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Can't Idle When Cold


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9 replies to this topic

#1 jj421

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Posted 04 February 2013 - 09:15 PM

Okay, this problem is bugging me. And I can't exactly figure out what it is.

When it's cold out, my Loyale doesn't not like to idle. I have to sit there and rev it at 2000 RPM for at least five minutes before it can idle at 500 RPM. Then, as I'm driving, whenever I push the clutch in, the RPMs fall so fast, the car can die. I must feather the throttle to keep the engine going (very hard to do when braking). After about 10-15 minutes of driving, a "switch" flips in the engine and it idles normally. If I let the car sit for more than four hours, it goes back to "cold mode" and I have to rev it until I can get going again.

Here's a list of thing I've done to the car (although some might not apply):

-Cleaned IACV
-Swapped out IACV with a junkyard one
-Cleaned the junkyard IACV
-Swapped out coolant temp sensor with a junkyard one
-Swapped out CTS with a brand new one
-Swapped out PCV valve with a genuine, OEM, brand new, dealership one.
-Swapped out fuel filter with a new WIX filter

So really, I'm lost. Search results come up with IACV and CTS, but nothing more. Oh, and just to answer any potential questions, the temp gauge inside the car reads fine. It rises above the "C" after 2-5 minutes and stays between 1/3 and 1/2 of the way. Do you guys have any other ideas for this?

I have a used/junkyard mass air flow sensor in my garage. Gonna probably swap it out tomorrow and see if that helps. Other than that, the next thing I am going to look towards is my fuel system and exhaust system. My exhaust system is two years old. Bought the car a year ago, and have receipts for exhaust work from the year before. Not sure how long exhaust systems last though. I have no idea with the condition of the fuel system.

What are your guys' opinions? It looks like future repairs are gonna run me a bunch of money, so I want to get a solid opinion towards a solution before I start dishing out cash. I'm also going to the junkyard on Sunday, so anything I should pull off the cars that are there? Thanks.

Edited by jj421, 04 February 2013 - 09:18 PM.


#2 rdweninger

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Posted 05 February 2013 - 02:43 PM

Try these two simple things... in order.
Unplug the maf... does your car run any better? If so... then clean the maf wires and electrical connections with CRC maf cleaner... If that does not fix it... try your spare maf from the garage (clean it first).
Second...replace your fuel filter(s). There may be two for your car.
Let us know if it works.

#3 86 Wonder Wedge

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Posted 05 February 2013 - 04:04 PM

Unplug the ECU plug (at the ECU) and check for voltage at pin 45 (small, yellow connector 10 pin) should be above 10V with KOEO. I had an intermittent CEL for the idle air valve and turned out to bed a bad connector at the plug in the engine bay AND a missing pin-anchor at the ECU plug. Would NOT idle when cold and would dip/stall when coming down from 3K RPM..

You can also run jump leads right to the pins on the IAC valve from the battery (or 12V source and listen/look for the valve to open and close)

#4 jj421

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Posted 21 February 2013 - 12:20 AM

Unplug the ECU plug (at the ECU) and check for voltage at pin 45 (small, yellow connector 10 pin) should be above 10V with KOEO. I had an intermittent CEL for the idle air valve and turned out to bed a bad connector at the plug in the engine bay AND a missing pin-anchor at the ECU plug. Would NOT idle when cold and would dip/stall when coming down from 3K RPM..

 

Okay, first off, sorry for not responding earlier. Between school and work and other things, haven't really had time to address this.

 

Anyways, this sounds like my problem. Just went out to my car and took a look at the ECU. There are three yellow plugs that are hooked up to the ECU. So which plug is it? And how do I know which is pin 45? And what did you do to fix it; buy a new plug/wire?

 

Oh, and I also messed with the MAF a bit. I grabbed one from a junkyard, and when installed, the engine would just die, no matter if I tried to rev it. Then I installed the one from my garage, and it had no effect whatsoever. I didn't clean either one, though.

 

 


Edited by jj421, 21 February 2013 - 12:23 AM.


#5 ivantruckman

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Posted 21 February 2013 - 11:56 AM

http://www.leoneturb...1_SPI_guide.pdf

this write up is awesome , has great pics although it is for converting an ea81 engine to spfi

#6 jj421

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Posted 21 February 2013 - 04:38 PM

Sweet. I'll definitely read that when I get some time. I did however go to the page with the ECU connectors and found what I believe to be pin 45 on my car. I took the first yellow plug, a 10-pin plug, and probed the pin in the very middle on the clip side. With the key on, engine off, I got zero volts. I'm guessing that that's my problem? Or maybe I did the wrong pin.



#7 86 Wonder Wedge

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Posted 23 February 2013 - 03:18 AM

Yep, should be the 10-pin connector, and on the wire side (not ECU/ female side) it's the top row, dead center. (RIGHT under the release tab). IIRC, GR/Y wire.. but don't quote me..

