Mivec Owners Group

ECU sends mivec output at 5200RPM(with no spike in RPM,change in sound etc), but mivec signal drops off again at around 5600RPM. (I installed a mivec light to verify this). Engine labours to around 6500rpm.Doesn't seem to go further.

I will change the caps as they are about due based on your recommendations. I will install an oil pressure gauge next week and get back to you on the findings.

My temperature needle is at about half mark. I believe the coolant temp sensor is working otherwise there wouldn't be a mivec output from the ECU right??

I removed some dents in the sump late last year. Plugs are 6's.

Am I overlooking anything else? Anyone with similar problems. I have been doing searches but would also like some direct feedback to my problem.

Cheers folks!!

the temp auge is not connected to the same sensor the ecu uses to get the head temp.

Yeah I know. The sensor for the gauge carries a single wire. The one to the ECU carries 2 wires and seems to be similar to the air temp sensor on the intake. My question is, based on your ECU diagrams, can I help eliminate the temp. as a possible problem by by-passing the temp. sensor temporarily? (Unplug the jack and jumper the contacts?) that way I can be sure the 5v signal goes back to the ECU at terminal 45. Is it
and this

Getting some gauges tomorrow. Will install soon. (Oil Pressure,etc)

Oh and guys, the mivec signal from ECU is in fact not dropping off at 5600rpm as previously thought-one of the mivec light connections was wrong. I corrected this and the mivec signal light now stays on from 5200-6500rpm. .

cant be the ecu caps or the temp sensor if the ecu is sending out the mivec signal
next thing to check is if the solenoid is infact engaging, then you need to see if the oil pressure is enough to activate and maintain activation of the mivec cams

^^Thats exactly my thinking. All hes to be well for the ECU to send a MIVEC signal. The solenoid is working(clicking when a voltage is applied). Whether it is clogged or not is what I will have to check. I'll replace oil and filter also as it is just about due. Then the only other thing is oil pressure.
Oh I have to replace oil seals. Had them replaced(Cam shafts I think) some time ago but the leak seemed to get worst. Will do this again. I'll buy a compression tester and do that as well if the options discussed earlier dont correct the problem.

Thanks for the input man.

Why does the mivec light only stay on until 6500?

^^Well part of my problem is that the car does not rev past 6500rpm. So the mivec is engaged(signal-wise) from 5200 to 6500. My bad on the phrasing.

I hope u understand now.

OK here's some results. I installed an oil pressure gauge today.

At start-up. Engine cold 80psi
Cruising just after to build coolant temp 60psi. Gradually dropped to 40psi. 2000-3000rpm
At 4500rpm 80psi. At 5200rpm(mivec light comes on) the pressure drops from approx 85/90psi to 80psi.
Idling at traffic lights 30psi??
Car still only revs to 6500rpm
Coolant temp was mostly steady at 80degC Until the last hard run where it went up to about 95-100degC, Fan was on and the temp. did not take long to go down to 85degC.

I will make a check on the sumpo.Last checked that some months ago.

Guys it's tiptronic eh. How much of a difference would that make?

What do you think about the whole thing?

Your oil pressure is fine at least. If you mivec light is is comming on, then the ECU is obviously working fine as well. I'd check your solenoids again.

With the engine 'cold' (so you have heaps of idle oil pressure), try manual activating the solienoid. Just unplug the connector and put 12v on there. It should cause the engine to run really rough or even stall completely.
If it doesn't change, then there is something wrong with your solenoid.

Ok thanks Bart. Will try that as soon as i get a chance in the morning.

[quote]Your oil pressure is fine at least. If you mivec light is is comming on, then the ECU is obviously working fine as well. I'd check your solenoids again.

With the engine 'cold' (so you have heaps of idle oil pressure), try manual activating the solienoid. Just unplug the connector and put 12v on there. It should cause the engine to run really rough or even stall completely.
If it doesn't change, then there is something wrong with your solenoid.[/quote]

^^Initial results:
Ok Bart. Did as u said. Used alligator clips to activate the MIVEc solenoid. At start-up 80psi.

Activate MIVEC solenoid=audible click, rough idle.
Deactivate MIVEC solenoid= smooth idle
Activate MIVEC again=no audible click,smooth idle(tried 4/5 times to ensure).
Hmmm pressure still at 80psi.

Switch off car and rechecked solenoid connections. Restarted and got the same sequence as above. Hmmm

Switched off car and activated solenoid. The clicking is very faint. Restart. Loud click rough idle. After that the click is faint and ther is no change in engine idle.

Maybe the solenoid is sticking or on the way out?? Or is it already out??

Glad to see I'm getting somewhere though. Thanks so far Bart (Hi 5)

Going back to car now to remove/clean the solenoid,etc.

I suspect your solenoid is sticking. Soaking and rinsing the internals should fix it up. Make sure you flush it with solvent in both open and closed positions after its been soaking a while. Obivously testing it on the bench will make it easy to check its all working perfectly before sticking it back in the car.

I just removed and sprayed up the solenoid with some solvent. It seems to be moving freely. Passages seem clear. It is moving/clicking when 12V is applied.

NOTE: Got this pic off the net...


The rectangle shows the shaft that is moving when the solenoid is activated. NOTE: if i place a finger there, there is no movement. Is that ok?

The arrow shows where there is a hole at the bottom of the solenoid. When solvent is sprayed in there, it comes out by the oval in the pic

Placed it back on the engine, start up, faint clicking, no change in idle

So I'm stuck there right now

Couldn't get 10w40 oil so I put in 10w30. Would this affect the MIVEC function? I am in the process of locating some 10w40 to switch to that though.

Pressure going up to 100psi at 4000 rpm and above. So it isn't affecting the pressure really.

Ok nothing yet. Actually I left it alone for a while. Busy.

Well after reading this post I decieded to check a few more things
viewtopic.php?f=29&t=7299

Well I opened up and my engine is not anywhere close to that condition. Everything was clean. All passages seemed clear. Still I took it all down and soaked,cleaned,etc. Same result.

Another thing I did(today) was check to see that 12v was reaching the mivec solenoid at the connector/harness by putting a multimeter on there and revving to 5200RPM(after letting car warm up). Sure enough there was 12v @ 5200rpm.

So here goes:

Coolant temp sensor= Good
ECU mivec output=Good
12V to mivec solenoid=Good
Oil Pressure ~90psi=Good
Mivec solenoid-Free=Good
Oil level=Good
Oil sump=Good

Really dunno what again. May have to take it in to check timing(I was only able to see the cam gears,both notches are lined up ok). Not sure about the crank.

Also will have to get the valve clearances checked.

Am I missing anything?

PS I'm wondering if bits of gasket maker could get in there and block up the shafts to the rockers. I'm guessing here :-?