M42 high idle after throttle body heater delete

[and_e30]

Ok, here is my 2 cents.
When you installed the throttle body back onto the intake, you didn't install the heater plate. You really don't need the heater plate, but you do need the spacing it provides on the two lower bolts that are used to reinstall the throttle body. As your picture shows you didn't install the plate. The upper two nuts work great, the bolts have enough threads to tighten up the nut. But the lower two bolts are too long. It may seem that they tighten up, but they are actually bottom'ing out. So, your throttle body is being attached to the intake by only the two upper nuts. Allowing air to be suck into the intake. More air=high idle You can compare the pic that I uploaded from your first post. There is a notable difference with the heater plate.
Note: Heater plate does not have to be hooked up, just used as a spacer. I hope this helps.

no, my lower bolts are just like my upper. they are threaded the entire way so there is no "bottoming out". my throttle body is on snug all the way around. no gaps.

[KVF]

M42 high idle after throttle body heater delete

I don't know the M42 that well, but the tps (throttle position switch) on the m20 has to be properly aligned on the throttle body. Did you have to remove or manipulate the TPS? If so, I'd check to make sure it's in proper position.

Edit...

Also, based off what jpatte mentioned about the spacer... Is it possible that by deleting the spacer you've moved the mounting point of the throttle cable a bit further forward, causing it to hold the throttle open just so slightly? Air leaks typically cause erratic idles, where sensors or improperly adjusted cables lead to consistent high or low idles.

[jpatte]

Air Gaps

Ok, like I said, 2 cents. On my car the throttle body has nuts on the upper and bolts on the lower. Keeping trying, you will find the solution.

[Balleristic31]

Did you change the valve cover gasket at the time of the all the rest of this? If so, did all of the bolts thread in without pulling the head threads? Loose valve cover or misaligned gasket (especially on the firewall side of the valve cover) could cause a vac leak.

Edit: also make sure u dipstick is all the way down and has a good oring.

[and_e30]

Did you change the valve cover gasket at the time of the all the rest of this? If so, did all of the bolts thread in without pulling the head threads? Loose valve cover or misaligned gasket (especially on the firewall side of the valve cover) could cause a vac leak.

Edit: also make sure u dipstick is all the way down and has a good oring.

no, the delete was after the valve cover gasket.

ironically, at least 3 of the bolts were already sheared off in the block and just resting in there when i removed the old valve cover to do the change. i went removed the bolts and re-tapped all the holes before putting the new gasket on. so all of the bolts are torqued down to spec.

it was amazing i wasn't getting a vacuum before hand with the valve cover in the shape it was.

i checked the dip stick and that snaps in good, so it seals fine.

i am going to install the new thermostat friday morning and I will report back with updates.

[and_e30]

new thermostat installed and did a coolant flush.

When the car starts cold rpms are normal then as the engine gets up to temp it hangs out around 1500.

This is a slight improvement as it used to be 2k rpm and also the engine temp gauge goes half way now instead of a quarter of the way previously.

So i guess it help improved the problem, but not totally fix it. I am still out of ideas.

[oldmann]

Try clamping the vac. line to the charcoal canister, if the valve is hanging open at idle you will have a vac. leak you won't find with starter fluid.

[Balleristic31]

Time to get/do a smoke test.

[and_e30]

Time to get/do a smoke test.

still think its a vacuum issue after all the hoses and valve cover gaskets have been changed?

after the heater delete there are like 3 vacuum lines left. I have looked them over 100 times and removed the intake manifolds at least 5 times and reassembled with the exact same issue after.

I am 99.99% confident it is not a vacuum leak.

[bmwman91]

So it runs ok when cold and badly when warm? It sounded like you reconnected that little black single wire connector on the firewall. That should not be connected since it causes bad running when warm. It was only supposed to be connected on cars without O2 sensors, which I assume yours has.

[and_e30]

So it runs ok when cold and badly when warm? It sounded like you reconnected that little black single wire connector on the firewall. That should not be connected since it causes bad running when warm. It was only supposed to be connected on cars without O2 sensors, which I assume yours has.

it is not connected. when connected still has no affect, but i left it unconnected anyways. my car does have an 02 sensor.

[falo91]

has the idle screw been messed with? the pic of the throttle body removed the small butterfly looks slightly open?

[and_e30]

has the idle screw been messed with? the pic of the throttle body removed the small butterfly looks slightly open?

no, haven't touched it. i just checked it anyway and it not even loose. i couldn't turn it with a screw driver easily.

[E30 Wagen]

Are you absolutely sure that the throttle is closed? When you remove the throttle heater plate, it's obviously going to pull the throttle body closer to the manifold, but if the throttle cable isn't lengthened then it cause tension in the cable which will hold the butterfly open. Had a similar issue with a high idle and it was only the throttle being held open just a tiny bit.

edit: eh, nvm, dumb idea.

[Dj Buttchug]

dude i think your ICV routing/ crankcase vent is wrong.