hey friends, somewhat new to the navigation of the forum, please forgive me if I posted this wrong or direct me where it should list..

I need Tech help regarding the IMRC valve (intake manifold runner control valve)- specifically it's timing via the stepper motor

My problem is this: (I have an '04 accord, v6, 3.0 w/ 6spd if that helps..)
I recently did an "upper end service" as I call it (valve adjustment, performance cams, new gaskets, plugs, oil change, etc.) while I was elbow deep I decided to do the egr port service clean and while handling the intake plenum I thought "hey I'll remove this IMRC motor so I don't damage it" haha

so now, no one has any idea at the dealership how to set the timing of the valve (90 degrees of a gear cog) to the stepper motor gear. 2 mechanics and the service technician said Honda doesn't use intake manifold control valves.... I ruled them out as helpful, after using THEIR books to describe and explain the system they still looked confused and said it should fix itself after a idle position relearn as stated in the Honda book... I said I didnt believe so but regrettable agreed to the $93.88 cost for them to attempt the relearn procedure to no avail.

Any techies ventured into this problem before? I've found the trouble shooting of the motor itself (i.e., checking voltage coorelation of the pin connector to ground, to ecm, etc.) but I want an explanation of how to "time" the gears? can the ecm find the motor's "home" position by itself? and if so where do i hold the imrc valve while meshing the motor??

thanks in advance!!

note: I have found the service bulletin 100102, date 20021001 category 0630000 engine and engine cooling::ehaust: "instal IMRC valve correctly but cannot access it!! can anyone find a copy of this?

 

See link "v8sho.com/SHO/imrc.html". From this discussion, you should be able to discern if a setting results in proper operation of the IMRC. The "Updated 11/7/2006" post seems to address your concern.

good luck

 

A lot of those technical service bulletin, etc. listed at other non-Honda sites may not be actual technical service bulletins or even the same number as Honda's bulletin numbers. What is listed is related to an October 2002 Honda Service News, which are not TSBs. It also wasn't directly related to an Accord; but, a CR-V. Here is the excerpt from that:

 

Thanks for the replies guys.

TexasHonda, the Ford IMRC system is not a very good model of Honda's, it operates under different load conditions and its makeup is completely different, thanks for the reply though. (I've done a few years of Ford performance building, and yes owned a pretty well built SHO Taurus too lol)

Redbull, yeah I'm finding out that stolen and reposted bulletins aren't the best resources but I'm digging regardless. Thanks for the info. I have gone to Denso's engineering and asked about info on this particular stepper motor to no avail. I have since (yesterday) removed the component, done a full wiring check according to the repair manual, and then disassembled and inspected the motor itself (it has to be replaced anyways so might as well learn something about it?). Turns out it was mechanically binded between the motor's worm gear and the gearset that turns the valve. I documented with pics and can post here soon if anyone is interested

 

If you don't mind, I would like to see pictures. Thanks. I like seeing the inner working of things; what I did as a kid too.

The Honda IMRC intrigues me as it appear that Honda/Acura has several different designs for the bypass valve. On some older Acura TLs, it appears they used an IRMC cable to operate opening and closing the butterflies in the intake manifold (see attached picture I copied from another site). Then on some CR-Vs, they used an IMRC solenoid valve.

For your generation Accord, looks like they only had the IMRC for the V-6 with 6-speed transmission (not on automatics) and yours used an IMRC actuator (different than early Acuras with the cable and the CR-Vs with the solenoid valve). The newest generation Honda/Acuras appear to be using the actuators though. From what I think I understand, the ECM/PCM has a monitor that detects the IMRC actuator position.

 

The following is generally the idle learn procedure:

Make sure all electrical items (A/C, audio, lights, etc.) are off. Disconnect battery for a short while (3 minutes would be fine). Turn ignition switch to ON (II) and wait 2 seconds. Start engine and hold engine speed at 3,000 rpm without load (A/T in P or N, M/T in neutral) until radiator fan comes on, or until engine coolant temp. reached 194 degrees F. Let the engine idle for about 5 minutes with the throttle fully closed. (If radiator fan comes on, do not include the running time in the 5 minutes.)

 

Yes. You're observations are all correct. This particular electric imrc was only used on the j30a4 engine with 6spd's.... as mine is one of these few odd creatures. The pcm monitors various inputs (map, tps, 02, crank pos I believe) to determine when to advance/retard the intake runner. The motor is called a "stepper motor" according to most articles and Honda mechanics I talked to, however it doesn't follow a prescribed set of positions or steps as the name implies, I would consider it just a standard 12v motor that opens or closes (the pcm reversing current flow accordingly) as directed by the computer. It seems to operate at all angles (observing with the top plenum cover removed, plexi glass template and gasket covering), at least I couldn't pinpoint specific stopping points. The motor is a Chinese built one (p/n RS-3BOSH (is this "Bosch"?)-RD563225) with worm gear with 2 pin outs (pos and neg), the casing of the motor assembly (Denso p/n 012010-1010-12v) has 5 pins, which are connected within the housing to allow the ecm to reverse flow when needed. There is a constant 5v output from motor to the ecm, I guess so the computer can verify it's operating? The Honda repair manual says to replace "unbolt, unplug. Installment is reverse." Which I thought was vague- I was thinking the gears between the runner and motor had to be timed (also under the original presumption that it was a true stepper motor). But upon closer examination the runner gear coming out of the intake plenum has an offset weight opposing the quarter-circumference of gear teeth- I initially thought this was merely for balance. Turns out the weight is a magnet that the motor uses to initialize position and "home out" upon installation. Without having much background in electronics and not taking the motor casing apart I now presume the motor is not a stepper motor, not a standard wound motor, but a type of electro-magnet motor? Dunno. I have electronics lab tomorrow so hopefully I can pick a few brains of my electric engineer friends and get a better explanation.

 

after doing some homework in mechatronics, yes this imrc motor is an example of a variable reluctance stepper motor. there are three sets of windings within the dc motor, and with a change in voltage, the ecu can control the runner's position from 0-90 degrees (fully open to close). the harness contains 5 pins, 3 of which (pins 3,4,5) are voltage inputs. pin 1 out is a constant 5v for a baseline to ecm (a constant signal), pin 2 is a voltage change output to ecm so that it can monitor real time position much like a PID (proportional-integral-derivative) controller works; it records past position, current position, and looks at other engine date including map and ckp to best evaluate where to position the intake runner at next (all happening seemingly instantaneous).

pretty cool i thought. Just thought I'd share for any mechanical geeks like myself...

 

Sounds interesting. Could you posts some of your documented pictures of the IMRC motor? Without the pictures, it kind of like hearing about how a dish is made; but, don't know how the dish looks like.