ECM Bypassed

coachpete

New Member
Apr 16, 2008
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I had my vehicle looked at for a stuttering problem I have been having and have posted in the last couple of weeks. When the tech looked at the vehicle he noticed that the ECM has been bypassed with a hose and had no idea why this was done. I did not bypass the ECM and have only owned the car for three months now but why would someone bypass the ECM??? The tech did show me where it was bypassed and I should have a picture of what i am talking about in a little why to show you guys but i wanted to post the question this morning. My 86 gt does have an inconsistent idle and does sputter when under power but i thought it was just bad gas. Any help is greatly appreciated!
 
How do you bypass an ECM with a "hose?" Also if the car is an 86, is it carb'd or EFI? I know if it were carbed there would be no ECM.

whats going on here...none of this makes any sense?

A picture would say 1000 words.
 
See the "Surging Idle Checklist for help with all your idle/stall problems. The first two posts contain all the updates to the fixes. At last count there were 24 possible causes and fixes] for surging idle/stall problems. I continue to update it as more people post fixes or ask questions.
 
The reason coolant runs through the EGR spacer is as an anti icing measure. Winter driving can cause icing issues with the TB and to keep this from happening Ford runs the antifreeze though the EGR spacer.

On the contrary, the coolant hoses are used to cool the EGR gases and the hot spot the EGR spacer becomes when exhaust gases are flowing through it. Different to the Cobra intakes, that creates the heat sink effect by not using a thin-walled spacer and using the upper thick casting....... if the coolant hoses were used for anti icing purposes, why doesn't the Cobra intake have provisions for them?

Not having the coolant hoses connected to the spacer, and a functional EGR system, will create a hot spot on the TB that could cause premature TPS failures due to temperature increases. I've worked 4 cases (1 Town Car, 2 Mustangs and a 1 F-150) that had recurring TPS failures in a 6-8 month time frame. The cause was the bypassed coolant hoses and having a functional EGR. This last item is key, since a non-functional EGR system will not cause the EGR spacer temperature to increase due to the absence of the exhaust gases flow.

Below is the description of the EGR system by FoMoCo and the reason for the coolant hoses in EEC controlled EGR systems.

EGR_Lines.webp
 
On the contrary, the coolant hoses are used to cool the EGR gases and the hot spot the EGR spacer becomes when exhaust gases are flowing through it. Different to the Cobra intakes, that creates the heat sink effect by not using a thin-walled spacer and using the upper thick casting....... if the coolant hoses were used for anti icing purposes, why doesn't the Cobra intake have provisions for them?

Not having the coolant hoses connected to the spacer, and a functional EGR system, will create a hot spot on the TB that could cause premature TPS failures due to temperature increases.

My bad. I was just stating what it says in my Ford Factory Service Manual.