Technical => Engine Tech => Topic started by: midnight cat on April 19, 2018, 05:39:50 PM
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on April 19, 2018, 05:39:50 PM
My 1986 Cougar 3.8 L V6 won't idle on its own. The milage is 135,000, which is relatively low for the age. If I manually spray starter fluid down into the throttle body the car starts right up and runs great until the fuel is burned off. I have replaced or done the following: 1. replaced the fuel pressure regulator 2. replaced the fuel injectors 3. replaced the control module 4. replaced the pick up coil 5. replaced the fuel filter 6. replaced the computer 7. replaced the battery cables 8. fuel pump is ok and fuel pressure is good 9. Bought a tune up kit for the throttle body and did that
After doing all of this there is no change and the car will not idle on its own. ANY ideas on how to get this car running again???
Title: 1986 Cougar 3.8 L won't idle.
Post by: JeremyB on April 19, 2018, 07:26:58 PM
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on April 19, 2018, 07:59:28 PM
Yes, same car - and very frustrating. And now it's over at a car repair shop and they say it's not showing any codes. Maybe this could be because the battery was disconnected over the winter therefore all codes would have been lost? Also, since they put a new computer in it would it show codes without being driven? The car hasn't been driven any distance since the "it won't idle" problem started last summer. The mechanic said the only thing they can think of doing is to replace the throttle body…this doesn't make sense to me since the throttle body has already been rebuilt/cleaned when I installed the new injectors. What do you think?
Also, I never did pull a spark plug to see if they could be the problem. Could new plugs solve this? I am lost…
Title: 1986 Cougar 3.8 L won't idle.
Post by: thunderjet302 on April 20, 2018, 12:45:11 AM
Did they actually check the codes or just look to see if the check engine light was on? These cars can still have fault codes with the check engine light off.
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on April 20, 2018, 01:15:29 AM
Quote from: thunderjet302;465347
Did they actually check the codes or just look to see if the check engine light was on? These cars can still have fault codes with the check engine light off.
The check engine light hasn't worked in the car for years. The mechanic I had the car towed to has the diagnostic equipment to check for codes even if the light isn't working or so I am told. He said it was throwing no codes. Besides, wouldn't the car need to be driven for a certain amount of time (miles) before it would show codes after the battery was disconnected for months (during the this past winter)?
Title: 1986 Cougar 3.8 L won't idle.
Post by: softtouch on April 20, 2018, 04:50:48 PM
Won't run or won't idle?
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on April 20, 2018, 05:34:42 PM
Quote from: softtouch;465351
Won't run or won't idle?
If I spray starter fluid (or pour in gasoline) directly into the throttle body the car runs great until it burns the fuel off. Also, I replaced the throttle body sensor (TPS) as well but it hasn't made any difference. Any ideas?
Title: 1986 Cougar 3.8 L won't idle.
Post by: softtouch on April 21, 2018, 01:37:38 PM
Well it sounds like a fuel delivery problem. You said (maybe in your other thread) that you had good fuel pressure. Was this checked at the Schrader valve test point in the CFI (throttle body)? If you have pressure at the fuel filter and not at the CFI, check for a crushed fuel line between the two.
If you have pressure at the CFI, check if the injectors are spraying fuel while cranking. Look, smell. dangle something in there to see if it gets gas on it.
If the injectors are spraying you may have a vacuum leak that is making the fuel/air mixture too lean to run.
"Good" fuel pressure is 39 psi.
Title: 1986 Cougar 3.8 L won't idle.
Post by: TheFoeYouKnow on April 21, 2018, 05:12:31 PM
Parts artillery, Ready, Aim, FIRE! or You could try testing. You've got lots of really technical guys here, who understand the product deeply and have very valuable insights and advice. You were asked if it doesn't run, or runs but doesn't idle. Translation: If you DON'T give it alternative fuel, will it start and remain running with throttle applied? This is a critical distinction, because if it runs with your foot on the gas, you could have one set of problems (such as a failed idle speed control motor or a large vacuum leak), but if it doesn't run at all, you could have a DIFFERENT set of problems (like no injector pulse, poor fuel volume, a failed MAP sensor, etc).
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on April 23, 2018, 02:42:25 AM
Thanks to all trying to help me with my Cougar. I am not a mechanic so please forgive my ignorance. To be clear, it will not start with the throttle applied. It will only start if fuel is manually sprayed or poured directly into the TBI.
