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Author Topic: Idle issue and gauges not working  (Read 2138 times)

That1guy

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    • 91 Mercury Capri XR2
Idle issue and gauges not working
« on: March 08, 2021, 09:29:24 PM »

I recently bought a 91 xr2 with 94k miles and when it cold starts, it will idle at 1500 then slowly rise over about 5-15mins until it hits 2000. It'll sit a 2k for 5-10mins and throw a check engine light. After about 5 more minutes and it warming up the rpm will slowly drop until it's a 800-900 like it should be and the check engine light goes away. Once its warm there is no problem. I've done multiple oil changes with full synthetic 5W-30 and replaced the pcv valve, thermostat, and coolant temp sensor. I replaced the coolant temp sensor in hopes my temp guage would start working and possibly fix the idle issue, but no luck. Is there another temp sensor other than the one in the thermostat housing? If anyone could help me out with this idle issue I would greatly appreciate it.  EDIT - It just started stalling out when warm started, doesn't die but its idling very low. After driving for 30sec its idling fine


Thanks - That1guy
« Last Edit: March 08, 2021, 11:12:19 PM by That1guy »
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Rocketman

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    • 91 BPT AWD Capri & 1991 XR2
    • http://www.werbatfik.com
Re: Idle issue and gauges not working
« Reply #1 on: March 09, 2021, 03:30:03 AM »

Idle issue:
It could be many things, but possibly a clogged idle valve. The idle valve has an electronic side and a mechanical side, the mechanical side has what is known as a "wax motor" which uses engine coolant to warm a cylinder full of wax. As the wax melts it expands, closing a needle valve and lowering idle. If the small coolant lines feeding the idle valve are not moving coolant, or the passages in the idle valve are blocked, the wax won't melt until the whole of the engine is warm. You could start by checking for coolant flow through the valve.

The other thing you can check for: When the car is at fast idle, can you manually close the throttle under the hood to lower the idle? There is a thing called a dashpot on the throttle that lets the throttle close softly at the end of its travel, this can sometimes hold the throttle open slightly. If the idle lowers by closing the throttle, it is something to look at.

Temp sensor:
There are three sensors in the Capri pertaining to coolant. The sensor in the thermostat housing is the fan switch, it turns on the fan. That's its only job. There is a sensor in the head on the other side of the thermostat, pointed to the firewall, with a round pin connector - that is the gauge's sensor. Check to make sure it is connected.
The third coolant sensor is for the ECU, it is installed in the bottom of the intake manifold in the flange that bolts to the head.

Have you pulled the code to see what it is? You can do this by jumpering the test terminal under the hood, key on engine off, and counting the check engine light flashes. They are coded, there is a lookup chart on the main teamcapri.com domain along with some more information.

And welcome to TeamCapri! Hope this information is useful.
-Matt "Rocketman"
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1.8L Turbo All Wheel Drive Capri... the "GTXR2"


That1guy

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    • 91 Mercury Capri XR2
Re: Idle issue and gauges not working
« Reply #2 on: March 09, 2021, 01:42:43 PM »

Cool thanks for the info. I didn't know the bacv worked like that and I couldn't find the other sensors for the life of me, so thanks :D. Im gonna clean the idle air valve today and see if there is any change. As for the sensor I will mkae sure its connected and if it is Ill take it off and test it.  I havent pulled the codes yet but I will next time it comes on.  Ill make a post letting you know how it goes. EDIT - I cleaned the idle air valve, no coolant was able to pass through it but its all good now. I got curious and took off the top part with the plug that houses the spring but now realize I dont know how to adjust the idle screw. Its idling a bit low now a starts to bog as it warms. I would tighten the screw to decrease the idle and lossen it to increase? Or do I have that backwards? Also are you supposed to adjust it with the car running? Hot or cold? If you could tell me how I would greatly appreciate it. EDIT 2 - Nvm I figured it out you just tighten it to decrease the air and loosen to increase. Got it idling perfect now, no problems.


Thanks - That1guy
« Last Edit: March 11, 2021, 12:59:47 AM by That1guy »
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greywolf27030

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    • 1991 XR2, 1992 XR2, 1993 XR2
Re: Idle issue and gauges not working
« Reply #3 on: March 10, 2021, 09:17:43 AM »

I have to clean my IAC also, how did you go about it?
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Jack Byrd

That1guy

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    • 91 Mercury Capri XR2
Re: Idle issue and gauges not working
« Reply #4 on: March 11, 2021, 12:57:43 AM »

Nothing special, just hooked up a power nozzle to a hose spicket and ran water through the coolant lines. I also let it fill with water and shook it up good about a dozen times. Afterwards I took and air compressor and ran air through the coolant and air lines. Tested it by blowing through it lol. Im sure theres better ways to clean it but I wanted to be quick. Hope this helps

-That1guy
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jdp

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    • 1994 Magenta Capri NA, 94 Reef greenXR2 and 92 XR2
Re: Idle issue and gauges not working
« Reply #5 on: March 14, 2021, 02:02:36 PM »

I usually use MAF spray cleaner to do the vacuum side and let it drain out.  Worked well when I had to do the IAC on my wife's 94.
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John

greywolf27030

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    • 1991 XR2, 1992 XR2, 1993 XR2
Re: Idle issue and gauges not working
« Reply #6 on: March 15, 2021, 09:08:49 AM »

So far I've tried WD49, TB cleaner and now PB Blaster, but to no avail. I don't have any way to apply pressure to it, so I'm going to try that this afternoon.
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Jack Byrd