RedFox
New Member
Hi all,
I'm new to this forum and to new to Mustangs. I need and appreciate any help you can offer. I'll try to provide as much info as I can.
I recently did a '93 Cobra manifold swap on my '89 Mustang GT. When I start the car, it idles way up to 4000 RPM and stays there. I'm assuming I have a manifold leak or more likely, a vacuum line run incorrectly. I did some digging on the web and I found the attached photo which is how I had my lines. I also found an update that indicates for BAP sensor cars like mine, remove the "T" fitting from the EGR line. I did this and plugged the port on the bottom of the upper manifold but the car still behaves the same. Does anyone have a photo or diagram of how these vacuum lines should go? Advice? My next step was going to be spraying some carb cleaning around the lines and gaskets to try to find the leak. The gaskets are new so I don't think that's the issue.
The cars emissions system has been modified by previous owners which is making this more challenging for me since I don't really have a baseline to compare it to. The EGR crossover tubes are still connected to the back of the heads but not to anything else. The EGR valve is attached to the intake and wired into the electrical harness but the small vacuum fitting is not connected to the manifold and I'm not sure if it should be? There is also no smog pump on the car.
Before swapping the manifold, the car would always high idle at around 2500 RMP, even on hot days, before warming up and dropping down to 1000RMP. I'm not sure if this is normal for these cars?
I tested the TPS sensor as well which seems to have been spliced in by a previous owner and it's giving me 2.4v on it's lowest position which I know is too high. I have an aftermarket throttle body which allows me to adjust but I cannot get it lower than this. I have a spare sensor which I can swap but I did test the TPS prior to this project and it was high then too so I'm not convinced this is the problem.
The throttle position screw is set to the lowest position it will go so I do not suspect this as being an issue.
It's possible the timing on the car could be off as I did remove the distributor when I did this swap. I checked the valves on cylinder 1 to ensure they were closed and on compression stroke and I marked the balancer. From what I can tell, it is running about 12 degrees before TDC. Even if the timing is a bit off, would it make the car idle this high?
Again, I'm sorry if this is something that has been covered before but I'm new so I thank you for any help you can offer to get my car back on the road.
I'm new to this forum and to new to Mustangs. I need and appreciate any help you can offer. I'll try to provide as much info as I can.
I recently did a '93 Cobra manifold swap on my '89 Mustang GT. When I start the car, it idles way up to 4000 RPM and stays there. I'm assuming I have a manifold leak or more likely, a vacuum line run incorrectly. I did some digging on the web and I found the attached photo which is how I had my lines. I also found an update that indicates for BAP sensor cars like mine, remove the "T" fitting from the EGR line. I did this and plugged the port on the bottom of the upper manifold but the car still behaves the same. Does anyone have a photo or diagram of how these vacuum lines should go? Advice? My next step was going to be spraying some carb cleaning around the lines and gaskets to try to find the leak. The gaskets are new so I don't think that's the issue.
The cars emissions system has been modified by previous owners which is making this more challenging for me since I don't really have a baseline to compare it to. The EGR crossover tubes are still connected to the back of the heads but not to anything else. The EGR valve is attached to the intake and wired into the electrical harness but the small vacuum fitting is not connected to the manifold and I'm not sure if it should be? There is also no smog pump on the car.
Before swapping the manifold, the car would always high idle at around 2500 RMP, even on hot days, before warming up and dropping down to 1000RMP. I'm not sure if this is normal for these cars?
I tested the TPS sensor as well which seems to have been spliced in by a previous owner and it's giving me 2.4v on it's lowest position which I know is too high. I have an aftermarket throttle body which allows me to adjust but I cannot get it lower than this. I have a spare sensor which I can swap but I did test the TPS prior to this project and it was high then too so I'm not convinced this is the problem.
The throttle position screw is set to the lowest position it will go so I do not suspect this as being an issue.
It's possible the timing on the car could be off as I did remove the distributor when I did this swap. I checked the valves on cylinder 1 to ensure they were closed and on compression stroke and I marked the balancer. From what I can tell, it is running about 12 degrees before TDC. Even if the timing is a bit off, would it make the car idle this high?
Again, I'm sorry if this is something that has been covered before but I'm new so I thank you for any help you can offer to get my car back on the road.