Title: 1986 Cougar 3.8 L won't idle.
Post by: TheFoeYouKnow on April 23, 2018, 06:49:28 AM
The backbone of the diagnostic process it SSCC, or Symptom, System, Component, Cause. Symptom - crank/no-start System - fuel system. When alternate fuel is introduced, the symptom is temporarily resolved Component - ? Cause - ?
This is where you are in the process. Here are the questions to ask: what are the components in the fuel delivery system?, which ones are working? Your other posts, talk about fuel pressure. You have roughly 40 psi? if that's the case, you can rule out the pump, it's wiring, and it's command, as well as the lines. You have a new regulator, so lets assume it's good. That leaves injectors (2) and wiring. Test: with key on, the injectors should have power, but not ground. Disconnect the injector connectors and check for power with a multi-meter. If you don't have one, a test light will do for now. If there's power, you'll want to see if the EEC is pulsing them on (by grounding them). To do that, you'll want to get what's called a "noid" light. If you plug in the noid light to the injector connector, and it flashes while you're cranking the engine (on both) your injectors are being fired. Are they actually spraying fuel? If yes, something got missed, if no, you have Component
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on April 23, 2018, 12:34:11 PM
Thanks for the suggestion! I think the mechanic already tried this test but I will pass this on to him - I am heading over there now. I miss my car!
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on April 23, 2018, 03:55:15 PM
Quote from: TheFoeYouKnow;465367
The backbone of the diagnostic process it SSCC, or Symptom, System, Component, Cause. Symptom - crank/no-start System - fuel system. When alternate fuel is introduced, the symptom is temporarily resolved Component - ? Cause - ? This is where you are in the process. Here are the questions to ask: what are the components in the fuel delivery system?, which ones are working? Your other posts, talk about fuel pressure. You have roughly 40 psi? if that's the case, you can rule out the pump, it's wiring, and it's command, as well as the lines. You have a new regulator, so lets assume it's good. That leaves injectors (2) and wiring. Test: with key on, the injectors should have power, but not ground. Disconnect the injector connectors and check for power with a multi-meter. If you don't have one, a test light will do for now. If there's power, you'll want to see if the EEC is pulsing them on (by grounding them). To do that, you'll want to get what's called a "noid" light. If you plug in the noid light to the injector connector, and it flashes while you're cranking the engine (on both) your injectors are being fired. Are they actually spraying fuel? If yes, something got missed, if no, you have Component
The mechanic has done the noir test and the injectors are firing as they normally should. However, they aren't getting any fuel. When starter fluid is sprayed into the TBI the car starts right up and the only way to keep it running is my pressing the gas pedal repeatedly. The car isn't drivable currently. My mechanic had a question: How does this car normally at start up get fuel to the injectors?
Title: 1986 Cougar 3.8 L won't idle.
Post by: TheFoeYouKnow on April 23, 2018, 11:31:42 PM
You have fuel pressure? Roughly 40 psi? Can fuel be seen spraying when the engine is cranking?
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on April 24, 2018, 03:08:43 AM
Quote from: TheFoeYouKnow;465388
You have fuel pressure? Roughly 40 psi? Can fuel be seen spraying when the engine is cranking?
I do know the fuel pressure is good. The psi is 35 or more which according to the shop manual is correct for a 1986 model. I will check with the mechanic to see if fuel is spraying when the engine is cranking. I don't think it is because if it was wouldn't the car start? The only way this car starts now is when starter fluid (or carb. cleaner) is sprayed directly into the TDI.
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on April 24, 2018, 03:14:17 AM
Quote from: midnight cat;465390
I do know the fuel pressure is good. The psi is 35 or more which according to the shop manual is correct for a 1986 model. I will check with the mechanic to see if fuel is spraying when the engine is cranking. I don't think it is because if it was wouldn't the car start? The only way this car starts now is when starter fluid (or carb. cleaner) is sprayed directly into the TDI.
If fuel can be seen spraying while cranking the engine what does that indicate? Does that mean it's not getting enough fuel and that's why it needs alternate fuel as well to start?
Title: 1986 Cougar 3.8 L won't idle.
Post by: JeremyB on April 25, 2018, 11:11:54 AM
Per your previous post, the car runs just fine with the exception that it won't idle without your foot on the gas pedal?
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on April 25, 2018, 04:47:00 PM
Quote from: JeremyB;465408
Per your previous post, the car runs just fine with the exception that it won't idle without your foot on the gas pedal?
