FML Another IMRC thread (stuck open)

[AZSN95SNAKE]

IMRC stuck OPEN. Any info on stuck OPEN?

I have been researching IMRC issues for awhile now as I have been suspecting mine are stuck closed, because the car feels sluggish. I have revved the engine past 3250rpm from the engine bay to see if the imrc cables jump like they should (I have seen them jump before), but have noticed that neither of the cables jump nor even move anymore.

No CEL on. I scanned the car anyways and came up with P1519 IMRC stuck open b1 (electric imrc). Through research apparently that should be the code for stuck closed? and stuck open should be P1518. I also found code P1270 for engine rpm or speed limiter reached (wtf made me lol).

Anyways I have already planned to clean them, just haven't found time. I already have read the how to's for cleaning them and have them bookmarked so I'm good there, but I'm finding mixed reviews on whether or not I need to replace the gaskets. My motor has 67500 miles if that makes any difference. I have located ford replacement gaskets for the intake to imrc plates but not for the head to imrc plates. Any suggestion on where to buy these?

I do not wish to delete them; just looking to clean them.

If the they are stuck open, wouldn't that not really be an issue? Almost as if I had zip tied them open. The car feels really sluggish and does not seem to pull as hard.

I have a Bama mail order tune which I believe is rubbish. The car has seen better days when it had the stock tune. My gas mileage has gone down considerably. Idle is at 1000 rpm which is too high imo. The car only runs well with the race tune. I reflashed the car back to stock as well as removed the codes and the car seemed to pull much better. My heart actually began to beat faster as I felt I was accelerating much faster than usual (which is not usual).

With the Bama tune on, the idle was quite weird. There were popping noises coming from the exhaust as if unburnt gas was being burnt in the pipes. The tune is complete garbage but I got it to get rid of the CEL for no cats (mils failed). The car seems to run very rich with the Bama tune. My other friends have no cats and there's a faint odor of having no cats but mine is unusually strong.

Where can I locate the head to imrc gaskets? (I found the intake to imrc gaskets from Ford and Felpro on LMR and CJ pony parts respectively)
Would cleaning the IMRCs fix the stuck open code since they are stuck open not closed?
Could it be that one or both of the cables are frayed?

Do to my limited time, I wish to be fully prepared to take on this task. I don't want to open it and find out I didn't need the gaskets after all or vice versa. I also don't want to find out my actuator is actually broken or that I need deletes bc I might not have all that time. ugh I need a vacation to fix all this.

Sorry for the long post, I like to be as detailed as possible. Thanks in advance fellas!

 

[UncleSAm]

you shouldn't need new gaskets. i have a controller box that works, and i also have the 98 cobra composite that are completely clean if you want those too, with gaskets

 

[98fourvalve]

Few years ago when I was in phoenix with my original 98 cobra. The imrc's were stuck closed and I didn't realize it. Went to the track and ran like a 15 something. After I realized they were stuck closed I deleted them and reran and ran a mid 13 with a pathetic 60 ft.


I've had my engine apart numerous times in both my 98 and 96 cobra's I have. Never once replaced the intake gaskets or the imrc gaskets. Have had both the aluminum and composite imrcs and haven't had an issue with either.


Good luck. If i were me as I'm cheap with dumb annoying things like IMRCs I'd delete them and never worry about them again.

 

[AZSN95SNAKE]

you shouldn't need new gaskets. i have a controller box that works, and i also have the 98 cobra composite that are completely clean if you want those too, with gaskets

that's what I was looking you hear. I'd rather spend the money on long tubes or a nitrous kit. ill let you know if I need the controller or gaskets when I tear it apart.

Few years ago when I was in phoenix with my original 98 cobra. The imrc's were stuck closed and I didn't realize it. Went to the track and ran like a 15 something. After I realized they were stuck closed I deleted them and reran and ran a mid 13 with a pathetic 60 ft.


I've had my engine apart numerous times in both my 98 and 96 cobra's I have. Never once replaced the intake gaskets or the imrc gaskets. Have had both the aluminum and composite imrcs and haven't had an issue with either.


Good luck. If i were me as I'm cheap with dumb annoying things like IMRCs I'd delete them and never worry about them again.

Phoenix eh? you are lucky it is burning here right now. Wow they really were harming your times. They really are restrictive when stuck closed. and its worse when there is no cel.

sweet that's good information from experience. I wanted to here it from someone with experience. I'll just reuse mine when I open it up. I would delete them but I don't want to pay for a tune just for IMRCs. Id like to do more mods at once than get a dyno tune.

