs perfectly elsewhere.

If the answer is that I am putting a bandaid on a bigger issue can someone give me specific instructions on where to look for a vacuum leak? I have had these cars forever but my first one ran well enough that it didn't force me to study the engine and vacuum diagrams. So perhaps take me by the hand on where to look.

 

The one thought I have, perhaps it's hopeful is that the engine is simply tightening up post rebuild. The new engine only has 300miles on it. Yesterday was the first real day of use for crysake.

 

which screw did you turn? the idle speed screw is the one kind of under the throttle body elbow, it screws IN to lower the idle speed. there is an air passage there, and the screw literally screws into the passage, less air = lower idle

 

This was on top of the throttle setup

 

This one. And I spoke to soon about warm start. Still alittle funny. But better.

 

that is the throttle stop.

 

Ok

So I backee that off all the way and that moved idle from 1700-1800 to 1025 ish.

 

another thing . Do you have idle air control ?

If your idle air control is stuck open by any chance it could cause this .

 

you need to put it back where it came from and use the normal idle speed screw. moving the throttle stop also plays with the TPS, as its telling the ecu that the throttle is closed, and then you moved that to a different place

 

Ok I will move it back.

I can play with the idle screw but something changed. I can't imagine the idle changing on its own. Something cause the idle to move up by 800rpms or some. Usually it's a vacuum issue I though. The Rpms are stable. Just elevated. Does that sound like a vacuum leak?

 

What is the idle air control? Are you talking about the screw under the manifold? Same one that the other person commenting is talking about?

If so can you take a pic?

 

Here is a good thread in case someone searchs down the road. https://www.rx7club.com/3rd-generation-specific-1993-2002-16/idle-screw-adjust-854571/

Can I remove the iac without taking the manifold off? I notice there is a gasket.

Is it safe to reuse that gasket?

Lastly I guess I need to remove elbow to get at that idle screw. Is it safe to run the car with the elbow off while trouble shooting the idle?

 

its a tight fit, but i think you can take the BAC valve off without taking off the manifold.

you do not need to take the elbow off, there is a little notch that lets you get a screwdriver in there

 

Tks for all the help. So I don't think it's isc. I just unclipped it and engine dies. If it was stuck I'd imagine there wouldn't have been an effect when I unplugged it. That logical atlesst

 

I am noticing a relationship to my warm start problem and my idle.

I put the throttle stop screw back to its original setting. As a result my idle is back to 1700-1800, bummer. But the kicker is that the warm start problem is gone now. If u see my earlier post I was saying same thing, "warm start problem gone but now there is an idle problem". I don't know if coincidence or what.

 

I'd check for a vacuum leak. If you just started boosting today and have a high idle all of the sudden then you may have popped something loose.

You can use carbcarb spray to locate it. Spray in suspicious areas and see if idle changes to find leak.

Or use a couple tennis ***** and block off intake. Hook up air compressor to a vacuum line while engine is off and pressurise the system. You'll hear air coming out of leaky area.

I wouldn't start taking apart the engine and messing with various things. Do the likely obvious stuff first. Is the shop who did the expensive rebuild far away?

 

If I had to guess I'd say the TPS moved/was bumped or else it suddenly just stopped working

If you need one let me know

Thanks,
Fritz

 

Seems like I fixed it. I backed out the throttle stop so it's just leaning on the butterfly arm. Tightened the air screw underneath the tb then backed off one half turn. Got the tps in scope although it's .55 and 1.25 which is top of spec on the vta2 field. Car idles nicely but with a small loop probably due to aggressive port. The starting is fixed too. I do think my injectors are a little leaky though. I get some white smoke. on some start ups. I am thinking the tps wasn't in spec when I got it back. Not sure.


Well alright. Time to burn it hard.

 

on mine the throttle body had been apart to be painted, so i had to go through all the adjustments, and its a PITA.

it took a while to figure out which things need to be done in what order. i've been meaning to post pics, but i think you want to go in this order.

1. set the idle speed screw under the t/b where you want it. half turn, full turn, wherever
2. fire it up and set the throttle stop to where it idles at the right rpm, give or take.
3. set the tps. i have a stock ecu, so its a HUGE pita to set the TPS, i shoot for the middle of the range, engine must be HOT.
4. set idle speed with idle speed screw.
5. there are actually 2 throttle stop screws, so the other one show be set too, its on the other side of the shaft.

the thermowax has two more adjustments, you have one that adjusts the RPM it goes to, and then the second controls what temperature it turns off at. this second one is labeled, so its easy to set. the one that controls the RPM isn't labeled, so it just needs to be turned in 1/8 turn increments until its right.