Correct.
Title: 1986 Cougar 3.8 L won't idle.
Post by: JeremyB on April 25, 2018, 05:38:51 PM
Quote from: JeremyB;461926
Highly doubtful. TPS or ISC are my first thoughts, but get the KOEO and KOER codes to give you some better direction.
Quote from: JeremyB;462561
I had to look it up myself to make sure I wasn't forgetting things. Getting old! (https://www.nmr.mgh.harvard.edu/~reese/MegaSquirtArticle/CFI%20ISC%202.jpg) ISC = Idle Speed Control. CFI's method to control idle. It physically moves the throttle blade to adjust airflow. IAC sends air through it and bypasses the throttle blades.
This...
You didn't indicate what the actual code that was thrown... Have you verified voltage at idle?
Although the 3.8 likes to blow head gaskets, the earlier ones aren't nearly as bad as the latter. Mine made it 226k before blowing.
Still my first thought. No offense, but not sure your mechanics have the background to solve the problem without just throwing parts at it.
Title: 1986 Cougar 3.8 L won't idle.
Post by: sarjxxx on April 25, 2018, 06:44:19 PM
Quote from: JeremyB;465421
ISC = Idle Speed Control. CFI's method to control idle. It physically moves the throttle blade to adjust airflow. IAC sends air through it and bypasses the throttle blades.
I'm thinking if this were the case though it would be causing a deficiency in air delivery, not fuel delivery right? Spraying alternative fuel should have no effect if its a case of not enough air making it through the TV
Title: 1986 Cougar 3.8 L won't idle.
Post by: JeremyB on April 25, 2018, 08:27:59 PM
Derp. Yeah.
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on April 26, 2018, 02:12:31 AM
Quote from: JeremyB;465421
Still my first thought. No offense, but not sure your mechanics have the background to solve the problem without just throwing parts at it.
I agree. I have lost confidence in the mechanics ability to diagnose as well. When I couldn't solve the problem myself I had the car towed to the mechanic because they had a reputation for working on Mustangs. Tomorrow they are replacing the idle speed control and rebuilding the throttle body (it was already rebuilt last summer) because we can't find a rebuilt TBI. I don't know if this will be fix the problem…I have my doubts. I can't keep dumping money into this car even though I've had it for 32 years. If I have to have it towed home I think I need to sell it.
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on April 26, 2018, 02:20:25 AM
Quote from: JeremyB;465425
Derp. Yeah.
How does this car normally at start up get fuel to the injectors? Does anyone have an answer to this question?
Title: 1986 Cougar 3.8 L won't idle.
Post by: TheFoeYouKnow on April 26, 2018, 06:53:33 AM
The fuel pump powers up for a few seconds to prime the line when you turn on the key, then comes on again once you start cranking. If you turn the key on, but don't crank the engine, you should hear it happening.
Title: 1986 Cougar 3.8 L won't idle.
Post by: JeremyB on April 26, 2018, 11:18:53 AM
Quote from: sarjxxx;465423
I'm thinking if this were the case though it would be causing a deficiency in air delivery, not fuel delivery right? Spraying alternative fuel should have no effect if its a case of not enough air making it through the TV
Not sure why I brain-freezed in my original reply.
Don't have the manual in front of me so I can't remember how it is supposed to function. The ISC has 4 pins. Power, +actuation (more throttle), -actuation (less throttle), and signal return which lets the ECU know the ISC is touching the throttle bracket (when the ISC touches the throttle bracket, a ground path is enabled. Might get some wonkiness if the ground isn't working. Or the TPS could be out of range. While cranking, WOT TPS voltage is a signal to not run the injectors to clear a flooded condition. The noid light results seem to refute that though.
A 'tired' injector might have issues responding to low idle pulse widths, but the've been replaced. The fact that is runs fine while not idling should rule out fuel/spark availability - at least initially.
There is a powertrain/troubleshooting manual that should have proper procedures to run through - but I highly doubt they have one.
What is the lowest rpm that the engine will run in idle? What is the position/voltage of the ISC/TPS at this rpm? What happens when you drop below it?
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on April 26, 2018, 01:12:44 PM
Quote from: TheFoeYouKnow;465433
The fuel pump powers up for a few seconds to prime the line when you turn on the key, then comes on again once you start cranking. If you turn the key on, but don't crank the engine, you should hear it happening.
Ok thanks!