Any info on the imrcs being stuck OPEN would that be bc they need to cleaned or my worst fear is the cable is broken?

 

[1996slowbra]

I have an extra set you could just have as well, they are the aluminum ones.

 

[GotJuice96]

Mine feels the same way right now. Im deleting my irmc. And changing my coils packs from. My spark plugs on sat. Should make my car feel way better )

 

[98fourvalve]

Being stuck open could be a number of things causing it. When I deleted mine I didn't have it tuned. Didn't notice a difference in drivability either. To this day I don't have a problem and my engine is built pretty well with some 106400s. Those are my problem right now until I get it tuned.

Definitely get it fixed before you beat on it. My engine destroyed itself not long after I beat it on with them closed. A week after I fixed it actually. Right next to Mesa Community College... lol

 

[AZSN95SNAKE]

I have an extra set you could just have as well, they are the aluminum ones.

Sweet I'll PM you if I decide to go that route and just JB weld them before putting them. That's if I don't take the other member that offered his.

Mine feels the same way right now. Im deleting my irmc. And changing my coils packs from. My spark plugs on sat. Should make my car feel way better )

It should definitely help. New plugs and coil packs after so many years is a good idea. I'd clean the IMRC soon.

Being stuck open could be a number of things causing it. When I deleted mine I didn't have it tuned. Didn't notice a difference in drivability either. To this day I don't have a problem and my engine is built pretty well with some 106400s. Those are my problem right now until I get it tuned.

Definitely get it fixed before you beat on it. My engine destroyed itself not long after I beat it on with them closed. A week after I fixed it actually. Right next to Mesa Community College... lol

I really hope it's just something simple. I hope they can get stuck open due to gumming up rather than cables being frayed or cut dry. Really? Everyone warns of drivability issues with no tune. That's good information though, I'll keep it in mind and might try it out. Those things are going to sound wicked! I'd love to get me some cams.

Is that so? Mine are stuck open though, so I figure the only downside would be running rich or lean. Wow thanks for the warning. I just got home from beating on it lol I was testing to see if they were opening and honestly I can't quite tell. It seems to be pulling healthy but not as fast as before; just slightly. Haha MCC lol at least maybe you saw some college tail while on the side of the road lol

 

[98fourvalve]

Haha yes indeed I did. But it sucks when you are stuck pushing a blown up cobra and they are like WTF!? When I say blown up I mean holes in the block kinda blown up.


But yes in your case with them stuck open then it's a bit different and I wouldn't worry as much as them closed. But regardless, without being 100% sure I still would tread carefully.

Have you tried parking/starting it. And revving the engine (just to around 3500... not to the moon) from under the hood while looking at the IMRC cables for movement. If you look carefully you should even be able to see the arm with the cable pivoting. Should tell you if they are open/close and if the box is doing its job and the imrcs are stuck or the box just isnt working.

 

[AZSN95SNAKE]

Hahaha that does suck to be caught pushing your car down the road in front of some fine college babes haha. DAMN holes in the block? That's insane. Damn IMRCs.

Yeah it's a different situation. I did read that when they are stuck open the IMRC spark adder tables are not switched and thus cause the car to hesitate on the top end. Mine doesn't seem to hesitate on the top end I just don't feel like it's even moving below 4800k rpm, which is where peak torque is. I need to open this sucker up but summer courses and a job just don't give me a break. Also na svt was going to make me a short runner and I figure I'd just delete them in the process but now that my sister is home from studying abroad and her car not in good shape she is driving the extra vehicle :/

Yes si, that's the first check I did. 2 weeks ago, only one of the cables was jumping like it is supposed to. As of now, niether of the cables move at all. I'm not sure on the arm ordeal; its pretty hard to see back there. There's this little plastic holder almost like a loom that holds and them and also pivots so that the cables can do their thing; the cables are not in the loom. They just there. Is it necessary for them to be attached or is that just a holder?

 

[mwolson]

I figure the only downside would be running rich or lean.

It won't run rich or lean with the IMRCs stuck open.

At idle and part throttle, the PCM is in closed loop so the AFR is kept at stoich based on feedback from the O2 sensors.

