so I have a 350 tpi it has run fine for Years it's in a 86 z28
had a new trans droped in her rebuilt the motor cats are deleted egr deleted ect full exsaust is Flowmaster
ran fine i perform regular maintenance in a schedule due to it being my daily

ond day she started up in park and idled up and up and say at 1500 rpm and wont go down

if i put into drive or reverse it even with full brake she violently breaks the rear out
but in gear it sits at 6_700 rpm happy
I've cleaned the injectors
I have no vacume leak tested new iac and adjusted it fully
I have no codes or check engine light
new cap rotor wires plugs
new fuel lines filters ect
im waiting on a coolant temp sencer
I'm at a loss it is going to break something with how rough it shifts into gear from park
I'm at a loss
I looked over a older post about this but it was a dead end nothing on it helped

other than that she runs like.a dream idles fine in park besides the 1500 rpm

and in gear it can stall once and a while but 90%of the time its fine

 

Sounds like unmetered air entering the intake.

 

I'll look into that

 

Did you ever find out the issue? Mine was the TPS was setting the idle too high, it was a strain on the transmission as well. Even after warming up it did not lower the RPMS? there is a small screw to adjust the idle, but likely it is a TPS issue. It can be pretty pricey to replace but may just need calibration.

 

no the it's still angry and no warming up does nothing to the rpm issue the screw is all the way set for lowest rpm possible if not the rpm idles at 25k

 

try spraying starter fluid around the air hoses and gaskets,the idle will increase if you have a vac leak.that will give you an idea where the leaks are.

 

Did you ever get the new coolant temp sensor?

 

not yet budget has prevented me from any further digging or parts

 

Sounds like mine... idled high at 1500 for years and was annoying and what not... I could not find any vacuum leaks etc.... tried many things and could NOT get the stupid thing to idle normally... sometimes it would but it would not idle normally more than a few seconds or would immediately idle high............ I think I tried like 8 times trying to get it to be normal... each time failed.

I just tackled it again yesterday and I think / hope i fixed it with minimal cost....... I pulled the throttle body. AGAIN.... and resealed it completely despite the thing passing a smoke test..... i got the gasket kit from Amazon for like $14. I redid the top plate gasket on the throttle body, and bottom part gasket for the idle air control valve / coolant lines............. while I had it apart, I took one of those small nylon bottle brush kits that attaches to a drill that i had on hand...(from oreilly). and cleaned out all the passages and sprayed with throttle body cleaner while brushing. Gave the whole throttle body a good cleaning, inside, under the plate and out....

While I was at it I cut the coolant / heater nipples off the IAC housing since I did the TB coolant bypass years ago (...hawaii lol) and made the idle control valve housing much smaller (it now only uses 3 / 7 screws) and sanded / ground it a little with a dremel so it looked good and wasnt sharp. FYI, those bottom screws are a bear cause the corrosion caused by the coolant.... I suspect the coolant also degrades the gasket a bit after years.......I then reinstalled the IAC with teflon tape and the gasket set came with a new IAC gasket as well.... I reused the gasket that attached the throttle body to plenum since I just replaced it recently...

Then I did the procedure from TGO on resetting the idle... so far it idles good and consistently. I think it idles too low actually..., but I was able to bump it up a little by adjusting the idle screw... I literally just tried adjusting it without checking the actual idle and , noticed it bumped it and was happy at the moment.....stil lneed to play with it but before the idle would shoot right up when it was re- started... currently it stays at normal idle and sounds good no matter how many times i shut it off and restart so Im hoping i fixed it. My THEORY is that you set base idle with the procedure below....and the ECM adjusts the IAC idle from there a few hundred RPM......... so once the ecm is set, you can play with the idle by adjusting the screw to your liking. so far this theory seems correct... so basically you do the IAC procedure, from there you can adjust the air flow a little bit with the idle screw (youre not making massive changes.. just enough to fine tune like a carb)



idle procedure from the tech article: Take the paper clip and open it up and form it into a big "U" shape. Insert the clip ends into the ALDL in the ‘A’ and ‘B’ pins.

Turn on the ignition, but don’t start the engine. Wait 30 seconds. Now, go remove the connector from the IAC.