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on April 26, 2018, 01:27:12 PM
Quote from: JeremyB;465436
Not sure why I brain-freezed in my original reply.
Don't have the manual in front of me so I can't remember how it is supposed to function. The ISC has 4 pins. Power, +actuation (more throttle), -actuation (less throttle), and signal return which lets the ECU know the ISC is touching the throttle bracket (when the ISC touches the throttle bracket, a ground path is enabled. Might get some wonkiness if the ground isn't working. Or the TPS could be out of range. While cranking, WOT TPS voltage is a signal to not run the injectors to clear a flooded condition. The noid light results seem to refute that though.
A 'tired' injector might have issues responding to low idle pulse widths, but the've been replaced. The fact that is runs fine while not idling should rule out fuel/spark availability - at least initially.
There is a powertrain/troubleshooting manual that should have proper procedures to run through - but I highly doubt they have one.
What is the lowest rpm that the engine will run in idle? What is the position/voltage of the ISC/TPS at this rpm? What happens when you drop below it?
I don't have the answers to your questions but I will ask the mechanic. Thanks!
Title: 1986 Cougar 3.8 L won't idle.
Post by: TheFoeYouKnow on April 26, 2018, 01:51:32 PM
His alt fuel probably has higher a oxygen content, similar to alcohol, so that the alt fuel brings extra oxygen with it. What happens if you create a small vacuum leak like disconnecting the PCV valve from the throttle body? (might be too large a leak, maybe cover with a thumb and let the port bleed a little)
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on April 27, 2018, 02:39:35 AM
Quote from: TheFoeYouKnow;465441
His alt fuel probably has higher a oxygen content, similar to alcohol, so that the alt fuel brings extra oxygen with it. What happens if you create a small vacuum leak like disconnecting the PCV valve from the throttle body? (might be too large a leak, maybe cover with a thumb and let the port bleed a little)
Any type fuel will start the car up when manually introduced to the TBI - I've used carb. cleaner, starter fluid and 93 octane raw gas. Could bad gas in the tank cause the idling problem? Haven't tried removing the PCV valve to create a vacuum leak.
Title: 1986 Cougar 3.8 L won't idle.
Post by: TheFoeYouKnow on April 27, 2018, 06:49:52 AM
What we need is someone who still has the 86 PC/ED manual.
Title: 1986 Cougar 3.8 L won't idle.
Post by: softtouch on April 27, 2018, 04:00:41 PM
Have the mechanic hook a vacuum gauge to the intake manifold. Start the engine and put something between the ISC(idle speed control) motor plunger tip and throttle linkage pad to keep the throttle open to where it will keep running at a steady RPM.
Scenario 10 & 12 check for a vacuum leak in the following write-up. http://www.secondchancegarage.com/public/186.cfm
Title: 1986 Cougar 3.8 L won't idle.
Post by: jcassity on May 05, 2018, 10:01:58 AM
tbi = chevy
cfi = ford
on the bottom rear driver side of the cfi there is a gold metal vac line fitting.
flip the cfi over and if that area if full of carbon build up, you will have the problem your speaking of.~yet you said the cfi was recently rebuit.
in my diy link there is a lot of cfi tips but.....
first,,,,
do you have fuel presure at the shrader= YES
do you have "whiteish blue spark"??????????
is the compression good enough across all cylinders.??????
since the car sat all winter,, eliminate bad gas by doing this (in diy link).... -jumper the tan / light green wire to the frame of the car at the triangle shaped code pulling connector in the engine bay up by the master cylinder. -disconnect the fuel supply line at the rear of the CFI -rig up a hose on the end like a garden hose or something that about 5' long. -drop the hose into a container to catch fuel. -turn the key "FORWARD ONLY" -the fuel pump will run 100% of the time now and extract all the fuel from the tank. -when fuel is done dumping, turn off key and button things up then remove jumper wire. -add new fuel -turn key on for 5 seconds and turn key off , repeat this 3 times to "refill" your fuel lines and fuel system bad fuel may be the reason why when you introduce "different fuel" the car runs
------------------------------------------------------------ on this car,, to answer your earlier question.................. you should never need to push on the gas to start... if its pushed to the floor, the fuel injectors actually shut off. -in the trunk there is a fuel pump relay located "most of the time" outboard of the passanger side trunk hinge. -there is a safety switch if rear ended, located "sometimes" inside the trunk on the rear driver side, black box with a white button. -this safety switch removes power delivery from the fuel pump -if you push the button down, that allows power to reach the fuel pump.