At full throttle, the AFR is driven from a table based on the MAF reading, so you will get very close to the commanded AFR at WOT. So you don't have to worry about stuck IMRCs damaging your engine.

 

[98$vt]

imrcs are such a pain in the ass. I had issuses with mine at about 95k and then found out one of my cables snapped and it was closed shut. i had to rip the entire intake off and what not and it was such a pain finding all the gaskets plus finding the imrc control. long story short i found an imrc off ebay for 20 bucks and the gaskets except the lower intake gaskets that go in the runners themselves but mine were still good somehow. ive heard sea foam works really good for cleaning those imrcs out but i think pulling them off would work 20 times better

 

[mwolson]

ive heard sea foam works really good for cleaning those imrcs out but i think pulling them off would work 20 times better

Seafoam doesn't do a thing to clean gunked up IMRCs. You have to take them out and scrub them with solvent. I tried it with mine back before I deleted them, and when I took them out right after using Seafoam, they were still badly gunked up.

 

[98$vt]

Yeah I think donno it's just what I heard. I mean it could be worth a shot can't really hurt it any

 

[98fourvalve]

I use seafoam. Have I ever noticed a difference? Nope. You are correct it really won't hurt to do it but it won't help the gunks. That stuff is caked on there and with how fast the seafoam goes through it doesnt have time to do the job.

 

[98$vt]

Yeah it gets pretty nasty in there I had to scrub my imrcs with a tooth brush and solvent

 

[AZSN95SNAKE]

It won't run rich or lean with the IMRCs stuck open.

At idle and part throttle, the PCM is in closed loop so the AFR is kept at stoich based on feedback from the O2 sensors.

At full throttle, the AFR is driven from a table based on the MAF reading, so you will get very close to the commanded AFR at WOT. So you don't have to worry about stuck IMRCs damaging your engine.

Mr. mwolson; I've been reading your IMRC posts on other forums. I kind of was hoping you'd pop in here.

Through searches I have found people saying it will run rich or lean due to either not enough air or too much air; I wasn't sure what to believe.

Yes, that makes complete sense especially since the IMRC are not open at idle nor before 3250.

I'm not up to spec on tuning but that explanation makes sense since cars with no imrc function in the exact same way. What's with the IMRC spark adder tables though? I found many threads talking about how when the CEL is on for IMRCs that the spark adder tables do not follow threw; again that's from the internet. When people do deletes and than they get a tune, I read that the tuner must not only shut off the IMRC from the tune but also have new tables since the IMRC "spark adder tables" will be useless?

If they are stuck open can it just be needing a cleaning? Or is that only for stuck closed situations.

I use seafoam. Have I ever noticed a difference? Nope. You are correct it really won't hurt to do it but it won't help the gunks. That stuff is caked on there and with how fast the seafoam goes through it doesnt have time to do the job.

I have seen pictures of IMRC right after a sea foaming and there were minimal results that wouldn't leave me satisfied. You could barely see a difference. Your right it is caked.

imrcs are such a pain in the ass. I had issuses with mine at about 95k and then found out one of my cables snapped and it was closed shut. i had to rip the entire intake off and what not and it was such a pain finding all the gaskets plus finding the imrc control. long story short i found an imrc off ebay for 20 bucks and the gaskets except the lower intake gaskets that go in the runners themselves but mine were still good somehow. ive heard sea foam works really good for cleaning those imrcs out but i think pulling them off would work 20 times better

The head to IMRC gaskets are a pain but I hope mine are good; the car only has 67k miles so it should be fine. You found that control for cheap! A few guys have offered theres and if they still have one when I do it I will snag it from them. But I need to message na svt about the short runner intake. Now would be a good time to do it and the deletes but I have to wait a month till summer school gets out.

 

[mwolson]

What's with the IMRC spark adder tables though? I found many threads talking about how when the CEL is on for IMRCs that the spark adder tables do not follow threw; again that's from the internet.

The stock tune has spark adder tables that contain spark advance that is added to the spark timing whenever the IMRCs open. If the PCM thinks that the IMRCs are not open, it will not add the spark from those tables. If the IMRCs are actually open or gone, and the PCM doesn't add the spark advance, you lose significant torque up top.

The thing I don't know is, if the PCM thinks they are stuck open, does it add the spark advance? It would be nice if someone who still has IMRCs could zip tie them open and then do a datalog of a WOT run to see if the spark is retarded.

