Engine 1993 GT - Engine dies when letting out clutch in gear.

Calcul0n

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Feb 7, 2018
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I have a 1993 Mustang GT that starts fine, idles fine, and revs fine, but when I try to drive in 1st or reverse, the engine quickly dies.
I made a video and here are some notes:
0:22 - Just revving to show it seems ok.
0:45 - Shift to first and try driving the car forward (engine dies)
1:05 - 1:25 - Idle is bouncing around (maybe because I recently unplugged battery?)
1:40 - Attempt 2 at driving forward
1:56 - Attempt 3, rev higher and drive forward
2:03 - Attempt 4, you get the idea.

View: https://www.youtube.com/watch?v=1VnK82dyWDM


Here are my mods:
1. Explorer intake (non-EGR version). I drilled and tapped runner 5 for ACT sensor.
2. Removed EGR valve from intake with a delete plate (https://static.summitracing.com/global/images/prod/xlarge/TFS-51500075_xl.jpg), and the associated delete plug for the EGR connector
3. Removed EGR Vacuum Regulator
4. Removed TAD/TAB solenoids
5. Removed most vacuum lines on passenger side. Only lines there now are the big A/C line that comes from the main tree, then that branches into the firewall for A/C, and there is another vacuum line going to the passenger wheel well (not sure what it is).
6. Smog pump delete
7. Removed clutch safety switch
8. 24 lb. injectors
9. MAF calibrated for 24 lb. injectors

My check engine codes are (my comments in parentheses):
34 O,R,C Canister or EGR valve control circuit or EVP voltage high (either my EGR delete plug isn't working, or leaving the EGR vacuum regulator unplugged is causing this)
67 O,R,C Neutral Drive Switch fault, switch circuit open / Air conditioner on during self-test (Probably from #7?)
81 O Air diverter solenoid fault, intake air control circuit fault / air injection diverter (TAD/TAB removal and leaving connectors unplugged?)
82 O Air diverter solenoid circuit fault or supercharger bypass circuit fault (TAD/TAB removal and leaving connectors unplugged?)
84 O,R EGR control circuit (Could be caused by EGR delete plug not working?)

Can anyone give me some advice as to what I should do? I checked the timing with the spout removed and set it to about 11 degrees, I set the idle, I replaced my TPS and made sure it reads 0.95. I cleaned the IAC a short time ago.
 
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You are a victim of your own efforts - #7 on your list. Now the engine will not dump the engine running codes and doesn't know what to do when you let the clutch out.


Code 67
Revised 18-Mar-2017 to include warning about the necessity of having a 5 speed O2 Sensor wiring harness when bypassing the wiring for test purposes

Cause of problem:
Clutch not depressed (5 speed) or car not in neutral (5 speed and auto) or not in park (auto) or A/C in On position when codes where dumped. Possible neutral safety switch or wiring problem. This code will prevent you from running the Key On Engine On tests.

External evidence from other sources claims that a code 67 can cause an idle surge condition. Do try to find and fix any issues with the switch and wiring if you get a code 67.

What the NSS (Neutral Safety Switch) does:
5 speed transmission: It has no connection with the starter, and the engine can be cranked without it being connected.
Auto transmission: It is the safety interlock that prevents the starter from cranking the engine with the transmission in gear.
What it does for both 5 speed and auto transmission cars:
The computer wants to make sure the A/C is off due to the added load on the engine for the engine running computer diagnostic tests. It also checks to see that the transmission is in Neutral (5 speed and auto transmission) and the clutch depressed (T5, T56, Tremec 3550 & TKO)). This prevents the diagnostics from being run when the car is driven. Key On Engine Running test mode takes the throttle control away from the driver for several tests. This could prove hazardous if the computer was jumpered into test mode and then driven.

The following is for 5 speed cars only. Do not do this unless you are sure that you have a 5 speed O2 Sensor harness!!!! Smoke, sparks and expensive pain in the wallet may ensue if you don’t.
The NSS code 67 can be bypassed for testing. You will need to temporarily ground computer pin 30 to the chassis. Computer pin 30 uses a Lt blue/yellow wire. Remove the passenger side kick panel and then remove the plastic cover from the computer wiring connector. Use a safety pin to probe the connector from the rear. Jumper the safety pin to the ground near the computer.
Be sure to remove the jumper BEFORE attempting to drive the car!!!

a9x-series-computer-connector-wire-side-view-gif.71316




Removing the pollution control equipment from a 5.0 Mustang is a bad idea. All you have accomplished is to make the computer mad and spit codes. The pollution control equipment all shuts off at wide open throttle, so the HP losses from it on the car are 2-5 HP. The catalytic converters may soak a few more HP than that. None of the pollution control equipment reduces the HP enough to cost you a race in anything but professional drag strip competition. I seriously doubt that you will be in the final runoff on “Pinks”, so leave the smog equipment in place and make sure it is working correctly.

Know what does what before removing it. Remove or disable the wrong thing and the computer sets the check engine light and runs in "limp mode". Limp mode means reduced power and fuel economy.

If you removed the smog pump and still have catalytic converters, they will ultimately clog and fail.

Here's a book that will get you started with how the Ford electronic engine control or "computer" works.

Ford Fuel Injection & Electronic Engine Control 1988-1993 by James Probst :ISBN 0-8376-0301-3.

It's about $20-$45 from Borders.com see http://www.amazon.com/ . Select books and then select search. Use the ISBN number (without dashes or spaces) to do a search

Use the ISBN number and your local library can get you a loaner copy for free. Only thing is you are limited to keeping the book for two weeks. It is very good, and I found it to be very helpful.

Remove any of the equipment and you will not pass a full smog check, cannot title the car in an area that does smog checks and have broken several federal laws. Granted that the Feds are short on people to check cars, but it is still Federal law.

"Why should I leave the smog equipment on if I live in an area that doesn't do smog inspections?"
What's good sauce for the goose is good sauce for the gander. I lived in Florida and had two smog pumps fail on two different 89 5.0 Mustangs. I replaced both of them, even though there was no emissions inspection. Why?

1.) It a federal law that requires emissions equipment to be in place and functional. I have no intention of breaking a law designed to protect my general health and wellbeing, even if I don't like it. I have respect for the rights and wellbeing of other people, and am not one of those whose nature is rebellion.

2.) Whatever imaginary "improvements" someone may strive for, there is very little evidence that the results of removing emissions results in a better car. I can achieve excellent results in performance with all the smog equipment in place and working properly. Maybe you can't, but that is no excuse for removing the emissions equipment. Look at the new 5.0 Mustangs – 281 cubic inches and 400+ flywheel HP with full emissions equipment with no aftermarket parts. That tells me that it is possible on a mass production car. It also shows that the guys that designed the engine knew what they were doing to achieve that goal.

3.) I like to breathe clean air, and working emissions equipment helps me do my part to make that possible. Los Angeles has breathable air even with millions of cars: Beijing, the capitol of China has some of the worst air in the world. Why – no emissions requirements for cars.

I don’t want to live where the air looks like this…
360_chinapollution_0304.jpg

See http://www.taipeitimes.com/News/feat/archives/2014/01/15/2003581312
 
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Thanks for the replies. This car will be an off-road use only car, which is why I got rid of emissions stuff.

I think I was getting confused between a clutch safety switch (plastic mechanism on clutch pedal) vs. the neutral safety switch (button type sensor that screws into the transmission). I have the clutch switch bypassed with a fuse, but it is likely my neutral safety switch is faulty since I changed to the T5-Z recently.

Thanks.