-------------------------------------- just notes / fyi for your future information.............. if the fuel pump is not powering up..... -go to the fuel pump relay in the trunk -there will be a small tan/light green wire. -side tap and ground the tan/ light green wire and ground it to the frame of your car. -if car starts,, let us know.
Title: 1986 Cougar 3.8 L won't idle.
Post by: jcassity on May 05, 2018, 10:04:46 AM
second rabbit hole to go down...
by chance did anyone decide to pull the distributor ?
i say yes because you say you replaced the pick up ,, which is down inside the distributor,, and ....so..............
did they dial in top dead center perfectly and drop in the distributor or is is possibly off one tooth??
i know from personal experience that the 3.8L cfi **WILL NOT** tolerate being off one tooth,, no matter if the tech says "well i should be able to adjust one way or the other for that".,,, nope,, noda. being off one tooth may not cause a backfire but *will* cause the symptom you are having.
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on May 31, 2018, 01:52:32 AM
Quote from: softtouch;465463
Have the mechanic hook a vacuum gauge to the intake manifold. Start the engine and put something between the ISC(idle speed control) motor plunger tip and throttle linkage pad to keep the throttle open to where it will keep running at a steady RPM.
Scenario 10 & 12 check for a vacuum leak in the following write-up. http://www.secondchancegarage.com/public/186.cfm
Soft touch - We will give it a try. Thanks!
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on May 31, 2018, 01:57:33 AM
Quote from: jcassity;465560
second rabbit hole to go down...
by chance did anyone decide to pull the distributor ?
i say yes because you say you replaced the pick up ,, which is down inside the distributor,, and ....so..............
did they dial in top dead center perfectly and drop in the distributor or is is possibly off one tooth??
i know from personal experience that the 3.8L cfi **WILL NOT** tolerate being off one tooth,, no matter if the tech says "well i should be able to adjust one way or the other for that".,,, nope,, noda. being off one tooth may not cause a backfire but *will* cause the symptom you are having.
Thanks jcassity. I will deliver your ideas to the mechanic as well. Sorry for not responding sooner but I've been busy on other projects. Hopefully one of your solutions will lead to fixing this. I miss my Cougar.
Title: 1986 Cougar 3.8 L won't idle.
Post by: softtouch on May 31, 2018, 02:40:49 PM
Another thing came to mind, the 3.8L CFI cars use a time delay relay for the EEC power. The relay takes about 5-10 seconds to drop out after you turn the key off. If you listen real close to the center area of the dash, you can hear it click when it drops.
This gives the EEC time to go through a shutdown routine before it turns off. The EEC will extend the ISC motor plunger to a "fast idle" position to prepare for the next start-up. (The engine has already stopped) Don't know if it does anything else.
If someone put a standard relay in the EEC power relay socket, you will lose this shut-down procedure.
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on August 15, 2018, 05:25:04 PM
So it's now August 15 and the car still isn't getting enough fuel to the new injectors to make the car idle. Could the solution be to replace the entire distributor? The distributor in the car now is the original. Any thoughts??
Title: 1986 Cougar 3.8 L won't idle.
Post by: Mikey97D on August 16, 2018, 11:14:12 AM
Does the car have fuel pressure? What is the fuel pressure?
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on August 16, 2018, 03:04:47 PM
Quote from: Mikey97D;466778
Does the car have fuel pressure? What is the fuel pressure?
The fuel pressure is 35, which is what it should be. That was the first thing I checked. Any other ideas? Thanks!
Title: 1986 Cougar 3.8 L won't idle.
Post by: Mikey97D on August 16, 2018, 03:19:13 PM
Quote from: midnight cat;466779
The fuel pressure is 35, which is what it should be. That was the first thing I checked. Any other ideas? Thanks!
Are the injectors getting signal to pulse/open?
Title: 1986 Cougar 3.8 L won't idle.
Post by: thunderjet302 on August 16, 2018, 04:30:00 PM
Distributor isn't the culprit. It's either a fuel flow issue or something in the injector harness.
Edit: Are you sure the fuel pump is getting full power?
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on August 16, 2018, 04:30:57 PM
Quote from: Mikey97D;466780
Are the injectors getting signal to pulse/open?
Yes.
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on August 16, 2018, 04:35:41 PM
Quote from: thunderjet302;466781
Distributor isn't the culprit. It's either a fuel flow issue or something in the injector harness.
