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Discussion Starter · #1 · (Edited)
1993 ford Mustang GT
OK guys i am just about to be finished restoring my 5.0 and then i ran into one last problem. My car is surging during idle from 900 to 600 making the idle very rough. It also hesitates when acceleration almost like its not getting spark or similar to a misfire. The car used to idle fine this is something that happened out of the blue.

So here are some things i have done:
New Spark Plugs
New Spark Plug Wires
New Cap & Rotor
New Ignition Coil
New Starter Solenoid
New IAC Sensor
New Fuel Filter
New Air Filter

Tests I have done for this problem consist of:
-measured volts at tps and got .99
-sprayed all vacuum lines with carb cleaner (looking for a raise in idle) i used 2 cans no luck
-i measured volts at the maf sensor and it was working from what i can tell as far as volts raising when moving throttle and it appears the previous owner changed it because it looks new

Also i heard about adding a IAC sensor adjuster and it sounds promising except my issue isnt only with idle its while driving too and my issue came out of nowhere so it leads me to believe that wouldnt work

Any info will be greatly appreciated because this is my daily and i am running out of ideas.
 

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Have you dumped the codes to see what the computer says is wrong... codes may be present in the computer even though the Check Engine Light isn't on.
 

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Discussion Starter · #3 ·
ok so yesterday i got a obd1 reader, i have been wanting to get for along time. I read the codes below:

1) 34- EGR Flow Insufficient
2) 67- Clutch Switch

I proceeded to check the clutch switch and notice that the guy before me had wired it up for automatic transmission and had one of the 2 plugs no attached and a wire was spliced and ran up to the steering column. I replaired the splice and fixed the wire and plugged it in.

As for the egr code i went and bought a New EGR Valve, New EGR Valve Sensor, and New EGR Vacuum Solenoid. I just installed this all this morning and started it up and it still surged and died. Then i thought that maybe i have to erase the codes. So i just disconnected the battery and I am currently letting it sit.

I was really hoping the issue would be one of those codes because both codes would cause surging and shut off.

Any ideas, do you think maybe the clutch switch is bad and thats why it was disconnected. It appeared to be in good shape

Any help will be greatly appreciated because this is my daily and it shuts off on me quite a few times while driving and that sucks
 

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Not saying it's your Neutral safety switch but you might try bypassing the Neutral safety switch so it's one less thing too worry about.


Code 67KOEO-CM: During the test clutch not depressed (5 speed) or car not in neutral or park (auto). Possible neutral safety switch or wiring problem. You can generally ignore this code, since it has no effect on engine performance.


Code 67 KOER: The computer wants to make sure the A/C is off due to the added load on the engine for the engine running tests. It also
checks to see that the transmission is in Neutral or 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 NSS code 67 can be bypassed for testing.
The easiest way to bypass the neutral safety switch is turn the key on and jump the solenoid on the fender well. It should crank if it is a neutral safety switch problem as this will bypass it.
OR
You’ll 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.
 

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Discussion Starter · #5 ·
from what i have herd and from what i have seen on a video the code 67 has alot to do with performance. It can cause surging and ev en cause the car to shut off. Also can you go more into detail on how to bypass it using the solenoid on the fender wall.

Also when I am driving the car it seems to hesitate alot. And it was wierd because yesterday after what i did with the egr and with the saftey switch i decided to grease all electrical clips and put a full charge on the battery and then i erased all codes and the surging idle cleared up alot but it is still hesitating when i drive.
 

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Remove the 90 degree rubber boot (18 GA Red/Blue ignition wire) and then use something like a screw driver and bridge across too the battery cable .
http://www.allfordmustangs.com/foru...844-little-help-please-starter_solenoid_2.jpg



You mentioned in your 1st post that It also hesitates when acceleration almost like its not getting spark or similar to a misfire and I saw where you said that you sprayed all vacuum lines with carb cleaner.
My question is do you still have all the smog equipment and did you spray around where the 4 plastic vacuum lines connect to one another with a rubber boot. The reason I asked is because I had that same problem and found out through trial and error the 2 halves had separated and was cause the same problem you're describing... just food for thought.
 
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