Engine Brief Check Engine Light On Deceleration

nelzfoxes

5 Year Member
Aug 20, 2013
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Anyone else experience this? A9L, egr intact, no tab or tad. The harness is m-12071-a50 which eliminates those two. Pro-Flow calibrated to the 24lb.’ers beneath gt40 tubular with accufab spacer and throttle body on the face of it. Cold start idle and flooring the throttle fast are where the car maybe stumbles a little. I did search and got the pull codes message. I even used the exact link you guys put in there and I also ordered the extension cord connection. Oh... and it’s a 351W. I will update with the codes pulled when the scanner arrives, but if you’v experienced something similar post it up.
 
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no clutch switch. I can start the car anytime. I am not sure the ford aftermarket harness ties in to clutch safety switch. I’m gonna have to look in to that one.
 
It's not the clutch safety switch, it's a second plug on the clutch switch that normal controls idle strategy with the stock a9x processor.

Was this engine off and engine running codes?
 
key on engine off. I have the ford aftermarket harness and nothing is plugged into the clutch at all. I will look at the instructions that came with the harness.
 
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
 
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The engine light came on again today and stayed on. I pulled over and tried to pull codes and activating the scan tool the engine died. I cycled the key and got the same 4 codes. I don’t think there is a wire from the computer on the new harness. I’ll look in to it.
 
Your going to need to run the engine running codes to really find the problem. None of those four codes would flash the CEL light.

Investigate pin 30 as you may need to ground it
 
Ok. The running codes are stored codes that triggered the engine light while I was driving it? Because the engine light is starting to come on more frequently now. Because the computer is not using oil pressure or oil level I just keep driving it. It is running fine. When the engine light is on and the car hasn’t fully warmed up, the engine will die as I approach a stop light and step on the clutch. Normally after that it doesn’t stall but the engine light comes on intermittently.
 
Ok. The running codes are stored codes that triggered the engine light while I was driving it? Because the engine light is starting to come on more frequently now. Because the computer is not using oil pressure or oil level I just keep driving it. It is running fine. When the engine light is on and the car hasn’t fully warmed up, the engine will die as I approach a stop light and step on the clutch. Normally after that it doesn’t stall but the engine light comes on intermittently.


There are three sets of codes. Engine off, continuous memory, and engine running.

Sounds like you've running all but the engine running codes?

Have you tried pulling the codes and then just starting the motor to see if they will dump?