 

And It should be 10+V at the ECU plug position 45 (described above, unplugged, of course) KOEO. If not, go into the engine bay and unplug the IAC connector and test for 10+V at the harness side connector on the W/R wire (I believe, one will have voltage, the other won't).HERE is where I had my problem. When I unplugged the connector, it would rest and I would have 12V. But when it was bent and plugged in, it would lose connection. Moral is, flex the connectors of both the IAC and harness side and check for intermittent connections.

 

If it is still ok, check ohms across IAC valve connector. Should be between 5-12 ohm.

 

If it still tests ok, then unplug the smaller of the 2 round large harness connectors on the driver's side, under the coil, aft of the battery tray. Check for voltage at the appropriate pin for 10+V, KOEO.

 

If STILL ok, then do continuity (resistance check) test from the body-side round bundle connector to the pin 45 in the ECU plug.

 

After that, and you still have 12V at the ECU, it might be the ECU.

 

Also, if the system checks out, plug the ECU back in, KOEO and actuate throttle with the IAC feed hose disconnected so you can see the pintle through the tube. As you bring the throttle off idle, the valve will open and shut.

 

You could also have a mal-adjusted TPS (the car thinking it's never at idle and the valve never opens to allow air into the chamber at idle). Run the voltage/resistance check according to the 89 FSM (the SPFI system is identical).

 

Good Luck!



#8 jj421

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Posted 23 February 2013 - 03:40 PM

Wow, thanks for the extremely detailed post!  :) I managed to do most of what you said, besides the two round connectors next to the battery. I'm gonna have to move some stuff in order to get to those. But yeah, I went out with my camera (I like photos) and did these tests.
 
 

Yep, should be the 10-pin connector, and on the wire side (not ECU/ female side) it's the top row, dead center. (RIGHT under the release tab). IIRC, GR/Y wire.. but don't quote me..
 
And It should be 10+V at the ECU plug position 45 (described above, unplugged, of course) KOEO.

 
Okay, I wasn't exactly sure which of the middle pins it was, so I tested both. And well....
 
P1130553_zpsf4679b32.jpg
 
P1130561_zpsb9301604.jpg

 

If not, go into the engine bay and unplug the IAC connector and test for 10+V at the harness side connector on the W/R wire (I believe, one will have voltage, the other won't).HERE is where I had my problem. When I unplugged the connector, it would rest and I would have 12V. But when it was bent and plugged in, it would lose connection. Moral is, flex the connectors of both the IAC and harness side and check for intermittent connections.

 

Okay, went under the hood, unplugged the connector, and tested it.

P1130554_zps8b00057a.jpg

So that seems to check out perfectly fine.

 

If it is still ok, check ohms across IAC valve connector. Should be between 5-12 ohm.

 

P1130556_zpsf7706de5.jpg

Got 9.4 ohms, so that is okay.

 

If it still tests ok, then unplug the smaller of the 2 round large harness connectors on the driver's side, under the coil, aft of the battery tray. Check for voltage at the appropriate pin for 10+V, KOEO.

If STILL ok, then do continuity (resistance check) test from the body-side round bundle connector to the pin 45 in the ECU plug.

After that, and you still have 12V at the ECU, it might be the ECU.

 

Again, like I said, I didn't test this. However, a quick look down there reveals that connectors look like they're about to disintegrate when I touch them, haha.

P1130560_zpsa821d283.jpg

I can't do that resistance check, as my multimeter leads are nowhere near long enough. But I have a feeling one of the wires corroded and my problem lies in there.

 

Also, if the system checks out, plug the ECU back in, KOEO and actuate throttle with the IAC feed hose disconnected so you can see the pintle through the tube. As you bring the throttle off idle, the valve will open and shut.

 

Did this. Undid the hose to the IACV, plugged everything back in, turned the key to the on position, and played with the throttle. I noticed no movement whatsoever inside the IACV.

 

You could also have a mal-adjusted TPS (the car thinking it's never at idle and the valve never opens to allow air into the chamber at idle). Run the voltage/resistance check according to the 89 FSM (the SPFI system is identical).

 

This was another thing that I was thinking about that could cause this problem. I can't find the "good" voltages/resistances for this though, and I don't know how to test it.

But yeah, so maybe this can help you tell me where I am and what I should do from here. When I get a chance, I can test those round connectors.



#9 matts87glsedan

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Posted 26 February 2013 - 11:51 AM

bump for an update? there is some good info here. 



#10 ivantruckman

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Posted 26 February 2013 - 01:36 PM

if you apply 12 volts to the iac valve you should hear a distinct click  as the solenoid coil opens the valve . there pretty durable, the most likely cause of failure is corroded or broken wires going to the solenoid itself.

 

and the TPS  does have an adjustment , its mounting holes are slotted ,  but putting it in the middle should be fine , it takes some movement before it begins to react to your ohm meter . I think the slots are designed to adjust the sensor so it doesn't cause the throttle plates to stay open .  Im going thru the same thing , hang in there , you will find it.


Edited by ivantruckman, 26 February 2013 - 01:42 PM.





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