If you decide to do the deletes and not do a new tune, there are two ways to handle it. One is to put a spring on the IMRC cables. The spring simulates the springs on the IMRC rods, which pulls the cables back out of the IMRC motor when the PCM tells the IMRCs to close. The feedback from the IMRC motor will tell the PCM that the IMRCs are open when it thinks they should be open and closed when they should be closed. This may not work if the cables are frayed.

The other way to fool the PCM into thinking the IMRCs are still there is to replace the motor with a relay circuit. Here is the writeup on how to make that circuit. It has been proven to work. IMRC Delete Relay Circuit

You may experience some noticeable loss in low end torque with this technique although many say they don't notice any loss. You will not experience any loss in high end torque with this method.

Many people believe (and I think it is likely) that you will pick up more low end torque from a custom tune for your specific engine than you lose from doing the the delete. And you may pick up some addition torque up top, so I recommend doing the tune if you can afford it.

When people do deletes and than they get a tune, I read that the tuner must not only shut off the IMRC from the tune but also have new tables since the IMRC "spark adder tables" will be useless?

SCT includes new base tunes for 96-98 Cobra tunes that come pre-packaged for IMRC deleted engines, making it really easy for a tuner or a PRP owner to do a tune for an IMRC deleted engine. It has a new, custom spark table that compensates for the missing IMRC spark adder tables. You don't have to worry about a tuner not getting it right, unless they don't start with the correct SCT base tune.

If they are stuck open can it just be needing a cleaning? Or is that only for stuck closed situations.

It is possible that gunked up IMRCs could stick open. I suspect it is more likely that they would stick closed from gunk than they would stick open. If they are sticking open due to gunk, I bet they are really badly gunked up.

My suspicion is that you have a frayed cable that is causing it to stick open, but that is just a guess on my part. My IMRCs are gone because they were sticking due to a frayed cable, and with a KB, I really don't need them.

Regardless of why they are sticking, you really need to take it apart and clean them up or delete them. If you haven't cleaned them recently, they are gunked up.

They are a good idea in theory, but in practice, the implementation is flawed. The primary ports (the square ones) are the ports that the injectors spray into. The fuel from the injectors does a good job of cleaning the primary ports and they are never gunked up like the secondaries. Since the secondaries are not open at low RPMs, it does not make sense to have the injectors shooting fuel into them. But without the fuel, the gunk starts to build up in each secondary port and it never gets cleaned.

I am pretty sure that is why Ford only produced them for 5 years (MK8 and Cobra). They are a serious PITA.

Be sure to tell us what you learn when you take it all apart. Get your digital camera ready.

PS, when I cleaned my IMRC gaskets, I just used simple dish soap and hot water. I let them dry and they were like new. I'd avoid using solvents on them since they seem to be getting hard to find.

HTH

 

[AZSN95SNAKE]

The stock tune has spark adder tables that contain spark advance that is added to the spark timing whenever the IMRCs open. If the PCM thinks that the IMRCs are not open, it will not add the spark from those tables. If the IMRCs are actually open or gone, and the PCM doesn't add the spark advance, you lose significant torque up top.

The thing I don't know is, if the PCM thinks they are stuck open, does it add the spark advance? It would be nice if someone who still has IMRCs could zip tie them open and then do a datalog of a WOT run to see if the spark is retarded.

If you decide to do the deletes and not do a new tune, there are two ways to handle it. One is to put a spring on the IMRC cables. The spring simulates the springs on the IMRC rods, which pulls the cables back out of the IMRC motor when the PCM tells the IMRCs to close. The feedback from the IMRC motor will tell the PCM that the IMRCs are open when it thinks they should be open and closed when they should be closed. This may not work if the cables are frayed.

The other way to fool the PCM into thinking the IMRCs are still there is to replace the motor with a relay circuit. Here is the writeup on how to make that circuit. It has been proven to work. IMRC Delete Relay Circuit

You may experience some noticeable loss in low end torque with this technique although many say they don't notice any loss. You will not experience any loss in high end torque with this method.

Many people believe (and I think it is likely) that you will pick up more low end torque from a custom tune for your specific engine than you lose from doing the the delete. And you may pick up some addition torque up top, so I recommend doing the tune if you can afford it.