Edit: Are you sure the fuel pump is getting full power?
The injectors are new. What do you mean by the injector harness? Fuel pressure is good. What do you mean by fuel pump getting full power?
Title: 1986 Cougar 3.8 L won't idle.
Post by: thunderjet302 on August 17, 2018, 12:02:32 AM
Quote from: midnight cat;466784
The injectors are new. What do you mean by the injector harness? Fuel pressure is good. What do you mean by fuel pump getting full power?
Is there 12-13 volts at the fuel pump connector? Is there any damage to the wiring harness that plugs into the injectors?
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on August 17, 2018, 02:20:27 AM
Quote from: thunderjet302;466786
Is there 12-13 volts at the fuel pump connector? Is there any damage to the wiring harness that plugs into the injectors?
Thanks Thunderjet. My car is still at the repair shop (pushed off to the side of their shop). I don't have the answers to your last 2 questions. I'll ask the mechanic(s) tomorrow. Even though I already replaced the distributor control module and pick up coil 5 months ago, their plan now is to replace the entire distributor. If that doesn't make the car run they want me to have the car towed back home. This whole thing is very frustrating.
Title: 1986 Cougar 3.8 L won't idle.
Post by: Mikey97D on August 17, 2018, 08:25:53 AM
IMO, I would find another garage. Does this garage have an ASE Master Mechanic?
Title: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on August 17, 2018, 01:37:47 PM
Quote from: Mikey97D;466790
IMO, I would find another garage. Does this garage have an ASE Master Mechanic?
I don't know if they are ASE Master mechanics. I had the car towed to them because they specialize in working on fox body mustangs. I figured since my '86 Cougar is also a fox body car they would have the answer.
Title: Re: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on June 21, 2020, 02:25:32 AM
Ok, so it's been over 2 years since I started this thread about my 86 Cougar. The car has been back home for over 2 years now and still won't idle. It will start right up when I spray carb cleaner down the TDI. Two different mechanics tried to fix the car but neither could figure out why it won't idle. It is not throwing any codes. As I mentioned at the start of this thread, I replaced a lot of parts to try to fix the car including the computer. The second mechanic replaced the original computer more than 2 years ago. I recently found out he replaced the original computer with a computer from a 86 Mustang in the junkyard. Could that be the problem? If I bought a new rebuilt computer ($93) and installed that could it maybe solve the problem? Please let me know what you guys think. Thanks!
Title: Re: 1986 Cougar 3.8 L won't idle.
Post by: softtouch on June 21, 2020, 08:43:34 PM
What method are you using to pull codes? There should always be some codes. The KOEO (Key On Engine Off) self test will test the sensor inputs to the EEC. If it finds a sensor out of specs it will post a fault code. If it successfully completes the tests without finding any faults it will post a nofaults code.
Title: Re: 1986 Cougar 3.8 L won't idle.
Post by: softtouch on June 23, 2020, 04:10:47 PM
Trying to avoid going the same rabbit hole of two years ago. The starting point should be to use the tools that are built into the EEC. If the KOEO shows no fault codes and also no code 11 to indicate the test ran successfully. this is where the trouble shooting should begin. I don't know if you have ever run the self tests or if you are still relying on what the mechanic said 2yrs ago.
If you are willing to acquire some basic tools. and willing to learn, I am willing to try to help.
Title: Re: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on June 27, 2020, 03:31:03 PM
Thanks for the advice. Is installing a new rebuilt computer a waste of time?
Title: Re: 1986 Cougar 3.8 L won't idle.
Post by: Haystack on June 28, 2020, 01:21:19 AM
Why replace something if you don't know if its broken?
I hate to say it, but there are really only maybe 6 wires the car needs powered up to run and there are really only a few critical sensors. The computer will tell you if things aren't working.
If you don't want to check if the computer is working, I really don't see much point in trying to fix the car.
It takes two minutes and a paper clip. Most 86's done have a check engine light, so we have to use a test light or a 12v buzzer or an buttstuffog volt meter.
Title: Re: 1986 Cougar 3.8 L won't idle.
Post by: midnight cat on July 05, 2020, 01:24:57 AM
The car has a check engine light but it doesn't work. I am not a mechanic. Is there a ASE master mechanic in the Dallas area in the group who can help me with this car?
Title: Re: 1986 Cougar 3.8 L won't idle.
Post by: Haystack on July 05, 2020, 02:43:40 PM