Start engine. You are now going to adjust "minimum air". There is a Torx screw on the side of the throttle body. This is what needs to be turned to adjust minimum air, or more commonly known as "idle speed". It comes from the factory with a protective metal cap over it. If the cap is still there, use a small punch to knock it out. Set the idle speed to 450 rpm, rotating the Torx screw clockwise to raise rpm, and counter-clockwise to lower rpm. Once the idle rpm is set, turn off the engine.

Re-connect the connector onto the IAC. Start engine. Idle speed is now once again governed by the ECM, but your idle should be smooth and steady, approximately 600 rpm in Drive (for unmodified cars).

If you set an SES light by having the IAC disconnected, then after shutting down the engine disconnect the negative battery terminal. Wait 5 minutes. This will clear the ECM of all trouble codes. Re-connect the battery and drive the car for 20 minutes to allow the ECM to relearn your driving style.

gasket from Amazon:

Standard Motor Products 2009 Gasket

 

I'll try it just threw on a new iac but have not done the reset yet I'll Try it and update

 

Any chance you can data log to see what's what? Data could steer you in the right direction. Sounds like throttle plate sticking, air leak or TPS. Data log will show you MAF g/sec, TPS voltage and IAC counts.

If air leak post MAF: a 1500rpm idle g/sec should be lower than normal (MAF not reading all air going in) + IAC would go to 0 count (trying to bring down idle) + TPS voltage would be normal.
If sticking throttle: TPS voltage would be higher than normal + MAF g/sec normal for 1500rpm light engine load + IAC normal (ecm thinks you are holding gas pedal).

In my experience, the procedure to adjust idle is more like this:
1) Warm-up engine to operating temperature.
2) Insert the clip ends into the ALDL in the ‘A’ and ‘B’ pins.
3) Turn on the ignition, but don’t start the engine (SES light will flash and fan might come on)
4) Wait 30 seconds to let the IAC pintle to fully extend
5) Disconnect the IAC valve
6) Turn off the ignition and deactivate the ECM diagnostic mode (remove paper clip)
8) Start the engine
9) Disconnect EST Bypass connector (might not be necessary on 86 TPI '7165 $32, this will bring SA to base 6*. On SD TPI 90-92, ecm tries correcting idle rpm with SA or SR, so disconnecting EST prevents ecm from countering what you are trying to do)
10) Adjust the throttle body screw for 450-500 rpm engine speed
11) Turn off engine
12) Reconnect EST Bypass connector
13) Reconnect the IAC valve
14) Reset ECM by disconnecting the Battery to clear code (you don't need 5 minutes!, 10 seconds is good)

If you have a data logger, once procedure done, you can monitor IAC counts and fine tune the idle screw to add or remove IAC counts at warm idle (need EST disconnected on SD TPI 90-92).

 

thats a new one... (disconnecting the EST) where did you find this? I never heard of anybody disconnecting the EST to reset idle. Normally the procedure is the same minus the est part.

 

I did not find it, that's what I do on SD TPI '7730. It's from observations after doing the procedure many times using OBD1 rpm monitoring (not dash cluster tach). Otherwise, the idle is trying to correct using SA or SR. It interferes with the procedure. I like it better set on initial timing. Just my own experience, not something I read and repeat but something I actually do. However, on '7165 MAF 86-89 ($32, $32B and $6E) idle is not corrected by SA/SR, so yes might not be necessary.

 

hmm interesting. Might try this next time i need to reset mine.

thx!

 

Someone might chime in and say I'm doing it all wrong... and guess what? It could be possible lol

I also like to tweak it after using OBD1, monitoring the IAC counts at warm idle add/remove counts by adjusting the idle screw. On very warm idle, I don't want the counts to be too high, in the 30s if not high 25s, but that's my own preference. Someone might think I am out to lunch... but works for me.

 

I mean wit hthese cars, it seems you need to try multiple methods to get the best performance / drivability ot of them! No one right answer Id say lol

 

Man I'm a novice with this stuff data logging is a bit out of reach for me rn I'm good with a wrench but this electronics stuff is confusing this 86 is the newest rig I have my previous car was a 64 dart only eltronic on it was a relay for a starter circuit any leads on where to start learning thus stuff or tools needed would help?