SCT includes new base tunes for 96-98 Cobra tunes that come pre-packaged for IMRC deleted engines, making it really easy for a tuner or a PRP owner to do a tune for an IMRC deleted engine. It has a new, custom spark table that compensates for the missing IMRC spark adder tables. You don't have to worry about a tuner not getting it right, unless they don't start with the correct SCT base tune.


It is possible that gunked up IMRCs could stick open. I suspect it is more likely that they would stick closed from gunk than they would stick open. If they are sticking open due to gunk, I bet they are really badly gunked up.

My suspicion is that you have a frayed cable that is causing it to stick open, but that is just a guess on my part. My IMRCs are gone because they were sticking due to a frayed cable, and with a KB, I really don't need them.

Regardless of why they are sticking, you really need to take it apart and clean them up or delete them. If you haven't cleaned them recently, they are gunked up.

They are a good idea in theory, but in practice, the implementation is flawed. The primary ports (the square ones) are the ports that the injectors spray into. The fuel from the injectors does a good job of cleaning the primary ports and they are never gunked up like the secondaries. Since the secondaries are not open at low RPMs, it does not make sense to have the injectors shooting fuel into them. But without the fuel, the gunk starts to build up in each secondary port and it never gets cleaned.

I am pretty sure that is why Ford only produced them for 5 years (MK8 and Cobra). They are a serious PITA.

Be sure to tell us what you learn when you take it all apart. Get your digital camera ready.

PS, when I cleaned my IMRC gaskets, I just used simple dish soap and hot water. I let them dry and they were like new. I'd avoid using solvents on them since they seem to be getting hard to find.

HTH

That's exactly what I got from my research, and if I am not mistaken that info was from you lol. It makes perfect sense. If the IMRC are stuck open wouldn't the PCM add the spark advance? or is that not always the case since I do have a code for it, I figure the PCM would not trigger the spark advance. It has hard to tell if the car is losing power up top. Although I firmly believe it is. I have raced my friends mach 1 various times and I have never lost to him. Since I noticed the car is sluggish, I get the initial hit (roll race) and as soon as I get into upper RPMs he passes me like I'm not moving. I might be able to get a video of this.

I'm wondering the same thing; will it add spark advance when they are stuck open or not. Like I said it might not since there is a code for it on. The code might not allow for the spark advance to come through. I may be able to zip tie them and do a datalog. I have an SCT tuner, I just need to download the livewire software and learn how to do it. Unfortunately I can't do this until my summer courses are over (hard pressed on time). In about 1 month.

Interesting way of fooling the PCM, haven't seen that one before. Sounds legit to me. Well with the deletes I know that some power is lost down low but it's nothing 4.10s can't cure. And I know that there are a few horses to be gained up top.

I have seen the relay circuit in old threads from non other than yourself. It's interesting. I have read good success when using it. I'd have to have my brother in law work that one out, I'm no good at electrical.

I concur. It is also think it is a frayed cable issue. I've just never seen IMRC's gunked and stuck open. It is possible I guess. If it's a frayed cable, I'm doing deletes forsure. One of the cables is stuck and won't budge when I tug on it a bit. It is stuck open, so it appears to be pushed in. So I suspect cable or the actuator is dead. Ah yeah a KB would negate any need for IMRC. Also you've saved yourself the headaches.

Yes I do need to take the top apart regardless. I will take pictures of it indeed. I'd like to get to the bottom of this. I might just delete them after all.

It's actually a pretty good idea but like you said the implementation is flawed. Some V6 and 3vs as well as other vehicles carry the same IMRC idea. Well the tumble port design of the C heads was a much better idea imo. I wish they would have thought of that sooner lol. Than I'd have some low end grunt.

Thanks for the tip on the gaskets! I've seen them get ruined using other solvents. I wouldn't try using brake cleaner nor carb cleaner on them. I'll make sure to let them dry up well.

About the SCT tunes; I did not know that. I'm going to email BAMA since I get free tunes from them. Since they should have these basic imrc delete tunes it would not be a bad idea to ask them. Although, the 3 tunes that I currently have from them are crap, unless it is just my motor. But if I switch to the street, or performance tune the car idles rough and out of no where a pinging sound pops up for a few seconds. Might just be my car though. The race tune is okay but it has done said pinging as well. I reverted back to the stock tune and the car runs and idles great! The CEL for the o/x has not come on after 2 tanks; which is the only reason I bought the tuner since my mils malfunctioned. They seem to function now though since there is no code

You sir have been a great help. It is definitely appreciated and respected.