whats holding me back
- Thread starter bowser1985
- Start date
Steve491
Member
Maybe they're not opening at all. A 96 GT didn't have IMRCs so it probably didn't have the wiring or the computer for it either.
blackfang
Founding Member
Did you take account for the wiring harness and also have a tune done to the vehicle?
blackfang
Founding Member
You will need a tune for starters. The ECU still thinks there is a 2V motor in the car.
You can remove the IMRC's but need a short runner intake and a 4.30-4.56 gear to make up for the low end torque loss.
COBRA90GT
Mustang Master
There's plenty of information about IMRCs in past threads; search results for "IMRC"
Mustang Forums at StangNet - Search Results
In a nutshell, IMRC stands for:
Intake
Manifold
Runner
Control
This engine feature was found on 96-98 cobras and consisted of a controller that opened up a set of secondary valves around the 3250rpm mark in 96-98 cobras to enhance performance.
The secondary valves stay closed until around 3250rpms in order to enhance low engine speed (RPM) performance and open up above 3250rpms in order to increase high engine speed performance.
Many folks would choose to delete the IMRCs when adding a power adder (and sometimes while remaining NA) in order to gain better engine breathing characteristics....
The IMRC plates/valves can get gunked up as well and a thorough cleaning is sometimes needed to bring them back up to speed (or a faulty controller/actuator could be the culprit).
Further:
IMRC Actuator
Picture:
Taken from David Simmons' website: Red Hot Venom
Yeah, just clean them. When my Cobra was still a little cold and I was at 50% throttle I could feel them opening @2800rpm. The car would just surge foreward a little better 
The 93-98 MarkVIIIs had them as well but they open closer to 3250. They get carbon build up over time and stick closed.
You do need a tune though unless the ECU from the Cobra was swapped over as well. If you are still running the stock ECU then you are down about 40+hp as well as some higher RPM issues if the IMRC is not hooked up. SOmeone makes a plate kit for that so you can remove it and still retain all the other factory stuff.
The 93-98 MarkVIIIs had them as well but they open closer to 3250. They get carbon build up over time and stick closed.
You do need a tune though unless the ECU from the Cobra was swapped over as well. If you are still running the stock ECU then you are down about 40+hp as well as some higher RPM issues if the IMRC is not hooked up. SOmeone makes a plate kit for that so you can remove it and still retain all the other factory stuff.
Steve491
Member
Shoobs99svt,
Cobra90gt explained it perfectly except I thought it was Intake Manifold Runner Controls. I'm sure my 97 needs a good cleaning job in the future. Until they are opened up a couple if times I have a little flutter around 3200. NO codes and really no problem, just a little bbbbbbrrrrrrrr between 3000 and 4000.
Your '99 does not have IMRC plates. Ford changed several things to eliminate them. Maybe the intake, cylinder heads, computer, etc, I don't know, somebody will chime in with info.
Back to bowser1985, the original post
If you don't have the computer open them they are worthless and hamper performance. Either eliminate the IMRCs or make them work. Low cost solution: Open them up mechanically, but you'll lose some low end. Just my opinion.
Steve
Cobra90gt explained it perfectly except I thought it was Intake Manifold Runner Controls. I'm sure my 97 needs a good cleaning job in the future. Until they are opened up a couple if times I have a little flutter around 3200. NO codes and really no problem, just a little bbbbbbrrrrrrrr between 3000 and 4000.
Your '99 does not have IMRC plates. Ford changed several things to eliminate them. Maybe the intake, cylinder heads, computer, etc, I don't know, somebody will chime in with info.
Back to bowser1985, the original post
If you don't have the computer open them they are worthless and hamper performance. Either eliminate the IMRCs or make them work. Low cost solution: Open them up mechanically, but you'll lose some low end. Just my opinion.Steve
blackfang
Founding Member
Well you have a GT and you installed the engine. So if you did not install a new ECU that answers that question. I am not sure if the GT ECU's are the same as the Cobras and just the tuning parameters are different. PM SVTTech on here as he is a Ford Technician.
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